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Thermbuilder: A Web-based teaching tool to study thermal processes in buildings
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Thermbuilder: A Web-based teaching tool to study thermal processes in buildings
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INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. ProQuest Information and Learning 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 800-521-0600 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. NOTE TO USERS This reproduction is the best copy available. UMI' R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. THERMBUILDER : A WEB BASED TEACHING TOOL TO STUDY THERMAL PROCESSES IN BUILDINGS Copyright 1999 By Geetika Tandon A Thesis Presented to the FACULTY OF TH E SCHOOL OF ARCHITECTURE UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree MASTER OF BUILDING SCIENCE (Building Science) Decem ber 1999 Geetika Tandon R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. UM I Number: 1409661 UM I Microform 1409661 Copyright 2002 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O . Box 1346 Ann Arbor, Ml 48106-1346 * R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. UNIVERSITY OF SOUTHERN CALIFORNIA SCHOOL OF ARCHITECTURE UNIVERSITY PARK LOS ANGELES, CA 90089*0291 This thesis, written Sy GEEt Pka TANPO-N_________ under the direction o f h'QJr* Thesis Committee, and approved B y ad its m em b ers, das B e e n presented to and accepted B y the (D ea n of Hie S ch aoC of Architecture in partiaC fulfillment o f the requirements fo r the degree of F bUllrPllUj S C I E N C E < D ean < D a t e _ THESIS COMMfrTJ R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. ACKNOWLEDGEMENTS: It is said that “ All great undertakings are achieved through mighty obstacles". However, in the case of my thesis, I would say that all undertakings big or small, cannot be achieved without the support of friends, family and guides who are always there to show you the way. They are there when you slip and fall. It is because they were there, that you did not get lost. I would like to start by thanking my parents, who have been the constant source of inspiration in any endeavor that I have undertaken. It is their encouragement and support that has got me here today. Secondly, Professor Marc Schiler, who is Director of this course and also my Committee chair. I am grateful to him for many things. Firstly, to have given me admission along with financial support. Furthermore, in guiding and encouraging all endeavors that I undertook, encouraging every idea, in being supportive in finishing my thesis early and accommodating for i t , in the vacation as well. I would not have been able to complete my thesis without his constant guidance and support. Thirdly, Professor Doug Noble and Karen Kensek, who were my committee members and who were always there, enthusiastically guiding me and providing me with new ideas, every time I was in a fix. And Last, but not the least, my husband Pankaj Sinha, who has been my friend, guide and philosopher through this entire course. He has given me his complete confidence and support, when I needed it most. I could not have taken on this task without his presence and I cannot adequately express my thanks to him. ii R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. TABLE OF CONTENTS Acknowledgments ii List o f Figures v Abstract viii Part I INTRODUCTION 1 1.1 Introduction 1 Part II BACKGROUND RESEARCH 3 2.1 Processes o f heat transfer 3 2.1.1 Conduction 3 2.1.2 Convection 4 2.1.3 Radiation 6 2.1.4 Latent H eat 7 2.2 Solar Factors Affecting Heat Transfer 8 2.2.1 Solar B asics 8 2.2.2 Solar Radiation 12 2.2.3 Shading 14 2.3 Factors in Thermal Comfort 20 2.3.1 W ind 20 2.3.2 Human Factor 22 2.3.3 Relative Hum idity 24 2.3.4 M ean Radiant Temperature 25 2.3.5 Correlation o f all factors 27 2.4 Climatic Factors 30 2.4.1 B asic Climate Types 30 2.4.2 Building Form and Shape 31 2.4.3 M icro-clim atic Factors 33 2 .4.4 Principles o f Vernacular Architecture 37 2.5 Heat Gain/Loss Calculations 42 2.5.1 Factors in Heat gain/Loss 42 2 .5.2 B asic theory and Formulae 45 2.6 Thermal Controls 49 2.6.1 Passive M eans 49 2.6.2 Active M eans 68 Part III THE W EB AS A TEACHING M ED IU M 80 3.1 Issues involved in using the web as a teaching medium 80 3.2 Analysis o f existing tools 83 3.2.1 Existing teaching web sites 83 3.2.2 Existing building technology web sites 89 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 3.3 Need for a new Tool 98 Part IV T H E R M B U IL D E R - A W EB B A SE D TEACHING TOOL 99 4.1 R esources used and needed 99 4 .2 Potential Users 103 4.3 W eb Considerations 104 4.3.1 Planning and organization 104 4 .3 .2 Advantages over an illustrated book/ CD-ROM 107 4 .3.3 Navigation Clarity 109 4 .3 .4 Dow nload Tim e 119 4.3 .5 Printing Considerations 120 4.4 Scope and limitations 121 4.5 Structure o f the site 122 4.5.1 Theory 124 4 .5 .2 Num erics 135 4 .5 .3 Thermal Controls 137 4 .5 .4 D esign Advisor 139 Part V INTO THE SU N N Y FUTUR E 140 Bibliography 142 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. List of Figures Figure 2-1: Process o f conduction 3 Figure 2-2: Process o f convection 4 Figure 2-3: Process o f radiation 6 Figure 2-4: Graph showing latent heat o f a substance at change o f state 6 Figure 2-5: Solar orbit 8 Figure 2-6: Diagram o f Azimuth angle 10 Figure 2-7: Diagram o f Altitude angle 11 Figure 2-8: Solar radiation calculator 14 Figure 2-9: Overlay o f radiation on solar stencil 14 Figure 2-10:Positioning o f the overhang 15 Figure 2-1 l:Vertical shading devices 17 Figure 2-12: Egg-crate shading devices 18 Figure 2-13: Graph o f air velocity and temperature 21 Figure 2-14: Diagram s showing good ventilation for heating and cooling 22 Figure 2-15:Factors in human loss and thermal comfort 23 Figure 2-16: Graph showing relative humidity and temperature 25 Figure 2-17: Graph showing M RT and temperature 26 Figure 2-18: Heat gain 28 Figure 2-19: Heat loss 28 Figure 2-20: Thermal balance 29 Figure 2-21: M ap o f United States showing basic climate layout 30 Figure 2-22: Summer winds 34 Figure 2-23: Winter winds 34 Figure 2-24: E ffect o f topography 34 Figure 2-26: Effect o f Vegetation 36 Figure 2-27: Harmony with nature 37 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Figure 2-28: Hot humid building design 38 Figure 2-29: Hot arid design 39 Figure 2-30: Vernacular architecture o f cold climates 40 Figure 2-31: Vernacular architecture o f temperate clim ates 41 Figure 2-32: Factors in heat gain/loss 43 Figure 2-33: Direct gain through windows 51 Figure 2-34: Direct gain system 51 Figure 2-35: Shading- louvets and awnings 52 Figure 2-36: Diagram o f water wall 53 Figure 2-37: Diagram o f trombe wall 53 Figure 2-38: Diagram o f roof pond ' 54 Figure 2-39: Isolated gain solar system 55 Figure 2-40: W ind m ovem ent and ventilation 58 Figure 2-41: Characteristics o f soil 61 Figure 2-42: Soil subsurface below the earth 62 Figure 2-43: Soil subsurface heat flow patterns around the building 62 Figure 2-44: Concrete subsurface structure 64 Figure 2-45: Flat plate collector 70 Figure 2-46: Evacuated tube collectors 71 Figure 2-47: Transpired air collectors 72 Figure 2-48: P V Cells 73 Figure 2-49: Inside a P V Cell 74 Figure 2-50: Crystalline Silicon Process 74 Figure 2-51: Roler blade o f a turbine 76 Figure 2-52: W ind turbine 76 Figure 2-53: Horizontal wind turbine 77 Figure 2-54: Horizontal wind turbine 77 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Figure 3-1: Snapshot o f web site o f Leicester University 85 Figure 3-2: Web site for teaching heat and mass transfer 87 Figure 3-3: Snapshot o f web site for teaching structures 88 Figure 3-4: Snapshot o f web site providing information on architectural atmospherics 89 Figure 3-5: Snap shot o f Hom e Energy saver main page 90 Figure 3-6: Snapshot o f start page o f Hom e Energy Saver 91 Figure 3-7: Snapshot o f the REED site 92 Figure 3-8 Snap shot showing a schem atic design tool 94 Figure 3-9: The Interactive User Interface o f B D A . 95 Figure 3-10: Snapshot o f THERN start 96 Figure 3-11: Graphic and analytical ability o f THERM 96 Figure 4-1 Shallow site layout 105 Figure 4-2: Deeep Site Layout 105 Figure 4-3: Balanced Site Layout 106 Figure 4-4: Structure o f Thermbuilder 106 Figure 4-5: Visible area o f the screen 111 Figure 4-6: Use o f attractive graphics for linking 111 Figure 4-7: Use o f global back buttons on each page 113 Figure 4-8: Back links provided by graphics 113 Figure 4-9: Use o f smaller windows for different subsections 114 Figure 4-10: U se o f a clear margin for sub-sections links 115 Figure 4-11: Use o f a com bination o f graphics and text for linking 116 Figure 4-12: Use o f mouseovers 116 Figure 4-13: U se o f m ouseovers in subsections 117 Figure 4-14: Example o f adhoc links in the web-page 118 Figure 4-15: Another exam ple o f adhoc links 118 with permission of the copyright owner. Further reproduction prohibited without permission. Figure 4-16: Snapshot o f the first page which has separate links to each part 123 Figure 4-17: Snapshot o f theory main page 124 Figure 4-18: Snapshot o f processes page 125 Figure 4-19: Snapshot o f radiation page 126 Figure 4-20: Snapshot o f convection m ovie starting shot 126 Figure 4-21: Snapshot o f the ventilation calculator in a room 127 Figure 4-22: Snapshot o f the Thermal Comfort M ain page 128 Figure 4-23: Snapshot o f the wind and air m ovement p page 128 Figure 4-24: Snapshot o f the Thermal Comfort correlations page 129 Figure 4-25 Snapshot o f the Thermal Comfort m ovie start page 129 Figure 4 -2 6 Snapshot o f solar factors main page 130 Figure 4 -2 7 Snapshot o f solar radiation page 131 Figure 4 -2 8 Snapshot o f the Sun Path m ovie start shot 131 Figure 4 -2 9 Snapshot o f the shading device m ovie 132 Figure 4 -3 0 Snapshot o f Climatic factors main page 133 Figure 4-31 Snapshot o f building form and shapes page 133 Figure 4 -3 2 Snapshot o f Vernacular architecture m ovie page 134 Figure 4-33 Snapshot o f climate types page 134 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. ABSTRACT The purpose of this project is to create a Web Based educational tool for teaching Thermal Processes in buildings. This teaching tool, provides basic information on “Thermal Processes in Buildings” in an interesting and interactive manner to a wide audience, and in so doing demonstrates the effectiveness of the web as a medium for education and learning over a textbook. The tool not only serves as a useful source of information but also allows for user interaction through its calculation tools, games and movies. Along with these it encourages the user to judge the effectiveness of the tool through its quizzes and feedback sections. R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. PART ONE INTRODUCTION TO THERMAL PROCESSES IN BUILDINGS Buildings and shelter have been one of the most important considerations for human beings on this earth. The process of making buildings has moved from simple mud and ice dwellings to sophisticated intelligent buildings of the 21st century and the scope of the builder, designer and architect have moved from art to physics, chemistry and engineering , giving birth to the field of Building Science, as it is today. Since the energy crisis in early 1970’s, this need to know all the physical and mechanical processes has further increased, so that once the processes are understood, they can be used to make energy efficient and thermally sound buildings. These various processes which effect heat transfer from buildings to the outside world and vice versa are called Thermal Processes in Buildings. These physical processes are what work behind the facades, making a building hot, cold, windy or sunny. There are various factors, which effect this interaction between the building and the environment such as the location and climate, the solar position of the buildings, temperatures inside and outside, the materials used in the buildings. Over the years many books have tried to capture the essence of these processes, in order to make the architect well aware and equipped to deal with energy and environmental issues. However, in the last few decades computers have invaded the living world and are now part and parcel of every aspect of our lives. Their use in design, analysis and simulation of processes in buildings has been steadily increasing. Even more recently, the advent of the internet and the world wide web have greatly enhanced the ability of the computers, bringing the world together as a community. l R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Computers and more so the W orld Wide Web, within the short span of two decades have become such an integral part of our civilization, that one philosopher has very rightly s a id : "I do not fe a r computers. I fe a r lack o f them." - Isaac Asimov Simply put, the W orld W ide W eb is a way to share resources with many people at the same time, even if some of those resources are located at opposite ends of the world. If you think of it as a research paper that lets each footnote take you right to the original source, then you've got the basic idea. W hat began as a research tool has blossomed into something unexpected and much more fun. W ith the introduction of Mosaic and more recently Netscape, Internet Explorer and other extremely advanced graphical web browsers, the web became a communications tool for a much wider audience. Web pages can include text information, pictures, sounds, video, FTP links for downloading software, and much more. One can create living documents that are updated weekly, daily, or even hourly to give web surfers a different experience every time they visit any pages. As the technology develops, even more amazing applications will be possible. Thus, it is the prime medium today, for research and development, getting information about anything, for increasing one’s knowledge on any topic and in essence it is already an excellent teaching tool. I have used the power of this medium to put together a tool which provides basic information about the Thermal Processes involved in buildings, the factors that effect it, ways of calculating the heat gained or lost by buildings and the various means of controlling these by active and passive processes.1 1 “E a sy to u se” com pared to a b o o k as the hyper lin king in a w eb to o l m akes it p o s sib le to g o to the desired inform ation in o n e or tw o click s o f the m ou se button (p rovid ed it has an e ffic ie n t n a v ig a tio n sy stem o f co u rse) as against the having to sh u ffle through several p a g es in a book. 2 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. PART TWO: FACTORS INVOLVED IN THERMAL PROCESSES IN BUILDINGS 2.1 PROCESSES OF HEAT TRANSFER Heat transfer involves four basic processes: 2.1.1 CONDUCTION Figure 2-1 Process of conduction Conduction of heat is the process of heat transfer in solids. The molecules in a solid start vibrating when heated and these vibrations are passed on to the adjacent molecules. This process of heat transfer is called conduction. In this process, heat is transferred only through the vibrations of the molecules. They do not physically move to do so. In buildings, heat is transferred by conduction, mainly by the walls or roof either inwards or outwards. Conduction flow rate through a wall of a given area can be described by the equation : Qc = A * U * AT where Qc = conduction heat flow , in W 3 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. A = surface area, in square meters U = transmittance value in Watts/sq mts deg C AT = temperature difference . This formula is very important and appears in almost all heat gain and heat loss calculations. 