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A high-performance SuperWall: designed for a small residence at Joshua Tree National Park

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A high-performance SuperWall: designed for a small residence at Joshua Tree National Park

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Content Copyright 2023 Archana Janardanan

A High-Performance SuperWall:

Designed for a small residence at Joshua Tree National Park

by

Archana Janardanan

A Thesis Presented to the
FACULTY OF THE USC SCHOOL OF ARCHITECTURE
UNIVERSITY OF SOUTHERN CALIFORNIA

In Partial Fulfillment of the
Requirements for the Degree
MASTER OF BUILDING SCIENCE

May 2023

ii

ACKNOWLEDGEMENTS

I am deeply grateful to all the individuals who have supported me throughout my master’s program
and made it possible for me to complete the research.
First and foremost, I would like to express my profound gratitude to my Chair, Professor Douglas
Noble, for believing in me and for being a constant source of encouragement, guidance, and
inspiration.
I would like to thank Professor Karen Kensek for her willingness to share her knowledge, patience,
and constructive feedback.
I would also like to thank Professor Sanjeev Tankha and Professor Gideon Susman for all the
technical and analytical support, for without them, it would be impossible for me to complete this
thesis.
I would like to acknowledge the efforts of my teammates, Aditya Bahl and Yuqing He, who have
provided me with valuable insights and constructive feedback that have been instrumental in
shaping my research.
I would also like to thank my family and friends for their unwavering belief in me. Their love,
support, and understanding have been my biggest source of strength and motivation throughout
this journey.
In conclusion it is with deep humility and gratitude that I acknowledge the immense contributions
of these individuals who have played a critical role in my academic journey. Their guidance and
encouragement has turned my thesis dream into reality.

Committee Chair: Committee No.2:
Professor Douglas E. Noble Professor Karen M. Kensek
Ph.D. FAIA LEED BD+C, DPACSA
Associate Dean for Academic Affairs Professor of Practice
USC, School of Architecture USC, School of Architecture
Email: dnoble@usc.edu Email: kensek@usc.edu

Committee No.3: Software Advisor:
Professor Sanjeev Tankha Dr. Gideon Susman
AIA EngD, LEED AP BD+C
Lecturer Lecturer
USC, School of Architecture USC, School of Architecture
Email: st_051@usc.edu Email: gsusman@usc.edu

iii
TABLE OF CONTENTS
ACKNOWLEDGEMENTS..............................................................................................................ii
TABLE OF CONTENTS.................................................................................................................iii
LIST OF TABLES .......................................................................................................................... vi
LIST OF FIGURES ..................................................................................................................... ..vii
ABSTRACT ................................................................................................................................. ..xii
CHAPTER 1:INTRODUCTION .................................................................................................... 1
1.1 Background & Context - Joshua Tree National Park .................................................. 1
1.1.1 Location .................................................................................................................... 1
1.1.2 Seasonal Rangers ...................................................................................................... 1
1.1.3 Climate Study............................................................................................................ 1
1.2 Housing Requirement at Joshua Tree National Park ................................................... 5
1.2.1 Small Residences and Prototypes ............................................................................. 6
1.3 Material Study ........................................................................................................... 10
1.3.1 Precast Concrete & Cast – in – Place Concrete ...................................................... 10
1.3.2 Precast in Hot Climates ........................................................................................... 10
1.3.3 Types of Precast Concrete Walls ............................................................................ 11
1.4 Prefabrication ............................................................................................................. 15
1.5 Building Insulation .................................................................................................... 18
1.6 Thermal Comfort ....................................................................................................... 18
1.6.1 Thermal Performance Tools ................................................................................... 19
1.7 Precast Concrete and Thermal Comfort .................................................................... 22
1.7.1 Thermal Mass.......................................................................................................... 22
1.8 Thermal Conductivity and Resistance ....................................................................... 22
1.8.1 Concrete and Thermal Battery ................................................................................ 23
1.9 Summary .................................................................................................................... 24
CHAPTER 2:LITERATURE REVIEW ....................................................................................... 25
2.1 Unique Architecture of Joshua Tree National Park ................................................... 25
2.1.1 High Desert House by Kendrick Bangs Kellogg .................................................... 25
2.1.2 Seasonal Pavilions by Arata Isozaki ....................................................................... 25
2.1.3 Folly by Cohesion Studio........................................................................................ 26
2.1.4 Joshua Tree Residence by James Whitaker ............................................................ 26
2.2 Tiny Homes and their advantages .............................................................................. 27
iv

2.2.1 Resource Consumption ........................................................................................... 27
2.3 Prefabrication and its benefits ................................................................................... 29
2.4 Influence of orientation on solar heat gain ................................................................ 29
2.5 Passive Solar Energy Use in Buildings ..................................................................... 30
2.5.1 Thermal storage walls ............................................................................................. 30
2.5.2 Building heat transfer .............................................................................................. 32
2.6 Thermal Comfort and evaluation methods ................................................................ 34
2.6.1 Predicted Mean Vote (PMV) .................................................................................. 34
2.6.2 Predicted Percentage Dissatisfied (PPD) ................................................................ 35
2.7 Summary .................................................................................................................... 35
CHAPTER 3:RESEARCH METHODOLOGY ........................................................................... 36
3.1 General Data Collection as a team ............................................................................. 36
3.1.1 Site & Orientation ................................................................................................... 37
3.1.2 Design Development ............................................................................................... 39
Standard California Truck Information ........................................................................................ 39
Weight calculations of small residence ............................................................................. 40
Structure ............................................................................................................................ 41
3.1.3 Material Study ......................................................................................................... 41
3.1.4 Mold & Prefabrication ............................................................................................ 43
3.1.5 Code Compliance .................................................................................................... 44
3.2 General Data Collection Individually (South Wall) .................................................. 45
3.2.1 Design ..................................................................................................................... 46
3.2.2 Details & Connections ............................................................................................ 46
3.2.3 Insulation Design .................................................................................................... 46
3.3 Thermal Study ........................................................................................................... 47
3.4 Details ........................................................................................................................ 48
3.5 Summary .................................................................................................................... 48
CHAPTER 4:SIMULATIONS & RESULTS ............................................................................... 49
4.1 Thermal Mass Studies ................................................................................................ 49
4.1.1 Honeybee Energy: Inputs and workflow for low thermal mass wall – wood-frame
building ............................................................................................................................. 50
4.1.2 Honeybee Energy: Inputs and workflow for high thermal mass wall – concrete ... 52
4.1.3 IESVE: Inputs and workflow for low thermal mass wall – wood-frame ............... 53
4.1.4 IESVE: Inputs and workflow for high thermal mass wall – concrete .................... 55
4.2 Thermal Comfort Study ............................................................................................. 57
4.2.1 IESVE – Thermal Comfort Study – Various base case models.............................. 57
4.2.2 Honeybee Energy: Thermal Comfort Study – Varying wall thickness .................. 62
4.2.3 IESVE: Thermal Comfort Study – Varying Wall Thickness .................................. 65
4.3 Thermal comfort – Insulation Studies ....................................................................... 68
v

4.3.1 Thermal Comfort Study – without insulation ......................................................... 69
4.3.2 Thermal comfort Study – with permanent insulation ............................................. 70
4.3.3 Thermal comfort Study – with dynamic insulation ................................................ 72
4.4 Details ........................................................................................................................ 82
4.5 Summary .................................................................................................................... 86
CHAPTER 5:DATA CONSOLIDATION FOR BASE MODEL OF POCKET LODGE ........... 88
5.1 Final Iteration Collected as a Team ........................................................................... 89
5.1.1 South wall ............................................................................................................... 89
5.1.2 North wall – Information as collected from team member: Yuqing He ................. 90
5.1.3 Roof – Information as collected from team member: Aditya A. Bahl .................... 91
5.2 Thermal comfort/Ventilation ..................................................................................... 91
5.3 Prototype Details ....................................................................................................... 92
5.4 Prototype Mold Design .............................................................................................. 94
5.5 Dynamic Insulation Movement ................................................................................. 94
5.6 Summary .................................................................................................................... 96
CHAPTER 6:BUILDING SIMULATIONS FOR POCKET LODGE ......................................... 97
6.1 Base case Overall Model ........................................................................................... 98
6.1.1 Material Properties .................................................................................................. 99
6.1.2 Thermal Comfort/Ventilation ............................................................................... 104
6.1.3 Dynamic Insulation Movement ............................................................................. 105
6.2 Proposed Overall Model .......................................................................................... 112
6.2.1 Material Properties ................................................................................................ 112
6.2.2 Thermal Comfort/Ventilation ............................................................................... 115
6.2.3 Dynamic Insulation Movement ............................................................................. 116
6.3 Summary .................................................................................................................. 123
CHAPTER 7:CONCLUSIONS AND FUTURE WORK ........................................................... 125
7.1 Overall Description .................................................................................................. 125
7.1.1 Background and data collection ............................................................................ 125
7.1.2 Research methodology and results........................................................................ 125
7.1.3 Results and comparison ........................................................................................ 129
7.2 Improvements and Future Work .............................................................................. 135
7.2.1 Improvements ........................................................................................................ 135
7.2.2 Future Work ........................................................................................................... 136
7.3 Summary .................................................................................................................. 137
BIBLIOGRAPHY ....................................................................................................................... 139
APPENDIX A ............................................................................................................................. 146

vi

LIST OF TABLES

Table 3-1: Summary of California Truck Weight Limits for Vehicles in Regular Operations .... 39
Table 3-2: Weight calculation matrix ........................................................................................... 40
Table 4-1: Winter monthly temperatures at Joshua Tree National Park ....................................... 74
Table 4-2: Spring monthly temperatures at Joshua Tree National Park ....................................... 75
Table 4-3: Summer monthly temperatures at Joshua Tree National Park .................................... 75
Table 4-4: Fall monthly temperatures at Joshua Tree National Park ............................................ 76
Table 5-1: Best test results of south wall. ..................................................................................... 89
Table 5-2: Best test results of north wall. ..................................................................................... 90
Table 5-3: Best test results of roof ................................................................................................ 91
Table 6-1: Winter monthly temperatures at Joshua Tree National Park ..................................... 117
Table 6-2: Spring monthly temperatures at Joshua Tree National Park ..................................... 117
Table 6-3: Summer monthly temperatures at Joshua Tree National Park .................................. 118
Table 6-4: Fall monthly temperatures at Joshua Tree National Park .......................................... 118
Table 7-1: Summary of four studies air temperature interior space results ................................ 135

vii

LIST OF FIGURES

Figure 1-1: Average hourly temperature, color coded into bands .................................................. 2
Figure 1-2 The percentage of days in which various types of precipitation are observed. ............. 3
Figure 1-3: The number of hours during which the Sun is visible ................................................. 3
Figure 1-4: The percentage of time spent at various humidity comfort levels, categorized
by dew point. ................................................................................................................................... 4
Figure 1-5: The average of mean hourly wind speeds ................................................................... 4
Figure 1-6: The average daily shortwave solar energy reaching the ground per square meter ..... 5
Figure 1-7: A real-life Tiny House on Wheels ............................................................................... 6
Figure 1-8: A backyard wooden garden house ............................................................................... 7
Figure 1-9: Shipping container home with modified portico elements .......................................... 8
Figure 1-10: A mobile RV parked in the woods.. ........................................................................... 9
Figure 1-11: Couple of Skoolies seen with an added overhead storage area. ................................. 9
Figure 1-12: View of a forest cabin .............................................................................................. 10
Figure 1-13: Calculating R-value with the addition of insulation and/more layers ...................... 11
Figure 1-14: Three basic types of precast concrete walls ............................................................. 12
Figure 1-15: Solid precast concrete wall ...................................................................................... 12
Figure 1-16: Precast concrete sandwich wall ................................................................................ 13
Figure 1-17: GFRC spraying process ........................................................................................... 14
Figure 1-18: Lite walls used in a parking garage. ......................................................................... 15
Figure 1-19: Palais de l’Assemblée. Chandigarh, India ............................................................... 16
Figure 1-20: Sydney Opera House, Sydney, Australia ................................................................. 16
Figure 1-21: Jubilee Church, Rome Italy ...................................................................................... 17
Figure 1-22: Ospedale Giovanni XXIII Chapel, Italy .................................................................. 17
Figure 1-23: Workflow for IESVE energy modeling ................................................................... 20
Figure 1-24: Overview of Honeybee energy modeling workflow ................................................ 21
Figure 1-25: Image explaining the concept of thermal mass ........................................................ 22
Figure 1-26: Left to right – Expanded polystyrene, extruded polystyrene, and
polyisocyanurate used in buildings for insulation ........................................................................ 23
Figure 2-1: View of the High Desert House ................................................................................. 25
Figure 2-2: Clockwise – Units showing concrete and glass ......................................................... 26
Figure 2-3: Images of the steel cabins – right image shows the opening on the roof
for star gazing ............................................................................................................................... 26
Figure 2-4: View of Joshua Tree Residence ................................................................................. 27
Figure 2-5: The floor area of new homes is going up although family size is going down.
Data from the U.S.Bureau of the Census and the National Association of Home Builders ......... 28
Figure 2-6: Comparative annual energy use for small versus large houses .................................. 28
Figure 2-7: Earth’s rotation and sun position ............................................................................... 30
Figure 2-8: Thermal storage wall (Trombe) ................................................................................. 31
Figure 2-9: Effect of temperature fluctuations in comparison to the wall thickness. ................... 31
Figure 2-10: Multilayer wall heat transfer .................................................................................... 33
Figure 2-11: An example of the PPD rating from the PMV index ............................................... 35
Figure 3-1: Research Methodology .............................................................................................. 36
Figure 3-2: Methodology diagram focusing on chapter 3. ........................................................... 37
viii

Figure 3-3: Unit orientation and surfaces ..................................................................................... 38
Figure 3-4: Critical overhang locations ........................................................................................ 38
Figure 3-5: Trailer standard dimension ......................................................................................... 39
Figure 3-6: Structural design of the unit ....................................................................................... 41
Figure 3-7: Mold inner and outer dimensions............................................................................... 43
Figure 3-8: Snippets from California Residential Codes .............................................................. 44
Figure 3-9: Snippets of single-family standard building design code .......................................... 45
Figure 3-10: Female and male sides of panels in the tube. ........................................................... 46
Figure 3-11: Diagrammatic representation of the dynamic external and internal insulation ....... 47
Figure 3-12: IES VE workflow ..................................................................................................... 48
Figure 4-1: Methodology diagram focusing on chapter 4. ........................................................... 49
Figure 4-2: Script for low thermal mass surface temperature analysis (see Appendix A) ........... 50
Figure 4-3: Wood-frame wall surface inside and outside temperature readings .......................... 51
Figure 4-4: Script for high thermal mass surface temperature analysis (see Appendix A) .......... 52
Figure 4-5: Concrete surface inside and outside temperature readings ........................................ 53
Figure 4-6: Twentynine Palms location fed into the IESVE model ............................................. 54
Figure 4-7: Base model of the pocket lodge ................................................................................. 54
Figure 4-8: Wood-frame wall surface’s inside and outside temperatures .................................... 55
Figure 4-9: Twentynine Palms location fed into the IESVE model ............................................. 56
Figure 4-10: Concrete wall surface’s inside and outside temperatures ........................................ 57
Figure 4-11: Base case model 01 Interior and Dry Bulb Temperature. ........................................ 58
Figure 4-12: Base case model 02 Interior and Dry Bulb Temperature. ........................................ 58
Figure 4-13: Base case model 03 Interior and Dry Bulb Temperature. ........................................ 59
Figure 4-14: Base case model 04 Interior and Dry Bulb Temperature. ........................................ 60
Figure 4-15: Base case model 05 Interior and Dry Bulb Temperature. ........................................ 60
Figure 4-16: Base case model 06 Interior and Dry Bulb Temperature. ........................................ 61
Figure 4-17: Tiny house thermal study script (see Appendix A).................................................. 62
Figure 4-18: Zone operative temperature (105F) with south wall thickness of 4” ....................... 63
Figure 4-19: Zone operative temperature (101F) with south wall thickness of 6” ....................... 64
Figure 4-20: Zone operative temperature (98F) with south wall thickness of 84” ....................... 64
Figure 4-21: Zone operative temperature (87F) with south wall thickness of 12” ....................... 65
Figure 4-22: Twentynine Palms location fed into the IESVE model. .......................................... 66
Figure 4-23: Interior Space Operative Temperature across 3 iterations on 15
th
August. ............. 67
Figure 4-24: The pocket lodge with the buffer zones and vertical fins added. ............................. 69
Figure 4-25: Yearly temperatures and a day temperature of 15
th
August ..................................... 70
Figure 4-26: Yearly temperatures and a day temperature of 15
th
August ..................................... 71
Figure 4-27: Comparative operative temperature graph between no insulation and
permanent insulation ..................................................................................................................... 71
Figure 4-28: The pocket lodge with the buffer zones, vertical fins, and the inside
and outside insulation zones added. .............................................................................................. 72
Figure 4-29: East and west window Macroflo profile .................................................................. 73
Figure 4-30: Exterior insulation open close profile – Fall months. .............................................. 77
Figure 4-31: Exterior insulation open close profile – Spring months. ......................................... 77
Figure 4-32: Exterior insulation open close profile – Summer months. ....................................... 78
Figure 4-33: Exterior insulation open close profile – Winter months. ......................................... 78
Figure 4-34: Interior insulation open close profile – Fall months. ............................................... 79
ix

Figure 4-35: Interior insulation open close profile – Spring months. ........................................... 79
Figure 4-36: Interior insulation open close profile – Summer months. ........................................ 80
Figure 4-37: Interior insulation open close profile – Winter months. .......................................... 80
Figure 4-38: Yearly operative zone temperature after proposing dynamic insulation on
south wall. ..................................................................................................................................... 81
Figure 4-39: Highest and lowest operative temperature in a year. ............................................... 81
Figure 4-40: Number of hours within a certain temperature range. ............................................. 81
Figure 4-41: Timetable plot from Climate Consultant ................................................................. 82
Figure 4-42: Dry bulb temperatures plot on sun path diagram. .................................................... 83
Figure 4-43: Shading calculator showing the overall red and cyan plots with probable
vertical degrees for best shading. .................................................................................................. 83
Figure 4-44: Angle and length of insulation cantilever ................................................................ 84
Figure 4-45: Design of the 6 feet cantilever exterior insulation panel. ........................................ 84
Figure 4-46: Design of the exterior insulation. ............................................................................. 85
Figure 4-47: Option 1 – Vertical opening of the louvers. ............................................................. 85
Figure 4-48: Option 2 – Sliding of the louvers. ............................................................................ 86
Figure 5-1:Methodology diagram focusing on chapter 5. ............................................................ 88
Figure 5-2: Exploded isometric representation of the overall pocket lodge and each team
member’s focus ............................................................................................................................. 89
Figure 5-3: South wall outside and inside dynamic insulation operating profiles ........................ 90
Figure 5-4: North wall outside dynamic insulation operating profiles ......................................... 90
Figure 5-5: Roof inside dynamic insulation operating profiles .................................................... 91
Figure 5-6: East and west window Macroflo profile .................................................................... 92
Figure 5-7: Angle and length of insulation cantilever. ................................................................. 92
Figure 5-8: Design of the exterior insulation and it’s working. .................................................... 93
Figure 5-9: Option 1 – Vertical opening of the louvers. ............................................................... 93
Figure 5-10: Option 2 – Sliding of the louvers. ............................................................................ 93
Figure 5-11: Mould inner and outer dimensions. .......................................................................... 94
Figure 5-12: All individual components’ interior and exterior insulation panels. ........................ 95
Figure 5-13: Combined seasonal dynamic insulation profiles. ..................................................... 95
Figure 5-14: Seasonal dynamic insulation profile of the south external insulation panel. ........... 95
Figure 6-1: Methodology diagram focusing on chapter 6. ........................................................... 97
Figure 6-2: Individual team member components added to the overall model. ........................... 98
Figure 6-3: Construction database of base case roof. ................................................................... 99
Figure 6-4: Construction database of the base case interior roof insulation ................................. 99
Figure 6-5: Construction database of the base case floor ........................................................... 100
Figure 6-6: Construction database of the base case east and west walls .................................... 100
Figure 6-7: Construction database of the base case east west windows ..................................... 101
Figure 6-8: Construction database of the base case south wall .................................................. 101
Figure 6-9: Construction database of the base case south wall exterior insulation .................... 102
Figure 6-10: Construction database of the base case south wall interior insulation ................... 102
Figure 6-11: Construction database of the base case north wall ................................................. 103
Figure 6-12: Construction database of the base case north wall exterior insulation .................. 103
Figure 6-13: Construction database of the base case north wall interior insulation ................... 104
Figure 6-14: East and west window Macroflo profile ................................................................ 105
Figure 6-15: Exterior insulation open close profile – Fall and Spring months. .......................... 105
x

Figure 6-16: Exterior insulation open close profile – Summer and Winter months. .................. 106
Figure 6-17: Exterior insulation set to an annual profile. ........................................................... 106
Figure 6-18: Interior insulation open close profile – Fall and Spring months. ........................... 107
Figure 6-19: Interior insulation open close profile – Summer and Winter months. ................... 107
Figure 6-20: Interior insulation set to an annual profile. ............................................................ 107
Figure 6-21: North Team member exterior insulation open profile. .......................................... 108
Figure 6-22: North team member exterior insulation annual profile. ......................................... 108
Figure 6-23: North team member interior insulation open profile. ............................................ 109
Figure 6-24: North team member interior insulation annual profile. .......................................... 109
Figure 6-25: Roof team member interior insulation open profile ............................................... 110
Figure 6-26: Roof team member interior insulation annual profile. ........................................... 110
Figure 6-27: Base case – Comparison of the dry bulb temperature against the operative
temperature output. ..................................................................................................................... 111
Figure 6-28: Base case: Lowest and highest temperatures ......................................................... 111
Figure 6-29: Number of hours within the thermal comfort range. ............................................. 112
Figure 6-30: Construction database of proposed roof................................................................. 113
Figure 6-31: Construction database of proposed floor. .............................................................. 113
Figure 6-32: Construction database of proposed east west walls. .............................................. 114
Figure 6-33: Construction database of proposed south wall. ...................................................... 114
Figure 6-34: Construction database of proposed north wall. ...................................................... 115
Figure 6-35: East and west window Macroflo profile ................................................................ 116
Figure 6-36: North wall external insulation: Fall and Spring months. ....................................... 119
Figure 6-37: North wall external insulation: Summer and Winter months ................................ 119
Figure 6-38: North wall internal insulation: Fall and Spring months. ........................................ 120
Figure 6-39: North wall internal insulation: Summer and Winter months. ................................ 120
Figure 6-40: Roof team member interior insulation open profile ............................................... 121
Figure 6-41: Roof team member interior insulation annual profile. ........................................... 121
Figure 6-42: Proposed – Comparison of the dry bulb temperature against the operative
temperature output. ..................................................................................................................... 122
Figure 6-43: Proposed: Lowest and highest temperatures. ......................................................... 122
Figure 6-44: Number of hours within the thermal comfort range. ............................................. 123
Figure 7-1: Research methodology showing work done individually and in group ................... 126
Figure 7-2: Weight calculations for pocket lodge....................................................................... 126
Figure 7-3: Prefabricating pocket lodge in tube forms. .............................................................. 127
Figure 7-4: Overall results of the base case initial iterations ...................................................... 127
Figure 7-5: Thermal mass material comparison. ........................................................................ 127
Figure 7-6: Operative temperature comparison and results with change in wall thickness ........ 128
Figure 7-7: South wall dynamic insulation overall thermal comfort .......................................... 128
Figure 7-8: Base case south wall, north wall, roof overall thermal comfort .............................. 128
Figure 7-9: Proposed south wall, north wall, roof overall thermal comfort ............................... 129
Figure 7-10: Only south wall - Comparison of the dry bulb temperature against the
operative temperature output. ..................................................................................................... 129
Figure 7-11: Only south wall: Lowest and highest temperatures ............................................... 130
Figure 7-12: Number of hours within the thermal comfort range. ............................................. 130
Figure 7-13: Thermal comfort heat map of average operative temperatures .............................. 130
Figure 7-14: Base case - Comparison of the dry bulb temperature against the operative
xi

temperature output. ..................................................................................................................... 131
Figure 7-15: Base case: Lowest and highest temperatures ......................................................... 131
Figure 7-16: Number of hours within the thermal comfort range. ............................................. 132
Figure 7-17: Thermal comfort heat map of average operative temperatures .............................. 132
Figure 7-18:Proposed - Comparison of the dry bulb temperature against the operative
temperature output. ..................................................................................................................... 133
Figure 7-19: Proposed: Lowest and highest temperatures. ......................................................... 133
Figure 7-20: Number of hours within the thermal comfort range. ............................................. 134
Figure 7-21: Thermal comfort heat map of average operative temperatures .............................. 134
Figure 7-22: Graphical representation of the pocket lodge ........................................................ 137

xii

ABSTRACT

One resolution for the severe housing shortage for the seasonal rangers at Joshua Tree National
Park can be providing housing that is modular and has a rapid production process. The housing
that is currently available is outside the national park uses mechanical systems to achieve
comfortable indoor temperatures. Precast concrete is a good candidate material considering its
high thermal mass and exceptional speed of construction. It is possible to design units that are fully
self-supporting by creating a high-performance building enclosure that can regulate the thermal
performance of the residence, and the south-facing wall - the face that receives maximum solar
gain – can be used to achieve internal thermal. The simulation iterations include varying concrete
thickness and exploring various insulating materials, their locations, and thickness. A
dynamic insulating layer is proposed as a strategy for using high diurnal temperature swings like
those at Joshua Tree National Park using the south wall as a thermal battery as the concept where
the concrete wall is pumped up with heat; the exterior and interior insulations are regulated
according to the outside temperatures; and the concrete wall slowly dumps the heat to achieve
thermal comfort inside The dynamic control setting is designed to function considering the outside
temperature. These iterations and simulations are tested and run on Honeybee Energy and IESVE.
The iterations on the south-facing wall show a thickness of 8 inches to be ideal with respect
to thermal calculations and weight restrictions with a dynamic thermal insulating layer with a
controlled setting that switches on and off according to the outdoor temperature for every season.
By adding an insulation layer on the south wall, north wall and on the roof, with a control setting
set to switch on and off according to the seasonal outdoor temperature, the indoor thermal comfort
increased by 29%. The iteration that was considered effective and ideal not only for regulating the
indoor temperature but also increase the indoor thermal comfort by 40% was by adding the
dynamic interior and exterior insulation with a seasonal control setting to the south wall alone.
This dynamic thermal insulation system with an 8” thick concrete wall can reduce the average
indoor temperature and help increase the energy savings by 45% in Joshua Tree National Park for
the designed small residence.