2.1.2 C O N V ECTIO N Figure 2-2 Process of Convection Convection is the process of transfer of heat in which molecules of cool air absorb heat from a warm surface air, rise, and carry it away. The cool air on top, which is denser replaces this warm air at the bottom, getting heated again and thus the process continues. In this process heat is transferred through the actual physical movement of the molecules. This form of heating is called convection. Convection heat flow in a building occurs mainly in the interior spaces - within a room, between an air gap in the walls, or roof or within two layers of glass in a window. A ir exchange between the interior of a building and the outside air is called infiltration. Convection and infiltration are both forms of mass flow but convection heat flow takes place mainly in the interiors while infiltration takes place between the building and the 4 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. outsied air. Ventilation is a form of infiltration. It depends on the rate at which this air exchange takes place which is called the rate of ventilation. This maybe, unintentional air infiltration or maybe deliberate ventilation. Winter heat loss(and summer heat gain in closed, cooled buildings) occurs when "fresh" outdoor air enters the building to replace "stale" indoor air. This heat exchange, is analogous to human lung heat losses/gains and must be calculated while sizing heating or cooling equipment or when estimating energy use per season. The rate of ventilation heat flow is described by the equation : Qv = 1300 * V * T where Q = ventilation heat flow rate, in W 1300 = volumetric specific heat of air in J/cuoic meters deg C V = ventilation rate in cubic meters/second T = temperature difference in deg C If the number of air changes per hour is given, then the ventilation rate can be found by: V = N(air changes per hour) * ROOM VOLUME/ 3600(no of seconds in an hour. R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 2.1.3 RADIATION V J f ^ J V V » . p v v t r > , heat toss by radiation Figure 2-3 Process of Radiation Radiation is the process of heat flow in electromagnetic waves from a hotter surface to empty space. The radiation balance “favors” the cold surface. This is the only method of heat transfer which does not require a medium for heat transfer. Radiation heat gain in the buildings is considered mainly through the fenestration’s and openings. If the intensity of solar radiation (I) is incident on the plane of the window, then this itself is behind the value denoting density of energy flow rate (W/ sq m e ter). It is multiplied by the area of the aperture to get the heat flow rate in watts. This gives the heat flow rate through an unglazed aperture. For glazed windows this value will be reduced by a solar gain factor (theta) which depends on the quality of glass and on the angle of incidence. The solar heat flow equation is given by : Qs = A * Sc* Sg where A = area of window exposed to the sun in square meters 6 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Sc= "shading coefficient (SC), a dimensionless ratio defined as Solar heat gain of fenestration/ Solar heat gain of double strength glass. For all purposes of our calculations we will take it as a constant. Sg = solar gain factor of window glass. 2.1.4 LATENT HEAT Latent heat of a substance is the amount of heat absorbed by unit mass of the substance at change of state(e.g. from solid to liquid) without any change in temperature. For example: For water the latent heat is : graph showing added for change of state lor a substance 1 i m | pi / 1 y 6 i S o lidf?L i quict las fh r— 1 i Solid Utiuid=>Gas ui k \ Liquid f l j >- S $4- r - 4 - 44 4- -t- -t- 4- 4- 4 - 14- 4- 4- -H - W 4- 4- ‘ ■..•a:d'ded;.. tieaI. / Figure 2-4 Graph showing latent heat of a substance at change of state Latent heat of a substance is the amount of heat absorbed by unit mass of the substance at change of state(from solid to liquid) without any change in temperature. For example : For water the latent heat is : of fusion ( from ice to w ater) 335 kJ/ kg of evaporation (from water to vapor) 2261kJ/kg 7 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Heating a mixture of water and ice will melt ice without changing the temperature until the ice is gone. The added energy is taken up by the latent heat. In buildings the latent heat is given out when evaporation takes place in the form of evaporation of sweat from people inside the building or evaporation of water from the roof or windows. Also, release of heat may take place in the form of condensation when water accumulates on glass windows, on bathroom mirrors or even in walls where it is known as interstitial condensation. This reaches wall layers inside making them wet and starts corrosion. A primary load of most air conditioning systems is the removal of moisture from ventilation air. 2.2 SOLAR FACTORS AFFECTING HEAT TRANSFER 2.2.1 SOLAR BASICS Given below are some important terms and definitions needed when referring to solar factors in buildings. 1. Solar O rbit It is very important to know the position of the sun in order to understand how the sun effects heat gain or heat loss in buildings. There's a tilt to the spin of the earth. Each day the sun travels in a circular path across the sky, reaching its highest point at noon. Right at Figure 2- 5 Solar orbit r & sunrise the sun path is at zero degrees. The altitude angle at this point is zero. In summer, 8 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. the sun rises north of due east, rises quite high and sets north of due west. In winter, it rises south of east and sets south of west. In September and M arch, i.e. the seasons of spring and fall, it rises due east and sets due west. At noon, on M arch 21 and September 23rd are the vernal and autumnal equinoxes. The sun is directly overhead at the equator at these times. On June 22nd is the summer solstice, in the Northern Hemisphere. The sun is at the 23.5 degrees Northern latitude. On December 22 is the winter solstice and the sun is directly overhead at 23.5 degrees but on the Southern hemisphere. D eclination is the angular distance of the sun north or south of the earth's equator. The earth's equator is tilted 23.45 degrees with respect to the plane of the earth's orbit around the sun, so at various times during the year, as the earth orbits the sun, declination varies from 23.45 degrees north to 23.45 degrees south. This gives rise to the seasons. Around December 21, the northern hemisphere of the earth is tilted 23.45 degrees away from the sun, which is the winter solstice for the northern hemisphere and the summer solstice for the southern hemisphere. Around June 22nd, the southern hemisphere is tilted 23.45 degrees away from the sun, which is the summer solstice for the northern hemisphere and winter solstice for the southern hemisphere. On March 22nd and September 23rd are the fall and spring equinoxes when the sun is passing directly over the equator. Note that the tropics of Cancer and Capricorn mark the maximum declination of the sun in each hemisphere. D eclination is calculated w ith the following form ula: d = 23.45 * sin [360 / 365 * (284 + N)] Where: 9 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. d = declination N = day number, January 1 = day't". 2. S un Angles a. A zim uth Angle solar azimuth Figure 2-6 D iagram of A zim uth angle The azimuth angle is the horizontal angle at which the suns rays are falling on a wall. It is measured from with respect to due south for all purpose of architectural calculations. Thus, it is always given as east of south or west of south. The solar azimuth angle is the angular distance between due South and the projection of the line of sight to the sun on the ground. A positive solar azimuth angle indicates a position East of South, and a negative azimuth angle indicates West of South. Note that in this calculation, Southern Hemisphere observers will compute azimuth angles around + /-1 8 0 degrees near noon. The azimuth angle is calculated as follows: cos (Az) = (sin (Al) * sin (L) - sin (D)) / (cos (Al) * cos (L)) 10 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. where: L = Latitude (negative for Southern Hemisphere) Az = Solar azimuth angle D = Declination (negative for Southern Hemisphere) A 1 = Solar altitude angle The sign of the azimuth angle also needs to be made equal to the sign of the hour angle when using the above equation b. Altitude Angle The altitude angle is the vertical angle between the sun and the wall section. It is always measured with respect to an imaginary line, running perpendicular to the wall. The altitude angle (sometimes referred to as the "solar elevation angle") describes how high the sun appears in the sky. The angle is measured between an imaginary line between the observer and the sun and the horizontal plane the observer is standing on. The altitude solar altitude v angle^ Figure 2-7 Diagram of altitude angle 11 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. angle is negative when the sun drops below the horizon. In this graphic, replace "N" with "S" for observers in the Southern Hemisphere. The altitude angle is calculated as follows: sin (Al) = [cos (L) * cos (D) * cos (H)] + [sin (L) * sin (D)] where: Al = Solar altitude angle L = Latitude (negative for Southern Hemisphere) D = Declination (negative for Southern Hemisphere) H = H our angle 2.2.2 SO L A R RADIATIO N The sun is the greatest source of heat and radiation and thus, solar radiation is an im portant part of passive design considerations in design. Each second, the sun releases an enormous amount of radiant energy into the solar system. The Earth receives a tiny fraction of this energy; still, an average o f 1367 watts (W) reaches each square meter (m2) of the outer edge of the Earth's atmosphere. The atmosphere absorbs and reflects some of this radiation, including most X-rays and ultraviolet rays. Still, the amount of sunshine energy that hits the surface of the Earth every minuve is greater than the total amount of energy that the world's human population consumes in a year! The orbit of the sun across the sky at a location will vary in angle and elevation with season and thus, the solar radiation will also vary. "The maximum possible intensity o f radiation that may be received at at particular location is determined by the latitude. Those rays o f the sun are received vertical to the surface o f the earth pass through the minimum amount o f the atmosphere. Vertical rays are not received north o f the Tropic o f Cancer and South o f the 12 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Tropic o f Capricorn. Oblique and tangent rays have to pass through a considerable amount o f atmosphere before reaching the surface o f the earth." 1 The design can be done such that the radiation gain is minimized in the summer and maximized in the winter. Since there are always humidity and clouds in the equator area, the greatest solar radiation does not happen at the equator, but the two Tropics where fewer clouds exist. In the northern hemisphere, a south facing slope can gain more solar radiation than the plain in the winter; but during summer, the plane gains more sun rays than a hill slope. In heat gain analyses this time of the day is selected, at which solar heat gain will be greatest, for example, a building with glass only on the west exposure will have a peak heat gain at 4 p.m. Solar radiation evaluation To evaluate the importance of solar shading the designer must know the importance of solar energy falling on the exposed surface. - The upper half of a radiation calculator charts the direct solar radiation falling on a horizontal plane under clear sky conditions. - The lower half charts the direct solar radiation falling on a vertical surface. - The radiation lines are indicated at BTU/sq. ft./hour intervals. - The calculator is generally on the same scale as the solar path diagrams. This calculator is transformed into a transparent overlay and superimposed on the solar path diagrams. When it is placed at the correct orientation, the solar radiation values can be read. 1 O a k eley , 1 9 61, p 27 13 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Figure 2-8 Solar Radiation calculator Figure 2-9 Overlay of radiation on solar stencil 2.2.3 SH A D IN G "The windows account fo r the greatest amounts o f heat entering the building and therefore shading them offers the greatest protections" Thus, it is crucial to shade the windows of our buildings when the outdoor temperature is above the shading line. The window should be well protected from the sun to reduce radiation in summer and should be able to get maximum radiation in winter. These shading devices can be inside the building in the form of blinds, rollers and curtains or outside shading devices such as fins and overhangs. The form er are placed behind the glass and can only reflect part of the radiation, while the most of the part is absorbed , convected and reradiated into the room. Outside shading devices actually shade the window from direct radiation, therefore preventing a large part of the heat from getting in. Hence, the location of these outside shading devices, is crucial. The ability of keeping radiation out increases as it is located behind, on or in front of the glazing surface. The most common shading devices are: 14 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 1. Horizontal shading devices - overhangs These are placed horizontally in front of the window, in various ways. Their, shape, type, depth and height all differ, all depending on the sun conditions. A window overhang is a (usually) horizontal surface that juts out over a window to shade it from the sun. This is desirable in order to reduce glare or solar heat gain during warm seasons. In temperate climates, where there are warm and cool seasons due to the tilt of the earth’ s axis of rotation in relation to the plane of its orbit, it is often desirable to shade a window during hot summer months but to allow sunlight to shine through a window in the winter to help warm a building. Because the sun is higher in the sky in the summer than the winter, it is possible for a fixed overhang to accomplish both summer shading and winter sunlight admission. As figure 2.10 illustrates, the basic concept is that an overhang can be positioned to totally allow low winter sun in the entire window while completely shading the entire window from summer sun. The design calculation is performed over a certain period of mid-summer and a certain period of mid-winter, typically a month or two on either side of the two solstices. The calculation is also performed only for a certain period during the day, typically near 2 [O lgay, 1963, p72], 15 T h e highest the v/inter.sun gets Overhang correctly ; ^p o sitio n ed t o ) b lo ck th e sum m er sun andadm it the winter sun. W indows Figure 2-10 Positioning of the overhang R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. solar noon since that is when it's most important to increase solar gain in the winter and reduce gain in the summer (because the sun is most intense then). In fact, it is not usually possible to design a horizontal overhang that works in the early morning or late afternoon because the sun is low in the sky in both the summer and winter. 2. V E R T IC A L SHA D ING DEVICES The vertical exterior louver and egg-crate solar shading devices, are primarily useful for east and west exposures. These devices also improve the insulation value of glass in winter months by acting as a windbreak, a. V ertical Louvers Vertical elements can be designed to vary angle according to the sun's position. M oveable, vertical louvers can provide Shading Coefficients from 0.15 to 0.10. Due to problems from icing, they are not practical in cold regions. On cloudy days, a photocell control device can set moveable louvers to the perpendicular position shown below for maximum light penetration. Indoor louvers with integral tubing for removing or putting heat as required, is also an option. 16 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Figure 2-11 Vertical shading devices b. Egg-crate The egg-crate solar shading device is a combination of vertical and horizontal shading elements. They are more commonly used in hot climate regions because of their high shading efficiencies.(e. S.C <= 0.10). The horizontal elements control ground glare from reflected solar rays. The device works well on walls. The east and west sides of a building can be shaped to provide shade by facing glass away from the sun. For example, a "saw-tooth" wall pattern, used in cool and temperate regions regions should concentrate glass towards the south. In the hot regions, glazing should face the north as shown in the sketch below. 