Hypothesis:
A residential south facing SuperWall can be designed to help achieve comfortable internal thermal
conditions in a desert climate at Joshua Tree National Park by using dynamic insulation panels.

KEYWORDS: precast concrete, dynamic insulation, thermal comfort, hot-arid climate, Joshua
Tree National Park

Research Objectives

• Design a small, precast concrete residence for seasonal rangers at Joshua Tree National
Park to help with the housing crisis.
• Design a south facing wall with precast concrete that utilizes the concepts of thermal
battery and dynamic insulation to achieve year-round internal thermal comfort.
• Prefabricate the residence in a way that transportation and assembly of the unit at the site
is easy and less labor intensive.
1

CHAPTER 1: INTRODUCTION

This chapter describes the background and context of Joshua Tree National Park, the housing
requirements in Joshua Tree National Park, material study, prefabrication, building insulation,
thermal comfort, precast concrete and thermal comfort, and thermal conductivity and resistance.

1.1 Background & Context - Joshua Tree National Park
This section describes the location context, seasonal rangers, and the climate of Joshua Tree
National Park. This study will be important to frame a baseline case and study the problems that
need to be addressed.

1.1.1 Location
Joshua Tree National Park is in south-eastern California and was established on October 31
st
, 1994.
It has an area of 795,156, acres and it has around 2.8 million annual visitors. Currently there are
four visitor centers at the park – Joshua Tree, Oasis of Mara, Cottonwood, and Black Rock. Joshua
Tree National Park has two categories of vegetation, a creosote bush potential vegetation type with
desert shrubland potential vegetation form in most of the area and juniper/pinyon pine (Wikipedia,
Date Accessed 11/09/2022).

There are three ways visitors can enter the park by car: from Yucca Valley in the west, Twentynine
Palms in the north, and Cottonwood Springs in the south. Outside the park sits the main Visitor
Center, in the nearby town of Joshua Tree (National Geographic, Date Accessed 11/09/2022).

1.1.2 Seasonal Rangers
Seasonal rangers are one of the most highly coveted seasonal positions in the National Park
Service. Seasonal rangers are typically employed for only a few months of the year, typically at
the peak visitor season. In many USA national parks, the peak season for visitors is in the summer
when schools are closed. In Joshua Tree National Park, however, the summers are far too hot, and
the peak visitation person is from about October through June. Seasonal rangers are hired for this
period to help with the dramatically increased visitor counts. The rangers usually protect and
improve park resources, interact, and educate park visitors, assist them, and help in providing
interpretive services for visitors regarding natural or cultural resources within the park. There are
around 100 full time employees at Joshua Tree National Park, out of which around 30 are seasonal
rangers (Seasonal Ranger Employment, Date Accessed 11/09/2022).

1.1.3 Climate Study
According to the Köppen climate classification system, Joshua Tree National Park has a hot desert
climate (Wikipedia, Date Accessed 11/09/2022). Joshua Tree is becoming hotter and drier due to
climate change. This increase in hot and dry climate conditions is leading to more
wildfires.(Wikipedia, Date Accessed 11/09/2022). Summers are sweltering, the winters are cold,
and it is dry and mostly clear year-round. The temperature – over the course of the year – varies
from 35°F to 99°F and is rarely below 28°F or above 105°F. The hot season lasts for 3.4 months,
from June 5 to September 18, with an average daily high temperature above 91°F. The hottest
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month of the year in Joshua Tree is July, with an average high of 99°F and low of 73°F. The cool
season lasts for 3.2 months, from November 20 to February 26, with an average daily high
temperature below 66°F. The coldest month of the year in Joshua Tree is December, with an
average low of 36°F and high of 59°F (Fig 1-1) (Weather Spark, Date Accessed 11/09/2022).

Figure 1-1: Average hourly temperature, color coded into bands. (Weather Spark, Date Accessed 11/09/2022)

Precipitation
Joshua Tree National Park is a very dry place. Joshua Tree National Park receives about four inches
of rain annually, but precipitation can occur in large amounts over short periods (Weather Spark,
Date Accessed 11/09/2022). Joshua Tree doesn’t expect lot of monsoons, but there are some
months when there can be a lot of rainfall. The wet season lasts 7.9 months, from July 27 to March
23, with a greater than 6% chance of a given day being a wet day. The month with the most wet
days in Joshua Tree is February, with an average of 3.0 days with at least 0.04 inches of
precipitation. The drier season lasts 4.1 months, from March 23 to July 27. The month with the
fewest wet days in Joshua Tree is June, with an average of 0.3 days with at least 0.04 inches of
precipitation. The month with the most days of rain alone in Joshua Tree is February, with an
average of 3.0 days. Based on this categorization, the most common form of precipitation
throughout the year is rain alone, with a peak probability of 12% on February 21 (Fig 1-
2) (Weather Spark, Date Accessed 11/09/2022).

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Figure 1-2 The percentage of days in which various types of precipitation are observed. (Weather Spark, 2022)

Sun
The length of the day in Joshua Tree varies drastically over the course of the year. In 2022, the
shortest day was December 21, with 9 hours, 53 minutes of daylight; the longest day was June 21,
with 14 hours, 26 minutes of daylight (Fig 1-3) (Weather Spark, Date Accessed 11/09/2022).

Figure 1-3: The number of hours during which the Sun is visible (Weather Spark, Date Accessed 11/09/2022)

Humidity
The humidity at Joshua Tree National Park is very low. The humidity comfort level is calculated
on the dew point as it tells whether the perspiration will evaporate from the skin, which will leave
a cooling effect on the human body. Over the course of the year does not vary significantly staying
within 2% throughout (Fig 1-4) (Weather Spark, Date Accessed 11/09/2022).

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Figure 1-4: The percentage of time spent at various humidity comfort levels, categorized by dew point.(Weather Spark, Date
Accessed 11/09/2022)

Wind
It is usually windy in the late afternoons at Joshua Tree National Park; this is also a characteristic
of a desert. The windier part of the year lasts for 4.0 months, from March 10 to July 9, with average
wind speeds of more than 7.9 miles per hour. The windiest month of the year in Joshua Tree is
April, with an average hourly wind speed of 9.1 miles per hour. The less windy time of year lasts
for 8.0 months, from July 9 to March 10 (Weather Spark, Date Accessed 11/09/2022). The month
with the least wind in Joshua Tree is August, with an average hourly wind speed of 6.8 miles per
hour. The predominant wind direction at Joshua Tree is usually from the west for 9.1 months, from
February 7 to November 11, with a peak percentage of 66% on June 17. For around 2.9 months,
the wind is from the north from November 11 to February 7, with a peak percentage of 51% on
January 1 (Fig 1-5) (Weather Spark, Date Accessed 11/09/2022).

Figure 1-5: The average of mean hourly wind speeds (Weather Spark, Date Accessed 11/09/2022)
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Solar Energy
There is high solar energy potential in Joshua Tree National Park as there is very little cloud
coverage and little precipitation. Therefore, most days it is sunny, even during winter (Weather
Spark, Date Accessed 11/09/2022). The average daily incident shortwave solar energy varies
seasonally over the course of the year. April 22 to August 2 is considered the brighter period of
the year, with an average daily incident shortwave energy per square meter above 7.6 kWh. The
sunniest month is June, and it has an average of 8.7 kWh. The months that don’t receive as much
solar energy are from November 5 to February 10, with an average daily incident shortwave energy
per square meter below 4.3 kWh. The darkest, however, is December, with an average of 3.2 kWh
(Fig 1-6) (Weather Spark, Date Accessed 11/09/2022).

Figure 1-6: The average daily shortwave solar energy reaching the ground per square meter. (Weather Spark, Date Accessed
11/09/2022)

1.2 Housing Requirement at Joshua Tree National Park
Many people visit Joshua Tree National Park (Visit California, Date Accessed 11/18/2022). People
visit year-round, and a new National Park Service (NPS) report finds that around 3 million visitors
are seen to visit Joshua Tree National Park (U.S. National Park Service, Date Accessed
11/09/2022). More visitors mean more rangers are required, and thus there is a need for increased
housing for rangers. One reason to make these units is that housing is not easily available in the 3
cities that are adjacent to the park, namely Yucca Valley, Joshua Tree, and Twentynine Palms.
Housing created specifically only for the rangers could also be located close to the park or even
inside the park. The National Park Service is looking to build homes for the rangers who will
typically stay at the park for around 4-6 months. Since the duration of their time and service at the
park is short, and these rangers have few possessions with them, the type of housing proposed is a
“tiny house.”

The design brief is to propose 12 small residences for the rangers within or adjacent to Joshua Tree
National Park. The idea is to prefabricate the precast concrete panels at a concrete facility and have
them transported to the project site. The reasons for doing this is because, the design and planning
of all 12 homes are going to be similar; climate at Joshua Tree National Park is not comfortable
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for construction workers - this will keep the National Park undisturbed with the large construction
area; and quality control is better in a factory than at a jobsite (SUB Construction Date Accessed
11/09/2022). In the sections below, a few prototypes of small residences are discussed.

1.2.1 Small Residences and Prototypes
The term "tiny home" refers to smaller transportable dwellings that are approximately the
dimensions of one room - 8 feet wide by 10-20 feet long (Anson, 2014). The tiny house movement
is an architectural and social movement that encouraged downsizing of living spaces, simplifying,
and essentially “living with less” (Tiny House Movement, Date Accessed 11/09/2022). Tiny
houses are a potential eco-friendly solution to the existing housing industry and are could also be
used for people who do not have a permanent residence. A small residence could be beneficial for
the seasonal rangers as it will help them have a shelter during the time when they are physically
present in the national park. These small residences can also have a smaller carbon footprint than
a larger building. The main reason for building tiny homes at Joshua Tree National Park is to
provide energy efficient, sustainable, housing for seasonal rangers who are only going to be around
for a few months.

1.2.1.1 Prototypes of Small Residences
This section will discuss the commonly seen tiny houses, their areas, and how they are used
generally by the people.

• Tiny House on Wheels (THOW)

The most generalized form of a tiny house is usually on wheels. A THOW allows tiny dwellers to
move about or park in and live permanently. There are as many different types as possible and
styles of THOWs. They offer everything a traditional home would, just in a much smaller package.
THOWs can be as small as 100 square feet and are usually towable by powerful truck (Fig 1-7)
(Davidson, Date Accessed 11/09/2022).

Figure 1-7: A real-life Tiny House on Wheels (Davidson Josh, Date Accessed 11/09/2022
7

• Tiny House Accessory Dwelling Units (ADUs)

Accessory Dwelling Units (ADUs) are permanently built onto a foundation, and most of them are
used as a secondary home on a lot that already has a primary home. They are comparatively
expensive as they are a unit that has all the grid connections already available and do not require
a trailer to function (Accessory Dwelling Units, Date Accessed 11/09/2022). ADUs are very
popular in cities with high housing costs. Los Angeles, San Francisco, and other expensive for
housing cities have seen a growth in ADU construction over the past few years (Fig 1-8)
(Davidson, Date Accessed 11/09/2022).

Figure 1-8: A backyard wooden garden house (Davidson Josh, Date Accessed 11/09/2022).
• Container Homes

Container homes use shipping containers as the shell for the house. They aren’t too expensive and
are available everywhere and are predesigned to be weather tight and highly resistant to damage.
A single 40-foot standard container offers around 285 sq ft of usable space – which is usually the
dimension of a standard container (IContainer, Date Accessed 11/09/2022). This can be expanded
by connecting more such containers together. Because of the shape of the container, running the
electrical and plumbing fixtures are very easy. Container homes are best known for their
modularity, ease of shipping, and now there are a lot of ready-to-move-in homes that can be easily
bought (Fig 1-9) (Davidson Josh, Date Accessed 11/09/2022).

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Figure 1-9: Shipping container home with modified portico elements. (Davidson Josh, Date Accessed 11/09/2022)
• RVs / Park Model Homes

Recreational vehicles include everything from as small as pop-up campers all the way to massive
Class A motorcoaches. A Class A motor coach is a bus-like RV that are usually powered by
gasoline or diesel engine and are typically 26 to 45 feet long (THOR Industries, 2022a). For tiny
living, the most common RV types are teardrops, tow-behind travel trailers, and Class C
motorhomes. A Class C motorhome is bus-like but offers more outdoor experiences. They are
usually 24 to 32 feet long (THOR Industries, Date Accessed 11/09/2022). Park model RVs have
exteriors that resemble modern tiny home aesthetics but interiors almost typical to RVs. RVs are
already furnished and include electrical, water, and sewage systems that make them attractive
options for those looking to get moving quickly and affordably. The downside is that most RVs
aren’t designed to be lived in full time. Many of the appliances, fittings, and furniture pieces in
RVs will wear out quickly when subjected to constant use (Fig 1-10) (Davidson Josh, Date
Accessed 11/09/2022).
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Figure 1-10: A mobile RV parked in the woods. (Davidson Josh, Date Accessed 11/09/2022).
• Skoolies

Skoolies are buses, usually school buses, that have been converted into highly mobile living
spaces. They offer similar space to many tiny homes but have their own engine, like an RV. Unlike
an RV, the interior is highly customizable. It is because of the shape and the size of a school bus,
gives more freedom for customization. Skoolies also offer significantly more storage space than a
van or smaller RV. They’re a great option for couples and families or those who want to travel
widely without sacrificing comforts (Fig 1-11) (Davidson Josh, Date Accessed 11/09/2022).

Figure 1-11: Couple of Skoolies seen with an added overhead storage area. (Davidson Josh, Date Accessed 11/09/2022)
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• Cabins / Yurts

One of the oldest and still popular types of tiny homes are cabins and yurts. They can be grid-
connected or off-grid (Fig 1-12) (Davidson Josh, Date Accessed 11/09/2022).

Figure 1-12: View of a forest cabin (Davidson Josh, Date Accessed 11/09/2022)
1.3 Material Study
In this section, precast concrete as a façade material, its various types, prefabrication, thermal
insulation, and thermal comfort will be discussed.

1.3.1 Precast Concrete & Cast – in – Place Concrete
Concrete is an important construction material used extensively in small, medium, or large
constructions. Concrete consists of water, cement, and aggregate (sand, gravel, or rock).

Precast concrete is one of many types of concrete that are used in construction, for example - plain
concrete, high-density concrete, light weight concrete, reinforced concrete, prestressed concrete,
glass reinforced concrete etc. (Gio Valle, Date Accessed 11/09/2022).

The main difference between concrete and precast concrete is its production and transportation.
Precast concrete is “offsite,” and is then delivered to its project destination for final use. While
cast-in-place concrete, as the name suggests, is poured, and cured on the job site itself. (Texas
Disposal Systems, 2022). Precast concrete is produced by casting concrete in a reusable mold or
"form" which is then cured in a controlled environment (Constro Facilitator, Date Accessed
11/09/2022).

1.3.2 Precast in Hot Climates
Studies have shown that precast concrete performs well in hot climates because of its thermal
insulation and thermal mass properties (H. Zhang et al., 2020). The overall mass of a material and
the internal areal heat capacity are necessary to reach the best performances for the envelope
buildings located in a hot climate – properties that concrete has. The results show that it is possible
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to achieve high performance precast walls also with light and ultra-thin solutions (Baglivo &
Congedo, 2015).

Thick concrete walls are usually known to keep the interior cooler in climates that have large
diurnal temperature swings. Concrete walls provide high thermal mass – they can absorb heat
during the day and radiate it out at night. The thermal value of the wall is significantly increased
with the addition of extra framing and insulation materials. These will collectively help achieve
the desired R-value. (Fig 1-13) (U.S. Department of Energy - Solar Decathlon, Date Accessed
11/18/2022).

Figure 1-13: Calculating R-value with the addition of insulation and/more layers (U.S. Department of Energy - Solar Decathlon,
Date Accessed 11/18/2022).
1.3.3 Types of Precast Concrete Walls
Precast concrete walls usually have four variations: solid, sandwich, thin shell, and lite walls (Fig
1-14) (CE Center, Date Accessed 11/18/2022). These can be panelized and erected in either a
horizontal or vertical position, depending on the mold form and the way it is cast and can be used
on all types of structures, from residential to commercial, and institutional to industrial. Wall
panels can be designed as non-loadbearing or loadbearing, carrying floor and roof loads, as well
as lateral loads.

12

Figure 1-14: Three basic types of precast concrete walls (CE Center, Date Accessed 11/18/2022)

1.3.3.1 Solid Walls
Solid wall panels are made from solid concrete. Typically, they do not include integrated
insulation. So additional insulation is added at a later stage and a wall finishing is given for a
cleaner look. These wall panels are cast in a flat orientation therefore the side that is in contact
with the form, called the form side, is typically the side that will be exposed to view in the final
construction as it will have a cleaner and an even finish. This front face can be finished with any
type of finish, and the back face is generally not given a complete finish so it can be completed
with a light broom finish (Fig 1-15) (Precast/Prestressed Concrete Institute, Date Accessed
11/18/2022).

Figure 1-15: Solid precast concrete wall (Precast/Prestressed Concrete Institute, Date Accessed 11/18/2022).

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1.3.3.2 Precast concrete sandwich wall (or insulated double wall) panels
Precast concrete sandwich wall (or insulated double-wall) panels consist of two wythes of
reinforced concrete separated by an interior void, and these are held together with embedded steel
trusses or reinforcements. It has been discovered that using steel trusses create a "thermal bridge"
that degrades thermal performance (Wikipedia, Date Accessed 11/09/2022). To achieve better
thermal performance, insulation is added in the void, and in many structures today the steel trusses
have been replaced by composite (fiberglass, plastic, etc.) connection systems (Precast Concrete -
Wikiwand, Date Accessed 11/09/2022). The best thermal performance is achieved when the
insulation is continuous throughout the wall section, i.e., the wythes are thermally separated
completely to the ends of the panel by this insulation. Using continuous insulation and modern
composite connection systems, R-values up to R-28.2 can be achieved (NCMA, Date Accessed
11/09/2022).

The overall thickness of sandwich wall panels in commercial applications is typically 8 inches, but
nowadays the walls can be customized to suit the construction. In a typical 8-inch wall panel the
concrete wythes are each 2-3/8 inches thick, sandwiching 3-1/4 inches of high R-value insulating
foam (Hynes et al., n.d.). The interior and exterior wythes of concrete are held together (including
the insulation) with some form of connecting system (steel or otherwise) to give the structural
support. Sandwich wall panels can be fabricated to the length and width desired. Panels of 9-foot
clear height are common, but heights up to 12 feet or more can be found. (Fig 1-16) (Hynes et al.,
n.d.)

Figure 1-16: Precast concrete sandwich wall (Precast/Prestressed Concrete Institute, Date Accessed 11/18/2022)

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1.3.3.3 Thin Shell and GFRC
Thin-shell walls consist of a thin outer-wythe of concrete with a thickness of around 1.5 to 3 inches
(CE Center, Date accessed 11/12/2022). This is then connected to a back-up system which us made
of steel framing studs or sometimes even concrete. This then connects to the main structural system
of the building and in the inside, it is usually given a dry wall with interior finishes. Between these
layers and connections, a rigid insulation can be found (CE Center, Date accessed 11/09/2022)

Glass Fiber-Reinforced Concrete (GFRC) is a thin-shell system where the exterior wythe of
concrete contains alkali-resistant glass fibers that is normally sprayed into forms. The fibers
increase tensile, flexural and impact strengths (Fig 1-17) (Precast/Prestressed Concrete Institute,
Date Accessed 11/18/2022).

Figure 1-17: GFRC spraying process (Precast/Prestressed Concrete Institute, 2022)

1.3.3.4 Lite Walls
Light or "lite" walls are shear walls used in parking structures cast with an opening in their center
to provide visual continuity in the parking garages, and to allow daylight to penetrate deeper into
the interior. Lite walls are cast horizontally, with three of the four sides created with a form. These
finishes are very smooth and most often remain "as cast" in the finished construction (Fig 1-18)
(Precast/Prestressed Concrete Institute, Date Accessed 11/18/2022).

15

Figure 1-18: Lite walls used in a parking garage. (Precast/Prestressed Concrete Institute, 2022)

1.4 Prefabrication
Prefabrication term is used where the assembly of various fully finished components are done in a
factory or at other manufacturing sites and these fully assembled units are transported to the site
where it is to be located. The term is used to distinguish this process from the more conventional
construction practice of transporting the basic materials to the construction site where all assembly
is carried out. (Wikipedia, Date Accessed 11/09/2022).

There are various advantages of a prefabricated construction techniques. Construction time savings
in a modular building can go up as much as 50% faster than traditional construction (PlanGrid,
2019). It mitigates labor shortage problem, is cost effective as moving assembled panels is more
economical that moving raw materials. There is lesser fuel consumption as the transportation is
reduced (BuildSteel.Org, Date Accessed 11/09/2022). Prefabricated units are high in quality as
these units are built and monitored in controlled environments (PlanGrid, 2019).

Precast concrete can have a variety of finishes, be used for different scales, can have different
shapes, and are best used for modular shapes. Below are some of the examples, across the globe,
where precast concrete has been used (Fig. 1-19 to 1-22) (Architecture Digest, 2022; Famous
Precast Concrete Buildings, 2023; Histart, 2022)

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Figure 1-19: Palais de l’Assemblée. Chandigarh, India (Histart, Date Accessed 11/18/2022).

Figure 1-20: Sydney Opera House, Sydney, Australia (Famous Precast Concrete Buildings, Date Accessed 03/27/2023)

17

Figure 1-21: Jubilee Church, Rome Italy (Famous Precast Concrete Buildings, Date Accessed 03/27/2023)

Figure 1-22: Ospedale Giovanni XXIII Chapel, Italy (Famous Precast Concrete Buildings, Date Accessed 03/27/2023)

18

1.5 Building Insulation
Building insulation is usually used in a building for thermal management. There are many types
of insulation and insulation materials. Insulation is an important investment in any home because
by installing insulation, buildings use less energy for heating and cooling, and occupants
experience fewer thermal changes even with the change in seasons (Wikipedia, Date Accessed
11/09/2022). Thermal insulation usually refers to the use of appropriate insulation materials and
design adaptations for buildings to slow the transfer of heat from the outside to the inside (or from
the inside to the outside in cold conditions) which helps in reducing heat loss and gain. The transfer
of heat is caused by the temperature difference between indoors and outdoors. Insulation reduces
unwanted heat loss or gain and can decrease the energy demands of heating and cooling systems
(Wikipedia, Date Accessed 11/09/2022).

Insulation refers to the material and this material slows the heat loss/gain into the building. Some
of the commonly used insulation materials are – cellulose, glass wool, rock wool, polystyrene,
urethane foam, wood fiber, plant fiber, animal fiber, etc. (Department of Energy, Date Accessed
11/09/2022).

Most conventional building insulations are permanently installed inside the wall system, but there
are some novel insulation techniques in the industry that employ dynamic/moveable insulation
system – where the insulation material or layer can be moved according to the outside conditions
and indoor temperature requirements (Department of Energy, Date Accessed 11/09/2022).

For an extreme diurnal climate condition like Joshua Tree National Park, a permanently installed
insulation layer may be less effective. The heat needs to be blocked from entering the inside spaces
during the daytime but should be radiated during the night when the temperature gets too cold. In
this case, the wall is working as a thermal battery. A thermal battery (like a Trombe wall) is a
physical structure used for the purpose of storing and releasing thermal energy. Thermal energy is
temporarily stored and is available at one time while released at another time. This may be useful
in summer and hot conditions (Wikipedia, Date Accessed 11/09/2022).

1.6 Thermal Comfort
Thermal comfort has been defined by Hensen as “a state in which there are no driving impulses to
correct the environment by the behavior” (Hensen, 1991). The American Society of Heating,
Refrigerating and Air-Conditioning Engineers (ASHRAE) defined it as “the condition of the mind
in which satisfaction is expressed with the thermal environment” (ASHRAE-55, 2017). The ideal
room temperature in summers is around 75°F to 80.5°F, and in winters from 68.5°F to 75°F (The
National Institute for Occupational Safety and Health, Date Accessed 11/09/2022). Although the
US Department of Energy recommends keeping it as 78°F to save energy (Department of Energy,
Date Accessed 02/08/2023).
Thermal sensations are typically different for different people, even if the environment is the same.
Thermal sensation is considered a very subjective sensation and there is said to be no one right
evaluation (Hensen, 1991). Satisfaction with the thermal environment is a complex subjective
response as it takes several interacting and less tangible variables into consideration, and so many
of these less tangible variations are subjective and often not measured accurately. In other words,
there is no absolute standard for thermal comfort. In general, comfort occurs when body
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temperatures are held within narrow ranges, skin moisture is low, and the physiological effort of
regulation is minimized (Voukelatou et al., 2021). Comfort also depends on behavioral actions
such as altering clothing, altering activity, changing posture or location, changing the thermostat
setting, opening a window, complaining, or leaving a space (Hensen, 1991).

Some of the main environmental factors that affect thermal comfort are air temperature, humidity,
radiation, air movement.

1.6.1 Thermal Performance Tools
Some of the software tools that help in performing thermal comfort analysis are the following:

1. EnergyPlus
EnergyPlus is a whole building energy simulation program that allows users to model both
energy consumption and water use. This is done for heating, cooling, ventilation, lighting
and plug and process loads. EnergyPlus simulations are simultaneous and integrated for all
thermal zone conditions. They can simulate for non-thermal zone conditions as well. One
other feature is the sub-hourly, user definable time steps for interaction between thermal
zones and the environment. (EnergyPlus, Date Accessed 01/27/2023)
Generally, the input processing is done by an input data file (.idf) and an input data
dictionary (.idd). The processing starts only after this is read by the software. And the
output processing (.out) is in text formatted reports, and they can be readily viewed in
spreadsheet programs – or any other similar software (EnergyPlusTM Input Output
Reference, 2021).

2. IES Virtual Environment
IES VE can do whole building energy simulation analysis. It is capable of handling basic
to complex geometries and requires information like the location and weather, construction
assemblies, materials, internal gains, and some baseline thermal input variables so that they
can be assigned collectively to sets of rooms and spaces for thermal calculations. (Building
Energy Modeling Software | IES Virtual Environment, Date Accessed 01/27/2023)

In IES VE, the standard input for starting any project is to prepare a UserModel – the
proposed design, and the standard baseline design. (Fig 1-23) (Overview IESVE, Date
Accessed 02/08/2023) The output is generally in a tabular gorm or in the form of graphs
from the data extracted and reports lot of information like energy use summary, unmet
loads hours. The Analysis Results file can also be obtained in a .XML file (Overview
IESVE, Date Accessed 02/08/2023).

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Figure 1-23: Workflow for IESVE energy modeling (Non-Residential compliance) (Overview IESVE, Date Accessed 02/08/2023)

3. OpenStudio
OpenStudio uses EnergyPlus and Radiance to run whole building energy simulations.
OpenStudio works as a plug in for various software platforms like Sketchup, Ladybug and
allows users to create 3D geometry, manage simulations and workflows, provide a
graphical interface of output files. (OpenStudio, Date Accessed 01/27/2023)

The workflow for OpenStudio is generally setting up the site and weather information,
schedules and construction, loads – space types, thermal zones (if any), and HVAC
systems. The output variables can be in various forms like in tabular form, unmet hours,
and data in graphical representation. Open Studio also provides an SQL file (OpenStudio
Workflow, Date Accessed 02/08/2023).

4. CBE Thermal Comfort Tool for ASHRAE 55
It is a web-based graphical user interface software that is used for thermal comfort
prediction according to the ASHRAE Standard 55. It includes models for conventional
building systems (predicted mean vote) and uses the adaptive comfort model for comfort.
(Standard 55 – Thermal Environmental Conditions for Human Occupancy, Date Accessed
01/27/2023)

The input data require basic method of evaluation such as the PMV method or the Adaptive
method. It requires operative temperature, air speed, relative humidity, metabolic rate, and
clothing level inputs. And the output is in form of charts showing the PMV, PPD levels
and if the overall input setting complies with ASHRAE standard 55-2020.

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5. Honeybee – Ladybug Tools
Honeybee supports detailed daylighting and thermodynamic modeling and is used during
mid and later stages of design. Specifically, it creates, runs, and visualizes the results of
daylight and radiation simulations using Radiance and energy models
using EnergyPlus/OpenStudio. It accomplishes this by linking the Grasshopper/Rhino
CAD environment to these engines. (Ladybug Tools, Date Accessed 01/27/2023)

The Honeybee workflow needs a Rhino model with Grasshopper inputs about the
geometry, and a weather file in the .epw file format. Initial analysis can be done on
Ladybug to generate visual data and for Honeybee, Energy Plus and Open Studio source
code interactions can be integrated. (Fig 1-24) (Honeybee-Overview-GitHub, Date
Accessed 02/08/2023)

Figure 1-24: Overview of Honeybee energy modeling workflow (Honeybee-Overview-GitHub, Date Accessed 02/08/2023)

6. Cove.tool
Cove.tool is an intuitive web-app for energy, daylight, LEED and more. It is an automated
design platform for intelligent building performance. (Cove Tool Help Center, Date
Accessed 01/27/2023)

IESVE and Honeybee Energy will be the two main software used in this research. Both the
tools have OpenStudio and EnergyPlus integrated as a plug in hence comparison of data
between the two software will also be a study that can be done for validation.

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1.7 Precast Concrete and Thermal Comfort
Precast concrete (and concrete in general) can help regulate building temperatures due to to thermal
mass and resistance.

1.7.1 Thermal Mass
Thermal mass is the property that allows a material to absorb, store, and later release a significant
amount of heat. Precast concrete walls act like thermal sponges absorbing heat during the day and
then slowly releasing the heat as temperatures fall at night. As the night air cools the walls, the
stored heat is released into the interiors. This cycle repeats itself each day. When outside
temperatures are fluctuating throughout the day, the thermal mass of concrete also flattens out
temperature changes (Fig 1-25) (National Precast Concrete Association, 2015).

Figure 1-25: Image explaining the concept of thermal mass (National Precast Concrete Association, 2015)
1.8 Thermal Conductivity and Resistance
The thermal conductivity of a material measures how that material absorbs and transmits energy.
It is also defined as the quantity of heat transmitted through a unit thickness of a material, in a
direction normal to a surface of unit area, due to a unit temperature gradient under steady state
conditions (National Precast Concrete Association, 2015). It is measured in SI units by watts per
meter Kelvin and in imperial by British thermal units per hour foot Fahrenheit. Higher thermal
conductivity means faster it will heat up and the faster the heat will spread to the areas with low
heat in that same material. Concrete has a low thermal conductivity which means it takes time to
heat up and its conductivity is around 1 watt per meter Kelvin – which is around 0.8 British thermal
units per hour foot Fahrenheit (National Precast Concrete Association, 2015). Concrete’s low
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thermal conductivity could prove advantageous as the concrete might restrict itself from
overheating the interior spaces.

All materials have a thermal resistance value, which is a measure of that material’s resistance to
conduct heat flow. This measure is expressed with an R value. Precast concrete has low R values
which vary based on the concrete’s density and other factors. For 144 pounds per cubic feet of
concrete, the R value is approximately 0.063 per inch². As concrete density decreases, the R value
increases. If a rigid insulation is added the R value will be around 5 per inch depending on the type
of insulation. (National Precast Concrete Association, 2015)

The R value for precast concrete wall panels with insulation typically varies from R-5 to R-50. The
types of rigid of insulation generally used with precast concrete wall panels and their per inch R
values are the following: (Fig 1-26)
7. EPS – Expanded Polystyrene: R values typically 3.8-to-4.4
8. XPS – Extruded Polystyrene: R values typically around 5
9. Polyisocyanurate: R values typically 6-to-8 (National Precast Concrete Association, 2015)

Figure 1-26: Left to right – Expanded polystyrene, extruded polystyrene, and polyisocyanurate used in buildings for insulation
(Poly Molding, Date Accessed 11/18/2022), (Ramli Sulong et al., 2019).
The table above shows the R-value per inch. The wall in question will be designed with precast
concrete that has an R value of 20 and an insulation material that has an overall R value – like that
of Polystyrene’s R value – between 4 to 50.

1.8.1 Concrete and Thermal Battery
Thermal battery is similar to thermal mass, as it uses the advantage of thermal mass as a concept
to store heat and be used as a battery. Thermal battery means that the material has the ability to
store heat. A well-insulated concrete wall acts as a thermal battery, as once it absorbs heat, it takes
a long time to heat and cool down while regulating the interior temperatures during that time. This
concept is good to reduce energy costs, as the thermal battery of concrete will help keep the indoor
temperatures within the thermal comfort (Smarterhomes.org, Date Accessed 11/18/2022).
In extreme hot climates, thermal mass/battery is known to reduce the room temperature during
mid-day and early afternoon and increase the room temperature late in the afternoon and early
evening hours. (Smarterhomes.org, Date Accessed 11/18/2022)
24

In winter, properly designed thermal mass will absorb the heat from the sunlight on it during the
day. Then, as the air temperature drops, the heat will move from the warmer thermal mass to the
cooler air and other surfaces in the room. In summer, thermal mass inside a dwelling should be
shaded from direct sunlight for the entire day and be exposed to cooling breezes to provide some
cooling on hot days and nights (Smarterhomes.org, Date accessed 11/18/2022).

1.9 Summary
This chapter discussed the background and context of Joshua Tree National Park, the housing
requirements in Joshua Tree National Park, material study, prefabrication, building insulation,
thermal comfort, precast concrete and thermal comfort, and thermal conductivity and resistance.

There is a housing need at Joshua Tree National Park for the seasonal rangers. The seasonal rangers
and peak visiting period are between October to June. Design strategies were studied with respect
to the hot desert climate. Various tiny homes were also studied and from the data collected – an
area in the ballpark of 200 square feet would be comfortable for a tiny house. It is evident that
concrete can perform very well in places with high temperatures, and the way to make the
production faster and error-free is to prefabricate it. Prefabrication also has other benefits such as
less embodied carbon and would be a great reason to use it in the project. The thermal conductivity
of concrete material is a useful study as it proves that concrete can be used as a construction
material in places with high diurnal temperatures and will be beneficial because it will restrict
itself from overheating the interior spaces. And building insulation materials, like Expanded
polystyrene, will help bring the interior spaces further into the thermal comfort zone.

25

CHAPTER 2: LITERATURE REVIEW

This chapter will describe unique architecture of Joshua Tree National Park, tiny homes and their
advantages, prefabrication and its benefits, influence of orientation on solar heat gain, passive solar
energy use in buildings, and thermal comfort and evaluation methods.

2.1 Unique Architecture of Joshua Tree National Park
The desert towns adjacent to Joshua Tree National Park have many residences and have been an
important location for many artists and thinkers for decades. Some of the unique homes that these
people have built are an inspiration to many and represent innovative and sculptural interpretations
of architecture. In this section, few of the architectural spaces that are presently found at Joshua
Tree National Park will be discussed.

2.1.1 High Desert House by Kendrick Bangs Kellogg
This modernist organic architecture is designed by the architect Kendrick Bangs Kellogg. It is
situated on the edge of Joshua Tree National Park and is built on a site overlooking the boulders.

The structure is built with 26 free standing concrete columns, each of which are sunken seven feet
into the bedrock. This is done to ensure stability of the structure. This structure is studied for the
purpose of understanding how concrete is a material can be used in this climate zone (Fig 2-1)
(Ignant Publications, Date Accessed 11/19/2022)

Figure 2-1: View of the High Desert House (Ignant Publications, Date Accessed 11/19/2022)
2.1.2 Seasonal Pavilions by Arata Isozaki
This project is located fifteen kilometers from Joshua Tree National Park. This project also uses
concrete as the material; and openings and the overhangs are strategically placed towards the
direction where more shade will be required. In this project the structures denote different seasons,
26

and the overhangs are also designed as per the shading angle in those seasons. The overhangs are
proposed towards the south side where the sunlight is going to cast year-round. This is an important
study to understand how to orient the tiny house building and towards which sides an overhang
should be provided. (Fig 2-2) (Ignant Publications, Date Accessed 11/19/2022).

Figure 2-2: Clockwise – Units showing concrete and glass (Ignant Publications, Date Accessed 11/19/2022)

2.1.3 Folly by Cohesion Studio
Cohesion Studio has used an abandoned steel cabins to convert it into a stay. Here the design of
the sky gazing space is interesting – which can be integrated in the design of a tiny residence (Fig
2-3) (Ignant Publications, Date Accessed 11/19/2022).

Figure 2-3: Images of the steel cabins – right image shows the opening on the roof for star gazing (Ignant Publications, Date
Accessed 11/19/2022)

2.1.4 Joshua Tree Residence by James Whitaker
The main form this project takes is from the clustered assembly of shipping containers. This is
interesting as the dimensions and the spatial quality of a shipping container can be studied to
27

understand the area planning of the tiny residence (Fig 2-4) (Ignant Publications, Date Accessed
11/19/2022).

Figure 2-4: View of Joshua Tree Residence (Ignant Publications, Date Accessed 11/19/2022)

2.2 Tiny Homes and their advantages
Large homes are generally referred to as non-eco-friendly as with the increase in size, increases
the use of more resources for construction, construction costs, and most importantly the energy
consumption post occupancy. As per data, the living area per family member in single family
house in the United States has increased by a factor of 3 since the 1950s (Wilson & Boehland,
2005). A compact house built to only moderate energy-performance standard uses substantially
less energy for heating and cooling than a large house. (Wilson & Boehland, 2005)

2.2.1 Resource Consumption
According to Gopal Ahluwalia, the director of research at NAHB, the material use per unit area of
floor area does not typically drop as the floor area increases, because larger houses tend to have
taller ceiling and more features, therefore they may consume proportionally more materials.
28

(Wilson & Boehland, 2005). Studies have also been done on the household size and the housing
size for few years and the results show that the average household size in the United States has
dropped steadily from 3.67 members in 1940 to 2.62 in 2002. The average size of new houses
increases from about 1,100 sq ft in the 1940s to 2,340 sq ft in 2002 (Fig 2-5) (Wilson & Boehland,
2005)

Figure 2-5: The floor area of new homes is going up although family size is going down. Data from the U.S.Bureau of the Census
and the National Association of Home Builders (Wilson & Boehland, 2005)

The heating and cooling costs studies show that when the floor area of the house is halved, heating
costs are slightly more than halved, whereas cooling costs are reduced by about a third (Fig 2-6)
(Wilson & Boehland, 2005)

Figure 2-6: Comparative annual energy use for small versus large houses (Wilson & Boehland, 2005)

Overall, a benefit of having a smaller space for residence is that it uses less energy.

29

2.3 Prefabrication and its benefits
Prefabrication is considered as a greener and an environmentally friendly construction option as it
minimizes the bad effects that construction usually has on the environment like waste, noise, dust,
and material use. Studies have shown that conventional construction produces 0.91 ton/m
2
average
waste as compared to prefabrication’s 0.77 ton/m
2
. (Lu et al., 2021).

With benefits such as improved construction process, reduced waste, and environmental effects,
there is also reduced carbon emissions which is a result of all the above benefits. There are studies
done on this and the results show embodied and operational carbon emissions between
prefabricated and traditional base cases varied significantly from 105 to 864 kg CO2/m
2
and from
11 to 76 kg CO2/m
2
respectively (Teng et al., 2018)

Life Cycle Carbon Assessment (LCCa) is an analysis that can be done to study in detail the results
of the embodied and operational carbon in prefabrication construction process. It is evident that
prefabricated buildings in general have lower LCCa, in both embodied and operational carbon
emissions (Arslan et al., 2023; Li et al., 2018). From the examined case studies of prefabricated
buildings there was a reduction seen in the average embodied carbon and it was by 15.6% and the
reduction in operational cardon was by 3.2%. The carbon reduction potential could be even higher
if a significant proportion of the structure is reused at the end of the building's life through
prefabrication (Teng et al., 2018).

2.4 Influence of orientation on solar heat gain
Orientation of a building is important when it comes to efficient energy design. The usual design
strategies are to maximize shading, provide overhangs, increase ventilation and these vary
according to the climatic zone the design is proposed for. In a temperature zone like in Joshua Tree
National Park, the south side usually receives lot of sun because of the movement of the sun.
Therefore, larger part of the south side needs to be protected from the sun when the heat is
unwelcome, and this can be done by adding overhangs. (Fig 2-7) (Solar Orientation, Date Accessed
02/02/2023)
30

Figure 2-7: Earth’s rotation and sun position (Solar Orientation, Date Accessed 02/02/2023)

2.5 Passive Solar Energy Use in Buildings
Passive solar systems are those that collect and utilize solar energy by natural means and do not
use mechanical power to circulate the heat. The thermal energy transfer in and out of the structure,
in and out of the storage medium, and around and through the conditioned space is by natural
means. (Williams, 1979)

Passive solar energy systems are generally classified as follows: (Arizona Solar Center - Passive
Solar Heating & Cooling Manual, Date Accessed 11/09/2022)

1. Direct gain systems
2. Thermal storage walls
3. Thermal storage roofs
4. Attached greenhouses.
5. Connective loops

In this section, thermal storage walls will be discussed in detail.

2.5.1 Thermal storage walls
Thermal storage wall or popularly known as Trombe wall – is a passive solar heating system where
the heat flows from outside to inside by natural means such as radiation, conduction, and
convection. The wall absorbs sunlight or heat energy on the outer face, this heat is then transferred
to the wall through conduction. The conducted heat is then distributed to the interior by radiation
from the inner surface of the wall (Hu et al., 2017). Thermal storage walls also typically use
concrete or other high-mass materials that can store heat (Fig 2-8) (Williams, 1979).

31

Figure 2-8: Thermal storage wall (Trombe) (Williams, 1979)

Trombe walls require a glazing face that faces outwards and towards the sun for maximum winter
solar gain and the thermal mass wall is usually located 4 inches or more directly behind the glass
(Trombe Wall – Wikipedia, Date Accessed 02/02/2023). One important part of the design would
be to consider the thickness. The thickness is dependent on the heat capacity and the thermal
conductivity of the material being used. In general, the thermal conductivity of the wall material
increases as the thickness increases. And the thicker wall will absorb and store more heat that can
be used at night. (Fig 2-9) (Trombe Wall - Wikipedia, Date Accessed 02/02/2023)

Figure 2-9: Effect of temperature fluctuations in comparison to the wall thickness. (Trombe Wall - Wikipedia, Date Accessed
02/02/2023)
Some problems with how Trombe walls currently work is that the thermal storage wall has a U-
value that is relatively low and in cold climates the heat losses on days when there is not enough
heat already are excessive compared to that with standard insulated construction. There are some
solutions looked into this problem and one of them is to introduce an additional cavity on the room
side of the storage wall with the wall on the room side thermally insulated (Page, 1981).
32

Thermal storage walls can work well in hot, dry climates with large daily temperature swings as
the thermal mass wall can take advantage of the heat accumulation during the daytime which can
then be used in the cold nights when the temperature swing happens (Trombe Walls -
GreenBuildingAdvisor, Date Accessed 02/02/2023). Joshua Tree National Park has similar
climatic conditions where a thermal storage wall could work.

2.5.2 Building heat transfer
The design of space-heating or cooling systems for a building requires the determination of the
building thermal resistance. Heat is transferred in building components by all modes: conduction,
convection, and radiation (Kalogirou, 2014). The rate of heat transfer through each building
component can be obtained from:

𝑸 =
(𝑨 ∗ 𝜟𝑻𝒕𝒐𝒕𝒂𝒍 )
𝑹𝒕𝒐𝒕𝒂𝒍 = 𝑼𝑨 ∗ ∆𝑻 𝒕𝒐𝒕𝒂𝒍
Where,

ΔTtotal = total temperature difference between inside and outside air (K);
Rtotal = total thermal resistance across the building element = ⅀Ri (m
2
K/W);
and
A = area of the building element perpendicular to the heat flow direction (m
2
).

We know:
𝑼 =
𝟏 𝑹𝒕𝒐𝒕𝒂𝒍

For conduction heat transfer through a wall element of thickness x (m) and thermal
conductivity k (W/m K), the thermal resistance, based on a unit area, is:

𝑅 =
𝑥 𝑘

The thermal resistance per unit area for convection and radiation heat transfer, with a combined
convection and radiation heat transfer coefficient h (W/m2 K), is:

𝑅 =
1
ℎ

Therefore, the thermal resistance due to conduction through a wall as shown in Fig 2-9 is x/k each
for the number of layers and the thermal resistance at the inside and outside boundaries of the wall
are and 1/hi and 1/ho respectively. Therefore, total thermal resistance is:

𝑅𝑡𝑜𝑡𝑎𝑙 = 𝑅𝑖 + 𝑅𝑤 + 𝑅𝑜 =
1
ℎ𝑖 +
𝑥 1
𝑘 1
+
𝑥 2
𝑘 2
+
𝑥 3
𝑘 3
+
1
ℎ𝑜

or
33

𝑈 =
1
𝑅𝑡𝑜𝑡𝑎𝑙 =
1
𝑅𝑖 + 𝑅𝑤 + 𝑅𝑜
=
1
1
ℎ𝑖 +
𝑥 1
𝑘 1
+
𝑥 2
𝑘 2
+
𝑥 3
𝑘 3
+
1
ℎ𝑜

The values of hi, ho and k can be obtained from handbooks (e.g. ASHRAE, 2005) (Kalogirou,
2014)

Figure 2-10: Multilayer wall heat transfer (Kalogirou, 2014)

For example, consider the following:

The thickness of the concrete wall = 6in (0.15 m)
Thickness of the insulation (ex. Polystyrene) = 2in (0.05m)
Thermal conductivity of concrete = 2.25 W/mK
Thermal conductivity of polystyrene = 0.15 W/mK
Temperature difference = 19C (42C is considered as outside temp and 23C as inside)

Therefore,
𝑅 =
𝑥 𝑘
𝑅𝑐𝑜𝑛𝑐 =
0.15
2.25
= 0.066 𝑚 2. 𝐾 /𝑊
𝑅𝑝𝑜𝑙𝑦 =
0.05
0.15
= 0.33 𝑚 2. 𝐾 /𝑊

Rtotal = 0.066 + 0.33 = 0.396 m
2
.K/W

Therefore,
𝑈 =
1
0.396
= 2.525 𝑊 /𝑚 2𝐾

So,
𝑄 = 2.525 ∗ 0.2 ∗ 19 = 9.595 𝑊𝑎𝑡𝑡

34

2.6 Thermal Comfort and evaluation methods
Human thermal comfort is the state of mind that expresses satisfaction with the surrounding
environment, according to ASHRAE Standard 55. Thermal comfort is described in terms of the
dry-bulb temperatures, relative humidity, and activity levels. These early studies were completed
in the 1970s at Kansas State University by Ole Fanger (Streinu-Cercel et al., 2008).

Thermal comfort in the recent times is being questioned as everyone feels different type of thermal
comfort in the same space and their satisfaction levels are also varied and defined by different sets
of environmental conditions. This could mean the thermal comfort range could be from anywhere
between 70-95%. This is due to the personal and ambient parameters (Enescu, 2017).

Personal parameters include
Clothing insulation: It is the amount of clothing that acts as a form of thermal insulation for the
person. Measured in clo units (1 clo = 155 m
2°
C.W) (Enescu, 2017).
Metabolic heat rate, also known as activity level Ṁ is the net heat generated from the human body
in a given period of time. Measured in met units (1 met = 58.2 W m
−2
) (Enescu, 2017).

Ambient parameters include
Temperature: The temperature of air surrounding the body. Measured in Celsius or degrees
Fahrenheit (°C or °F) (Enescu, 2017).
Air velocity: is the rate of air movement at a given distance over time. If the air velocity goes
above 40 feet/min (that is, 0.2032 m/s), it can produce discomfort (Enescu, 2017).
Relative Humidity: is the ratio between the measured (actual) water vapor pressure in the air and
the maximum quantity of water vapor pressure contained by the air at a known temperature. It is
usually represented in percent (Enescu, 2017).

In this section thermal comfort models and indices will be discussed.

2.6.1 Predicted Mean Vote (PMV)
The PMV index is calculated by using the Fanger comfort equation for human body heat exchange
(S. Zhang & Lin, 2020). The PMV index uses a steady state air-conditioned environment and
cannot predict transient responses (Hoof, 2007). Steady state air-conditioned space means the
temperature inside and outside do not change and the air condition is running constantly (Floris,
2015). The PMV is not recommended for predicting the overall thermal comfort of the occupants
in non-air-conditioned buildings, like naturally ventilated spaces, due to the relatively high
difference between the PMV and thermal comfort analyses (S. Zhang & Lin, 2020).

There are some newer modified indices for PMV which are described in the following paragraphs.

2.6.1.1 Adaptive Predicted Mean Vote (aPMV)
The term Adaptive Predicted Mean Vote (aPMV) describes “the thermal comfort in a warm
environment” and predicts the same optimum operative temperature but uses mean outdoor
temperature as the only input instead of the usual four inputs (clothing insulation, metabolic rate,
relative humidity, and air velocity) required by the analytic PMV method (de Dear, 1998). This
format is usually used for naturally ventilated buildings. Here all types of thermal comfort criteria
35

are adapted, which include the thermal comfort criteria from the traditional PMV method and
dynamic characteristics of thermal adaptations (S. Zhang & Lin, 2020).