17 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Figure 2-12 Egg-crate shading devices 3. SHA DING FR O M SURROUNDINGS S hading from buildings Buildings can provide useful shade on nearby structures. For example, the building located at 40 deg north latitude will be shaded as shown below on the afternoon of July 23rd. A building may be designed with the best intentions but if the buildings around are not kept in mind then, it might become totally shaded and cold at certain times of the day. In the same way, trees and vegetation can be used to provide shade when it is beneficial. S hading from vegetation Vegetation is infact a powerful tool in shading, as well as in reducing solar radiation, wind and precipitation and trees planted well can save up to 30 percent of a building’s 18 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. total energy requirement.3 Trees and vegetation can be used to provide shade where it is seasonally beneficial. In hot places, plants and trees, planted in front of a window dos not only reduce solar radiation but the evaporation process also helps to cool the air. In winter, properly placed trees and shrubs shield your home from cold winds, reducing heat loss by 10 to 30 percent. In summer, shade provided by trees and the cooling effect of water evaporating from leaves can significantly reduce your need for cooling. The purpose of identifying the right tree type for a particular building requires the following steps: • Identifying the "solar window," which is how much sun the building receives given its placement on the lot. For example, the Pacific Northwest climate, the ideal solar window is 90 degrees east and about 50 degrees west of true south. • The building should be kept clear for winter warmth and light. If there is need to plant trees inside the solar window, minimize the impact by planting deciduous, "solar friendly" trees that have open crowns in the winter, leaf late spring and drop their leaves early in the fall (for example: redbud, green ash, and honey locust.). Tall, high crowned trees planted close to the building are the best. Palm trees are often chosen for this . Vines are also a common choice for this purpose. When properly placed, mature trees have shading coefficients (S.C) from 0.25 to 0.204 • Outside the solar window, conifers or deciduous trees with dense winter crowns should be planted to protect from the cold winter wind. Deciduous trees may be preferable on the west side because they'll give more light in the winter. 3 M o ffa t and Schiler, L andscape D esign th at sa ves energy, 1 9 8 1 , p i 1 19 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 2.3 THERMAL COMFORT W h a t is th e r m a l c o m f o r t ? Thermal Comfort can be described as the state in which there is complete balance between the various methods of heat transfer and the temperature achieved inside the building is such that there is no need for any artificial means of heating or cooling. It is a state of complete harmony between the building and its outside environment to achieve ideal conditions inside. Thermal comfort is achieved when the building is in the steady state of thermal balance and the temperature inside is within the comfort range of 20 to 24 deg centigrade. However, the comfort conditions inside a building depend on a number of other conditions, such as relative humidity, wind speed and ventilation, people, equipment and the materials and color. The basic factors that describe thermal comfort are: by. • Wind • Human Factor » Temperature • Solar Radiation ® Relative Humidity Solar Radiation as a factor has already been discussed with relation to Solar Factors. A basic explanation of other factors follows in the next few sections. 2.3.1 WIND Wind and air movement influences bodily heat balance and hence, thermal comfort by: 4 Solar energy in architecture and urban planning. Prestel Verlag, 1996. 20 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 1. Affecting the rate of conductive and convective heat transfer between the skin and the air. 2. Affecting the rate of heat transfer between the building and the outside environment, through ventilation.. The former is governed by air dry bulb temperature. Increasing the air speed increases the rate of heat transfer, but the direction of heat flow depends upon whether the temperature of the air is greater or less than the skin temperature. Heat is removed from the body when the air temperature is less than 90 deg. F, but heat is added to the body when the air temperature approaches and exceeds skin temperature. The rate of evaporation is governed by both air speed and vapor. Increasing air speed always increases evaporative cooling effect, although at high vapor pressures, the overall effect may be small. The comfort range in the building depends on air velocity and the air movement within the building. The factors related to air motion in buildings can be placed under two major categories : 1. Air velocity Air velocity plays an important role in determining the comfort condition within the building.. Under the same the same conditions , air motion can be a pleasant cooling breeze while under others it can be a draft5. Consequently, 5 Egan, Design for Thermal Comfort, M cGraw Hill, N ew York(1983). 21 SLIG HTLY H ARM Z< INE 3 o < z Q > 5 j H 3! 2 s COS1FORT ZONE h m e 3 2 * m m S 33 2 5 0 C O 3 ! m SUGH OV CO OL ZONE >0 10 5 0 AlR\/ELpCITYINfp m (ato.ccupgr)t.hpadloyel) Figure 2-13 Graph of air velocity and temperature R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. the combination or air temperature and velocity must be carefully controlled. The graph gives the relationship between moving air stream temperature in degree Fahrenheit and air velocity in feet per minute (fpm). The shaded region indicates an average zone for human comfort. Under some conditions air motion can be a pleasant cooling breeze while under others it can be a draft. Consequently, the combination of air velocity and temperature must be controlled. Typical temperature and velocity limitations are indicated in the comfort zone on the above graph. 2. Air distribution within the room Figure 2-14 Diagrams showing good ventilation for heating (left) & cooling(right). The amount of air entering the building also needs to be evenly distributed evenly within the building at one level and within each room at the other level. Consequently, the primary comfort requirement of the climate region, determines the outlet conditions. The shaded areas given above indicate the distribution pattern for the primary air. The arrows indicate convection currents caused by the difference in temperature room air and enclosure surface temperatures. 2.3.2 HUMAN FACTOR The human body maintains its balance with its environment through minor physiological changes i.e. by increasing or decreasing the flow of blood to the skin. Body heat losses stagnant air d r a f t s a tr e s s f lo o r ir s m c o ld w a ll se r ia te s 22 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. are primarily by convection, evaporation and radiation. Criteria for total thermal comfort depend on each of the human senses and it is dependent on air temperature, relative humidity, air movement and mean radiant temperature. The basic heat loss and thermal comfort factors of the human body are as given below: Human h eat lo ss factors :onductlorr (v e ry little). radiation ( a b o u t . 4 0^ ) te m p e ra tu re a irm o tto n Thermal com fort factors Figure 1-15 Factors in human heat loss and thermal comfort Human body temperature and heat loss 23 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. In turn, the human body also affects comfort conditions inside the building by the number of people inside a building, the activity they are engaged in and the state of the body. Man is a constant temperature animal with a normal body temperature of about 98.6 deg F. Human skin surface temperature should be about 92 deg F for comfort. The human body will radiate heat to anything at a colder temperature or be heated by anything at a warmer temperature. T he hum an body as a source o f m oisture Moisture control in buildings is important as moisture from building occupants, equipment, etc. influences the size o f refrigeration elements required for summer cooling because moisture will change the condition of the air. High humidity retards heat loss by evaporative cooling and by respiration. Low humidity tends to dry throat and nasal passages. In buildings, it can also cause loosened furniture joints, cracked book bindings etc. 2.3.3 R E L A T IV E H U M ID ITY Relative humidity in percentage is the amount of moisture in air compared to the amount of moisture in air compared to the maximum amount that can exist at a given temperature without condensation. Relative humidity is measured by the difference between the wet bulb temperature and the dry bulb temperature and the greater the difference between the two, the lower the relative humidity. /T h e comfort range" of relative humidity "depends"onlhe dry'bulb temperature, but ’ generally it can be said that it lies between the are where the realtive hum idity is about “ , V J . * , J , 'W • h < . i , a > t , V ^ * * t ^ ^ ^ i . I 20 to 60% and the temperaturejis 6etw eenl74 tb'78% centigrade. ' f * - ! 24 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Excess humidity is a problem only during the cooling season. Most energy conserving design options do not deal with humidity directly but rather increase natural ventilation and desiccant cooling to make a humid environment more comfortable. Conversely, pools and fountains added to a dry site can make it feel cooler. The graph shows the relationship between temperature and relative humidity in a room. The colored area represents the zone of "thermal comfort". This clearly indicates that as the humidity increases the comfort range temperature range for the comfort zone decreases. The following chart is based on lightly clothed subjects with air velocities in the range of 15 to 60 fpm. In the comfort zone, human tolerance to humidity is much larger than tolerance to temperature. Consequently, room air temperatures must be more carefully controlled. Humidity control is also important, however, since high room humidity can cause condensation on glass surfaces and in summer, low humidity rate can cause static electricity problems. 2.3.4 MEAN RADIANT TEMPERATURE The mean radiant temperature is defined as the uniform surface temperature of an imaginary black enclosure with which human beings exchange the same heat by radiation as in the actual environment. It is a weighted average of the various radiant influences in a space. If all the surfaces in an environment were uniform at this temperature, it would 25 S U G h TLY WiiRM 2 0 M E comfort zone .n u v l i i 'i .urab'i'ir SUOHTLY COOLZdNE Figure 2-16 Graph showing relative humidity and temperature R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. produce the same net radiant heat balance as the given environment with its various surface temperatures. The radiant heating or cooling ability of any surface, therefore, must be evaluated in the context of its area in proportion to the area and temperature of other surfaces in the room. The angle of exposure of surface to the body and the orientation of exposed parts of the body should be considered. Although the rate of radiant heat exchange between the body and its surroundings is dependent upon surface temperature differences between these, several factors must be considered in analyses of heat balance. It is measured by a globe thermometer. It can be estimated by the by the following formula: MRT = TO/360 = tiO + t20 + t3 0 ..............................................+ tnOn/ 360 where T = Total temperature t = surface temperature of an object in degree Fahrenheit 0 = surface exposure angle(relative to occupant )in degrees The graph shows the relationship between air temperature and mean radiant temperature. The shaded region indicates an average zone for human comfort.. The following chart is based on lightly clothed subjects with air velocities in the range of 15 to 60 Figure 2-17 Graph showing MRT and temperature » , COMFORT ZONE SLIGH TLY CO !L ZO N E R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. fpm. The MRT here is 50% and air velocities range from 15 to 50 fpm for the data presented. The higher the M RT value, the lower the corresponding air temperature for comfort conditions as indicated by the slope of the comfort zone. 2.3.5 CORRELATION OF FACTORS IN THERMAL COMFORT As with many facets of architectural design, the sum of the parts is different from the whole. Temperature, humidity, wind and sun data are pertinent to design strategies but must be considered simultaneously to get a true picture of the comfort conditions of the site or building. Thermal Comfort can be described as the state in which there is complete i balance between the various methods of heat transfer and the temperature j .................................^ - ! 1 achieved inside the building is such that there is no need for any artificial means j; V 4.'^:-/i't ,?i: ^ V - y . - p . ' ' - ^ ^ ^ ‘ ^ «rr.| *^V ^ ^ 'v J - ' V - .vNv* 1 1 -V -; '■ ;Arr ^ j 'A 7;- ■ v =,V.^ '• :v ^ ; i : V - ’.*i > 5 >1 ; T " of heating or cooling. It is a state of complete harmony between the building and its outside environment to achieve ideal conditions inside. Psychrometric chart A psychometric chart describes the relation between dry-bulb temperature, wet bulb temperature and relative humidity. The psychrometric chart provides the correlation between all factors and determines the actual comfort zone. Plotting any one of these numbers will yield the third one. If the plot of the actual data falls within the "comfort zone", the outside conditions on the site will be comfortable. The overlay of the climate envelope on the psychrometric chart indicates the passive design strategies to alleviate conditions that would otherwise require mechanical heating and air-conditioning. W hen conditions of temperature and relative humidity fall outside 27 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. the comfort zone, corrective measures - winds, sunshine, or moisture - can produce comfortable conditions. Prevailing conditions are plotted on the chart to find what corrective measures are needed. The thermal conditions inside a building can be placed into three major categories: C O N D ITIO N O F H EA T GAIN - - - ‘ ■ ■ The condition in which the total heat lost by a building is less than the total heat gained by the building is called the condition of heat gain. In this condition the temperature inside a building steadily rises and the F igure 2-18 H eat gain conditions become hot and uncomfortable inside. In such a situation, artificial means are employed for cooling the building and bringing it in thermal balance, where the total heat lost is equal to the total heat gained. C O N D ITIO N O F H E A T LOSS The condition in which the total heat lost by a building is more than the total heat gained by the building is called the condition of heat loss. In this condition, the w p w temperature inside a building steadily decreases and the conditions become cold inside. In this situation, F igure 2-19 H eat loss artificial means are required for heating the building and restoring its thermal balance. 28 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. THERMAL BALANCE Thermal balance is the state in which the total heat lost is equal to the total heat gained by the building and it achieves a steady state. The steady state can be achieved naturally, by the process of design of artificially by employing mechanical means. Figure 2-20 Thermal balance REFERENCES W atson, Donald FAIA, The Energy Design Handbook, The American Institute o f Architects press, W ashington D.C. Egan, D avid M , Concepts in Thermal Comfort, N ew Y o r k : M cGraw-Hill, c l9 8 3 Schiler, M , Landscape Design that Saves Energy, 1981 Christoper Flavin, Energy and Architecture: The Solar and Conservation Potential.W ordwatch Institute, 1980 Prestel, Verlag, Solar energy in architecture and urban planning. 1996. 29 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 2.4 CLIMATIC FACTORS 2.4.1 BASIC CLIMATE TYPES The purpose of categorizing geographical areas by climate is to develop a manageable number of guidelines for energy conscious design. These regional guidelines are especially useful and helpful in the programming and schematic phases of design, where basic energy-conserving strategies are selected. At the design development level, however, they may be coupled with analysis of the specific site, where topography, vegetation, proximity to water and other factors can sometimes radically alter the regional guidelines. Perhaps, the most well known categorization, of climates in the United states is the four-climate scheme given in Victor Olgays' Design with Climate, which has the main categories as : • Cool • Temperate • Hot-Arid • Hot-humid. Each climate type has its own characteristics and building types, particular to it. The diagram below shows the major climatic regions of the United States. Figure 2-21 Map of the United sates showing basic climate types. 30 COLD TEMPERATE HOT-ARID R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 2.4.2 BUILDING FORM AND SHAPES Building form and shape are important while considering heat loss or gain in buildings. They play an important role in the thermal processes taking place within the building as well as with the building and its surroundings. Square and rectangle are the basic shape for the buildings. Usually, buildings with more surface area gain heat and lose heat much more quickly than those with less surface area. The surface to volume ratio dominates the condition inside of buildings. If a building has a large surface area, the internal condition is more influenced by the external climate than in one with less surface areas. Smaller buildings have larger skin/volume ratio than large buildings. A building with less surface area is dominated by its internal load, which is the heat of the people, machinery, lighting and so on. Since the land cost in an urban area is much higher than in a suburban area, to optimize the usage of the entire real estate, high rise buildings become a preferred choice. Here, curtain walls are mostly glass which permits daylight to enter the building. On the other hand, curtain walls act as wrap to seal the whole building and thus they seal the whole building making it dependent on a mechanical cooling system. Olgay's conclusions for basic building forms are : 1. The square building is not the optimum form in any location. 2. All shapes elongated on the north-south work both in winter and summer with less efficiency than the square one. 3. The optimum in every case is a form elongated some where along the east-west direction. 6 6 Olgay, Victor, Design with Climate 31 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Climate and building shapes There is a steady progression on the building form, as we move from cold climates to hot-arid areas. Studies of square and various oblong shapes and orientations of buildings in major climate regions show that there are certain standard shapes for minimum heat gain and heat loss. These shapes are a balance between the cold season when solar radiation can be beneficial, and the overheated season, when radiation should be avoided. • COLD CLIMATES A compact shape which conserves as much heat within the building envelopes and maintains the temperature by preventing the building heat from escaping is preferred in cold climate. TEMPERATE CLIMATES Buildings in the temperate climates are best elongated along the east west direction, to get as much heat as possible in the winter and reduce heat gain in the summer. 32 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. HOT ARID CLIMATES In hot arid areas, the courtyard building is the most popular form among all because the center courtyard helps to create a micro-climate within the building. HOT HUMID CLIMATES In hot humid climates, instead of a big building, the shelter is best broken into small parts to increase ventilation, and increase the building skin area to prevent heat accumulation inside. 2.4.3 MICROCLIMATIC FACTORS The site and its immediate surroundings also play a very important role in the heat gain/loss to the surroundings. Many factors mentioned in the sections before might change drastically due to the existing surroundings as well as micro climate conditions. Som e’ of the important factors that need to be considered while taking decisions on thermal issues are: 1. Solar considerations The sun angle chart for the latitude should be used to study and compare exterior building designs. Also shadows from adjacent buildings should be computed and evaluated to be best used according to the climate and timings. 33 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 2. Wind considerations winter winds Figure 2-22 Summer winds Figure 2-23 Winter winds The building should be protected from the cold winter winds with as few openings on that side as possible or by use of vegetation and surrounding buildings. Prevailing summer winds should be allowed to enter and enhanced if possible with the orientation of the building and cluttering of vegetation. 3. Topography and soil conditions 80 The subsurface and soil conditions can greatly modify prevailing climatic conditions. Some important factors in the site topography are : • Elevation is a prime example of climate modifier. In mountainous areas the temperature drops with every one degree for every 330 foot rise in summer and every 400 foot rise in winter. • Hills and valleys- Valley walls and bottom surface cool off at night. Air flow occurs towards the valley floor. On the valley slopes, a series of small circulations mix with the neighboring warm air, causing intermediate temperature conditions. air ccicd by evaporation fro m w ater and vegetation Figure 2-24 Effect of topography 34 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Accordingly, the temperatures at the plateau will be cold, and the valley floor will be very cold, but the higher sides of the slope will remain warm. In temperate zones, the thermal belt may be 10 degrees F or more warmer than the valley, and therefore can be the most advantageous place for a building. • Slopes influence wind speeds and directions and indirectly temperatures. Upslope and downslope winds can influence temperatures, either upward or downward, and inversions can cause cooler temperatures in valleys or at the base of slopes. • Ground surfaces such as asphalt, concrete or grass absorb, reflect and emit radiation in different ways, thus affecting their temperature, rainfall and snow covering. • Soil type has a significance for under-ground buildings and basements. Tight clay soils, such as those that are highly impervious, require expensive water removal and water proofing. Reflectance is a special characteristic of ground surfaces, important not only to thermal calculations, but also to day-lighting strategies. 4. Water Site proximity to bodies of water also affects the microclimate. Because water has a higher specific heat than land, it is normally warmer in winter and cooler in summer, and usually cooler during the day and warmer at night, than the terrain. Accordingly, the proximity of bodies of water moderates extreme temperature variations, raising the temperature lows in winter and lowering the highs in summers. At the largest scale, oceans and ocean currents have great impact on the temperature of coastal areas, where the water temperatures may be 30 degrees F warmer than adjacent surfaces. 35 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 5. Built forms Existing or future built forms on a site will affect the site in much the same way as their natural counterparts. Buildings, walls and fences can be used like trees for windbreaks and deflectors, the surface qualities of built surfaces such as concrete must be considered for reflectivity and permeability like natural ground covers. 6. Vegetation Figure 2-26 Effect of vegetation The effects of vegetation on a site's microclimate can be considerable : trees can reduce sunlight and wind speeds by 90 percent, and temperatures by 15 degrees F. In addition, vegetation can usually be manipulated more easily than topography or adjacent buildings. 36 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 2.4.4 P R IN C IP L E S O F V ERN ACULAR A R C H IT E C T U R E H a r m o n y " u ild in gs. Vernacular architecture includes all the buildings that are constructed using traditional materials and to traditional forms by builders not schooled in the formal architectural tradition of their society. The anonymously-built log cabins, bam s, and spring houses that can be seen along country roads are good examples o f vernacular architecture. In the past man , technology was not the powerful means of survival as it is today. Human beings as a result devised methods and practices to be in harmony with nature and get the most benefits from it, without harming it in the least. These principles and practices are called, what is known as VERNACULAR ARCHITECTURE TODAY. Vernacular architecture is region based and the following F ig u re 2-27 H arm ony w ith n a tu re sections describe the principles of vernacular architecture with respect to the four basic climatic regions in the US. The four basic climate types the vernacular architectural practices in them are: 1. HOT HUMID CLIMATIC REGION In this climatic region the, day-night temperature difference is not as great as in hot arid region, and thus, increasing shade for elimination of radiation, and augmenting ventilation to catch any available air movement are the two main goals in building design. Ventilation is the most effective way to cool the environment, the buildings are placed loosely in order to achieve this goal. In this region, high-canopied palm trees are common, and ideal for the site. They provide shade from the cruel summer sun and allow 37 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. breezes to pass through to the structure, and thus provide a wind channel to guide the cooling breezes into interior space. F ig u re 2-28 H o t-h u m id b u ild in g d esig n Some basic principles are : • Loosely spaced buildings to allow air flow and wind channeling. • High atrium space to allow ventilation within the building. • Palm trees for shade as well as to catch the breezes and winds. • A large number of openings to allow for cross ventilation. 2. HOT ARID CLIMATIC REGION Hot, arid regions would permit an elongated building design, the heat in summer is so severe that a compromise is required and the traditional solution is a compact, inward looking building with an interior courtyard. This minimizes the solar radiation impact on the outside walls and provides cool air within the building. The courtyard is an important element in building design in a hot-rid. It is shaded by walls, trees, or trellis to prevent direct radiation from the sun, and it usually contains a pool, a fountain, or vegetation to provide an evaporative cooling effect. Since reducing surface area can reduce heat gain, 38 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. the buildings in a hot arid climate tend to be jointed together in order to achieve protection against the heat shaded structures. Vines are also a common choice for wall or roof covering to protect the structure from direct sunlight, often the south-facing facade requires a maximum amount of shading. Since there is a water shortage in most hot-arid areas, a drought resistant ground covering is a preferred selection. On both east and west facades, low trees or bushes are favored because of the low morning and afternoon sun. However, trees with loose structure and light foliage are desirable at the east side of the building, since they can reduce the radiation generated by the morning sun but allow the pleasant dawn light to enter. Figure 2-29 Hot arid design Some basic principles of design are: • The central courtyard in the middle with rooms facing all around it allows for cross ventilation and air circulation in every room. • High mass walls which are used for might time flushing, keeping temperature ranges at a minimum, inside the building. • The central courtyard in the middle with rooms facing all around it allows for cross ventilation and air circulation in every room. 39 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. • Trees and water bodies in the central court keep the central area and surrounding rooms cool in addition to providing a pleasant environment. 3. COLD CLIMATES Buildings in cold climates should be compact structures which allow very little heat to escape form within their structures. The best shape for a cold climate is that of an igloo or an upside down cup, which has the minimum surface area and thus is compact allowing very little heat to escape. Large windows on the south face allow maximum sunlight to enter the building. Super insulation and sun and earth berming are other means of preserving heat within the building. Tall evergreen coniferous trees act as windbreaks. The windows on all other sides are tiny for allowing light to enter. In zoning, the kitchen is kept in the center with room all around to keep them warm. Figure 2-30 Vernacular architecture of the cold climate The basic rules of thumb can be summarized as : • Compact shape to keep the heat inside the building. A square or circular shapes works best in such cases. • Snow or earth covering provides insulation and prevents heat from escaping outside. 40 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. • South facing windows allow maximum sunlight into the building. • Tall coniferous trees act as wind breaks. • Compact structure with less surface area, preserves heat and keeps the building warm at all times. 4. TEMPERATE CLIMATES Temperate climates are probably one of the hardest to deal with as one has to take care of summer gain as well as winter losses. The building should be oriented along the east west direction, to get maximum sun in the winter and minimum in the summer. Use of verandahs to provide shade and let the winter sun com e in while cutting off summer sun is common. Use of deciduous trees on the South facade. Fire place in the middle of the house with baffles to increase the path, warming a larger area. Smaller trees all around the facade, with a north buffer zone are all elements used in vernacular architecture of temperate climates. F ig u re 2-31 V e rn a c u la r a rc h ite c tu re o f te m p e ra te clim ates The basic rules to be kept in mind are: • Building shape is long and narrow in the east west direction to get maximum sun at all times during winter and minimum in the summer. 41 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. • Deciduous trees on the south of the facade prevent the summer sun from entering while allow the winter sun to enter. • Verandahs allow shade and relaxing areas, which allow winter sun and cut off summer sun. • Long narrow building with east west oriented windows allow maximum sunlight in winters and minimum in the summer. • Temperate climates are hardest to deal with an require taking care of various factors from the building shape, orientation, trees, windows and facades. 4.5 HEAT GAIN/LOSS CALCULATIONS 4.5.1 FACTORS EFFECTING HEAT GAIN/LOSS Now that we have discussed the basic processes in heat transfer in detail, this section brings them all together and discusses the heat gain and heat loss calculation of the entire building involving all of the processes described earlier As already stated, the basic methods of heat transfer are : • Conduction • Convection • Radiation • Latent Heat. These are the various methods by which a buildings loses or gains heat. The calculation of the total heat loss or heat gain in any building involves an estimation of these processes along with various other factors which effect the amount of heat lost or gained 42 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. by a building at any particular time of the day or year. These factors include factors such as the lighting and appliances within the building, the number of people inside the building. The diagram below gives all the factors responsible for heat gain/loss in the building along with their basic definition. radiation conduction Factors effecting foe at gain/loss in buildings people convection lighting appliances Figure 2-32 Factors in heat gain/loss Other factors Besides these basic factors there are other factors such as color, u-value of building materials and zoning in the building which also affect the heat gained or lost at any given time. A basic explanation of the various factors follows: 1. Effect of color Light colors tend to reduce building heat gain in summer. Accordingly, light colored walls of heavy mass will have the lowest ETD values. Most farmers have traditionally used white paint for their houses but used the less expensive red paint for their bams. 2. Building heat and zoning 43 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Small buildings that have fairly steady occupancy (e.g offices, residences), or buildings with a considerable amount of glass, will have a peak heat gain largely controlled by solar radiation. However, buildings that have a variable occupancy (e.g restaurants, theaters), generally will have a maximum total heat gain at the time of the greatest number of occupants. The design of the mechanical system should be based on the hour of the day at which the heat gain from the various sources - sun, lighting, people, etc - is the greatest. In large, multi-use buildings, there may be many different peak heat gains throughout the building. For examp'e, a tall building may have large conference rooms with glass on the north exposure, interior office and secretarial spaces and a cafeteria on the top floor with the glass on the west exposure. Consequently, these buildings are often separated into areas or "zones" to handle the various cooling and heating requirements. 