2.6.1.2 Extended Predicted Mean Vote (ePMV)
This form of model works for people and cases based on local climate and in a space where
mechanical ventilation is not popular. The ePMV model is only suitable for warm and humid
climates in non-air-conditioned building where the indoor air temperature rises significantly
(Enescu, 2017).

2.6.2 Predicted Percentage Dissatisfied (PPD)
The PPD model computes the percentage of persons that are dissatisfied with a certain thermal
comfort. The PPD index depends on the PMV index (i.e., the number of people voting −3, −2, +2
or +3 within the PMV scale) (Fig 2-10) (Enescu, 2017)

Figure 2-11: An example of the PPD rating from the PMV index (Enescu, 2017)
2.7 Summary
This chapter described unique architecture of Joshua Tree National Park, tiny homes and their
advantages, prefabrication and its benefits, influence of orientation on solar heat gain, passive solar
energy use in buildings, and thermal comfort and evaluation methods.

Tiny homes exist around Joshua Tree National Park and their significance and materials as this
would help decide the look and aesthetic to target. The result of the resource consumption
comparison study was the significance of a small space and the use of equipment in the tiny house.
This will help in deciding the light fixtures, charging plug devices, etc inside the pocket lodge.
The pocket lodge will be oriented along the east-west axis with no windows on the north and south.
The Trombe wall strategy could provide an initial way of considering the south wall as a solar
battery for providing better thermal comfort in the interior space. The expanded thermal evaluation
technique is most ideal for the tiny house because of the non-usage of the mechanical ventilation
and because the location has extreme diurnal temperature. Therefore, this thermal evaluation
technique will be implemented.
36

CHAPTER 3: RESEARCH METHODOLOGY
The chapter describes general data collected as a team, site and orientation, general data collected
individually for south wall, thermal study, and details.

The tiny house was designed as a team. The team consists of three team members focusing on
separate surfaces – south wall, the roof, and the north wall. Although there will be references made
to the information that is collected by the other team members to understand the research
holistically, the south wall will be discussed in detail apart from the information that was collected
as a team.

The research methodology had 4 main parts: individual component simulations, base case
combined unit simulations, proposed combined unit simulations, and details. The individual
component simulations and details will be discussed in chapters 3 and 4. The combined unit
simulations and results, both base case and proposed, will be discussed in chapters 5 and 6 (Fig.
3.1).

Figure 3-1: Research Methodology

3.1 General Data Collection as a team

In this section the general data is collected, both as a team and as individually pertaining to the
south wall. The general data collection was done as some of the design decisions were critical and
restricted with respect to other criteria. The following sections will discuss these in detail (Fig 3-
2).

37

Figure 3-2: Methodology diagram focusing on chapter 3.

3.1.1 Site & Orientation
The orientation on the tiny house on the site was essential for thermal comfort. The axis along
which the unit is oriented would decide the passive strategies that would need to be implemented.

The optimum orientation for solar heat gain is an elongated building on the east-west axis. The
sun is lower in the sky during winter and in the summer, the east and west axis get minimum
exposure. The orientation can deviate to the east or west by 20° and not reduce heat gain
appreciably (Solar Orientation, Date Accessed 02/02/2023). Therefore, the tiny unit will also orient
towards the east west axis and the calculations are done considering this orientation. (Fig 3-3)

38

Figure 3-3: Unit orientation and surfaces
This orientation is considered best to minimize the heat gain inside the unit. However, the south
side would always receive solar radiation throughout the year. To protect the unit from overheating
and with the current orientation, the south side would require shading from direct sunlight. There
is an overhang proposed for this which also doubles up as an insulation material on the exterior
side of the south wall. Similarly, to minimize the east and west sides from sun exposure, especially
during summers, there are shading louvers/fins that are proposed to help deal with the glare and
direct sunlight (Fig 3-4).

Figure 3-4: Critical overhang locations

39

3.1.2 Design Development
The dimensions of the tiny house were derived based on the legal dimensions and restrictions of
the truck as per the state of California. This was done because of the prefabrication construction
technique which is going to be the process to make and transport the tiny house eventually to the
site. Hence, keeping the truck dimensions and designing the unit to fit on a truck was key. If the
transportation of the component was kept within the legal dimensions and restrictions, it would
avoid the need of any additional costs or permit requests.

Standard California Truck Information
According to the California trailer laws, the total length of the trailer is 65 feet (includes bumpers),
width of 102 inches and the loads on top may not exceed more than 10 inches on each side of the
vehicle. The height maximum restriction is 13 feet. (Fig 3-5) (California Trailer Laws & Trailer
Regulations, 2022; Tesla Semi Dimensions, 2022)

Figure 3-5: Trailer standard dimension (Tesla Semi Dimensions, Date Accessed 12/06/2022)

One other important regulation is weight limits for trucks. In California, the Vehicle Code provides
that no vehicle can have a weight of more than 80,000 pounds. (Easton & Easton, n.d.) (Table 3-
1) (US Department of Transportation, Date Accessed 12/06/2022)

Table 3-1: Summary of California Truck Weight Limits for Vehicles in Regular Operations (US Department of Transportation,
Date Accessed 12/06/2022)
Single Axle 20,000lbs.
Alternative method of computation: 18,000
lbs. Alternative method of computation, limit
on steering axle: 12,500 lbs.
Tandem Axle 34,000lbs. Alternative method of computation:
33,600 lbs.
40

Tridem Axle Not defined in statute but subject to provisions
Gross Weight 80,000lbs. Alternative method of computation:
76,800 lbs.
Therefore, the dimension of the tiny house was restricted to (all outer dimensions)
Length: 28’0”
Width: 8’5”
Height: 9’0”

The measurements for the small residence were largely driven by the trailer that would be used to
transport the fully fabricated residence from the concrete facility to the job site. The trailers have
weight and dimension restrictions.

Weight calculations of small residence
To study the weight that will be generated by the small residence, some iterations were done for
the dimensions that would typically be comfortable for living. Weights were assumed at this point
to derive at a dimension for the residence. The calculations were done as follows. (Table 3-2)

Table 3-2: Weight calculation matrix

Interation No. Components Lenght (Inch) Height (Inch) Thickness (inch) Volume (Cubic Inches) lb/cubic inch Weight (lbs)
South Wall 360 120 6 259200 0.087 22550.4
North Wall 360 120 6 259200 0.087 22550.4
Roof 360 102 6 220320 0.087 19167.84
Base 360 102 6 220320 0.087 19167.84
Total 83436.48
South Wall 336 120 6 241920 0.087 21047.04
North Wall 336 120 6 241920 0.087 21047.04
Roof 336 102 6 205632 0.087 17889.984
Base 336 102 6 205632 0.087 17889.984
Total 77874.048
South Wall 336 120 12 483840 0.087 42094.08
North Wall 336 120 6 241920 0.087 21047.04
Roof 336 102 6 205632 0.087 17889.984
Base 336 102 5 171360 0.087 14908.32
Total 95939.424
South Wall 336 108 10 362880 0.087 31570.56
North Wall 336 108 6 217728 0.087 18942.336
Roof 336 96 6 193536 0.087 16837.632
Base 336 96 5 161280 0.087 14031.36
Total 81381.888
South Wall 336 108 8 290304 0.087 25256.448
North Wall 336 108 5 181440 0.087 15785.28
Roof 336 96 5 161280 0.087 14031.36
Base 336 96 5 161280 0.087 14031.36
Total 69104.448
1
2
3
4
5
Note: Base Model
Note: Length reduced to 336 inches (28 feet)
Note: South Wall Thickness = 12 inches and Base = 5 inches
Note: South Wall Thickness = 10 Inch, Height = 9 & Width = 8 feet
Note: South Wall Thickness = 8 Inches
41

Structure
The tiny house was to be prefabricated at the concrete facility and transported to the job site. The
structural stability of the unit on the truck was essential and this was achieved by fabricating the
entire tiny house into tiny several hollow tubes that would relate to the help of joints and post-
tension tendons. This concept allows the unit to be structurally stable, earthquake resistant and
helps with the overall alignment of these smaller units (Fig 3-6).

Figure 3-6: Structural design of the unit

3.1.3 Material Study

Precast concrete: The precast concrete that will be used in the fabrication of this tiny residence is
produced with a standard concrete mix. This concrete mix was discussed with the team at
Precast/Prestressed Concrete Institute, led by Douglas Beaver, and the standard concrete mix was
decided based on the practice that is followed with units and fabrication of units/projects of similar
dimensions and requirements.

The concrete mix that will be used will be a high strength concrete mix. A concrete mix is
measured in its compressive strength in pounds per square inch (psi). A high strength concrete
mix’s psi rating would be above 6,000 psi (High-Strength Concrete, n.d.). The ratio of the mix
will be set to standards, and a self-consolidating mix will be used to produce the units as the flow
of the concrete slurry will be easy, given the height of the mold and the height at which the concrete
slurry will be poured. The self-consolidating mix will avoid any air gaps and will avoid the usage
of any vibrators (in most cases). The composition of the mix will be a standard mix as suggested
by PCI and as follows:
• Portland cement: 750 lbs/yard
• Sand: 1250 lbs/yard
• Water: 36 gallons
• Aggregates: 1600 lbs

Insulation Material: In addition to the integration of the unit with climatic conditions, it is also
necessary to use improved construction materials – in this case an insulation material. The tiny
house will require an insulation material especially on the south side. With the addition of an
insulation material, the R value of the wall is greatly improved and serves as a thermal blanket
around the wall – to reduce heat infiltration (Types of Insulation | Department of Energy, 2023).
The insulation material should have the following characteristics that reduces internal heat gain:
• High thermal resistance (R)
42

• Low thermal conductivity (λ)
• Thickness of the insulation (e)
• Density of the insulation

Some of the sustainable insulation material choices currently adapted in the industry are mineral
wool, hemp etc. Mineral wool is mainly made from two types of fibers: one from natural stone
fibers and the second from spinning slag. In terms of thermal performance, mineral wool
insulations achieve R-15 value. They are significantly higher than the regular conventional
insulation materials. Although mineral wool is energy efficient, durable, fire resistant, etc., it costs
about 10 percent more expensive than the conventional insulation materials (Buildwithrise,
Accessed on 04/24/2023). Due to constraints in the budget with the project, the insulation materials
that will be considered for testing are polystyrene, polyurethane board, foam board, batt and roll
insulation. Their R values per inch are as follows: (Thermal Insulation Materials, Technical
Characteristics and Selection Criteria, Date Accessed 02/08/2023)
• Polystyrene R7
• Polyurethane board R6.25
• Foam board R6.5-R7
• Batt insulation R3.7-R4.2

Glass & Frame: The east and west walls of the unit will have glass panels for ventilation and
daylight purposes to help increase occupant comfort. In hot climate like at Joshua Tree National
Park, the windows must be high-performing ones that mitigate solar heat gain. Window design is
important and should be selected according to the climate conditions it is supposed to be installed
in, the orientation, etc. For the tiny house the following glass and frame properties with respect to
thermal properties will be considered:
• Low emissivity glass: A low emissivity glass or a Low-E glass has a coating that blocks
out a substantial portion of UV light and infrared light – allowing abundant amount of
daylight but lessens the passage of heat (Glazing Properties, Date Accessed 02/19/2023).
• Multi-pane glass: Multi-pane in general sense could refer to a double-pane or a triple-pane
glass window. This helps in saving energy as the gases present between each pane create
an additional insulation. One example of the gas that is used in such window systems is
Argon. Argon is considered very efficient and affordable (Glazing Properties, Date
Accessed 02/19/2023). Vacuum glass is a new age glazing system that consists of two lites
of 4mm glass separated by a non-leaded proprietary metal seal and a vacuum space. This
glass system can achieve wall like R-values such as R14+ and is considered an ultimate
thermal glazing (Vitro Architectural Glass, Date Accessed 04/24/2023).
• U-Factor: The rate of heat flow through the window is measured as U-Factor. The window
is said to be high-performing and better insulating when the number of the U-Factor is
lower – which will be considered in the simulations (Glazing Properties, Date Accessed
02/19/2023).
• Solar Heat Gain Coefficient: SHGC tells how much solar heat comes through the window
and usually a lower number means less solar heat penetrates in. Therefore, a window
system with a lower SHGC number will be considered (Glazing Properties, Date Accessed
02/19/2023).

43

Shading louvers/fins: The fins/louvers proposed on the east and west side of the tiny residence
are for daylight and glare filtering. So, the material of these fins because important because they
should be made from low thermal conductivity properties. One such material which is low cost,
versatile with high performance is vinyl (An Introduction to Vinyl, Date Accessed 02/08/2023).
As these fins are proposed in the exterior face, they should have moisture resisting properties and
vinyl is not susceptible to water or moisture.

3.1.4 Mold & Prefabrication
The next important step in the decision and design making was to design a mold that was modular
and a material that can withstand the repeated pours. Modularity in mold makes the design
efficient, cost effective, and faster production. Plywood as the mold material would be effective
as it is cheap, and it will hold the number of pours that would be needed to fabricate the tiny house.
With reasonable maintenance, a plywood formwork can hold more than five pours. The following
parameters should be considered while designing a plywood mold:

Releasing agent: To aid the release of the concrete from the mold, the surface should be coated
with a releasing agent. It could be simple items like cooking spray, motor oil, vegetable oil etc or
products that are solely designed for this purpose, such as spray or brush-on silicone-based, semi-
permanent sealer and release agent (Wallender, 2022).

Exposed Removable Fasteners: With repeat pours and removal of the concrete structure, comes
wear and tear. It is always ideal to provide fasteners that are easy to remove and are exposed on
the outside (Wallender, 2022).

The size of the box is determined by the overall dimensions of the tube, and the thickness of the
mold itself. Plywood come in various sizes, but the most common size is 4 x 10 feet. And the
thickness varies from 1/8 inch to 3/4 inches. In this case a 3/4 inches thick plywood is considered
so that the longevity of mold usage increases. The overall hollow tube mold looks like the figure
shown. (Fig 3-7)

Figure 3-7: Mold inner and outer dimensions

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3.1.5 Code Compliance
Building and energy codes were extracted to meet compliance for building the tiny house.
California Residential Code 2021 (IRC 2021) was followed to meet with the building allowances.
(Fig 3-8) (California Residential Code 2022 Based on the International Residential Code 2021
(IRC 2021), 2021)

Figure 3-8: Snippets from California Residential Codes (California Residential Code 2022 Based on the International Residential
Code 2021 (IRC 2021), 2021)
45

Title 24 from Energy Code Ace Reference mentions the minimum requirements for energy
efficiency. (Fig 3-9) (Energy Code Ace - Reference Ace 2022 Tool, 2022)

Figure 3-9: Snippets of single-family standard building design code (Energy Code Ace - Reference Ace 2022 Tool, 2022)
According to the codes – the minimum R value for a roof/ceiling should be between R19-R36.
Minimum R value for walls that are above grade should be R8. Minimum R value for floors should
be between R8-R19.

To summarize, the pocket lodge of 28’0” x 8’5” x 9’0” is oriented along the east-west axis to
effectively mitigate solar gain inside the space. These dimensions are also derived from the length
and weight restrictions of the truck that the pocket lodge will be transported on. The pocket lodge
is made of precast concrete as the base material, and it has insulation boards to regulate the interior
thermal conditions. The process of prefabricating the pocket lodge is a tubular form, and this is
done to have better structural ability and the tubular shape helps with connections and making
varied combinations for the pocket lodge.

3.2 General Data Collection Individually (South Wall)
This section covers the information of the iterations and analysis done on the south wall.
46

3.2.1 Design
Determining the thickness of the south wall to work as a thermal battery effectively is important.
This south wall must soak up the heat from the sun during the day if it will be needed at nighttime
and release it slowly into the unit when the temperature drops. As thermal mass materials like
concrete, conduct heat very well, they absorb the sun’s heat quickly to their core, storing heat much
more effectively than lower mass materials, like wood-frame. It is most effective when the sun
shines directly on the wall, and this also means that there is a concrete thickness beyond which
there is generally no added benefit – in terms of solar energy storage. This optimal thickness for
storage of heat from day to night is 3-12 inches (100-300mm) (Designing Comfortable Homes,
Date Accessed 02/14/2023). Wall thicknesses between 3 and 12 inches will be tested to understand
the ideal dimension, while keeping in mind the weight of the wall.

3.2.2 Details & Connections
Horizontal wall to wall connections is equally important as vertical wall to wall connections. The
unit will be cast as tubes and each of these tubes will have to be connected to each other. There
will be a male side of the panel and a female side of the panel. Each of these tubes will have both
these sides of the panels as they will all be cast from the same mold and to continue with the
modularity. (Fig 3-10)

Figure 3-10: Female and male sides of panels in the tube.
3.2.3 Insulation Design
Good insulation is essential to maximize the benefits of thermal mass. It's vital that thermal mass
is insulated from outside temperature fluctuations. Insulation helps to maintain more constant
internal temperatures and reduces the need for heating in winter and cooling in summer.
Designing the position and placement of the insulation material needs to be climate specific. Day–
night (diurnal) temperature ranges are generally quite significant and can be extreme. High-mass
47

construction with high insulation and airtightness levels is ideal in these conditions. (Tibbetts et
al., 2020)

In the case of the tiny house, the climate zone of Joshua Tree National Park – ASHRAE Climate
zone 3 – because of its high diurnal temperature swings a study on both internal and external
insulation will be required to test the effectiveness of thermal mass. The insulation materials will
be moving/dynamic so that they let the wall to collect heat, store it, and release it when needed
(Fig 3-11)

Figure 3-11: Diagrammatic representation of the dynamic external and internal insulation
3.3 Thermal Study
Computer analytical modelling is done to predict and demonstrate the expected performance of
any space and make smart and efficient design choices before it is built. Two analytical software
were tested, and the process of the testing was validated. The following will show the steps through
the energy modelling.

Honeybee Energy (Grasshopper Plug-in)
The thermal mass and the indoor thermal performance of the unit was first tested on the Honeybee
Energy software. Following show the input variables and the workflow process that was followed
for the pocket lodge energy simulation (Fig 3-12).

IES Virtual Environment (IES VE)
The energy performance of the unit was also tested on IESVE to derive a comparative analysis
and validation of the inputs and the outputs (Fig 3-13).

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Figure 3-12: IES VE workflow

3.4 Details
The insulation panels and the window systems needed additional and innovative detailing which
can increase the occupant comfort and can be easily handled by any user.

Insulation panels on south wall
For the insulation panel on the south wall, a shading study was done to understand an ideal height
and length of the insulation panel’s projection and the detail was detailed out in a way that the
insulation panel, in its open position, will double up as a shading cantilever.

East west fins/louvers
These fins are proposed to cut down direct heat gain from the window systems and to cut down on
the glare. But these had to be designed keeping occupant comfort in mind hence the detailing is to
be done in a way that any type of user residing in this unit can operate the fins. Two design options
are proposed, one detail involves the louvers to open and close vertically and the individual panels
can be rotated according to the occupant’s needs. The other detail involves sliding of each of these
individual panels of the louvers and rotating them in place.

3.5 Summary
The chapter describes general data collected as a team, site and orientation, general, data collected
individually for south wall, thermal study, and details. The tiny house was designed as a team of
three members and each team member focused on separate surfaces – south wall, the roof, and the
north wall and the general data that was collected as a team was discussed first and the south wall
was discussed in detail in the later parts.

Following are the important considerations:
1. An east-west orientation of the pocket lodge was selected to have better indoor thermal
comfort by allowing for the use of the south wall as a solar battery.
2. The dimensions of the pocket lodge were derived from the weight and length of the
California truck. The tiny house will have a length of 28 feet, width of 8 feet 6 inches and
a height of 9 feet.
3. Precast concrete will be used. R-values from 5-10 will be tested.
4. The tiny house was designed in a tube form, as this would be beneficial with the structural
stability and easy of construction.
5. The insulation panels of the south wall will be dynamic based on the outside and inside
temperatures.

Simulations of different options will be carried out in Chapter 4.

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CHAPTER 4: SIMULATIONS & RESULTS

The chapter describes thermal mass studies, thermal comfort study, thermal comfort – insulation
studies, and details. Different profiles were assigned to the insulation materials and the windows,
basic construction properties were assigned; and their results are discussed. (Fig 4-1).

Figure 4-1: Methodology diagram focusing on chapter 4.
4.1 Thermal Mass Studies
The initial study that was done was to understand the material and its thermal mass properties.
Thermal mass generally means the thermal behavior of a material as a function of its density,
50

thermal conductivity, and specific heat capacity (Marceau Medgar, 2009). Thermal mass studies
also help understand the properties of absorbing, storing, and slowly releasing the heat.
To test this, a Honeybee Energy script was written and an IESVE model was made where the
material of the tiny house was input, and the results were taken on the surface temperatures.

To better understand the thermal mass properties of concrete and to understand concrete as the
perfect candidate as the building material, a thermal mass study was first performed on a wood-
frame building, a material that has a low thermal mass compared to concrete and the results are
compared against each other.

The inputs and workflows of Honeybee Energy are discussed first, followed by IESVE results.

4.1.1 Honeybee Energy: Inputs and workflow for low thermal mass wall – wood-frame
building
The input variables and the process of the workflow for a low thermal mass option is discussed in
detail (Fig 4-2).

Figure 4-2: Script for low thermal mass surface temperature analysis (see Appendix A)

Input and workflow
• Location: The location is the next step in the process of energy modelling in Honeybee
Energy. The location is usually fed into the Honeybee script as a form of an .epw file. The
location file that was used in this case was that of Twentynine Palms, one of the cities
closest to Joshua Tree National Park. This was chosen as there was unavailability of the
weather file for Joshua Tree National Park. The weather and climatic conditions of
Twentynine Palm is the same as that of Joshua Tree National Park, therefore the outputs
for both the cases would hold good.
• Model: A shoebox model is drafted on Rhinoceros software, with all the basic dimensions
as discussed in the previous section. Each face is drafted as a single surface, such as the
floor, roof, north wall, south wall, and the east and west surfaces. The east and west
windows are given glass material from the Rhino material library.
51

• Adding Honeybee Faces: Each of these individual faces from the Rhino model are
referenced in the Grasshopper interface so that the geometry is now a part of the Honeybee
script.
• Construction Input: The material construction information was set to each face, and in this
case the material properties of a wood-frame were set to all the faces except for the east
and west sides. The east and west surfaces were given construction properties of a glass
wall. Construction properties such as thermal conductivity, density, and specific heat
capacity of a wood-frame were set. The thickness of the south wall was set to 4 inches.
• Combining it to Honeybee Model: Each of these individual spaces were combined to a
Honeybee Model since the simulation will only run if the model is closed. And a closed
model space can generate indoor temperatures.
• This entire set model was converted to an Open Studio model to run thermal simulations.
• The data extracted from this is in the SQL format. Therefore, to read this and to visualize
this data, there is a component used that reads an SQL data into energy results and
visualizes the outputs on the Rhino interface.
• Data such as individual face’s interior temperature, exterior temperature, and energy flow
can be read and visualized by connecting these components to a visualization parameter.
• Other data results like the room’s operative temperature, radiant temperature, relative
humidity can also be read which are all essential deciding factors for thermal comfort.

Here the surface’s outside and inside temperatures are measured. The Analysis Period is set to
15th of August, one of the peak summer days at Joshua Tree National Park. In the case of a wood-
frame, a low thermal mass wall, the outside surface temperature peaks up to 113°F while the inside
temperature is at 108°F. The values of the temperature are read from the graph and the color
representation (Fig 4-3).

Figure 4-3: Wood-frame wall surface inside and outside temperature readings

52

4.1.2 Honeybee Energy: Inputs and workflow for high thermal mass wall – concrete
In the next step, a similar script was written but changing the material properties of the wall to
concrete. To have a fair comparison of the results, the thickness of the walls continued to be the
same from the wood-frame script (Fig 4-4).

Figure 4-4: Script for high thermal mass surface temperature analysis (see Appendix A)

Input and workflow
• Location: The location is the next step in the process of energy modelling in Honeybee
Energy. The location is usually fed into the Honeybee script as a form of an .epw file. The
location file that was used in this case was that of Twentynine Palms– one of the cities
closest to Joshua Tree National Park. This was chosen as there was unavailability of the
weather file for Joshua Tree National Park. The weather and climatic conditions of
Twentynine Palms is the same as that of Joshua Tree National Park, therefore the outputs
for both the cases would hold good.
• Model: A shoebox model is drafted on Rhinoceros software, with all the basic dimensions
as discussed in the previous section. Each face is drafted as a single surface, such as the
floor, roof, north wall, south wall, and the east and west surfaces. The east and west
windows are given glass material from the Rhino material library.
• Adding Honeybee Faces: Each of these individual faces from the Rhino model are
referenced in the Grasshopper interface so that the geometry is now a part of the Honeybee
script.
• Construction Input: The material construction information was set to each face, and in this
case the material properties of concrete were set to all the faces except for the east and west
sides. The east and west surfaces were given construction properties of a glass wall.
Construction properties such as thermal conductivity, density, and specific heat capacity
of concrete were set. The thickness of the south wall was set to 4 inches.
• Combining it to Honeybee Model: Each of these individual spaces were combined to a
Honeybee Model since the simulation will only run if the model is closed. And a closed
model space can generate indoor temperatures.
This entire set model was converted to an Open Studio model to run thermal simulations.
53

The data extracted from this is in the SQL format. Therefore, to read this and to visualize this data,
there is a component used that reads an SQL data into energy results and visualizes the outputs on
the Rhino interface.
Data such as individual face’s interior temperature, exterior temperature, and energy flow can be
read and visualized by connecting these components to a visualization parameter.
Other data results like the room’s operative temperature, radiant temperature, relative humidity
can also be read which are all essential deciding factors for thermal comfort.

Here the surface’s outside and inside temperatures are measured. The Analysis Period is set to 15
th

of August, one of the peak summer days at Joshua Tree National Park. In the case of concrete, a
high thermal mass wall, the outside surface temperature peaks up to 106°F while the inside
temperature is at 103°F. The values of the temperature are read from the graph and the color
representation (Fig 4-5).

Figure 4-5: Concrete surface inside and outside temperature readings

With the addition of a wall of high thermal mass – there is a considerable drop in the interior
temperature of the space. This also proves that the usage of a high thermal mass in a very hot
climate might be beneficial.

In the following section, same study is done by using IES VE analytical software to make a
consistent comparison of the results.

4.1.3 IESVE: Inputs and workflow for low thermal mass wall – wood-frame
Here, the thermal mass properties of wood-frame and concrete are studied.

Input and workflow:
• Location: The location is added as an .epw file. The location file that was used in this case
was that of Twentynine Palms – one of the cities closest to Joshua Tree National Park. This
was chosen as there was unavailability of the weather file for Joshua Tree National Park.
The weather and climatic conditions of Twentynine Palms is the same as that of Joshua
54

Tree National Park, therefore the outputs for both the cases would hold good. The location
is added on the APLocate tab where the .epw file is loaded (Fig 4-6).
•

Figure 4-6: Twentynine Palms location fed into the IESVE model

• Model: A model is created in the IESVE ModelIT Building modeler component, with all
the basic dimensions as discussed in the previous section.
• Windows: To this shoebox model, window and doors are added as per the accurate
measurements on the east and west sides (Fig 4-7).

Figure 4-7: Base model of the pocket lodge

55

• Thermal Template: Since the research focusses on a building with no mechanical
ventilation systems – no thermal template was assigned to the model.
• Construction Database: The walls were given wood-frame structure properties and the
south wall was given a thickness of 6-inches. In all the iterations, the window properties
were kept the same.

The simulation was set to run for an entire year but the results for 15
th
of August was taken. The
south wall’s interior and exterior surface temperatures were studied, and the results show that the
exterior temperature goes up to 133°F and the inside temperature reads around 130°F. This results
in an extremely uncomfortable indoor thermal condition. This goes to prove that a low thermal
mass wall will not be suitable in a climate like Joshua Tree National Park.
From the graphs of the exterior and interior temperatures, the exterior temperature peaks at 133°F
at around 6 PM in the evening and at that same time the inside surface temperature of the wall us
130°F. This is because of the low thermal mass of wood-frame and hence the lag in the temperature
between the outside and the inside isn’t too big (Fig 4-8).

Figure 4-8: Wood-frame wall surface’s inside and outside temperatures
4.1.4 IESVE: Inputs and workflow for high thermal mass wall – concrete
The same study is done by changing the material property to concrete and the south wall’s exterior
and interior surface temperatures are recorded.

Input and workflow:
• Location: The location is added as an .epw file. The location file that was used in this case
was that of Twentynine Palms – one of the cities closest to Joshua Tree National Park. This
was chosen as there was unavailability of the weather file for Joshua Tree National Park.
The weather and climatic conditions of Twentynine Palms is the same as that of Joshua
Tree National Park, therefore the outputs for both the cases would hold good. The location
is added on the APLocate tab where the .epw file is loaded (Fig 4-9).
56

Figure 4-9: Twentynine Palms location fed into the IESVE model

• Model: A model is created using the IESVE ModelIT Building modeler component with
all the basic dimensions as discussed in the previous section.
• Windows: To this shoebox model, window and doors are added as per the accurate
measurements.
• Thermal Template: Since the research focusses on a building with no mechanical
ventilation systems – no thermal template was assigned to the model.
• Construction Database: The walls were given concrete properties and the south wall was
given a thickness of 6-inches. In all the iterations, the window properties were kept the
same.

The simulation was set to run for an entire year but the results for 15
th
of August was taken. The
south wall’s interior and exterior surface temperatures were studied, and the results show that the
exterior temperature goes up to 103°F but the inside temperature reads around 98.5°F. The results
show considerable improvement in the internal thermal comfort condition. This is because of
concrete’s thermal mass properties and its inability to conduct heat.

From the graphs of the exterior and interior temperatures, the exterior temperature peaks at 103°F
at around 5 PM in the evening and at that same time the inside surface temperature of the wall us
98.5°F. And during the early morning hours, around 6 AM, even though the exterior surface
temperature goes as low as 85°F, the inside surface temperature only goes upto 85°F at around 9
AM. This time lag is because of the high thermal mass property of concrete as the dumping the
heat from the outside surface to the inside surface takes place slowly (Fig 4-10).
57

Figure 4-10: Concrete wall surface’s inside and outside temperatures

4.2 Thermal Comfort Study
Even though concrete’s results came out positive for the research, some more tests are now done
on an entire model level. The iterations start from a low thermal mass material property, such as
wood-frame, and go on until the material properties of a high thermal mass material, such as
concrete.
The tests are studied by creating base case models. In these models’ various material/construction
properties are changed, and the inside temperature of the space is recorded. This test was conducted
to understand the thermal comfort of the inside space by varying material properties.

4.2.1 IESVE – Thermal Comfort Study – Various base case models
Various base case models were tested on the IESVE software. The analysis was done in this
process of lowest to highest thermal mass materials and lowest to highest performing glass.

• Base case model 01: 4” low thermal mass (wood-frame) + Low performing glass – Here
the model was given a construction database of a 4-inch wood-frame which has a very low
thermal mass (just to see how wood-frame would behave), and the east and west windows
are given a single pane clear glass window property. The thermal simulation was run for a
period of 1 year and the highest temperature recorded was 138F and the lowest temperature
recorded was 32F. These temperatures were studied against the dry bulb temperature of
Joshua Tree National Park. These temperatures are not within the thermal comfort range
of 65 – 85F (Fig 4-11).

58

Figure 4-11: Base case model 01 Interior and Dry Bulb Temperature.

• Base case model 02: 4” concrete walls + Low performing glass: – the model was given a
construction database of a 4-inch concrete walls, and the east and west windows continued
to have the same single pane clear glass window property. The thermal simulation was run
for a period of 1 year and the highest temperature recorded was 146°F and the lowest
temperature recorded was 25°F. This phenomenon is seen because the concrete is now
retaining some amount of heat in the inside spaces, and the heat is not being let out. These
temperatures were studied against the dry bulb temperature of Joshua Tree National Park.
These temperatures are not within the thermal comfort range of 65 – 85°F (Fig 4-12).

Figure 4-12: Base case model 02 Interior and Dry Bulb Temperature.
59

• Base case model 03: 4” concrete walls + Operable low performing glass: Since the
temperatures in the previous iteration increased, there needs to be a way to let the heat out.
In this case, the model was given a construction database of a 4-inch concrete walls, and
the east and west windows were continued to have the same single pane clear glass window
property, but the windows were set in an operable mode. The thermal simulation was run
for a period of 1 year and the highest temperature recorded was 123°F and the lowest
temperature recorded was 25°F. The results show an improvement by adding the operable
window property. These temperatures were studied against the dry bulb temperature of
Joshua Tree National Park. These temperatures are not within the thermal comfort range
of 65 – 85°F (Fig 4-13).

Figure 4-13: Base case model 03 Interior and Dry Bulb Temperature.
• Base case model 04: 6” concrete walls + Operable DGU glass: – The model here was given
a construction database of a 6-inch concrete walls, and the east and west windows were
given a double-glazed unit window system. From the previous studies, the increase in
thickness of the concrete wall helped with stabilizing the internal thermal conditions and
double-glazed unit also has a better U property, which helps in resisting the heat gain. The
thermal simulation was run for a period of 1 year and the highest temperature recorded was
116°F and the lowest temperature recorded was 35°F. The results show an improvement
by adding the DGU system and a thicker concrete wall. These temperatures were studied
against the dry bulb temperature of Joshua Tree National Park. These temperatures are not
within the thermal comfort range of 65 – 85°F (Fig 4-14).

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Figure 4-14: Base case model 04 Interior and Dry Bulb Temperature.
• Base case model 05: 6” concrete walls + Operable DGU glass + Buffer Space: – Apart
from the construction database from the previous base case – an additional buffer space
was added on the east and west sides of the model that acts as a layer helping in regulating
the indoor thermal comfort. The thermal simulation was run for a period of 1 year and the
highest temperature recorded was 113°F and the lowest temperature recorded was 35°F.
The results show an improvement by adding the buffer space. These temperatures were
studied against the dry bulb temperature of Joshua Tree National Park. These temperatures
are not within the thermal comfort range of 65 – 85°F (Fig 4-15).

Figure 4-15: Base case model 05 Interior and Dry Bulb Temperature.
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• Base case model 06: 8” South concrete wall + Operable DGU glass + Buffer Space + Code
Compliance: – This iteration has an 8 inch south concrete wall thickness; the window
properties and the buffer space continue to have the same information as per the previous
iteration and to the construction materials – the R values are input according to the ones
mentioned in the bylaws.
• Roof – minimum of R38
• Walls – minimum of R8
• U factor – minimum of 0.3
The thermal simulation was run for a period of 1 year and the highest temperature recorded
was 109°F and the lowest temperature recorded was 33°F. The results show an
improvement by adding construction materials have the material properties in compliance
with the byelaws. These temperatures were studied against the dry bulb temperature of
Joshua Tree National Park. These temperatures are not within the thermal comfort range
of 65 – 85°F (Fig 4-16).

Figure 4-16: Base case model 06 Interior and Dry Bulb Temperature.
These studies show the improvement in the thermal properties by varying the materials and their
properties and by changing some design features. The thermal range is still not within the thermal
comfort range of 65-85°F, so the next set of tests will be done on the insulation materials and how
they affect the thermal comfort of the inside space.

From the above results, a high thermal mass material, concrete, is ideal for the pocket lodge. To
proceed further with the material and to understand the thickness of concrete for the pocket lodge,
a thermal comfort study was done by varying the wall thickness of the south wall.
The tests and simulations are run both on Honeybee and IES VE.

62

4.2.2 Honeybee Energy: Thermal Comfort Study – Varying wall thickness
The thermal comfort of the interior space is tested by changing the thicknesses of the walls as this
would show the thickness and the range of thicknesses that will be ideal on the south side of the
tiny house to work as a thermal battery efficiently (Fig 4-17).

Figure 4-17: Tiny house thermal study script (see Appendix A)

Inputs and workflow:

• Location: The location is the next step in the process of energy modelling in Honeybee
Energy. The location is usually fed into the Honeybee script as a form of an .epw file. The
location file that was used in this case was that of Twentynine Palms – one of the cities
closest to Joshua Tree National Park. This was chosen as there was unavailability of the
weather file for Joshua Tree National Park. The weather and climatic conditions of
Twentynine Palms is the same as that of Joshua Tree National Park, therefore the outputs
for both the cases would hold good.
• Model: A model was created in the Rhinoceros software, with all the basic dimensions as
discussed in the previous section. Each face is drafted as a single surface, such as the floor,
roof, north wall, south wall, and the east and west surfaces. The east and west windows are
given glass material from the Rhino material library.
• Adding Honeybee Faces: Each of these individual faces from the Rhino model are
referenced in the Grasshopper interface so that the geometry is now a part of the Honeybee
script.
• Construction Input: To each of these faces – the material construction information was set
and in this case the material properties of concrete were set. A number slider was set to the
south side wall and the number slider ranged from 2 inches to 12 inches. The thicknesses
were varied here for each of the tests. Construction properties such as thermal conductivity,
density, and specific heat capacity of concrete were set.
• Combining it to Honeybee Model: Each of these individual spaces were combined to a
Honeybee Model since the simulation will only run if the model is closed. And a closed
model space can generate indoor temperatures.
63

• This entire set model was converted to an Open Studio model to run thermal simulations.
• The data extracted from this is in the SQL format. Therefore, to read this and to visualize
this data, there is a component used that reads an SQL data into energy results and
visualizes the outputs on the Rhino interface.
• Data such as individual face’s interior temperature, exterior temperature, and energy flow
can be read and visualized by connecting these components to a visualization parameter.
• Other data results like the room’s operative temperature, radiant temperature, relative
humidity can also be read which are all essential deciding factors for thermal comfort.
The results of the face temperatures were compared to understand the thermal mass properties of
concrete and the thickness of concrete that would be ideal for the south wall. The results showed
a decrease in the inside temperature with the increase in the concrete wall thickness. There is a
significant temperature drop with the increase in concrete wall thickness. The temperature dropped
from 105°F to 87°F with just the change in the thickness of the south wall (Fig 4-18 to 4-21).

Figure 4-18: Zone operative temperature (105F) with south wall thickness of 4”
64

Figure 4-19: Zone operative temperature (101F) with south wall thickness of 6”

Figure 4-20: Zone operative temperature (98F) with south wall thickness of 84”
65

Figure 4-21: Zone operative temperature (87F) with south wall thickness of 12”
These iterations did not involve any insulation panels on them. The role of dynamic insulation was
not studied in the Grasshopper simulations; therefore, the same process was then detailed on IES
VE software and similar simulations were run.

4.2.3 IESVE: Thermal Comfort Study – Varying Wall Thickness

In the IESVE model, the thermal comfort of the interior space is tested by changing the thicknesses
of the concrete walls as this would show the thickness and the range of thicknesses that will be
ideal on the south side of the tiny house to work as a thermal battery efficiently.

Input and workflow: South wall thickness
• Location: The location is added as an .epw file. The location file that was used in this case
was that of Twentynine Palms – one of the cities closest to Joshua Tree National Park. This
was chosen as there was unavailability of the weather file for Joshua Tree National Park.
The weather and climatic conditions of Twentynine Palms is the same as that of Joshua
Tree National Park, therefore the outputs for both the cases would hold good. The location
is added on the APLocate tab where the .epw file is loaded (Fig 4-22).
66

Figure 4-22: Twentynine Palms location fed into the IESVE model.

• Model: A model was created in IESVE ModelIT Building modeler component, with all the
basic dimensions as discussed in the previous section.
• Windows: To this model, window and doors are added as per the accurate measurements.
• Thermal Template: Since the research focusses on a building with no mechanical
ventilation systems – no thermal template was assigned to the model.
• Construction Database: The walls were given concrete properties and the south wall were
given three thickness iterations – 4-inch, 6-inch, 8-inch and 12-inch thicknesses. In all the
iterations, the window properties were kept the same.
This study was done to study the zone operative temperatures in the interior space by changing the
concrete wall thickness and by studying the conduction gain of the south wall across 24 hours. For
this simulation – a specific date of August 15
th
was chosen to study the effect of thermal mass at
summertime when the temperature at Joshua Tree National Park is very high. With the change in
the thickness of the south wall, the operative air temperature in the inside of the space saw a drop
in the temperature during the daytime (Fig 4-23).

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Figure 4-23: Interior Space Operative Temperature across 3 iterations on 15
th
August.
Sim 1 = 4-inch-thick south wall
Sim 2 = 6-inch-thick south wall
Sim 3 = 8-inch-thick south wall
Sim 4 = 12-inch-thick south wall

This shows:
1. In a 4-inch-thick south wall condition (blue line) – During the nighttime, between 21:00hrs
to 06:00hrs, the temperature inside the space is a lot cooler than the other iterations. This
is because a thinner wall section of concrete is not able to conduct and store a large amount
of heat during the day making the interior spaces during the night get colder soon. Between
10:00hrs to 15:00hrs the inside temperature is a lot hotter than the other iterations and the
reason for that is again the thinner wall section. A thinner wall section of concrete means
that it does not have enough mass to conduct heat and store in the wall. So, it starts to
release the heat into the inside space quickly.

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2. In a 6-inch-thick south wall condition (green line) – During the nighttime, between
21:00hrs to 06:00hrs, the temperature inside the space is better than the 4-inch-thick wall
condition but not as good as the 8-inch-thick wall condition. The thermal mass property of
the concrete can be studied in this and with the increase of the thickness the temperature
moderation of the inside space is seen. Between 10:00hrs to 17:00hrs the inside
temperature is hotter than the 8-inch-thick wall iteration but cooler than the 4-inch-thick
wall condition. During this time of the day, the temperature inside should be more
comfortable and within the thermal comfort range. This effect can be seen to get better
with changing the thickness of the walls.

3. In an 8-inch-thick south wall condition (black line), the conditions here seem to be more
ideal out of the other two iterations discussed. The inside temperature is seen to be getting
warmer during the nighttime and colder during the daytime. This is the effect of the thermal
mass of the concrete and with increase in the wall section; the concrete can store
considerable amount of heat and the thermal mass properties of the concrete is aiding in
time lag resulting in slower release of the heat energy into the interior space.

4. In a 12-inch-thick south wall condition (red line) – Of all the iterations, the condition in
this option seems to be the most ideal. The inside temperature is the warmest during the
early hours of the morning when it tends to be extremely cold outside and as the day
progresses, the temperature inside seems to get colder than all the other iterations,
maintaining a thermal condition that is better than the rest and towards the night time, the
temperature inside gets warmer than all the other options aiding to a better thermal comfort
in the inside space.

These thickness iterations were carried out as there is a weight constraint that needs to be
considered while loading a fully fabricated unit on the trailer and an 8-inch wall thick south wall
was within the weight limits.

The tests performed in this section only show south wall thickness variation results, and there is
no insulation considered at this point.

4.3 Thermal comfort – Insulation Studies
Thermal comfort refers to the satisfaction that the human feels in a space due to tangible and
intangible factors – therefore, in this set of the model and simulations, other factors such as buffer
zones and shading elements (Fig 4-24).

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Figure 4-24: The pocket lodge with the buffer zones and vertical fins added.

4.3.1 Thermal Comfort Study – without insulation
In this set of tests, the insulation studies were done with respect to their locations and their control
profiles. This study was essential because adding a layer of insulation would drastically help in
bring the temperatures down, improving the indoor thermal comfort as the wall insulating
properties are improved. But to understand the importance of the insulation layer, a base model
was created with no insulation and the input and workflows are discussed in detail below.

The existing pocket lodge model is used in this case and the construction properties of the walls
are edited. In this case, there is no insulation layer added to the walls, floors, and the roof. The
simulations were run for a whole year and the results for the 15
th
of August were studied. The
results show the yearly temperatures peak at 106°F on the 16
th
of August and the lowest it gets is
40°F on the 4
th
of December. On the 15
th
of August the temperature of the south surface is
measured the highest t
em
perature is 105°F and the lowest is 84°F. These temperatures are just from
the thermal properties of the concrete wall (Fig 4-25).

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Figure 4-25: Yearly temperatures and a day temperature of 15
th
August

4.3.2 Thermal comfort Study – with permanent insulation
The existing pocket lodge model from the previous iteration is used in this case but an additional
permanent inside and outside insulation layers are added to the south wall. The simulations were
run for a whole year and the results for the 15
th
of August were studied. The results show the yearly
temperatures peak at 105°F on the 14
th
of July and the lowest it gets is 41°F on the 4
th
of December.
On the 15
th
of August, the temperature of the south surface is measured, the highest temperature
is 101°F and the lowest is 82°F. These temperatures are just from the thermal properties of the
concrete wall (Fig 4-26).

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Figure 4-26: Yearly temperatures and a day temperature of 15
th
August

To get a better idea of the two iterations, a comparison study was done on the operative temperature
between the two and the results show that with the addition of the permanent insulation layer, the
operative temperature inside the space gets better but is still gets very uncomfortable during the
daytime (Fig 4-27).

Figure 4-27: Comparative operative temperature graph between no insulation and permanent insulation
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4.3.3 Thermal comfort Study – with dynamic insulation
After studying permanent insulation is beneficial to the thermal comfort of the inside space but the
temperatures inside the space still go beyond the comfort zone, the dynamic insulation strategy
was tested. This section will discuss the input and workflow in detail.

Thermal comfort refers to the satisfaction that the human feels in a space due to tangible and
intangible factors, therefore, in this set of the model and simulations, other factors such as shading
elements and ventilation were added.

• Model: A model was created in the IESVE ModelIT Building modeler component, with all
the basic dimensions as discussed in the previous section. To this, the shading elements are
also added. Shading elements include the two buffer spaces on both ends of the pocket
lodge and the vertical fins. And the interior space of the pocket lodge was partitioned into
2 zones – one for the external insulation and one for the internal insulation. (Fig 4-28)

Figure 4-28: The pocket lodge with the buffer zones, vertical fins, and the inside and outside insulation zones added.
• Thermal Template: Since the research focusses on a building with no mechanical
ventilation systems – no thermal template was assigned to the model.
• Ventilation input: The windows on the east and west ends are now given a ventilation
profile that controls its open and close times, area of opening, and the opening type.
The east and west windows are given a ventilation control profile that opens and closes
according to the temperatures outside. First a daily profile is set with a formula and this is
fed to a weekly profile:
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𝑡𝑎 > 𝑡𝑜 & 𝑡𝑜 > 75
where,
ta = the air temperature of the room
to = the outside temperature

The formula translates to the east and west windows opening when the air temperature
inside the room is greater than the outside temperature and when the outside temperature
is greater than 75F (Fig 4-29).

Figure 4-29: East and west window Macroflo profile

• Construction Database: Here the construction properties of all the materials are set.
o The floor and the roof of the pocket lodge was given a concrete material property
and was set to have an R value complying to the codes. R value for the floor was
set to a minimum of R19 and the R value of the roof was set to a minimum of R38.
The thickness of the roof and the floor was 5 inches each.
o The east and west windows were set as a double-glazed windows and the overall U
value of the glass was set to 0.0709. The cavity between the two panels were set to
Krypton which helped bring the U-value of the entire system down. The frames
around the window systems were set to PVC – closer to the vinyl frames that was
researched. The thickness of the east and west walls was set to 4 inches.
o The north wall was set to have a thickness of 4 inches and the R-value was set to a
minimum of R8, to comply with the codes.
o The south wall in this iteration was set to have a thickness of 8 inches. The south
wall in this case is the partition wall between the two insulation layers that were
constructed. Although the 12” thick wall showed better thermal mass and thermal
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lag properties – the weight of that wall might go against the weight restrictions
allowable on a California Truck.
o There are two spaces that are created in the pocket lodge, each of these spaces have
a window which has an open-close setting on Macroflo. The outer space has a
window in its outer face and the inner space has a window in its inner face.
o These windows were given material properties that were very close to that of an
insulating material – in this case the properties of Polyurethane foamboard were
given to these windows and the Macroflo profile was set to respond to the interior
air temperature and the seasonal temperature changes at Joshua Tree National Park.
▪ There was one set of simulations that were done with inputting the formula
“ta>to & to>75” and this formula was set to both the inner and the outer
window/insulating material. Simulations were run for a whole year and the
results were read for the thermal temperature in the inside space. The results
were not positive and there was no considerable impact on the temperature
inside, so this process was not taken forward for the simulations. The
process that was taken forward was to set the open and close times
according to varying seasons and temperature at Joshua Tree National Park.
▪ The seasonal temperatures and the insulation open/close profile times were
set up by studying the hourly temperatures at Joshua Tree National Park
across the whole year (Twentynine Palms, CA Weather Conditions, Date
Accessed 02/26/2023). The months were split into four seasons: winter,
spring, summer, and fall. And in each of the months the highest temperature
fluctuation in a day was picked to design for the worst-case scenario,
highlighted in the cells. And for each of these worst-case scenarios, an ideal
insulation profile open and close times were selected (Table 4-1 to 4-4).