2. U Values and Time-lag Values Materials with low U-values are those which enclose, trap or contain a film of air and generally are lightweight. On the other hand, materials with long thermal time-lags (i.e., building temperature lags behind out-door temperature) are dense and heavyweight. Consequently, massive constructions will tend to produce more stable conditions(e.g., massive west walls, east walls, and roofs can greatly minimize solar heat impacts in summer); whereas, light weight constructions are more sensitive to short-term solar impacts. 4 4 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 2.5.2 BASIC FORMULA AND THEORY Heat gain analysis Heat gain is usually calculated for the purposes of cooling systems design. In such a situation the system employed for the purpose of providing artificial cooling should be able to combat or deal with the warmest conditions at its peak capacity. Again, the highest temperature for 90% of the time is taken as 'design outdoor temperature' and solar radiation intensity is taken on similar grounds. General guidelines: Establish design conditions Establish design conditions by determining the indoor and outdoor temperature and wind conditions. According to ASHRAE, the design dry bulb temperature and outdoor summer design temperature are used for almost all basic heat gain calculations. Identify heat gain factors 1. Calculate, or find in tables, the U-values for: a. exterior walls b.roof c. doors d. glass 2. Estimate the equivalent temperature differentials(ETD) for the opaque building constructions, the ETD concept is used to compensate for thermal time-lag as well as solar radiation effects. Qc=AU(ETD) 45 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 3. As already discussed in the earlier sections, calculate the solar heat gains through all the openings, using shading coefficients for all the glass, landscaping and shading screens as well as the solar heat gain factor for the different types of glass used in the building. Qc= AU(To - Ti) Qr=ASg(S.C) 4. Calculate the internal heat gains from: Occupants and their activity. Qp=nM where n = number of occupants M =activity sensible heat gain in Btuh Electrical-mechanical equipment Qm=3.4W c. Sources of artificial lighting. Qi = Light sources are marked with their watts(W). For preliminary estimates of heat gain from lighting systems, use 2to6 watts/sq. ft. In office buildings, lighting typically produces about one third of the total heat gain. If wattage is unavailable for other equipment, multiply amperage by the voltage for a rough estimate. 5. Add all the various factors together to calculate the total heat gain in the building. This is the sensible heat gain of the building and this figure can be used for estimating the size of air-handling units and ducts since Q(sensible)/22 for cooling. Heat loss analysis 46 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Heat loss is usually calculated for the design of a heating installation. Heat loss rate is calculated for a condition which is the coldest or the lowest peak value, valid for 90% of the time is taken. This value is then used to design heating installation which produces heat at the same rate. Under less severe conditions, in the remaining 10% of the time, this peak normally occurs in short spells and maybe bridged by the thermal inertia of the building. General guidelines: Establish design conditions Establish design conditions by determining the indoor and outdoor temperature and wind conditions. According to ASHRAE, the design day temperature is the winter temperature that is equaled or exceeded about 98% of the time, the outside winter design temperature is the available standard provided by weather data of the area. The indoor design temperature is based on the space usage. Identify heat gain factors 1. Calculate, or find in tables, the U-values for: a. exterior walls b. roof c. doors d. glass 2. Estimate the heat loss through all roof and exterior opaque and glass wall constructions. In winter the heat gain from solar radiation through glass is considered negligent for heat loss calculations. During cloudless days, however, 47 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. buildings with glazed openings will conserve heating energy when solar radiation can penetrate, warming inside air. For this, yet again we use the same basic formula for conduction is used. Q c= A U ( t - t o ) 3. Calculate the floor slab edge heat loss : Q e= F P (T i - T o) where F is factor of 0.81 for floors without edge insulation; of 0.55 for floors with edge insulation. 4. Calculate the infiltration heat loss using: Q i = 0.018 q (T i - To) where 0.018 is the air infiltration factor. 5. Add all the various factors together to heat the total heat gain in the building. This is the sensible heat loss of the building and this figure can be used for estimating the size of heating. REFRENCES Benjamin Stein and John S. Reynolds, M echanical a n d E lectrical equipm ent f o r bu ildin gs, S '* 1 Edition. Watson, Donald FAIA, The E nergy design H andbook, The American Institute of Architects press, Washington D.C. Egan, David M, C oncepts in Thermal Com fort, New York : McGraw-Hill, cl983 48 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 2.6 THERMAL CONTROLS 2.6.1 PASSIVE SYSTEMS A passive system is a non-mechanical heating and cooling system. A passive heating system will use building components - windows, walls, and floors - to capture, store and distribute the energy gained from various natural processes. The energy required to achieve heating or cooling in passive systems is also obtained from natural means. It is not produced or converted using the common active elements. In passive systems there are no mechanical collectors to convert natural energy into heat nor pumps or fans to distribute the heat. The energy is used directly. A passive cooling system will use the building components, such as roof overhangs, awnings and window insulated curtains to impede the heat gain during the summer. The four main means of passive control are : 1. Passive solar systems. 2. Wind systems. 3. Earth sheltering. 4. Insulation. 1. PASSIVE SOLAR SYSTEMS Solar energy is a radiant heat source that causes natural processes upon which all life depends. Some of the natural processes can be managed through building design in a manner that helps heat and cool the building. The basic natural processes that are used in passive solar energy are the thermal energy flows associated with radiation, conduction, and natural convection. When sunlight strikes a building, the building materials can reflect, transmit, or absorb the solar radiation. Additionally, the heat produced by the sun 49 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. causes air movement that can be predictable in designed spaces. These basic responses to solar heat lead to design elements, material choices and placements that can provide heating and cooling effects in a building. All passive solar homes have these common elements: • Collection - To collect solar energy, double-glazed windows are used on the south- facing side of the house. • Storage - After the sun's energy has been collected, some heat is immediately used in the living spaces and some is stored for later use. The storage, called thermal mass, is usually built into the floors and / or interior walls. Mass is characterized by its ability to absorb heat, store it, and release it slowly as the temperature inside the house falls. Concrete, stone, brick, and water can be used as mass. • Distribution - Heat stored in floors and walls is slowly released by radiation, convection and conduction. In a hybrid system, fans, vents, and blowers may be used to distribute the heat. The four basic approaches that serve to classify passive systems are distinguished according to how they gain solar heat. With Direct Gain, the solar radiation enters a room directly through large areas of south-facing glass. For Indirect Gain, the solar radiation is intercepted by an absorber and storage element (e.g., a wall) that separates the south- facing glass from the room. And for Isolated Gain, the solar radiation is captured by a separate space such as a sunspace or atrium. Thermosyphon is another word that describes the natural movement of air or water due to differences in temperature. Thus, the most common passive solar systems are: 50 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. a. Direct Gain systems Direct gain is the collection and containment of radiant solar energy within the occupied space. Sunlight enters the home through south-facing windows and heats the room. It also strikes floors and walls, which absorb, store and reradiate heat to the building’s interior. If heavy construction materials are used for these interior walls, their mass serves both to minimize drastic temperature changes from night to day and to store the heat energy for sunless periods. Some basic rules of thumb in direct gain are: ® South facing glass admits solar energy into the house where it strikes directly and indirectly thermal mass materials in the building such as masonry floors and walls. • The direct gain system will utilize 60 - 75% of the sun's energy striking the windows. The amount of south-facing glass and thermal storage mass should be balanced. If the windows collect more heat than the floor or walls can absorb, overheating occurs. Since the direct gain system is part of the living space, this can be Figure 2-34 Direct gain system C lerestory syrfenu 51 Direct gainthrough t h e ^ Figure 2-33 Direct gain through windows R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. uncomfortable for those living in the building. • Clerestory windows and skylights are sometimes used to increase the amount of sunlight hitting the back area of walls or floors. They can help improve the performance of the direct gain systems. • Shading is needed to reduce heat gain in the summer. Overhangs, awnings, trellises, louvers, solar screens, and movable insulation are some choices. Most designers recommend exterior shading rather than interior shading because exterior screens and other devices stop heat before it gets into the house. The overhang lets in the winter sun while shading south facing glass in the summer. b. In d ire c t gain system In the indirect gain, a storage mass collects and stores heat directly from the sun and then transfers heat to the interior space. The sun rays do not travel through the occupied space to reach the storage mass. There are several indirect gain passive solar systems : Awnings and windows Figure 2-35 Shading - louvers and awnings 52 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. b .l W a te r w all One of the most W a te r s t o r a g e m a s s G lazing m ateria) important indirect- gain passive solar building type is the water wall, in which the sun's rays are intercepted beyond the collector glazing Indirect gain water wall system by a water storage mass, F ig u re 2-36 D ia g ra m o f w a te r w all then converted into heat and distributed by convection and radiation to the living space . The water wall involves the same principles as the mass wall, but employs a different storage material and different methods of containing that material. b .2 T ro m b e w a ll The second indirect gain solar building type is the mass wall, in which the sun’s rays are intercepted directly behind the collector glazing by a massive wall that serves as heat storage. Ill tirisCSV.jCfc.-.J i • j g g § | j 'TM feS! Trombe wall sysfem F ig u re 2-37 D ia g ra m o f tro m b e w all 53 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. A Trombe wall is a masonry or concrete wall covered externally with a glass skin. A small air space of 4-8 inches is left between the wall and the glazing. Solar radiation passes through the glass and is absorbed by the mass wall. The glazing should have exterior insulating shutters for night time use in order to prevent the heat gained from being returned back to the outside. The mass is heated during the day and releases its warmth to the interior during the evening and night hours. Vents may also be placed in the wall to permit heat to flow directly into the room during the day. b.3 R oof pond W intertime heating em ploying a roof pond sy ste m Glazing material Insulation Day Might F igure 2-38 D iagram of roof pond The third indirect gain building type is the roof pond. In the roof pond building type, the passive collector storage mass has been relocated, from the floor and wall o f the building, into the roof , for radiant heat distribution to the occupied space. The roof pond systems requires a body of water to be located in the roof, protected and controlled by exterior movable insulation. This body of water is exposed to direct solar gain, which it absorbs and stores. Since thermal storage is the ceiling of the building, it will radiate uniform 54 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. low-temperature heat to the entire layout in both sunny and cloudy conditions. Distribution of solar heat from the roof pond is by radiation only, so proximity of the ceiling to the individual being warmed is important since radiation density drops off with distance. c. Isolated gain system In the isolated -gain passive solar concept, solar collection and storage are thermally isolated from the occupies areas of the building. This concept is contrasted with the direct- gain passive solar concept where the collection and F igure 2-39 Isolated gain solar system storage are integral with the occupies spaces, and with the indirect-gain concept, where collection and storage are separate from the occupied spaces but directly linked thermally. The isolated gain concept thus allows collector and storage to function independently of the building. An isolated gain system has its integral parts separate from the main living area of a house. T h e ability to isolate the system fro m the prim ary living areas is the point o f distinction fo r this type of system. Examples are a sunroom and a convective loop through an air collector to a storage system in the house. The sunroom has some advantages as an isolated gain approach in that it can provide additional usable space to the house and plants can be grown in it quite 55 .Storage mass Sunspace Glaring material Isolated gain solar enegy system R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. effectively. The convective air collector by comparison becomes more complex in trying to achieve additional functions from the system. The isolated gain system will utilizes 15 - 30% of the sunlight striking the glazing toward heating the adjoining living areas. Solar energy is also retained in the sunroom itself, d. T herm osyphon (rem ote collection) It includes a collector space, which intercedes between the direct sun and the living space and is distinct from the building structure. A thermosiphon heat flow occurs when a cool air or liquid naturally falls to the lowest p o in t, and once heated by the sun rises up into an appropriately placed living space or storage mass, causing somewhat cooled air or liquid to fall again, so that a continuous heat gathering circulation is begun. Solar heat is collected on a dark metal or wood absorber surface, heating up the adjacent fluid, which the rises naturally into a storage mass for convective or radiant distribution. In the thermosiphon solar building type, the collector location is not fixed by the building and thus can take maximum advantage of sun exposure. Thermosiphon systems rely on natural convection warm water rising to circulate water through the collectors and to the tank, which is located above the collector. As water in the solar collector heats, it becomes lighter and rises naturally into the tank above. Meanwhile, the tank's cooler water below flows down pipes to the bottom o f the collector, causing circulation throughout the system. 