Table 4-1: Winter monthly temperatures at Joshua Tree National Park

1 67 45 Open Close Open Close 1 64 44 Open Close Open Close 1 68 55 Open Close Open Close
2 67 50 2 60 39 2 63 53
3 70 50 3 64 37 3 68 48
4 70 48 4 67 41 4 67 47
5 69 49 5 71 44 5 73 43
6 67 50 6 74 47 6 79 58
7 69 48 7 72 47 7 77 55
8 68 45 8 75 52 8 85 50
9 69 45 9 75 53 9 87 65
10 67 44 10 73 57 10 85 66
11 56 45 11 77 54 11 92 59 11am - 7pm 8pm - 10am 11pm - 8am 9am - 10pm
12 54 39 12 73 51 12 86 64
13 62 39 13 75 50 13 86 54
14 64 41 14 80 57 11am - 4pm 5pm - 10am 9pm - 8am 9am - 8pm 14 84 53
15 65 42 15 72 58 15 71 50
16 67 47 16 75 52 16 73 49
17 62 40 17 73 53 17 72 54
18 65 44 18 74 53 18 76 49
19 66 40 19 77 50 19 81 54
20 68 44 20 78 55 20 79 55
21 76 45 21 75 48 21 73 55
22 72 49 22 71 60 22 66 48
23 73 49 23 78 55 23 56 44
24 83 51 12pm - 5pm 6pm - 11am 10pm - 8am 9am - 9pm 24 80 51 24 62 42
25 81 55 25 79 51 25 69 41
26 79 56 26 70 53 26 71 50
27 66 56 27 74 47 27 76 44
28 72 51 28 72 53 28 86 44
29 66 55 29 67 50
30 68 52 30 80 50
31 57 49 31 72 49
Avg 68 47 Avg 73 50 Avg 75 52
Outside Insu Inside January February December Outside Insu Inside Outside Insu Inside
INSIDE INSULATION OPEN TIMES 9PM - 8AM 8AM - 9PM INSIDE INSULATION CLOSED TIMES
OUTSIDE INSULATION OPEN TIMES OUTSIDE INSULATION CLOSED TIMES 5PM - 11AM 11AM - 5PM
75

Table 4-2: Spring monthly temperatures at Joshua Tree National Park

Table 4-3: Summer monthly temperatures at Joshua Tree National Park

1 93 58 Open Close Open Close 1 87 59 Open Close Open Close 1 92 68 Open Close Open Close
2 90 58 2 85 61 2 95 68
3 83 60 3 81 63 3 94 63
4 70 56 4 91 61 4 97 66
5 66 50 5 93 65 5 102 70
6 70 46 6 98 66 6 100 69
7 72 48 7 98 72 7 98 71
8 73 51 8 101 70 7am - 6pm 7pm - 6am 12am - 5am 6am - 11pm 8 84 67
9 77 49 9 99 71 9 82 63
10 75 54 10 89 66 10 83 58
11 74 54 11 81 62 11 81 55
12 81 58 12 75 58 12 88 55
13 61 58 13 78 52 13 99 67
14 86 56 14 84 55 14 107 75
15 88 58 15 87 57 15 108 74 2am - 7am 8am - 1am 9am - 4pm 5pm - 8am
16 85 64 16 88 64 16 101 71
17 85 60 17 92 59 17 98 71
18 88 61 18 100 66 18 100 72
19 85 63 19 94 68 19 100 73
20 82 59 20 87 63 20 86 70
21 86 55 21 88 61 21 90 66
22 90 67 8am - 6pm 7pm - 7am 11pm - 7am 8am - 10pm 22 76 57 22 95 66
23 87 63 23 85 59 23 98 69
24 90 61 24 87 63 24 100 72
25 96 66 25 92 64 25 101 77
26 93 68 26 96 67 26 102 75
27 91 66 27 91 69 27 99 73
28 79 59 28 86 65 28 89 70
29 77 53 29 94 63 29 91 68
30 87 56 30 98 67 30 95 66
31 81 59 31 98 69
Avg 82 58 Avg 89 63 Avg 95 68
INSIDE INSULATION CLOSED TIMES
Outside Insu Inside
OUTSIDE INSULATION OPEN TIMES 8AM - 6PM 6PM - 8AM OUTSIDE INSULATION CLOSED TIMES
March April May Outside Insu Inside Outside Insu Inside
INSIDE INSULATION OPEN TIMES 11PM - 7AM 7AM - 11PM
1 103 76 Open Close Open Close 1 111 87 Open Close Open Close 1 104 86 Open Close Open Close
2 103 78 2 108 82 2 109 88
3 102 74 3 105 77 3 109 87
4 100 74 4 100 73 4 98 89
5 100 72 5 102 74 5 103 86
6 104 75 6 103 77 6 112 84
7 105 79 7 106 79 7 106 88
8 105 81 8 109 80 8 105 88
9 106 82 9 112 78 9 106 87
10 110 85 10 114 84 10 108 86
11 113 85 1am - 8am 9am - 12am 8am - 7pm 8pm - 7am 11 115 81 11 108 86
12 111 81 12 113 83 12 107 89
13 102 79 13 112 83 13 101 84
14 106 76 14 108 87 14 107 87
15 108 78 15 113 87 15 106 87
16 109 81 16 115 92 11pm - 7am 8am - 10pm 11am - 6pm 7pm - 10am 16 110 87
17 102 79 17 114 92 17 110 88
18 96 70 18 110 88 18 111 88
19 99 67 19 114 88 19 106 87
20 102 72 20 113 88 20 102 85
21 106 76 21 113 86 21 108 86
22 102 84 22 112 87 22 107 87
23 109 0 23 103 85 23 107 86
24 109 81 24 102 85 24 104 88
25 111 80 25 99 84 25 106 87
26 108 79 26 108 83 26 112 87 12am - 8am 9am - 11pm 8am - 5pm 6pm - 7am
27 105 86 27 103 86 27 111 83
28 113 88 28 107 85 28 105 82
29 112 87 29 101 84 29 106 83
30 110 86 30 104 87 30 115 88
31 104 89 31 115 91
Avg 106 76 Avg 108 84 Avg 107 87
June July August Outside Insu Inside Outside Insu Inside
INSIDE INSULATION OPEN TIMES 8AM - 6PM 6PM - 8AM INSIDE INSULATION CLOSED TIMES
Outside Insu Inside
OUTSIDE INSULATION OPEN TIMES 11PM - 8AM 8AM - 11PM OUTSIDE INSULATION CLOSED TIMES
76

Table 4-4: Fall monthly temperatures at Joshua Tree National Park

o In the winter months, the temperature difference between daytime and nighttime is between
80°F and as low as 39°F. Any possibility of heat during the day should be captured and
stored in the wall so that it can be released inside the space when it gets too cold. Therefore,
the external insulation is set to open during the daytime and remain closed at night while
the internal insulation opens during the nighttime, to release the absorbed daytime heat
inside the space.
o In the spring months, the overall dry bulb temperature at Joshua Tree National Park doesn’t
fluctuate too much. Therefore, the external insulation opens during the daytime to for a
short time and radiates the absorbed heat into the space during the nighttime, meaning the
inside insulation opens during the nighttime.
o In the summer months, the temperatures at Joshua Tree National Park varies from 113°F
during the daytime to 72°F during night-time. The south wall is going to get solar radiation
throughout this period. Therefore, the external insulation is set to open only during the
nighttime to absorb the cooler degrees of the temperature and remain closed during the
daytime so that the wall doesn’t absorb the hotter temperatures. The wall retains the colder
temperature absorbed during the night and radiates it into the inner space during the
daytime as the interior insulation panel opens.
o In the fall months, the temperature difference between the daytime and nighttime is
between 99°F and 71°F. To be able to bring the temperature down during the daytime to a
comfortable zone, the external insulation is set to open during the nighttime so that it can
absorb the cooler temperatures, store it, and radiate it to the inside space during the daytime,
meaning the internal insulation opens during the daytime.

These open and close times are set in the Macroflo profile manager for every season for both the
inside and the outside insulation (Fig 4-30 to 4-37).

1 109 89 Open Close Open Close 1 95 72 Open Close Open Close 1 81 64 Open Close Open Close
2 105 88 2 95 74 2 75 59
3 109 89 10pm - 9am 10am - 9pm 11am - 6pm 7pm - 10am 3 103 78 10pm - 7am 8am - 9pm 11am - 5pm 6pm - 10am 3 69 56
4 111 91 4 101 80 4 74 50
5 112 92 5 99 81 5 75 51
6 114 89 6 97 77 6 77 53
7 105 87 7 97 76 7 77 54
8 107 86 8 95 78 8 67 57
9 91 75 9 95 76 9 67 55
10 85 74 10 97 74 10 72 48
11 97 77 11 93 74 11 71 50
12 90 78 12 97 69 12 71 49
13 95 79 13 99 74 13 71 48
14 97 77 14 99 71 14 72 49
15 96 72 15 89 68 15 73 48
16 98 71 16 84 67 16 73 56
17 96 70 17 92 69 17 75 52
18 94 68 18 93 68 18 75 48
19 97 66 19 92 70 19 73 57
20 97 68 20 93 69 20 77 53 9am - 5pm 6pm - 8am 10pm - 8am 9am - 9pm
21 97 71 21 94 70 21 75 47
22 99 66 22 84 66 22 76 48
23 101 78 23 79 62 23 75 47
24 106 81 24 77 60 24 76 60
25 108 81 25 79 55 25 76 50
26 109 86 26 81 58 26 73 48
27 107 79 27 83 60 27 73 51
28 99 83 28 81 59 28 70 53
29 99 80 29 86 57 29 71 52
30 100 75 30 89 59 30 69 49
31 89 62
Avg 101 79 Avg 91 69 Avg 73 52
November Outside Insu Inside
INSIDE INSULATION CLOSED TIMES
Outside Insu Inside
OUTSIDE INSULATION OPEN TIMES 10PM - 9AM 9AM - 10PM OUTSIDE INSULATION CLOSED TIMES
Outside Insu Inside
INSIDE INSULATION OPEN TIMES 11AM - 6PM 6PM - 11AM
September October
77

Figure 4-30: Exterior insulation open close profile – Fall months.

Figure 4-31: Exterior insulation open close profile – Spring months.

78

Figure 4-32: Exterior insulation open close profile – Summer months.

Figure 4-33: Exterior insulation open close profile – Winter months.

79

Figure 4-34: Interior insulation open close profile – Fall months.

Figure 4-35: Interior insulation open close profile – Spring months.

80

Figure 4-36: Interior insulation open close profile – Summer months.

Figure 4-37: Interior insulation open close profile – Winter months.

ApacheSim was run after setting the following parameters and a full year simulation was taken.
The results were as follows (Fig 4-38 to 4-40). The blue shaded region shows the expanded comfort
zone that is determined for this project.

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Figure 4-38: Yearly operative zone temperature after proposing dynamic insulation on south wall.

Figure 4-39: Highest and lowest operative temperature in a year.

Figure 4-40: Number of hours within a certain temperature range.

The table shows there are 6915 hours out of the 8760 hours in a year that are within 65°F – 85°F,
which is close to 79% of the time in the year. The number of comfortable hours is increasing
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because of the use of the dynamic insulation and with the right use of the material and the profile
setting. For the overall model setting, the same profiles and the same material properties will be
used.
4.4 Details
Insulation panels on south wall
The insulation panels on the South wall will operate according to the close and open profile times
and when the insulation panel is open, it will act as a shading cantilever. So, to understand the
ideal lengths and height of the insulation panel, a shading study was conducted. The first step for
figuring out the measurement was to extract the Timetable Plot from Climate Consultant of
Twentynine Palms (close to Joshua Tree National Park) which gives hourly dry bulb temperatures
across the entire year (Fig 4-41).

Figure 4-41: Timetable plot from Climate Consultant
These red and the cyan zones along every month and across the time periods are noted and the
same areas are plot on the sun path diagram. The sun path diagram also consists of months and
time stamps on its axis, so the same information is plot on the sun path diagram. The areas that are
within the red region will be focused on more as these are the time periods that will need shading
(Fig 4-42).

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Figure 4-42: Dry bulb temperatures plot on sun path diagram.
After this step, these same spherical plots made on the sun path diagram will be transferred on to
the shading protractor where the horizontal, vertical projection calculations for the cantilever will
be made (Fig 4-43).

Figure 4-43: Shading calculator showing the overall red and cyan plots with probable vertical degrees for best shading.
The image shows that a 30° angle would cover most of the red zones but that would also mean
very deep cantilevers. This wasn’t ideal in the case of this project. So the closest angle that was

84

ideal with the cantilever and the shading of the wall was 55°, and a 55° vertical shading angle
would give a 6 feet overhang. (Fig 4-44).

Figure 4-44: Angle and length of insulation cantilever
The exterior insulation was designed to cover the entire height of the south wall. The height of the
south wall is set to 9 feet. For the exterior insulation to cover the entire south wall, the height of
the insulation panel must also be 9 feet. But the insulation panel should also be designed to open
and close which would require and introduction of a hinge in the centre of the panel that would
allow it to fold open and close. At the centre of the 9 feet tall insulation panel would mean both
the halves of the panel would be 4.5 feet high each. But the cantilever needed as per the shading
calculation is 6 feet. Therefore, to solve the problem of 1.5 feet difference, the insulation material
on the top half was designed to overlap the bottom half of the insulation material and this overlap
was of 1.5 feet, which when folded, would result in a 6 feet cantilever (Fig 4-45 and 4-46).

Figure 4-45: Design of the 6 feet cantilever exterior insulation panel.
85

Figure 4-46: Design of the exterior insulation.

East west fins/louvers
These fins are proposed to cut down direct heat gain from the window systems and to cut down on
the glare. But these had to be designed keeping occupant comfort in mind hence the detailing is to
be done in a way that any type of user residing in this unit can operate the fins.

Two design options are proposed – one detail involves the louvers to open and close vertically and
the individual panels can be rotated according to the occupant’s needs. The other detail involves
sliding of each of these individual panels of the louvers and rotating them in place (Fig 4-47, 4-
48).

Figure 4-47: Option 1 – Vertical opening of the louvers.
86

Figure 4-48: Option 2 – Sliding of the louvers.
The details of the insulation panel and the east and west fins show the various possibilities an
occupant can control the temperature and the daylight inside the space.
For the exterior insulation, a 6 feet long cantilever where the exterior insulation panel is divided
into two halves work best for it to be able to open and close and adequately shade the south wall.
For the east and west fins, the possibility of sliding the fins to one corner would be more ideal
from the occupant’s point of view.

4.5 Summary
The chapter described thermal mass studies, thermal comfort study, thermal comfort – insulation
studies, and details.

The thermal and ventilation studies done on two programming software and the results of this are
as follows:
1. It is seen that a high thermal mass wall like concrete would be better at controlling the
internal room temperature as compared to that of a low thermal mass wall like wood-frame.
The inside and outside surface temperature of a concrete wall reads much lower than that
of a wood-frame building.
2. When the thermal comfort of the inner space was tested on base case models ranging from
a lower thermal mass wall like wood-frame to a high thermal mass wall like concrete, it
was seen that by increasing the thickness of the walls and by changing properties of
window, the indoor temperature goes down by 30° improving the overall thermal comfort
inside the space.
3. By varying the concrete wall thicknesses of the south wall from 4 to 12 inches, the inside
temperature kept decreasing proportionally. This study was important to learn the concrete
thermal conductivity properties and to arrive at an ideal wall thickness. The thickness of
concrete was set to 8 inches, and that was the thickest it could be and still have the tiny
house stay within the weight restrictions provided by the truck.
4. The study of dynamic control setting for the insulation works best in a climate zone such
as Joshua Tree National Park as the concrete can be used as a heat storing battery during
the times when the outside temperature is very high, and the insulation panels can be set to
open and close as per when the heat needs to be radiated into the internal space.
5. The insulation panel and the windows show details where the occupant can control the
open and close times and settings and can moderate the internal temperature with these
design details.

87

For the next chapter, a south wall thickess of 8 inches will proposed as the starting thickness, and
a ventilation profile set to the equation of ta>to and to>75, where ta refers to the temperature of
the space inside the pocket lodge and to refers to the outside temperature, will be used and the
dynamic insulation will be set to the seasonal profiles.

88

CHAPTER 5: DATA CONSOLIDATION FOR BASE MODEL
OF POCKET LODGE

This chapter will describe the final iteration collected as a team, thermal comfort/ventilation,
prototype details, prototype mold design, and dynamic insulation movement.
To complete a holistic analysis, the north and south wall elements and the roof element are
assembled into a single model. This model is tested under four different seasonal conditions.
Individual tests were run by the team members on their respective walls and their best results were
shared with each other to make a base model where all the best results of the south, north, and the
roof were modelled together. This was then simulated on IESVE to derive an ideal thermal comfort
period (Fig 5-1). The information gathered and the process for simulating in the next chapter are
discussed.

Figure 5-1:Methodology diagram focusing on chapter 5.
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5.1 Final Iteration Collected as a Team
For the following analyses, the data is collected and consolidated for the south wall, north wall,
and the roof so that the results can be modeled on one final complete base model (Fig 5-2). Then
that assembled model will be used for further simulations in Chapter 6.

Figure 5-2: Exploded isometric representation of the overall pocket lodge and each team member’s focus

5.1.1 South wall
The south wall is used as a hot battery that collects heat and releases the heat energy into the
internal space during the times when the temperature gets low. The south wall also has both
internal and external insulation system, working in a dynamic profile setting to control the heat
transfer. This external insulation panel doubles up as a roof overhang canopy providing additional
shade to the south wall.
The radiation on the south wall is usually very high and an insulation panel on the exterior is
beneficial. The best results of south wall after running the individual simulations are as follows
(Table 5-1):

Table 5-1: Best test results of south wall.
South Wall
Thickness 8 inches
Insulation thickness Approx. 3 inches
Insulation material Expanded polystyrene
Insulation position Both inside and outside
90

The dynamic insulation profiles for the south wall are as follows (Fig 5-2):

Figure 5-3: South wall outside and inside dynamic insulation operating profiles
5.1.2 North wall – Information as collected from team member: Yuqing He
The north wall in this case is used to bring in the cold energy into the inside space. The north wall
is functioning with the use of just the outside insulation which has a dynamic profile setting.
The best results of north wall after running the individual simulations are as follows (Table 5-2):

Table 5-2: Best test results of north wall.
North Wall
Thickness 5 inches
Insulation thickness Approx. 3 inches
Insulation material Expanded polystyrene
Insulation position Only outside

The dynamic insulation profiles for the north wall are as follows (Fig 5-3):

Figure 5-4: North wall outside dynamic insulation operating profiles
December December
January January
February February
March March
April April
May May
June June
July July
August August
September September
October October
November November
9PM - 8AM
8AM - 6PM
8AM - 6PM
8AM - 6PM
11PM - 4AM
11AM - 5PM
Months
South Wall
Inside Insulation Open Times
9PM - 8AM
9PM - 8AM
11AM - 6PM
11AM - 6PM
11AM - 6PM
Winter Spring Summer Fall
11PM - 7AM
11PM - 7AM
11PM - 7AM
8AM - 12PM
8AM - 12PM
8AM - 12PM
10PM - 9AM
10PM - 9AM
10PM - 9AM
Winter Spring Summer Fall
Months
11AM - 5PM
11AM - 5PM
South Wall
Outside Insulation Open Times
11AM - 5PM
11AM - 5PM
December
January
February
March
April
May
June
July
August
September
October
November
Fall
6PM - 7AM
6PM - 7AM
Off continuously
Summer
6PM - 7AM
6PM - 7AM
6PM - 7AM
Spring
Off continuously
Off continuously
6PM - 7AM
Winter
Off continuously
Off continuously
Off continuously
Months
North Wall
Outside Insulation Open Times
91

5.1.3 Roof – Information as collected from team member: Aditya A. Bahl
The roof is used to protect the interior spaces from getting overheated. The roof extends on the
east and west sides – creating buffer spaces – helping the internal spaces from glare. The roof also
is used to generate electricity by installing solar panels and is coated with a reflective material on
the exterior surface. This team member assisted not only in the generation of the electricity but
also in the lighting and glare design. The best results of roof after running the individual
simulations are as follows (Table 5-3):

Table 5-3: Best test results of roof
Roof
Thickness 5 inches
Insulation thickness Approx. 3 inches
Insulation material Expanded polystyrene
Insulation position Only inside
Highest incident radiation 2096 kWh/m2
Daylight lux level 23

The dynamic insulation profiles for the roof are as follows (Fig 5-4):

Figure 5-5: Roof inside dynamic insulation operating profiles
5.2 Thermal comfort/Ventilation
The windows on the east and west ends are now given a ventilation profile that controls its’ open
and close times, area of opening, and the opening type.
The east and west windows are given a ventilation control profile that opens and closes according
to the temperatures outside. First a daily profile is set with a formula -

𝑡𝑎 > 𝑡𝑜 & 𝑡𝑜 > 75
where,
ta = the air temperature of the room
to = the outside temperature

December
January
February
March
April
May
June
July
August
September
October
November
Fall
On continuously
On continuously
On continuously
Spring
6PM - 11AM
6PM - 11AM
6PM - 11AM
Summer
Off continuously
Off continuously
Off continuously
Months
Roof
Outside Insulation Open Times
Winter
Off continuously
Off continuously
Off continuously
92

The formula translates to the east and west windows opening when the air temperature inside the
room is greater than the outside temperature and when the outside temperature is greater than 75F
(Fig 5-5).

Figure 5-6: East and west window Macroflo profile
5.3 Prototype Details
In this tiny house project, to protect the south wall from most amount of direct heat gain, an
insulation panel is proposed on the exterior and this insulation panel – in its open position – doubles
up as a cantilevered roof projection. A 6 feet cantilever is designed which, when is folded, covers
the entire length of the vertical wall (Fig 5-6 and 5-7). The insulation panel needs to open at 90deg
during the times when the exterior insulation should be kept in “open” setting for the south wall to
heat up.

Figure 5-7: Angle and length of insulation cantilever.
93

Figure 5-8: Design of the exterior insulation and it’s working.
East west fins/louvers
These fins are proposed to cut down direct heat gain from the window systems and to cut down on
the glare. But these had to be designed keeping occupant comfort in mind hence the detailing is to
be done in a way that any type of user residing in this unit can operate the fins. Two design options
are proposed – one detail involves the louvers to open and close vertically and the individual panels
can be rotated according to the occupant’s needs. The other detail involves sliding of each of these
individual panels of the louvers and rotating them in place (Fig 5-8, 5-9).

Figure 5-9: Option 1 – Vertical opening of the louvers.

Figure 5-10: Option 2 – Sliding of the louvers.
94

5.4 Prototype Mold Design
Plywood is used as the mold material as it can hold multiple pours, is of low cost and the board
size available in market are 4’x8’ and 4’x10’ (Plywood – Curtis Lumber & Plywood, Date
Accessed 03/19/2023). The measurement 4’x10’ suits the requirement of the pocket lodge. ¾
inches thick plywood is considered to increase the longevity of the formwork usage. The size of
the mold is derived from the dimensions of the tube (Fig 5-6).

Figure 5-11: Mould inner and outer dimensions.
5.5 Dynamic Insulation Movement
Dynamic insulation movement refers to the times in the day when the interior insulation is on an
individual component and when it is not. The design allows two out of the three individual
components to have the inside insulation panels on the surface at the same time. This means that
when two of the individual components have the inside insulation panels active on them, the third
component won’t have an inside insulation panel active on it. Since the south wall has an exterior
insulation as well, the same matrix is given to the exterior insulation as well. But the interior
insulation is critical to analyze as it interacts with all the other components’ insulation profiles as
well. In this case, the dynamic insulation controls are defined by seasons summer, spring, fall, and
winter. Each individual component is tested separately, and a matrix is derived according to the
times when the insulation is needed (Fig 5-11).
The data was consolidated as per individual simulations and when the interior insulation panels
are needed and when they are not needed (Fig 5-12). The cross marks “X” indicate the times when
the insulation is in open position, which means the insulation is not actively placed on the
wall/roof. The checkmarks “√” indicate the times when the insulation is in close position, which
means the insulation is active and is placed on the wall/roof.

95

Figure 5-12: All individual components’ interior and exterior insulation panels.

Figure 5-13: Combined seasonal dynamic insulation profiles.

Figure 5-14: Seasonal dynamic insulation profile of the south external insulation panel.

In the summer, the roof would have both the insulation panels active during the daytime but during
the night-time, one of the panels from the roof will move to the south wall and rest there. In spring,
only the south and the roof need the insulation panel on them during the daytime. In the fall, only
96

the south wall needs the insulation during the night-time so it will have both the insulation panels
active on it during the night. In wintertime, all three components need the insulation panel on them
during the daytime. Since there are only two available inside insulation panels, this simulation
iteration will be tested and analysed in Chapter 6 to determine a best case where only two insulation
panels are used, and a thermally comfortable zone is still achieved.

5.6 Summary
This chapter described the final iteration collected as a team, thermal comfort/ventilation,
prototype details, prototype mold design, and dynamic insulation movement.

The data consolidation of all team member’s individual components concludes and an overview
of the information that will be taken forward to Chapter 6 is mentioned. The north and south wall
elements and the roof elements are assembled into a single model and the dynamic insulation
control timings are derived after consolidating the individual tests run by the team members on
their respective walls. This model will be tested for an entire year covering all four different
seasonal conditions, summer, spring, fall, and winter seasons. This will then be simulated on
IESVE to derive an ideal thermal comfort period.

• The thickness of the south wall is 8 inches, and the thickness of the insulation panel is 3
inches.
• The thickness of the north wall is 5 inches, and the thickness of the insulation panel is 3
inches.
• The thickness of the roof is 5 inches, and the thickness of the insulation panel is 3 inches.
• All the components use expanded polystyrene as their insulation material.
• For the ventilation, on the east and west windows the ventilation formula of ta>to and
to>75, where ta refers to the temperature of the space inside the pocket lodge and to refers
to the outside temperature, will be applied.

The dynamic insulation control open and close times will be set to the ones consolidated
individually however the discrepancy in the wintertime will be simulated again and addressed in
detail in Chapter 6.

97

CHAPTER 6: BUILDING SIMULATIONS FOR POCKET
LODGE
This chapter will describe the base case overall model, its material properties, thermal
comfort/ventilation, and dynamic insulation movement, and proposed overall model and its
material properties, thermal comfort/ventilation, and dynamic insulation movement and their
results.
All three individual components’ information are fed into one single model. The thermal and
ventilation tests are run for one entire year while comparing the inside room temperature with the
outside dry bulb temperature of Joshua Tree National Park. The single model with all the
information is first run without making any change to the data consolidated from the team and then
another simulation is run after making changes to some of the individual components to achieve
the most ideal interior room temperatures. The springtime interior insulation simulation needs to
be tested again to accommodate only two interior insulation panels to the individual components
while making sure best thermal comfort range is achieved (Fig 6-1).

Figure 6-1: Methodology diagram focusing on chapter 6.

98

6.1 Base case Overall Model
The overall material, thermal and dynamic insulation movement details are discussed and the
thermal comfort analysis over a period of one year is run. No changes are done to the data
consolidated from the team members to create a new overall single model.

Inputs and workflow:
To generate the overall model, the IESVE model of the south wall was used, and additional details
were added to that model.
North Wall – To add north wall related information in the ModelIT interface, two subset spaces
were generated in the north side of the pocket lodge. This is done to introduce the dynamic
insulation properties into the calculation. These two spaces have a window which has an open-
close setting on Macroflo. The outer space has a window in its outer face and the inner space has
a window in its inner face.
Roof – To add roof related information in the ModelIT interface, a separate space is created above
the ceiling level of the pocket lodge, leaving a minimum space between the two. This is done so
that different element and material properties can be assigned while the space continues to interact
with the adjacent pocket lodge. The inner face of the space is given a window which has an open-
close setting on Macroflo (Fig 6-2).

Figure 6-2: Individual team member components added to the overall model.
99

6.1.1 Material Properties
In the base case overall model, the materials, their thicknesses and the R and U values were not
altered. The consolidated data from the previous chapters were directly fed into the overall single
model.
The images show the data and the thickness of the individual components (Fig 6-3 to 6-13).

Figure 6-3: Construction database of base case roof.

Figure 6-4: Construction database of the base case interior roof insulation
100

Figure 6-5: Construction database of the base case floor

Figure 6-6: Construction database of the base case east and west walls
101

Figure 6-7: Construction database of the base case east west windows

Figure 6-8: Construction database of the base case south wall
102

Figure 6-9: Construction database of the base case south wall exterior insulation

Figure 6-10: Construction database of the base case south wall interior insulation
103

Figure 6-11: Construction database of the base case north wall

Figure 6-12: Construction database of the base case north wall exterior insulation
104

Figure 6-13: Construction database of the base case north wall interior insulation
This construction database information is entered as per the thicknesses and the consolidated data.
In this version, the R values of the materials aren’t considered and aren’t code complying.

6.1.2 Thermal Comfort/Ventilation
The ventilation input for the east and west windows are given the equation from chapter 5. The
windows’ open and close settings are set to the outside dry bulb temperature and to the inside
temperature of the pocket lodge.

First a daily profile is set with a formula, and this is entered to the weekly profile:

𝑡𝑎 > 𝑡𝑜 & 𝑡𝑜 > 75
where,
ta = the air temperature of the room in Fahrenheit
to = the outside temperature in Fahrenheit

The formula translates to the east and west windows opening when the air temperature inside the
room is greater than the outside temperature and when the outside temperature is greater than 75°F
(Fig 6-14).

105

Figure 6-14: East and west window Macroflo profile

6.1.3 Dynamic Insulation Movement
The dynamic insulation profile values are set in the Macroflo interface for each of the individual
insulation components. The information received from the teammates are added directly into the
Macroflo profiles without making any edits. South wall has one external and one internal insulation
component. North wall has one external and one internal insulation component, and the roof has
only one internal insulation component.

• South wall’s external insulation component profiles:
The insulation components are set to seasonal profiles, such as summer, winter, spring, and fall.
And these seasonal components are referenced to an annual profile (Fig 6-15 and 6-16).

Figure 6-15: Exterior insulation open close profile – Fall and Spring months.

106

Figure 6-16: Exterior insulation open close profile – Summer and Winter months.
Each of these profiles are set to an annual profile according to each of the seasons (Fig 6-17).

Figure 6-17: Exterior insulation set to an annual profile.

• South wall’s internal insulation component profiles:
The internal insulation components are also set to seasonal profiles, such as summer, winter,
spring, and fall. And these seasonal components are referenced to an annual profile (Fig 6-18 and
6-19).

107

Figure 6-18: Interior insulation open close profile – Fall and Spring months.

Figure 6-19: Interior insulation open close profile – Summer and Winter months.
Each of these profiles are set to an annual profile according to their seasons (Fig 6-20).

Figure 6-20: Interior insulation set to an annual profile.
• North wall’s external insulation component profiles:
The insulation profile open and close times as received from the North wall team member, Yuqing
He, are fed directly into the Macroflo interface. The exterior insulation in the north wall has an
open profile setting of 6PM to 7AM for the months of May to October and in the other months the
profiles set are to OFF (Fig 6-21 and 6-22).
108

Figure 6-21: North Team member exterior insulation open profile.

Figure 6-22: North team member exterior insulation annual profile.

• North wall’s internal insulation component profiles:
The interior insulation profile open and close times as received from the North wall team member,
Yuqing He, are fed directly into the Macroflo interface. The interior insulation in the north wall
has an open profile setting of 7AM to 6PM only for the months of December and January and in
the other months the profiles set are to ON (Fig 6-23 and 6-24).
109

Figure 6-23: North team member interior insulation open profile.

Figure 6-24: North team member interior insulation annual profile.
• Roof’s internal insulation component profiles:
The roof has only one insulation layer, and it is on the inside of the roof. The interior insulation
profile open and close times as received from the Roof team member, Aditya Bahl, are fed directly
into the Macroflo interface. The interior insulation in the roof has an open profile setting of 6PM
to 11AM only for the months of March, April, and May and in the months of December, January,
February, June, July, and August the profiles set are to OFF while in the months of September,
October, and November the profiles are set to ON. (Fig 6-25 and 6-26).

110

Figure 6-25: Roof team member interior insulation open profile

Figure 6-26: Roof team member interior insulation annual profile.

After setting these values and profiles, the simulation is run for one entire year, and the operative
temperature for the inside space is taken and is compared against the dry bulb temperature at
Joshua Tree National Park. The results show that during the winter months, the temperatures rise
to extreme temperatures, as high as 110°F. But the lowest temperature recorded is around 70°F,
which is within the thermal comfort zone for the pocket rangers. The green shaded region shows
the expanded comfort zone that is determined for this project (Fig 6-27).

111

Figure 6-27: Base case – Comparison of the dry bulb temperature against the operative temperature output.

The lowest temperature recorded is 70.45°F in the month of January and the highest recorded is
around 110.42°F in the month of March.

Figure 6-28: Base case: Lowest and highest temperatures
The number of hours between the 65°F and 85°F thermal comfort range is 3626 hours, which is
around 41% of the time across the entire year. There are no hours under the 65°F, but there are
5134 hours above the 85°F, which is around 58% of the time across the entire year.

112

Figure 6-29: Number of hours within the thermal comfort range.
The number of hours between the thermal comfort range has dropped down by half as compared
to the iteration where only the south wall insulation was involved, as in chapter 4. The reason for
such result could be the profiles set to the insulation panels and the material properties. These
details will be edited in the proposed overall model iteration in the following section.
6.2 Proposed Overall Model
In the proposed overall model, the same base case model is used for the simulations but the
material properties, Macroflo profiles, and their values are changed to arrive at a result that is
closer to the thermal comfort range.
6.2.1 Material Properties
In the proposed overall model, the materials, their thicknesses and the R and U values are altered
to achieve a more thermally insulating material. In the proposed model, the R values of the concrete
walls of the south wall, north wall, floor, roof, and the east and west window walls are altered to
match with the codes, and an increased R value also means better thermal insulation as that is
required in the pocket lodge to achieve thermal comfort. The R value of the dynamic insulation
panels are kept the same and the value is not altered from the base case.
The images show the data and the thickness of the individual components (Fig 6-30 to 6-34).
113

Figure 6-30: Construction database of proposed roof.

Figure 6-31: Construction database of proposed floor.

114

Figure 6-32: Construction database of proposed east west walls.

Figure 6-33: Construction database of proposed south wall.
115

Figure 6-34: Construction database of proposed north wall.
All the construction database information is fed to the construction database manager.

6.2.2 Thermal Comfort/Ventilation
The ventilation input for the east and west windows are given the same equation followed from
the base case. The windows’ open and close settings are set to the outside dry bulb temperature
and to the inside temperature of the pocket lodge.

First a daily profile is set with a formula, and this is fed to a weekly profile:

𝑡𝑎 > 𝑡𝑜 & 𝑡𝑜 > 75
where,
ta = the air temperature of the room in degrees Fahrenheit
to = the outside temperature in degrees Fahrenheit

The formula translates to the east and west windows opening when the air temperature inside the
room is greater than the outside temperature and when the outside temperature is greater than 75°F
(Fig 6-35).

116

Figure 6-35: East and west window Macroflo profile
6.2.3 Dynamic Insulation Movement
The dynamic insulation received from the team members was then modified to achieve a better
thermally comfortable temperature inside the pocket lodge. Since the iteration with solely the south
wall insulation profile gave a better result in the interior temperatures, the profile information for
the south wall will not be edited in the proposed model. The section below has the edited profile
information for the north wall exterior and interior insulation panels and the roof’s interior
insulation panel.

• North wall’s external insulation component profiles:
The north wall’s external and internal insulation profiles were changed to match more closely to
the seasons and the temperatures in each of the seasons. The seasonal temperatures and the
insulation open/close profile times were set up by studying the hourly temperatures at Joshua Tree
National Park across the whole year (Twentynine Palms, CA Weather Conditions, Date Accessed
02/26/2023). In each of the months the lowest day temperature and night temperature was picked
to design for the worst-case scenario, highlighted in the cells. For each of these worst-case
scenarios, an ideal insulation profile open and close times were selected (Table 6-1 to 6-4).

117

Table 6-1: Winter monthly temperatures at Joshua Tree National Park

Table 6-2: Spring monthly temperatures at Joshua Tree National Park

1 67 45 Open Close Open Close 1 64 44 Open Close Open Close 1 68 55 Open Close Open Close 1 81 64 Open Close Open Close
2 67 50 2 60 39 1pm-5pm 5pm-1pm 1am-7am 7am-1am 2 63 53 12pm-4pm 4pm-12pm 5am-8am 8am-5am 2 75 59
3 70 50 3 64 37 3 68 48 3 69 56
4 70 48 4 67 41 4 67 47 4 74 50
5 69 49 5 71 44 5 73 43 5 75 51
6 67 50 6 74 47 6 79 58 6 77 53
7 69 48 7 72 47 7 77 55 7 77 54
8 68 45 8 75 52 8 85 50 8 67 57
9 69 45 9 75 53 9 87 65 9 67 55
10 67 44 10 73 57 10 85 66 10 72 48
11 56 45 11 77 54 11 92 59 11 71 50
12 54 39 12pm-5pm 5pm-12pm 2am-7am 7am-2am 12 73 51 12 86 64 12 71 49
13 62 39 13 75 50 13 86 54 13 71 48
14 64 41 14 80 57 14 84 53 14 72 49
15 65 42 15 72 58 15 71 50 15 73 48
16 67 47 16 75 52 16 73 49 16 73 56
17 62 40 17 73 53 17 72 54 17 75 52
18 65 44 18 74 53 18 76 49 18 75 48
19 66 40 19 77 50 19 81 54 19 73 57
20 68 44 20 78 55 20 79 55 20 77 53
21 76 45 21 75 48 21 73 55 21 75 47
22 72 49 22 71 60 22 66 48 22 76 48
23 73 49 23 78 55 23 56 44 23 75 47
24 83 51 24 80 51 24 62 42 24 76 60
25 81 55 25 79 51 25 69 41 25 76 50
26 79 56 26 70 53 26 71 50 26 73 48
27 66 56 27 74 47 27 76 44 27 73 51
28 72 51 28 72 53 28 86 44 28 70 53 1PM - 6PM 6PM - 1PM 2AM - 8AM 8AM - 2AM
29 66 55 29 67 50 29 71 52
30 68 52 30 80 50 30 69 49
31 57 49 31 72 49
Avg 68 47 Avg 73 50 Avg 75 52 Avg 73 52
INSIDE INSULATION OPEN TIMES 1AM - 7AM 7AM - 1AM INSIDE INSULATION CLOSED TIMES
OUTSIDE INSULATION OPEN TIMES OUTSIDE INSULATION CLOSED TIMES 5PM - 12PM 12PM - 5PM
January February December Outside Insu Inside Outside Insu Inside November Outside Insu Inside Outside Insu Inside
1 93 58 Open Close Open Close 1 87 59 Open Close Open Close 1 92 68 Open Close Open Close
2 90 58 2 85 61 2 95 68
3 83 60 3 81 63 3 94 63
4 70 56 4 91 61 4 97 66
5 66 50 5 93 65 5 102 70
6 70 46 1pm-6pm 6pm-1pm 4am-8am 8am-4am 6 98 66 6 100 69
7 72 48 7 98 72 7 98 71
8 73 51 8 101 70 8 84 67
9 77 49 9 99 71 9 82 63
10 75 54 10 89 66 10 83 58
11 74 54 11 81 62 2pm-5pm 5pm-2pm 2am-6am 6am-2am 11 81 55 3pm-6pm 6pm-3pm 4am-7am 7am-4am
12 81 58 12 75 58 12 88 55
13 61 58 13 78 52 13 99 67
14 86 56 14 84 55 14 107 75
15 88 58 15 87 57 15 108 74
16 85 64 16 88 64 16 101 71
17 85 60 17 92 59 17 98 71
18 88 61 18 100 66 18 100 72
19 85 63 19 94 68 19 100 73
20 82 59 20 87 63 20 86 70
21 86 55 21 88 61 21 90 66
22 90 67 22 76 57 22 95 66
23 87 63 23 85 59 23 98 69
24 90 61 24 87 63 24 100 72
25 96 66 25 92 64 25 101 77
26 93 68 26 96 67 26 102 75
27 91 66 27 91 69 27 99 73
28 79 59 28 86 65 28 89 70
29 77 53 29 94 63 29 91 68
30 87 56 30 98 67 30 95 66
31 81 59 31 98 69
Avg 82 58 Avg 89 63 Avg 95 68
7AM - 3AM INSIDE INSULATION CLOSED TIMES INSIDE INSULATION OPEN TIMES 3AM - 7AM
Outside Insu Inside
OUTSIDE INSULATION OPEN TIMES 1PM - 6PM 6PM - 1PM OUTSIDE INSULATION CLOSED TIMES
March April May Outside Insu Inside Outside Insu Inside
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Table 6-3: Summer monthly temperatures at Joshua Tree National Park

Table 6-4: Fall monthly temperatures at Joshua Tree National Park

o In the winter months, the north wall doesn’t receive a lot of sun, but to keep the internal
temperatures comfortable, the north wall should capture as much heat it can during the day.
Therefore, the external insulation is set to open during the daytime and remain closed at
night while the internal insulation opens during the nighttime, to release the absorbed
daytime heat inside the space.
o In the spring months, the overall dry bulb temperature at Joshua Tree National Park doesn’t
fluctuate too much. Therefore, the external insulation opens during the noon for a short
time and radiates the absorbed heat into the space during the nighttime, meaning the inside
insulation opens during the nighttime.
o In the summer months, the north wall’s insulation profile is set only to the month of June.
The temperatures in the months of July and August are already very high and the south
wall already received lot of heat because of its orientation. So, both of north wall’s
insulation panels will remain closed: set to ON, and in the month of June, north wall’s
external insulation is set to open only during the night for a short time to absorb the cooler
1 103 76 Open Close Open Close 1 111 87 Open Close Open Close 1 104 86 Open Close Open Close
2 103 78 2 108 82 2 109 88
3 102 74 3 105 77 3 109 87
4 100 74 4 100 73 4 98 89
5 100 72 5 102 74 5 103 86
6 104 75 6 103 77 6 112 84
7 105 79 7 106 79 7 106 88
8 105 81 8 109 80 8 105 88
9 106 82 9 112 78 9 106 87
10 110 85 10 114 84 10 108 86
11 113 85 11 115 81 11 108 86
12 111 81 12 113 83 12 107 89
13 102 79 13 112 83 13 101 84
14 106 76 14 108 87 14 107 87
15 108 78 15 113 87 15 106 87
16 109 81 16 115 92 16 110 87
17 102 79 17 114 92 17 110 88
18 96 70 2AM - 7AM 7AM - 2AM 2PM - 5PM 5PM-2PM 18 110 88 18 111 88
19 99 67 19 114 88 19 106 87
20 102 72 20 113 88 20 102 85
21 106 76 21 113 86 21 108 86
22 102 84 22 112 87 22 107 87
23 109 0 23 103 85 23 107 86
24 109 81 24 102 85 24 104 88
25 111 80 25 99 84 25 106 87
26 108 79 26 108 83 26 112 87
27 105 86 27 103 86 27 111 83
28 113 88 28 107 85 28 105 82
29 112 87 29 101 84 29 106 83
30 110 86 30 104 87 30 115 88
31 104 89 31 115 91
Avg 106 76 Avg 108 84 Avg 107 87
Inside
INSIDE INSULATION OPEN TIMES 2PM - 5PM 5PM - 2PM INSIDE INSULATION CLOSED TIMES
Outside Insu Inside
OUTSIDE INSULATION OPEN TIMES 2AM - 7AM 7AM - 2AM OUTSIDE INSULATION CLOSED TIMES
June July August Outside Insu Inside Outside Insu
1 109 89 Open Close Open Close 1 95 72 Open Close Open Close
2 105 88 2 95 74
3 109 89 3 103 78
4 111 91 4 101 80
5 112 92 5 99 81
6 114 89 6 97 77
7 105 87 7 97 76
8 107 86 8 95 78
9 91 75 9 95 76
10 85 74 1AM - 6AM 6AM - 1AM 3PM - 7PM 7PM - 3PM 10 97 74
11 97 77 11 93 74
12 90 78 12 97 69
13 95 79 13 99 74
14 97 77 14 99 71
15 96 72 15 89 68
16 98 71 16 84 67
17 96 70 17 92 69
18 94 68 18 93 68
19 97 66 19 92 70
20 97 68 20 93 69
21 97 71 21 94 70
22 99 66 22 84 66
23 101 78 23 79 62
24 106 81 24 77 60 11PM - 6AM 6AM - 11PM 1PM - 6PM 6PM - 1PM
25 108 81 25 79 55
26 109 86 26 81 58
27 107 79 27 83 60
28 99 83 28 81 59
29 99 80 29 86 57
30 100 75 30 89 59
31 89 62
Avg 101 79 Avg 91 69
September October Outside Insu Inside
INSIDE INSULATION CLOSED TIMES
OUTSIDE INSULATION OPEN TIMES 12AM - 6AM 6AM - 12AM OUTSIDE INSULATION CLOSED TIMES
Outside Insu Inside
INSIDE INSULATION OPEN TIMES 1PM - 6PM 6PM - 1PM
119

degrees of the temperature and remain closed during the daytime so that the wall doesn’t
absorb the hotter temperatures. The wall retains the colder temperature absorbed during the
night and radiates it into the inner space during the daytime as the interior insulation panel
opens.
o In the fall months, the temperature difference between the daytime and nighttime is
between 99°F and 71°F. To be able to bring the temperature down during the daytime to a
comfortable zone, the external insulation is set to open during the nighttime so that it can
absorb the cooler temperatures, store it, and radiate it to the inside space during the daytime,
meaning the internal insulation opens during the daytime.
These open and close times are set in the Macroflo profile manager for every season for both the
inside and the outside insulation (Fig 6-36 to 6-39).

Figure 6-36: North wall external insulation: Fall and Spring months.

Figure 6-37: North wall external insulation: Summer and Winter months
120

Figure 6-38: North wall internal insulation: Fall and Spring months.

Figure 6-39: North wall internal insulation: Summer and Winter months.

• Roof’s internal insulation component profiles:
The roof has only one insulation layer, and it is on the inside of the roof. The interior insulation
profile open and close times are edited according to the seasons. Since the previous base case
iteration showed an increase in the wintertime temperatures, therefore the profiles are set in the
wintertime to allow more cold temperatures inside the pocket lodge. The interior insulation in the
roof has an open profile setting of 6PM to 11AM in the months of November, December, January,
and February. (Fig 6-25 and 6-26).

121

Figure 6-40: Roof team member interior insulation open profile

Figure 6-41: Roof team member interior insulation annual profile.

After setting these values and profiles, the simulation is run for one entire year and the operative
temperature for the inside space is taken and is compared against the dry bulb temperature at
Joshua Tree National Park. The results show that during the winter months, the temperatures rise
to extreme temperatures, as high as 110°F. But the lowest temperature recorded is around 70°F,
which is within the thermal comfort zone for the pocket rangers. The green shaded region shows
the expanded comfort zone that is determined for this project (Fig 6-42).

122

Figure 6-42: Proposed – Comparison of the dry bulb temperature against the operative temperature output.

The lowest temperature recorded is 66.26°F in the month of January and the highest recorded is
around 102.76°F in the month of July.

Figure 6-43: Proposed: Lowest and highest temperatures.
The number of hours between the 65°F and 85°F thermal comfort range is 6165 hours, which is
around 70% of the time across the entire year. There are no hours under the 65°F but there are
2595 hours above the 85°F, which is around 29% of the time across the entire year.

123

Figure 6-44: Number of hours within the thermal comfort range.
The interior space of the room has a better thermally comfortable temperature year-round as
compared to the base case model. This is because of the change in the R values of the materials,
increasing the insulating properties, and the change in the open and close timings of the profile.

6.3 Summary
This chapter described the base case overall model, its material properties, thermal
comfort/ventilation, and dynamic insulation movement, and proposed overall model and its
material properties, thermal comfort/ventilation, and dynamic insulation movement and their
results.
All three individual components’ information were combined into one single model. The thermal
and ventilation tests are run for one entire year while comparing the inside room temperature with
the outside dry bulb temperature of Joshua Tree National Park. The single model with all the
information was first run without making any change to the data consolidated from the team and
then another simulation was run after making changes to some of the individual components to
achieve the most ideal interior room temperatures.
Important learnings from this chapter are
1. The profiles set to seasons work effectively as there can be a control on the open and close
settings and the insulation profiles can be used to monitor the internal room temperature.
2. The materials should follow minimum code compliant R and values. The higher the R
value of the material, the better its’ insulating property and the better is the internal thermal
temperature.
3. The highest and lowest temperatures in base case model without editing the information
provided by the teammates are 110°F and 70°F.
124

4. The highest and lowest temperatures in the proposed model after editing the material
properties and the insulation open/close profiles are 102°F and 66°F.
5. The higher temperatures, above 85°F are seen in the months of July, August, and
September. The seasonal rangers do not live in the park during these months. The months
between October to June are the times when the seasonal rangers stay within the park and
during those times the temperature inside the pocket lodge is more comfortable.
6. There might be an additional need for mechanical ventilation to narrow the graph and to
bring the temperatures across the year within the thermally comfortable range.

125

CHAPTER 7: CONCLUSIONS AND FUTURE WORK
This chapter describes the overall description, background and data collection, research
methodology and results, results and comparisons, improvements and future work.

7.1 Overall Description
The overall research findings and the final summary of the process are discussed.

7.1.1 Background and data collection
From the background information collection on Joshua Tree National Park, it was learned that the
temperatures throughout the year showed higher ranges of dry bulb temperatures during the
months of June, July, August, and September, while the temperatures during the winter times can
fall below freezing. The design strategies implemented needed to consider these temperature
ranges. Prefabrication is a preferred technique because the natural habitat of the national park will
be less disturbed during the construction phase. The entire tiny home unit will be fabricated off
site, transported to the site, and then placed on site. Other construction techniques and design
strategies such as passive solar energy, and thermal storage walls helped decide the orientation of
the pocket lodge along the east west axis to allow a better flow of wind through the building to
better help achieve thermal comfort. There are no windows on the north and south. The expanded
thermal evaluation technique is ideal for the tiny house because of the non-usage of mechanical
ventilation, and the seasonal rangers are young and fit, therefore they will be able to tolerate
temperatures slightly higher and lower than the normal thermal comfort ranges and because the
location has extreme diurnal temperature. Since the seasonal rangers reside in the park only for a
few months at a time and are capable to withstand temperatures of a much wider range, the thermal
comfort range was expanded for the analysis and the range was considered from 65°F to 85°F.

When the buildings around Joshua Tree National Park were studied, it was seen that most buildings
extensively used concrete as the building material, therefore considering concrete for the pocket
lodge was beneficial. To have better resource consumption and an energy efficient building, a
small sized area would be beneficial for a single occupant. From the previous area studies of
different tiny houses, an area of around 160sqft seemed reasonable, therefore a pocket lodge of
this area is designed and taken into consideration for all further simulations.
As for the material properties, a self-settling concrete mix is beneficial for the mold dimensions
and for the overall tubular structure proves beneficial for the structure and for the design
combinations and possibilities

7.1.2 Research methodology and results

The research methodology consisted of two parts: where the data was collected and analyzed
individually and where the data was collected and analyzed as a group. This methodology was
complicated as it lengthened the process of the research and consolidating all the data from the
team member was particularly difficult (Fig 7-1).

126

Figure 7-1: Research methodology showing work done individually and in group
Thermal, material, and weight calculations were conducted to finalize a real design.
The weight calculations showed that overall weight of the pocket lodge had to be restricted within
80,000 pounds as the trailer on which the fully prefabricated unit due to the transportation weight
restrictions as per California Trailer standards (Fig 7-2).