2. WIND SYSTEMS The basic passive measure in wind systems is to allow for ventilation such that there is cooling in the summer and air flow is blocked in winter to protect from chilly winds. Some basic forms of passive wind systems are: 56 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. a. Windows and openings » Basically the placement of the window opening , has an effect on how much air flows through a shelter. In order to let air flow through a space, both inlet and outlet openings are required. Inlet openings control the amount of air flow and the outlet openings direct the air stream. Acording to Givoni, “when the wind angle is perpendicular to the inlet window, windows on adjacent comer walls work better and if windows are positioned 45 degrees to the wind direction, the average indoor air velocity is increased and better indoor air circulation is provided". • The size of inlets also effects the air speed. The inlet should be related to the flow pattern in order to catch the incoming air movement. The interior air velocity is increased if the outlet is larger and inlet smaller, which is known as the Venture effect and used commonly in hot-arid climates. Conversely if the outlet is smaller than the inlet, the interior space will receive a decreased air velocity. Figure 2-40 indicates the relationship of inlet openings. • An unobstructed straight flow ensures the speediest air movement. Partitions affect flow patterns only when they are placed in the air stream. Placing partitions in the air flow stream will slow movement and reduce the ventilative ability. The velocity is lowest when the partitions is in front of, or near the inlet window, as the air has to change direction upon entering. b. Wind Tower The basic idea of a wind tower is to catch unobstructed high level breezes. It is popular in hot -arid areas such as the Persian Gulf and North Africa. In areas where wind is mainly from one direction, the tower forms a scoop with only one opening facing the that 57 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. direction. In areas where wind is from several directions, the tower has openings in all directions. Air exharistedthrough high windows in stairwell PrevaiKiigBreezes daws Open Stairwell F ig u re 2-40 W in d m o v em en t a n d v e n tila tio n T h e w in d to w e r fu n c tio n s in th e follow ing m a n n e r: “The air entering the tower from the windward opening with positive wind pressure coefficient, leaves through any opening which has a pressure coefficient smaller than that at the windward opening. That is, part of the air which has entered the tower is lost through the tower openings, (which has negative pressure coefficient) and the rest enters the house. The portion entering the house may be partially cooled by the structure, if a sufficient amount of coolness has been stored in the structure from the night before. W hen air flows over moist surfaces, it is further cooled evaporatively. During the night, when air is flow ingthrough the tower and the building , the ambient air coolness is also 58 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. stored in the building mass. With heavy structures, this energy plays an important role in providing thermal comfort.”7 The disadvantages of traditional wind towers are: • Dust, insects and small birds can enter the building. • A portion of the air admitted in the tower is lost through the other tower openings and never enters the building. • The amount of coolness which can be stored in the tower mass is very limited compared to the cost of the tower. • It does not find any application in areas with a low wind speed, c. Roof and dome ventilation Increasing roof surface helps increase the rate of heat loss. In many hot arid areas, curved roofs are widely chosen over flat roofs. The curved roof s increase the ability of heat transfer and hence are easily cooled. Warm air which is less dense, then rises within the domes or vaults away from the living space and since the hot air is kept within the curved roof, the heat transfer from the roof is minimized . As the velocity of air increases when it flows over a curved roof, the pressure decreases. The reduction of pressure the draws the hot air out from the dome, then the cooler air enters the lower openings. 3. EARTH SHELTER Earth sheltered underground architecture has existed for a long time. We are merely re discovering it through necessity. From the cave man to the pit houses of the ancient Southwest Anasazi Indians, to the more recent dug-out "sod buster" prairie houses of just 100 years ago, people from every part of the globe have been digging in. In situations of 7 Bahadori, 1985, pi 19 59 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. extreme heat, cold, or violent wealth conditions, man has always sought the protection of the earth on which he stood. W ithin a few feet of the surface is a relatively constant temperature environment and protection from the elements, as well as protection from man-made hazards. Along with the "defensive" measures, early man also discovered an added ben efit.... the surrounding earth minimized both the daily and seasonal temperature fluctuations and provided a far more comfortable habitat than he could create on the surface above grade. ADVANTAGES There are many advantages to earth-sheltered construction. An earth-sheltered home is less susceptible to the impact of extreme outdoor air temperatures, so you won't feel the effects of adverse weather as much as in a conventional house. Temperatures inside the house are more stable than in conventional homes, and with less temperature variability, interior rooms seem more comfortable. Because earth covers part or all of their exterior, earth-sheltered houses require less outside maintenance, such as painting and cleaning gutters. Constructing a house that is dug into the earth or surrounded by earth builds in some natural soundproofing. Plans for most earth-sheltered houses "blend" the building into the landscape more harmoniously than a conventional home. Finally, earth-sheltered houses can cost less to insure because their design offers extra protection against high winds, hailstorms, and natural disasters such as tornadoes and hurricanes. C haracteristics of the earth A very important factor which makes earth sheltered buildings energy efficient and advantageous for passive heating and cooling is due to the thermal characteristic of soil.: 60 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. If air could not easily move from one place to another the weather would be a lot calmer and if it took a lot of energy to change the temperature of air, then there would be practically no weather changes at all. Such is the case within the earth. Outside of earthquakes or mudslides, earth does not move at all so convection is non existent and since soil is about a 1000 times denser than air, it takes a lot of energy to change the temperature of a small mass of soil. The resultant is a stable soil climate. Rapid change is almost non-existent below ground and any change is small in comparison to that above ground. b*- porw*/ / v ; ' : ' : ; > p } , L - S E H A V i d ! U R P d F ig u re 2-41 C h a ra c te ris tic s o f soil The ideas of thermal conductivity and R values take on a new meaning in relation to soil. W hen heat flows from the wall to the ground, the ground gets heated as it cannot get away or move with convection, thus the first layer of soil gets heated as fast as the air above, however the second fraction may only change by half the amount and may not start to change 15 minutes after the air begins to change temperature. The smaller temperature change occurs because with increasing depth more and more mass is 61 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. available to absorb heat flows from the surface. The time delay occurs because it takes time for the mass to change temperature and the more the mass, the slower is the change. The same process applies to greater and greater depth. The effects of mass on the rate of heat flow are magnified and increasingly large time delays occur between surface temperature changes and subsurface temperature changes with increasingly small variations relative to surface variations. a rtestfan w dl C B rtiw iftxut w tfl sftaaa O Jb ew fR M W rtC f M tuioleo 90* — "s- ; 's^^T)oTrt2fT«^tian^i35r , umvd ^ THE SOIL SUBSURFACE BELOVA THE EART Figure 2-42 Soil subsurface below the earth i w as'f 3 5 r 'F i h e a t- llo w lin es v/// 6 0 T heal- producing J • . producing ■ I5 T H E A T F L O W P A T T E R N G IV E N O F A N O B JE C T 1 0 0 F T U N D E R G R O U N D - Figure 2-43 Soil subsurface heat flow pattern around an object 62 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Observations show that for average soil every foot below the surface introduces a one - week time delay and temperature-averaging effect. That means that variations that are noted at the 1 foot depth reflect not hourly nor daily but weekly average temperature changes. In order for the changes from surface to depth to be smooth curves, one basic assumption is involved that the thermal characteristics of soil are uniform throughout. Designing for earth sheltered structures There are two basic types of earth-sheltered structures. Certain characteristics such as the location and soils of the site, the regional climate, and design preferences are central to which type will work best for a particular place. •Underground housing means an entire structure built below grade or completely underground. A bermed structure may be above grade or partially below grade, with outside earth surrounding one or more walls. Both types usually have earth-covered roofs, and some of the roofs may have a vegetation cover to reduce erosion. From these two basic types, three general designs have been developed. They are the: • Atrium (or courtyard) plan-an underground structure where an atrium serves as the focus of the building and the entry into the dwelling; • • Elevational plan, a bermed structure that may have a glass south-facing entry. • • Penetrational plan, which is built above or partially above grade and is bermed to shelter the exterior walls that are not facing south. An earth-covered dwelling may have as little as 6 to 8 inches (0.2 meters) of sod or as much as 9 feet (2.7 meters) of earth covering the structure. Architectural Design Techniques a.Build into slope of a hill 63 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. b.Create earth berms c.Build earth integrated structures only d.Develop areas that are fully below graded e.Raise sill heights f.Increase exterior wall weight in DETAIL FOR ELECTRICAL WIRlKlS IN A CONCRETE H6USE‘ ' Figure 2-44 Concrete subsurface structure Every building is a natural shield against fallout radiation. Some buildings are better than others. Providing fallout radiation protection in buildings is becoming a popular design element, the technique is building beneath the ground. Below ground is increasingly viewed as a viable alternative to above ground locations. Sub-surface facilities are subject to little or no shear during an earthquake. Also, machines that require the utmost in stability have fewer problems in sub-surface construction. Since environmental conditions are more constant, machines remain accurate longer. The potential of vibration is reduced in sub-surface facilities. 12" poured concrete walls with Re-bars are very good application, however 12" concrete masonry units (reinforced) can be used in place of 64 Iri.interior tram? .walls' R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. poured concrete walls. 8" reinforced concrete slab can be poured in place as shown in photo - also CMU walls must be grouted, trucks must have easy access to site for cost effective construction. All vertical and horizontal elements burried in earth must be water proofed 3. INSULATION AND VAPOR BARRIERS A large difference between indoor and outdoor temperatures encourages warm indoor air to escape. Winter winds force dense, cold outdoor air through the openings into buildings. In buildings that have been weatherized, air leaks account, on the average, for 30-40% of the heat lost. Insulation is any material which slows the rate of heat flow from a warm area to a cooler one. The more the rate is slowed, the better the insulative qualities of the material. Its ability to resist heat flow is measured as an R or RSI (metric) value, the higher the R- value, the more the material will resist the flow of heat. In order to be effective, insulation materials must be able to reduce the transfer of heat by conduction, convection and radiation, this is determined by both its physical properties and installation. • Conduction - Since conduction is the transfer of heat through solid objects, most insulations usually contain tiny 'pockets' of still air. The air pockets reduce the conductive heat loss by minimizing the amount of 'solid' material within a wall or ceiling cavity. • Convection - In large air spaces, such as a wall cavity, large amounts of heat can be lost through convection (and radiation). As long as the insulation is carefully installed to completely fill the cavity, there should be no air spaces in which convective heat loss can occur. 65 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. • R adiation - M ost insulation have a cellular structure which block the flow of heat by radiation. If the cavity is completely filled with insulation, radiant heat loss from the inside finish to the outside sheathing is virtually eliminated. Choosing A n Insulation The R-value is not the only consideration when choosing insulation, other factors which deserve consideration are the materials fire, mold, insect, vermin and moisture resistant properties, as well as its cost and ease of application. There are many different types of insulation materials, each with properties which make it suitable for certain applications while being unsuitable for others. Insulation is most effective under steady state conditions or if the direction of heat flow is constant for long periods. Insulation may be categorized into two types: a. R esistance insulation The insulation value of the material, characterized by the “U ” factor. The lower the U Value , the better the insulating effect. Air is one of the best insulators because of its weight and low thermal conductivity. Roofs and walls often contain two or three layers of air gap to reduce heat transfer. However, reducing heat transfer depends on the enclosed surface which acts as a heat transferring medium across the space. Therefore, choosing a highly reflective material such as metal foil for air space is recommended because it can reduce thermal conductivity. Also, the angle of the roof and the direction affects heat convection and conduction. b. C apacity Insulation 66 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Capacity insulation is often referred to the heat storage value of a material, characterised by the density times specific heat. The larger the heat storage value the longer time it takes for heat to go through the material to reach an equilibrium temperature is called “time-lag”. M aterials with large time-lag are usually of heavy weight and higher density. 67 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 2.6.1 ACTIVE SYSTEMS Active system is one which employs the use of mechanical means heating and cooling system. A passive heating system will use building components - pumps, valves, and controllers to create as well as capture, store and distribute the energy. The energy required to achieve heating or cooling in active systems could be gained from natural means by employing a mechanical equipment such as a pump. In passive systems there are no mechanical collectors to convert natural energy into heat nor pumps or fans to distribute the heat or covert into some other form for storage or use. The various active systems for thermal control in buildings existing today can be categorized into: • Active solar systems • Active wind systems • Active evaporative coolers • HVAC systems 1. ACTIVE SOLAR SYSTEMS Active solar systems use electric pumps, valves, and controllers to circulate water or other heat-transfer fluids through the collectors. There are three types of active systems: • Open-loop active systems use pumps to circulate water through the collectors. These systems are appropriate in areas that do not freeze for long periods and do not have hard or acidic water. • Closed-loop active systems pump heat-transfer fluids such as a mixture of glycol and water antifreeze through collectors. Heat exchangers transfer the heat from the fluid to the water stored in the tanks. 68 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. • Drainback systems use pumps to circulate water through the collectors. Because the water in the collector loop drains into a reservoir tank when the pumps stop, this is a good system for colder climates.8 There are various types of active systems in the market today and even newer ones are available every day. The web site gives a concise description of some of the most common and popular existing solar active systems with links in the end to the web sites which keep abreast of the new systems coming out. Some of the more common active systems are: a. Solar collectors Solar collectors are at the heart of most active solar energy systems. They are the key component of active solar systems, and are designed to meet the specific temperature requirements and climate conditions for the different end-uses. The collector absorbs the sun's light energy and changes it into heat energy. This thermal energy can then be used to provide heated water for residential or commercial use, to provide space heating or cooling, or for many other applications where fossil fuels might otherwise be used. There are several types of solar collectors: • Flat-plate collectors • Evacuated-tube collectors • Concentrating collectors • Transpired air collectors 8 Aspen Energy Forum.Solar architecture : proceedings, Ann Arbor, Mich.: Ann Arbor Science Publishers, 1978. 69 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Residential and commercial building applications that require temperatures below 200°F typically use flat-plate or transpired air collectors, whereas those requiring temperatures greater than 200°F use evacuated-tube or concentrating collectors, a.l Flat-plate collectors They are the most common collector for water-heating and space-heating installations. A typical flat- plate collector is an insulated metal box with a glass or plastic cover— called the glazing—and a dark-colored absorber plate. Figure 2-45 Flat plate collector The glazing can be transparent or translucent. Translucent (transmitting light only), low- iron glass is a common glazing material for flat-plate collectors because low-iron glass transmits a high percentage of the total available solar energy. The glazing allows the light to strike the absorber plate but reduces the amount of heat that can escape. The sides and bottom of the collector are usually insulated, further minimizing heat loss. 70 Mat-Flate Collector Inlet C o n n e c tio n — G U fin g fmnne — C U iin g Outlet connection E ikI o c u io — -v flo w tubes— '’ ’ A K w iib m pU to—'' lira] tit! cm— R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. a.2 E vacuated tube collectors Evacuated-tube collectors Evanuled-Tube Collwtor outer glass tube and strikes sunlight enters through the evacuated-tube collector, flat-plate collectors. In an at higher temperatures than are typically more efficient O utetgbH tuta — Abunblngoutlng f V\VV '~ tnnci gU « tub* — Qyl]}- fluid tuba aT Jjljj'" C o fP « t E v K U lfa ltp K C C U tin g In flo w Retimtoi the absorber, where the F igure 2-46 E vacuated tu b e collectors energy is converted to heat. The heat is transferred to the liquid flowing through the absorber. The collector consists of rows of parallel transparent glass tubes, each of which contains an absorber covered with a selective coating. The absorber typically is of tin- tube design, although cylindrical absorbers also are used. a.3 C oncen tratin g collectors Concentrating collectors use curved mirrors to concentrate sunlight on the receiver at up to 60 times its normal intensity. These high-temperature systems are used primarily in commercial and industrial applications. Concentrating collectors use mirrored surfaces to concentrate the sun's energy on an absorber called a receiver. Concentrating collectors also achieve high temperatures, but unlike evacuated-tube collectors, they can do so only when direct sunlight is available. The mirrored surface focuses sunlight collected over a large area onto a smaller absorber area to achieve high temperatures. 71 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. a.4 Transpired air collectors Transpired air collectors are made of dark, perforated metal. The sun heats the metal, and a fan pulls ambient air through the holes in the metal, which heats the air. They have been used for pre-heating ventilation air and for crop drying. Transpired air collectors have achieved efficiencies of more than 70% in some commercial applications. b. Photovoltaics The "photovoltaic effect" is the basic physical process through which a PV cell converts sunlight into electricity. Sunlight is composed of photons, or particles of solar energy. These photons contain various amounts of energy corresponding to the different wavelengths of the solar spectrum . When photons strike a PV cell, they may be reflected or absorbed, or they may pass right through. Only the absorbed photons generate electricity. When this happens, the energy of the photon is transferred to an electron in an atom of the cell (which is actually a semiconductor). With its newfound energy, the electron is able to escape from its normalposition associated with that atom to become part of the current in an electrical circuit. By leaving this position, the electron causes a "hole" to form. Special electrical properties of the PV cell—a built-in electric field— provide the voltage needed to drive the current through an external load (such as a light bulb). To induce the electric field within a PV cell, two separate semiconductors are 72 Solar Air Collector Warm d r out Glazing Absorber In su latio n Coot dr in Figure 2-47 Transpired air collectors R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. sandwiched together. The "p" and "n" types of semiconductors correspond to "positive" and "negative" because of their abundance of holes or electrons. When the p-type and n- type semiconductors are sandwiched together, the excess electron the n-type material flow to the p-type, and the holes thereby vacated during this process flow to the n-type. Figure 2-48 PV Cells The PV cell is the basic unit in a PV system. An individual PV cell typically produces between 1 and 2 watts, hardly enough power for the great majority of applications. But we can increase the power by connecting cells together to form larger units called modules. Modules, in turn, can be connected to form even larger units known as arrays, which can be interconnected for more power, and so on. In this way, we can build a PV system to meet almost any power need, no matter how small or great. 73 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. * 1 * Holci filled byfrcod electron! Figure 2-49 Inside a PV cell Some of the most common forms of manufacturing photo- voltaic are : b.2 Crystalline silicon process Polycrystalline thin-film devices require very little semiconductor material and have the added advantage of being easy to manufacture. Like 1 ™ ^ Figure 2-50 Crystalline silicon process amorphous silicon, the layers can be deposited on various low-cost substrates like glass or plastic in virtually any shape—even flexible plastic sheets. Single-crystal cells have to be individually interconnected into a module, but thin-film devices can be made monolithically (as a single unit). Layer upon layer is deposited sequentially on a glass 74 . AritircHectioct coating. • • :• • • ••Tram parent • ; conducting . C Q A t i n g * V v '■ (unction form ed’ • b e tW o o n tw o sem iconductor • r,t' niat£naJi*qf opposite conduction typvV • •Substrate Ohn>ic c o n ta c t • • B ottom j>typc“Absorber* I layer fo.rrneo bysecond i sem iconductor ™ atom ]. . L — Top n-type' .Window"- • layer formed by first v sem kopduttor m atonal R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. superstate, from the antireflection coating and conducting oxide, to the semiconductor material and the back electrical contacts. b.2 Amorphous Silicon Amorphous solids, like common glass, are materials in which the atoms are not arranged in any particular order. They do not form crystalline structures at all, and they contain large numbers of structural and bonding defects. Amorphous silicon absorbs solar radiation 40 times more efficiently than does single-crystal silicon, so a film only about 1 micron (one one-millionth of a meter) thick can absorb 90% of the usable solar energy. b.3 Gallium arsenide (GaAs) Gallium arsenide (GaAs) is a compound semiconductor: a mixture of two elements, gallium (Ga) and arsenic (As). Gallium arsenide's use in solar cells has been developing synergistically with its use in light-emitting diodes, lasers, and other electronic devices. One of the greatest advantages of gallium arsenide and its alloys as PV cell materials is the wide range of design options possible. A cell with a GaAs base can have several layers of slightly different compositions that allow a cell designer to precisely control the generation and collection of electrons and holes. 2. ACTIVE WIND SYSTEMS Wind power like water power has provided energy to pump water and run mills and other machines. .Modem wind turbine technology has made significant advances over the last 10 years. Today, small wind machines with 5 to 40 kW capacity can supply the normal electrical needs of homes and small industries. Medium-size turbines rated 100 kW to 500 kW produce most of the commercially generated electricity. At present, the larger, heavier blades required by large turbines upset the desirable ratio between size and 75 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. weight and create efficiency problems. Assuming a 35% operation capacity at a favorable site, the energy input/output ratio 2 of the system is 1:5 for the material used in the construction of medium size wind machines. ® 1998 _ , , , w w * w iN D P o w E R .d k Figure 2-51 Rotar blade Figure 2-52 Wind turbine A typical 600 kW wind turbine has a rotor diameter of 43-44 metres, i.e. a rotor area of some 1,500 square metres. The rotor area determines how much energy a wind turbine is able to harvest from the wind Since the rotor area increases with the square of the rotor diameter, a turbine which is twice as large will receive 22 = 2 x 2 = four times as much energy. The graph gives you an estimate of how wind speeds decrease behind a blunt obstacle, i.e. an obstacle which is not nicely streamlined. In this case we use a seven story office building, 20 meter’s tall and 60 meter’s wide placed at a distance of 300 m from a wind turbine with a 50 m hub height. They can be divided into two basic categories: a. Horizontal Axis Wind Turbines Most of the technology described on these pages is related to horizontal axis wind turbines (HAWTs, as some people like to call them). The reason is simple: All grid- 76 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. connected commercial wind turbines today are built with a propeller-type rotor on a horizontal axis (i.e. a horizontal main shaft).The purpose of the rotor, of course, is to convert the linear motion of the wind into rotational energy that can be used to drive a generator. The same basic principle is used in a modem water turbine, where the flow of water is parallel to the rotational axis of the turbine blades. Figure 2-52 Horizontal wind turbine Figure 2-54 Horizontal wind turbine b. Vertical axis wind turbines Vertical axis wind turbines (VAWTs as some people call them) are a bit like water wheels in that sense. (Some vertical axis turbine types could actually work with a horizontal axis as well, but they would hardly be able to beat the efficiency of a propeller-type turbine). The only vertical axis turbine which has ever been manufactured commercially at any volume is the Darrieus machine, named after the French engineer 77 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Georges Darrieus who patented the design in 1931. The Darrieus machine is characterized by its C-shaped rotor blades which make it look a bit like an eggbeater. It is normally built with two or three blades. Some basic rules of thumb for wind turbines are: • They should be at least 30 feet higher than any surrounding building and the ratio of the distance from the buildings should be 3-5 times the height. • The basic formula to be kept in min is K.E = Vi mv2. If speed is less than 10 mph then it is not useful. At 13 miles per hour, it pays for itself and higher than that it is extremely useful. 3. ACTIVE EVAPORATIVE COOLERS Evaporative cooler offers an energy-efficient, ozone-friendly way to further cool off a building. An evaporative cooler basically consists of a large fan and water-wetted pads. Fresh outside air is cooled by about 20 degrees as it is drawn through the wet pads and blown into the house. The cooler slightly increases the humidity of the entering air. This contrasts with air conditioners, which reduce humidity as they recycle the air in the house. The wetted pads on an evaporative cooler are fairly efficient air filters, trapping particles on their wet surfaces. The continuous wetting of the pads flushes the trapped particulates into the sump, where they are contained. The low power requirement means one can just plug an evaporative cooler into a nearby 120 volt wall outlet on all but the largest units. Usually no special wiring is needed. Many air conditioners require their own high amperage power circuit. It needs to a water supply; some small coolers are filled manually, while for the larger ones a ball-valve "Y" hose fitting on a outside hose bibb will do the job. Water consumption can be from 3 to 15 gallons a day. Evaporative 78 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. coolers are relatively quiet, simple appliances which use less than a quarter as much electricity as an air conditioner. Cooling Performance The cooling performance of a single stage evaporative cooler is determined primarily by the temperature and relative humidity of the incoming air. Typically, the relative humidity falls to around 30% on a 100 degree day in the Willamette Valley, yielding a cooled air temperature of about 82 degrees. 4. HVAC(CONVENTIONAL HEATING AND VENTILATION SYSTEMS) The design and calculation of HVAC systems which are the most common and widely used systems today, requires a detailed explanation of governing processes and factors. I have left that element as a part that can be added later. My theoretical research on the subject ends at this point. REFERENCES S.R. Hastings. Passive solar commercial and institutional buildings: a sourcebook o f examples and design insights Chichester ; N ew York : J. W iley, c l9 9 4 . Australian Academ y o f Science. Report o f the Committee on Solar Energy Research in Australia.Canberra : Australian Academ y o f Science, 1973. Patrick O'Sullivan.Paw/ve solar energy in buildings London ; N ew York : Published on behalf o f the Watt Com m ittee on Energy by E lsevier Applied Science ; N ew York, N Y , U SA . Elsevier Science Pub. Co., c l9 8 8 . 79 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. C H A PT E R TH R EE T H E W EB AS A TE A C H IN G M ED IU M 3.1 ISSUES INVOLVED IN USING THE W EB AS A TEACH ING M EDIUM Over the years, research in the field of education and learning has revealed three key philosophies which govern the learning ability of human beings at any age. These are: • L earning by doing: A large body of research shows that people learn most effectively by actually performing the skills and exercising the knowledge they are trying to acquire, especially in creating realistic environments that allow people to practice skills and apply knowledge in simulated worlds. • L earning from failure: Failures provide people with the best opportunities to learn. It is at precisely the point at which a student has become aware of a mistake that he is most ready to acquire the new knowledge that will help him avoid similar mistakes in the future. • L earning from stories: Stories are a memorable way to illustrate general principles providing the concrete detail that people need to apply those principles to their own situations. The advent of the W orld Wide Web comes at an exciting, yet controversial juncture in education reform. Possibly the most important point that must be addressed is the current emphasis towards interactivity in the learning process. The term "interactivity" has become somewhat of a buzzword in teaching and commerce - for example, some educational software packages attempt to add to their appeal by emphasizing the product's "interactive" nature. In other words, passive learning doesn't work, yet interactive learning works wonders. Yet beyond all of the hype and rhetoric surrounding 80 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. interactivity in education, there is a solid backdrop of empirical analysis to support the positive nature of interactive learning1 . Simply put, students of all ages learn better when they are actively engaged in a process, whether that process comes in the form of a sophisticated multimedia package or a low-tech classroom debate on current events. Engaging students from a variety of angles and allowing them to feel as if they are a part of the subject matter will often lead to them becoming more interested in (or at least more willing to discuss) that subject. Therefore, they invest more m ental energy and thus commit the concept to memory with a better comprehensive understanding of it. Students, when encouraged and given the proper opportunity and medium, can express a wealth of opinions on nearly any subject. And by giving them the chance to articulate and share their thoughts, they can grasp the meaning of the subject and thus understand it better. From a curricular point of view, the W eb can be used to design tutorials and on-line lessons for a variety of subjects. For example, Roger Blumberg o f the Institute for Brain and Neural Systems at Brown University has created an online tutorial on basic genetics known as Mendel Web. With Mende IWeb, students are introduced to basic genetics and the writings of scientist Gregor Mendel and his Experiments in Plant Hybridization The hypertext version of Mendel's writings contain links to a dictionary of terms, as well as annotated comments from other readers that can be added to by any user. Yet the potential of Web tutorials has yet to be realized largely because most Web books have been technically oriented, and in order for this technology to reach the mainstream, 1 Interactive learning. 