Figure 7-2: Weight calculations for pocket lodge
Interation No. Components Lenght (Inch) Height (Inch) Thickness (inch) Volume (Cubic Inches) lb/cubic inch Weight (lbs)
South Wall 360 120 6 259200 0.087 22550.4
North Wall 360 120 6 259200 0.087 22550.4
Roof 360 102 6 220320 0.087 19167.84
Base 360 102 6 220320 0.087 19167.84
Total 83436.48
South Wall 336 120 6 241920 0.087 21047.04
North Wall 336 120 6 241920 0.087 21047.04
Roof 336 102 6 205632 0.087 17889.984
Base 336 102 6 205632 0.087 17889.984
Total 77874.048
South Wall 336 120 12 483840 0.087 42094.08
North Wall 336 120 6 241920 0.087 21047.04
Roof 336 102 6 205632 0.087 17889.984
Base 336 102 5 171360 0.087 14908.32
Total 95939.424
South Wall 336 108 10 362880 0.087 31570.56
North Wall 336 108 6 217728 0.087 18942.336
Roof 336 96 6 193536 0.087 16837.632
Base 336 96 5 161280 0.087 14031.36
Total 81381.888
South Wall 336 108 8 290304 0.087 25256.448
North Wall 336 108 5 181440 0.087 15785.28
Roof 336 96 5 161280 0.087 14031.36
Base 336 96 5 161280 0.087 14031.36
Total 69104.448
1
2
3
4
5
Note: Base Model
Note: Length reduced to 336 inches (28 feet)
Note: South Wall Thickness = 12 inches and Base = 5 inches
Note: South Wall Thickness = 10 Inch, Height = 9 & Width = 8 feet
Note: South Wall Thickness = 8 Inches
127

The fabrication of the unit will follow a tube structure to increase resistance against seismic forces,
for ease of mold repetition and to encourage modularity in the overall design (Fig 7-3).

Figure 7-3: Prefabricating pocket lodge in tube forms.
The thermal simulation calculations were carried out in in several phases. The first phase of
simulations tested various base case overall models where various individual component details
were edited. The iterations were tested using IES VE software and the results show the highest
temperature fluctuation in the iteration where concrete material was introduced and a low
performing glass was added, and the least temperature fluctuation was achieved when the a thicker
concrete wall was proposed to the south wall and a better glazing system was proposed, with buffer
spaces added in the design and all other materials were code compliant with respect to their
insulating properties (Fig 7-4) .

Figure 7-4: Overall results of the base case initial iterations
Individual component simulations were tested using Honeybee Energy software and IES VE and
the results show that the inside and outside surface temperature of a concrete wall are smaller and
more stabilized as compared to that of a wood frame, low thermal mass wall (Fig 7-5).

Figure 7-5: Thermal mass material comparison.
Testing the inside operative temperatures of the model by changing the thickness of the concrete
wall in the south and the results show that with the increase in the thickness of the wall, the inside
room temperature decreases (Fig 7-6).
Overall base case models
35 113
33 109
25 146
25 123
35 116
4” Concrete walls + Operable low performing glass
6” Concrete walls + operable DGU system
6” concrete walls + DGU system + Buffer
8” South concrete wall + DGU system + Buffer fins + Code compliance
3
4
5
6
Lowest temp (F) Highest temp (F)
Description Iterations
1
2
4” low thermal mass wall + low performing glass
4” Concrete walls + low performing glass
32 138
Results
98.5 2
4 inch thk timber south wall
4 inch thk concrete south wall
108 113 130
103 106 85
1
Inside surf temp (F) Outside surf temp (F)
Thermal Mass studies tested for 24 hour period (August 15th)
IES VE Results
133
Iterations Description
Honeybee Energy Results
Inside surf temp (F) Outside surf temp (F)
128

Figure 7-6: Operative temperature comparison and results with change in wall thickness
The thermal comfort study to the pocket lodge was done by adding dynamic insulation to the south
wall alone, and a ventilation profile was added to the east west windows which read ta>to & ta>75,
where ta = the inside room temperature and to the outside temperature. The external and internal
dynamic insulation on the south wall was set to open and close with respect to the outside
temperature for every season. The results show decrease and a good stabilization of the inside
operative temperature with these inputs. The highest and the lowest recorded temperature are 65°F
on 8
th
January and 98°F on 14
th
July. The thermal comfort is achieved for around 80% of the 8760
hours when measured across one year but since the pocket rangers do not usually reside in the park
during the months of July, August, and September, the thermal comfort overall, excluding these
months is 95% (Fig 7-7).

Figure 7-7: South wall dynamic insulation overall thermal comfort
Adding dynamic insulation on all the walls (as shared from the work by the research teammates
on this project) and without changing any of the dynamic insulation properties and data, the overall
pocket lodge was run for one year and the result showed a performance that was worse than the
one with the dynamic insulation just on the south wall. The results showed the highest temperature
of 110°F on 11
th
March and lowest temperature of 70°F on 1
st
January. The thermal comfort is
achieved for around 41% of the 8760 hours (Fig 7-8).

Figure 7-8: Base case south wall, north wall, roof overall thermal comfort

When changes to the north wall dynamic insulation profiles and to the roof insulation profiles were
made, the condition improved. The north wall exterior and interior insulation was set to a seasonal
profile and the roof was given a similar profile. The results showed the highest temperature of
8 inch thk concrete south wall
12 inch thk concrete south wall
3
4
98 92
87 88
2 6 inch thk concrete south wall 101 95
1 4 inch thk timber south wall 105 97
Thermal comfort studies tested on different concrete thickness
Iterations Description
Honeybee Energy Results IES VE Results
Operative temp (F) Operative temp (F)
Wall thickness Insulation thickness Ext. Insulation open times Lowest temp (F) Highest temp (F)
79%
Winter : 11am to 4pm
Spring : 8am to 6pm
Fall : 11pm to 10am
Int. Insulation open times
Summer : 7am to 1pm
Winter : 9pm tp 8am
Spring : 10pm to 8am
Fall : 11am to 6pm
Summer : 11pm to 4am
Thermal comfort percentage
South wall 8" 3"
65 98
Thermal comfort percentage
South wall 8" 3"
Summer : 7am to 1pm Summer : 11pm to 4am
Winter : 9pm tp 8am
Wall thickness Insulation thickness Int. Insulation open times Ext. Insulation open times Lowest temp (F) Highest temp (F)
North wall 5" 3"
Dec - Jan : 7am to 6pm Nov - Apr : OFF continously
70
Mar - May : 6pm to 11am
Jun - Aug : OFF continously
110 41%
Dec - Feb : OFF continously
Feb - Nov : ON continously May - Oct : 6pm to 7am
Winter : 11am to 4pm
Spring : 10pm to 8am Spring : 8am to 6pm
Fall : 11am to 6pm Fall : 11pm to 10am
Sep - Nov : ON continously
3" 5" Roof NA
129

102°F on 12
th
July and lowest temperature of 66°F on 1
st
January. The thermal comfort is achieved
for around 71% of the 8760 hours (Fig 7-9).

Figure 7-9: Proposed south wall, north wall, roof overall thermal comfort

7.1.3 Results and comparison
Several models were simulated and results shown: south wall dynamic insulation, base case
overall model, and proposed overall model.

• South wall dynamic insulation results
The first result discussed here show the results of the dynamic insulation when applied on the south
wall (Fig 7-10).

Figure 7-10: Only south wall - Comparison of the dry bulb temperature against the operative temperature output.
The lowest temperature recorded is 65.31°F in the month of January and the highest recorded is
around 98.95°F in the month of July (Fig 7-11).

Thermal comfort percentage
South wall 8" 3"
Summer : 7am to 1pm Summer : 11pm to 4am
66 102 71%
Winter : 9pm tp 8am
Wall thickness Insulation thickness Int. Insulation open times Ext. Insulation open times Lowest temp (F) Highest temp (F)
North wall 5" 3"
Summer : 1pm to 6pm Summer : OFF continously
Winter : 11am to 4pm
Spring : 10pm to 8am Spring : 8am to 6pm
Fall : 11am to 6pm Fall : 11pm to 10am
Roof 5" 3"
Summer : OFF continously
NA
Winter : 6pm to 11am
Spring : OFF continously
Fall : OFF continously
Winter : 1am to 8am Winter : 11am to 5pm
Spring : 2am to 8am Spring :12pm to 7pm
Fall : 12pm to 7pm Fall : 12am to 7am
130

Figure 7-11: Only south wall: Lowest and highest temperatures
The number of hours between the 65°F and 85°F thermal comfort range is 6915 hours, which is
around 79% of the time across the entire year. There are no hours under the 65°F but there are
1845 hours above the 85°F, which is around 21% of the time across the entire year (Fig 7-12 and
7-13).

Figure 7-12: Number of hours within the thermal comfort range.

Figure 7-13: Thermal comfort heat map of average operative temperatures
• Base case overall model results
January February March April May June July August September October November December
00:30 69 72 72 73 78 83 89 88 80 78 77 73
01:30 69 72 72 73 77 82 88 87 79 79 77 73
02:30 69 72 72 73 77 81 87 86 79 79 77 73
03:30 69 72 72 73 76 80 86 85 78 79 77 73
04:30 69 72 72 73 76 79 85 84 78 79 77 72
05:30 68 71 71 73 75 78 83 82 78 78 76 72
06:30 68 71 71 72 75 79 82 81 78 78 76 71
07:30 68 71 71 73 76 79 83 81 78 78 76 71
08:30 68 71 71 73 77 80 84 82 79 78 77 72
09:30 69 71 72 73 77 82 87 85 79 78 77 72
10:30 73 75 76 77 81 85 91 88 82 82 81 76
11:30 74 77 78 79 83 88 93 91 85 80 82 78
12:30 75 77 77 79 83 90 95 93 86 81 83 78
13:30 72 74 75 77 81 88 93 92 85 80 79 75
14:30 71 73 74 76 81 87 93 91 85 80 78 74
15:30 71 73 74 76 80 87 92 91 85 80 78 74
16:30 70 73 74 76 80 87 92 91 85 80 78 74
17:30 70 72 74 75 80 87 92 91 84 79 78 73
18:30 70 72 73 75 80 87 92 91 84 78 78 73
19:30 70 72 73 74 79 86 92 90 83 77 78 73
20:30 70 72 73 74 79 86 91 90 83 77 77 73
21:30 70 72 73 74 79 86 91 89 82 78 77 73
22:30 70 72 73 74 79 85 91 89 82 78 77 73
23:30 70 72 73 74 79 84 90 88 81 78 77 73
131

The base case overall model is where all the best test individual component details from the team
members are collected and thermal simulation for one year is run without changing any data shared
by the team members. show the results of the dynamic insulation when applied on the south wall
(Fig 7-14).

Figure 7-14: Base case - Comparison of the dry bulb temperature against the operative temperature output.
The lowest temperature recorded is 70.45°F in the month of January and the highest recorded is
around 110.42°F in the month of March (Fig 7-15).

Figure 7-15: Base case: Lowest and highest temperatures

The number of hours between the 65°F and 85°F thermal comfort range is 3626 hours, which is
around 41% of the time across the entire year. There are no hours under the 65°F but there are
5134 hours above the 85°F, which is around 58% of the time across the entire year (Fig 7-16 and
7-17).

132

Figure 7-16: Number of hours within the thermal comfort range.

Figure 7-17: Thermal comfort heat map of average operative temperatures
• Proposed overall model results
The next results shown are the ones where the data received from the team members are
manipulated in a way that the internal temperatures see a more comfortable range across the year.
The result of the proposed model are shared here for a quick overview (Fig 7-18).
January February March April May June July August September October November December
00:30 81 90 87 83 81 84 89 88 80 82 88 91
01:30 81 90 87 83 81 82 88 87 79 82 88 90
02:30 81 90 87 83 80 81 87 86 78 82 87 90
03:30 81 90 87 83 79 80 85 84 78 82 87 90
04:30 81 90 87 84 79 79 84 83 78 82 87 90
05:30 79 88 86 82 78 78 83 81 78 81 86 88
06:30 78 87 85 81 78 78 81 80 77 80 85 87
07:30 78 88 85 82 79 79 82 80 78 80 85 87
08:30 79 88 85 83 80 80 84 81 79 81 86 88
09:30 80 89 86 83 81 82 87 84 79 82 87 89
10:30 89 99 96 90 87 87 92 89 83 89 95 99
11:30 95 104 101 94 89 90 95 92 86 87 100 104
12:30 97 106 99 93 89 93 98 95 89 86 101 106
13:30 90 97 90 88 88 93 98 96 89 83 93 99
14:30 86 94 86 86 87 93 98 96 89 82 89 94
15:30 85 92 86 86 86 92 98 96 89 83 89 92
16:30 84 91 85 85 86 92 98 96 88 83 88 92
17:30 83 91 85 85 86 93 97 95 88 82 88 92
18:30 83 91 84 84 85 92 97 95 87 80 88 92
19:30 83 91 83 83 84 91 96 94 86 79 88 92
20:30 82 91 84 83 84 90 95 92 85 79 88 91
21:30 82 91 85 82 84 89 94 91 84 80 88 91
22:30 82 91 86 82 83 87 92 90 83 81 88 91
23:30 82 91 87 82 82 85 91 89 81 81 88 91
133

Figure 7-18:Proposed - Comparison of the dry bulb temperature against the operative temperature output.
The lowest temperature recorded is 66.26°F in the month of January and the highest recorded is
around 102.76°F in the month of July (Fig 7-19).

Figure 7-19: Proposed: Lowest and highest temperatures.

The number of hours between the 65°F and 85°F thermal comfort range is 6165 hours, which is
around 70% of the time across the entire year. There are no hours under the 65°F but there are
2595 hours above the 85°F, which is around 29% of the time across the entire year (Fig 7-20 and
7-21).

134

Figure 7-20: Number of hours within the thermal comfort range.

Figure 7-21: Thermal comfort heat map of average operative temperatures
Note that the model for the south wall only gave the best results. The results turn out best in this
case because the insulation layers on the south wall alone help with reducing any additional heat
gain inside the space and the ventilation profile engage in ventilation and removing the heat build-
up. At a climate with extreme heat and cold, the heat gain needs to be controlled in the interior
space and use it in the occupant’s favour when it gets too cold. This is possible by controlling and
installing dynamic insulation on the south side alone as more amount of solar heat gain comes
from the south side. The roof is given a good insulating value in its construction property and that
aids in regulating the heat flux in the interior space. Whereas in all other cases with the insulation
layers on the other components as well might be helping in adding to the solar heat gain inside the
January February March April May June July August September October November December
00:30 73 79 79 78 79 83 89 88 80 79 81 80
01:30 73 79 79 78 79 82 88 87 78 80 81 80
02:30 73 79 79 78 78 80 86 85 78 80 81 80
03:30 73 79 79 78 78 79 85 84 77 80 81 80
04:30 73 79 79 78 77 79 84 83 77 80 81 80
05:30 71 77 77 77 76 77 82 81 77 79 79 78
06:30 71 77 77 76 76 78 81 80 77 78 79 77
07:30 71 77 77 77 77 79 82 80 77 78 79 77
08:30 71 78 77 77 78 79 84 81 78 79 80 78
09:30 72 78 78 78 79 82 87 84 79 80 81 79
10:30 80 86 87 84 85 86 92 89 82 86 88 87
11:30 85 91 91 88 87 90 95 92 86 84 92 92
12:30 86 92 89 87 88 92 98 95 88 84 93 93
13:30 80 86 83 84 86 92 97 95 88 81 86 87
14:30 77 83 80 82 85 91 96 95 88 81 83 83
15:30 76 82 80 81 84 91 96 95 87 81 83 82
16:30 75 81 80 81 84 91 96 94 87 81 82 82
17:30 75 80 80 81 84 91 96 94 86 80 82 81
18:30 74 80 79 80 83 91 95 93 85 79 81 81
19:30 74 80 78 79 82 89 94 92 84 78 82 81
20:30 74 80 78 78 81 88 93 91 84 77 81 81
21:30 74 80 78 78 81 87 92 90 83 78 81 81
22:30 74 80 79 78 81 86 91 90 82 79 81 80
23:30 73 79 79 78 81 85 90 89 81 79 81 80
135

space, trapping and keeping the heat inside the space due to the interference of the insulation layers
with each other. The software might also be over calculating these insulation layer interactions as
the software has been manipulated to consider the tiny spaces and dynamic insulation panels
(Table 7-1).

Table 7-1: Summary of four studies air temperature interior space results
≤ 65°F > 65°F to ≤ 85°F > 85°F
Only south wall model 0 6915 1845
Base case team model 0 3626 5134
Proposed improved model 0 6165 2595

7.2 Improvements and Future Work
The results, details, and simulations for the pocket lodge could be improved and there is a high
potential to carry forward the simulations for future work. Some of the improvements, challenges,
and future work opportunities are discussed here.

7.2.1 Improvements
The basic improvement that can be done was to the methodology of the pocket lodge itself. The
team members focused on individual components whereas it would have helped to control and
design the pocket lodge overall by each team member and compare the overall results to
understand the impacts of each member’s idea and concept.

There are improvements that can be done to the pocket lodge with respect to the structure and the
software:

• Improvements with respect to design

1. Consider the size of the lodge. There could be a heat buildup in the space because of
the small volume of the pocket lodge. A pocket lodge of a larger volume might help
with controlling the indoor temperatures and reducing the heat flux.
2. Study the qualities of concrete more thoroughly. A better form of precast concrete
would have helped with the transportation and the thermal properties if not for the
monetary restrictions.
3. Determine a method of using earth as an insulation material without disturbing the
ground. The entire pocket lodge’s foundation design could be designed in such a way
that it is pushed under the grade level. This phenomenon will help with moderating the
indoor heat.
4. More design options can be generated for the interior layout of the pocket lodge and
designing spaces for toilets and a kitchen area that can help the seasonal rangers with
their stay in the national park.
5. Consider how to provide electricity for times that are still not thermally comfortable.
Generate more power than what is needed to sustain the pocket lodge and try to provide
that power to the adjacent buildings to sustain on PV powered energy.
136

6. Design the pocket lodge to be locked and kept safe during the days when it is not
occupied. This can be achieved by designing to design the roof overhangs on the east
and west side fold down and lock the pocket lodge during no occupancy.
7. Design the building in a way that it can be easily dismantled or relocated, if needed.
8. Design the pocket lodge in a way that it can be used by the visitors or the natural fauna
to use the space and interact with the natural surroundings.

• Improvements with respect to materials
1. Experiments with different thermal mass materials, which are lighter in weight and
have better thermal conductivity properties as compared to concrete. This might be
beneficial with the weight restrictions.
2. The south wall can focus on having a textured surface that will help with the dissipation
of the solar heat on the external surface.
3. Research admixtures that go into the concrete mixture that are sustainable and might
help with the heat absorption. A material that will help with the thermal battery concept
on the south wall.
4. Explore interior finishes that will work best for the heat buildup inside the space. For
examples: choice of floor tiles, or the insulation materials.
5. Explore various insulating property materials that have better heat insulating
properties, that are environmentally sustainable, energy efficient, with relatively small
thickness.

• Improvements with respect to software

1. Run more detailed, and longer duration of thermal analysis can be performed and more
iterations on the dynamic insulation can be performed for accurate results.
2. Research alternative software programs that can be used to simulate natural ventilation
and thermal comfort inside a space.
3. Test for other national parks. The pocket lodge can be tested for other climatic
conditions.

7.2.2 Future Work
There is considerable scope left to better design a pocket lodge. Some of the things that can be
considered for more substantial future work are the following:
1. Create a software program that can run thermal simulation calculations for naturally
ventilated buildings. A software that takes different materials, its thermal conductivity into
consideration, thermal lag, and thermal mass properties into consideration, and generate
the thermal simulation outputs.
Develop a tool for calculating thermal mass properties by inserting different material
compositions and their properties and generate thermal energy outputs for different
building types.
2. Develop a prototype model for each type of climate zone that thoroughly discusses the
design strategies best suited for each of those climate types. This will help with coming up
137

design guidelines for those wishing to use passive design, especially walls for retaining
heat and cold as appropriate.
3. Calculate the number of hours that are within the thermal comfort range and the number of
hours that are outside this range. Develop strategies where mechanical ventilation or fans
can be introduced which will help with bringing those hours also within the thermal
comfort range.
4. Design the automated control systems for the insulating layers that are set to function
according to the occupants’ comfort conditions.
5. One immediate future work that this pocket lodge sees is to produce a physical
prototype/model with the current design and simulations and install it on the site. This will
need prefabrication of the walls, roof, and floor and this will need designing all the corner
joints, connection details, and creating an overall composite model. All details pertaining
to the production of this unit should be designed and discussed.
6. A thermal data collector can be installed inside the space and on the wall surfaces to test
and validate the data generated by the analytical software and to compare it against real-
life data.

7.3 Summary
The pocket lodge was rendered and visualized on Lumion to place it in site (Fig 7-22).

Figure 7-22: Graphical representation of the pocket lodge
This chapter described the overall description, background and data collection, research
methodology and results, comparisons, improvements, and future work. The severe housing
138

shortage for the seasonal rangers at Joshua Tree National Park are discussed and resolved by
designing units that are free-flowing and have an exceptional speed of construction.
An 8-inch south wall with a dynamic inside and outside insulating layer is found ideal with respect
to the indoor thermal temperatures and the weight restrictions to achieve comfortable thermal
temperature for 80% of the hours in a period of one year as compared to the iteration when the
dynamic insulating layer is added on the north wall, and the roof. The iteration with the dynamic
inside and outside insulating layers on the south wall also help in increasing the energy savings by
45% in Joshua Tree National Park. The parameters used in the iteration with the best thermal
comfort result had the dynamic insulation installed only on the south wall with the interior and
exterior insulations set to have an open and close control with respect to the seasonal temperatures.
The windows were also given a ventilation profile that is set to open and close according to the
outside temperature and according to the rise in the inside temperature. This yielded in 6915 hours
of thermal comfort out of the overall 8760 hours in a year.
A small residence that provides thermally comfortable inside temperatures year-round has
significant benefits on the occupants, environment, and the housing industry. A prefabricated unit
that can maintain a comfortable inside temperature helps in construction time and quality with
minimal site disturbance. It also saves energy by using passive design strategies. The small size
makes the unit more affordable. A different climate zone variant could be used as a prototype for
other national parks and/or other areas as a strategy for affordable housing.

139

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146

APPENDIX A

This section comprises of the images from the research.

Appendix 8-1: Script for low thermal mass surface temperature analysis
Appendix 8-2: Script for high thermal mass surface temperature analysis
Appendix 8-3: Tiny house thermal study script

Appendix 8-1: Script for low thermal mass surface temperature analysis
This script is used to find the inside and outside surface temperature of a low thermal mass
wall.

147

Appendix 8-2: Script for high thermal mass surface temperature analysis
This script is used to find the inside and outside surface temperature of a high thermal mass
wall.

148

Appendix 8-3: Tiny house thermal study script
This script is used to test the thermal comfort of the inside space of pocket lodge.

Abstract (if available)

Abstract One resolution for the severe housing shortage for the seasonal rangers at Joshua Tree National Park can be providing housing that is modular and has a rapid production process. The housing that is currently available is outside the national park uses mechanical systems to achieve comfortable indoor temperatures. Precast concrete is a good candidate material considering its high thermal mass and exceptional speed of construction. It is possible to design units that are fully self-supporting by creating a high-performance building enclosure that can regulate the thermal performance of the residence, and the south-facing wall - the face that receives maximum solar gain – can be used to achieve internal thermal. The simulation iterations include varying concrete thickness and exploring various insulating materials, their locations, and thickness. A dynamic insulating layer is proposed as a strategy for using high diurnal temperature swings like those at Joshua Tree National Park using the south wall as a thermal battery as the concept where the concrete wall is pumped up with heat; the exterior and interior insulations are regulated according to the outside temperatures; and the concrete wall slowly dumps the heat to achieve thermal comfort inside The dynamic control setting is designed to function considering the outside temperature. These iterations and simulations are tested and run on Honeybee Energy and IESVE.
The iterations on the south-facing wall show a thickness of 8 inches to be ideal with respect to thermal calculations and weight restrictions with a dynamic thermal insulating layer with a controlled setting that switches on and off according to the outdoor temperature for every season. By adding an insulation layer on the south wall, north wall and on the roof, with a control setting set to switch on and off according to the seasonal outdoor temperature, the indoor thermal comfort increased by 29%. The iteration that was considered effective and ideal not only for regulating the indoor temperature but also increase the indoor thermal comfort by 40% was by adding the dynamic interior and exterior insulation with a seasonal control setting to the south wall alone. This dynamic thermal insulation system with an 8” thick concrete wall can reduce the average indoor temperature and help increase the energy savings by 45% in Joshua Tree National Park for the designed small residence.

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Creator Janardanan, Archana (author)

Core Title A high-performance SuperWall: designed for a small residence at Joshua Tree National Park

School School of Architecture

Degree Master of Building Science

Degree Program Building Science

Degree Conferral Date 2023-05

Publication Date 05/03/2023

Defense Date 03/31/2023

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag dynamic insulation,hot-arid climate,Joshua Tree National Park,OAI-PMH Harvest,precast concrete,thermal comfort

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