81 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. we must also design Web tutorials for architecture, music, language arts, and other less technically-minded disciplines. 82 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 3.2 AN ANALYSIS OF EXISTING SITES AND TOOLS 3.2.1 EXISTING TEACHING SITES ON THE WEB Given below is a list of some of the tools that have been developed for teaching different subject matter to students, with the sole aim of enhancing the learning ability of students as well as reaching out to a wider audience. SOFTWARE_________ PJ PURPOSE ; • Is it a Rembrandt? Partner: Professor Larry Silver, Department of Art History, University of Pennsylvania Playing the role of an art investigator at the fictional "American Museum of Art", the student must investigate three paintings thought to be Rembrandts. By examining the paintings, performing technical analysis, and consulting a database of 450 expert video clips, students learn about art history, Rembrandt, and attribution. Invitation to a Revolution Partner: Professor Gerald M ead, Department of French and Italian, NU Transported to a computer-simulated Versailles garden, the student plays the role of a m em ber of the Third Estate delegation to the Estates General of 1789, taking on the mission of recruiting other delegates to join the nascent National Assembly. By conversing with members of the many different groups within French society, students becom e familiar with the social, political, and cultural situation prevailing in France just prior to the French Revolution. Immunology Acting as a consulting clinical im munologist to a general 83 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Consultant Partners: Professor Carl W altenbaugh, NU Medical School; Professor Michael Altman, NU Medical School physician, a student must help explain a puzzling case having an immunological etiology. By interviewing the patient, requesting laborator tests, and consulting a large database of experts, students learn the basic physiology and patho-physiology of the immune system. ChemLab Partners: Dr. Joyce C. Brockwell, Department of Chemistry, NU ChemLab is a virtual laboratory which gives undergraduate chemistry students the ability to perform Thin-Layer Chromatography in simulation before trying it in the real lab. Students can spend unlimited time practicing the procedure and consulting experts, making mistakes in simulation and learning how to avoid them in the real world. Fire Commander Partners: Wauconda, Illinois Fire Department and the Illinois Fire Service Institute Fire Commander teaches children fire safety, fire science and behavior, and firefighting techniques. The student is placed in the role of a fire commander at the scene of a house fire. As fire commander, the student must make all major decisions at the fire scene - which part of the fire to control first, family safety, how to handle bystanders, etc... The student must decide the best way to organize his crew, help the victims and prevent the further spread of the fire. 8 4 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. INNOVATIVE TEACHING MATERIAL 1. Innovative teaching in microbiology Dr Alan Cann of the Department of Microbiology and Immunology has developed a powerful, flexible and interactive system for delivering innovative teaching materials in Biology and Medicine via the World Wide Web(WWW). Over 100Mb of materials, including text, high quality images and video, are now available from this system, which can be viewed online at the following URL: http://www-micro.msb.le.ac.uk/ u ftjiliw fliB H n ra w iD ia B B H n H M ia B m n H ira M w a B H B H B lr lf f j V* W e . < fjverit* •;Io d r E ] 8«ck Ferw anJ St# H err* PavtritM HWay.; .'•'AMftLA.;.Vvv'Cil. LRwCtiJa : :..' • :"V' nth b a ...u l a { n a m a s i — 1 SE A R C H : ’ ' IH w itL'T. & '' • M mTSjk v .. & 1 * V W W /U jrtirt k . * ♦ MMWB i L a W o rk : i i ‘ QcJin? Erptrirr* nD A il # 1 : M tcw btolosv Ne-.vsrtom % : BSE: d ; U ieitK ew i 'S s jj ' MirroW olorvViifolibruy h}- i * * * « » * 1 ' •ht'/in* MOCltf i i • B51&S: > lDtrodtK'JMiloMirfobidagy ■&I 1 . BS210: fell ; M ittobidejyl m i 4 2S22A: jM ia o b io k g y ll i«ji IptLeicester ^University D e p a rtm e n t o f M ic ro b io lo g y & Im m u n o lo g y > Mkfc-foolcw & tannac&ay Staff 1 Research Tonic* 19$$ • Microbiology & Irrgmgicjogy Assessment Procc& gc for A P G .p h t) Students ' Leicester* U nrvfrstv Horae P-vc 1 Leicester Unjvct’ Sjy Librasv: Crncra! Hbrmaiifrfl i Directory ofm icrobiolsav information from the American S c c srtr for M::rohiole.gy ■ Irrtcm elR orourcerfor Reteaech on Bacterial Palhorenerb ' Jus! for Fun liTHT: fZ I . : . - .... . Figure 3-1 Snapshot of web site of Leicester University However, the most innovative aspect of this project is the use of interactive teaching materials, including multiple choice questions, student text submission facilities and interactive tutorials. Recently, Dr Cann has begun development of a virtual hospital 85 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. which medical students (including postgraduates) will visit in their own time or as required by the medical curriculum to examine real or simulated patients illustrating a variety of clinical specialties. All of these exercises can be constructed as self-guided learning exercises, or used as part of the assessment process as required. However, at present, these interactive aspects of this project require the ability to write custom scripts for each application. In order to extend this facility to academic staff in all subject areas, it is proposed to develop a high level authoring shell which will enable all staff to participate in this new learning technology by learning a simple set of markup commands. 2. Teaching heat transfer through the web This particular site is an interesting attempt to teach the process of heat transfer in solids and fluids through the web. There are small programs to analyze heat flow in various situations and students can change factors to get different heat flows. There is also a quiz section which inquires about the basics of heat flow and thermodynamics. In this, the student can either submit their answer or review it for oneself. The site is a pioneer in the field of thermodynamics, as it is one o f the best existing tools on the web, for teaching heat transfer. http://www.people.virginia.edu/~rir/modules/ 8 6 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. E h E d) . y i n F i v o l n l o o k ’ K * E n a ■s i o B a c k - ''. F om « d -S lo p ';- , R c fttth H orn - Saarch Fevorttf Hbtwy ; Mai -•’ P rin t-- E dt ■ > .< ■ R a aC u d a j Ajdaw |^htlp:/<W»t<)goptt.vfQini» B du/^fir/m cK fcjtei/ z Ji C ^i SiWEduicaiional Software ;Heat-and'Mass Transfer WJKMRifittmW -.ViVn'-'v,: U L 'S -fi ' I n t e r n a l f l w i ........... Extended S m , fo rfa ( H h jV ■ • • J. .* • IfcftU&htBSfiB' • .• • ■ * .; : > : ,■ •'.} > • H aiU tlo n A T n f Facfrn) ' .•• ■ • ^ U n d e rs ta n d in g th e . ■?.'^ ^ ’ dam tntH ls o f h e a t a n d m iii* tra n s fe r w h ile exposing " / ' th e m to m oddnl.coirqjiU atioi^.^yisU alizataon • . ' • an d design tech n iq u es; _ . . > : M :•. ^ ' ‘ ^ •' Ftiir-color^walizfltion o f fundamcntJil concepts . 4»:Simple'{s t r a g h t . f o r w a r d u s e r - i n p u t .' ' • ■ * ’ .G raphical output emphasising student in s is t ••tfY:'# Sieahiless integration o f Fortran end Visual Basic . Easy inicrtioninto existing engineering curriculum ;ConitVuten System Requirements .■ ■ ■ • - : IS :. z i I ,; ; ! ® ln>wnol .. | C 0 # £ V ,5 5 9 PM l i ^ S l w l | |^ lM to :rK i» > irf.< w < :iy H k a o « cftW « (i-.~ ..|-W P « i* M u * lc ‘ M ^ ^ P f l^ ^ y p r M n y .. |,B A d o feo P h o to tf« p [ijjff h « i » y ^ .b r n f r ..| ‘ F ig u re 3-0-1 W eb site for teaching heat an d m ass tra n sfe r 3. W eb Site fo r T eaching Structures to students S-Frame for W indows is a 2D/3D structural analysis package with a wide range of modelling and analytical facilities, ranging from simple beam elements to 3D frames, cables, shells membranes and plates. The program has as its basis a finite element analysis engine which allows the user to integrate the full range of structural elements encountered in typical constructional works. This particular site provides the basics of structure and frame analysis in theory as well as the software itself. The information is presented in a straight forward, easy to understand manner, though there is little attempt to enhance interest through the use of graphics, animation or even activated hyperlinks. http://w w w .um ist.ac.uk/~civresrc/sfram e/2dtut.htm 8 7 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. BH H b i KBHW S K B i f l M i n S r B H f l H f l ■aoB SB SH K U naa •_1 » i x ]■ P» "£<*,(ipw w "F jrv o riu w ;}; .io o b ;'IM S5;r: t S ' v • ■ ;Back" ''--I Forw ard1 Stop Refraeh 'Home '• ] - Search F avorite! m - HiHay, v ’ .Mai ■ Print'. £& RwCiide |AjJdett Ntp:/AwmuTaieci4i/~cMeuc/rt<TO/2dt<jl.hin 1 . - ...................................................... .................... 4 o UMIST Department of Civil & Structural Engineering O S -F ra m e S tr u c tu ra l A n a ly s is S o ftw a re W e b R e s o u r c e s ijl f Home Page 12D Tutorial 1 Download ] S -F ram e © C5C(UK) Lim ited ;j Q u e rie s? • E m ail:- m ichaftl.rt95Son@ um ist.ac uk ! ! ; • 2D TRUSS TUTORIAL || - INDEX . -j, 1 .0 Introduction . !}• 2 .0 P ro g ra m Interface fjl 2.1 T h e P rc-Proccssor 2 j2 T h e P o st-P ro cesso r jjj 3 .0 D efining a Structure for Analysis 3.1 T he f ir s t Steps ♦ A 2D T ru ss : 3 .2 Setting Suitable G eom etry W indow Options . o i r> -g— ,r t- . *r _ ' . ' ■ Z i 1 • - I- Inter*.. - y ^ :7 '/ i^ S t i i i l l ljf tU iw S uppott.-2 .. . j jgyM icmtcflW ord«T h e .} Q 0 e« M u ile« M lcQ ;-.| <PRMPlayarM nyeRi„.} fgthcorriort.brnp-Paint' | ; : ; ;| Figure 3-2 Snap shot of web site for teaching structures 4. Architectural Atmospherics This site is provides information on how buildings interact with the environment. It touches the topics of heat transfer in buildings and is thus unique in that sense, that it is the one of the few sites which provide actual teaching information on the subject. However, the subject matter present on the web is a non-interactive page by page description with no search tool or interaction with the user. The user is forced to visit every page to get any information and there is little attempt to enhance the clarity of the page through interesting hyperlinks. http://www.columbia.edu/cu/gsapp/BT/RESEARCH/Arch-atmos/index.html 88 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ' 3 A ic h ile c lu ia ! A tm 6 sp h e iic * ‘ M iC (oi6iU hlc<pc( C x p lo rtt p to v id c d bV ^ S N . -. E f e £ t £ ' ; ’ • y i e w - ■ F j v o r i i s i ' i I o o b • H e l p © c a S 3 3 ■ w ; • • t . h i c u . ; - ' . . F o n v w L ’ ■ S t o p a ; R d i « h i " ' . H o m e ; • ' . . S e a e H F a v a l s * . : H e l o r j » • • v . P i r t ' r E d t : j A j d e r i j g ] h W y Z / y ^ . e o k O T b i a . c d u / e u / o t a p p / S T / R E S E A H C H / A i d v a t f n o i / i n d e i c h t f f i l ~ v j i ^ G c {Architectural Atmospherics A rchitectural A lm o sp h iric s is an NSF-G atcw ay sponsored joint p ro jctt o f Professor Vjjay M odi and the fBufldin;? Technologies Grcupl The project is turned at I accurately modeling air flow in buildings and heat transfer across building enclosures. W e plan to use our modeling capabilities for the thermal analysis of existing > buildings, for optimizing the performance of proposed passive convective healing and cooling systems, and for developing high velocity, high pressure air distribution systems for multistory commercial structures. < • O ur first project is a thermal-performance study o f Idles Van der Rohe's Farnsworth House. W e are currently using “ Phoenics 2.1a software for determining flow \ fields, and closed form, spreadsheet based calculations for heat transfer through the building envelope. \ \ O v e rv ie w : H c u t T r a n s f e r C o n s id e r a tio n s I n A r c h i te c t u r e • S u m m a r y o f W o r k to D a te j 1. PreHminarv W ork [ o PoiseuiDe Flow; pressure driven flow between two plates j Closed form solution i, Pheonics test case j_ o Turbulent Natural Convection V 2. Comparisons with dosed form models V Overview y \ o Laminar flow — Ra = 6.06E-H)3 » •* » o Turbulent flow - - P a = 6 75E-FQ5 • ' T u r K n l * * * f t , m w — T J t . a “Z “ X P P - l - f l F ; i l l l J l O ; b ! t y f / ! ^ .e © l i r f W A e 4 i ^ e M p t y B T # E S E A R a V & c M ! T ) ^ i 1 © fi:: f g & S i a | | f r V f e h i l M l u ^ A I . , : . . ! i j y W m i < ^ W n d - ~ T I ^ . | r . j n b r a ^ B j t j n O t P h a a i h c a I . ' t S f f l f r P - 6:32 P M ; j Figure 3-4 Snap shot of site providing information on architectural atmospherics 3.2.2 EXISTING BUILDING TECHNOLOGY SITES ON TH E WEB 1. The Home Energy Saver The internet is an important new resource for energy efficiency. While many applications amount to little more than reformatting static text into Web pages, the internet shows its true potential when its users interactively obtain customized information. One such tool is the Home Energy Saver, which was one of the first internet based tool for calculating energy use in residential buildings. The Home Energy Saver quickly computes a home's energy use on-line, based on methods developed by Center researchers. By changing one or more features of the modeled home to improve energy-efficiency, users can estimate how much energy and money they can save. Hypertext links lead the user to hundreds of 89 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. other Web sites that provide detailed information on energy-efficient products, home builders, residential utility programs, government programs, practical newsletters, energy software, and other useful topics. http://hes.lbl.gov/ Virtual H om e Energy Advisor How much can homes in your area save? Analyze your home for energy savings L ib rarian o A host o f web resources Frequently Asked on home enersv savings Questions Figure 3-5 Snap shot of the Home Energy Saver main page 90 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The Home Energy Saver W eb site consists of four main elements. With a single mouse click, the Quicklook module instantly compares energy use for typical and energy- P r e s s I n fo r m a tio n H o m e E n D r g y ^ S a y o r D e m o M o y io » • ; A w a r d s & A c c o la d o s — H om eow ners w a n te d to participate in a liom e en e rg y rese a rc h project. Details.,.,. D e v e lo p e d by th * L a .^ i i ^ j r .S c i X L ^ ► U L sa id L jlw tiiu ti S p p n tm g -J by tt>o a n d th » y X X 't i n . r l m t d i l . y ' f ___________________________________ _ J J tBrrTvTTr^rTrr.,...: .• - .tt"":-.. .t.~ . ........s .'...: .....- - ~ ~ i H u m C n w g ~ 1 {y M f r w o ftW a r f.T tw L .j - P ) & f n ~ M ’ ut I f l - H o n '.I O fliw fW g r.T w * M w _ | 3 & < to b w P h o to C c c { ■ : ■ .5 .1 J W Figure 3-6 Snapshot of the start page of the Home Energy Saver efficient homes in different parts of the country. The Home Energy Saver's Virtual Home Energy Advisor goes a step further by calculating energy use in a particular city, based on a detailed description of the home provided by the user. In addition to calculating energy use on-line, the Home Energy Saver's Librarian connects users to an expanding array of related information resources on the Internet; the Answer Desk provides answers to a variety of frequently asked questions. However, mostly it has more of an advanced research content which is very useful, but intended for professionals with prior knowledge on the subject. 2. REED (Residential Energy Efficiency Design tool) A similar tool has been developed by the Southern California Gas company for estimating the energy usage in a house and then advising on the layout, the type of I j V y d v t t i 'i i n p / / i x > i IV • > « a r i i x t w * v r > l?*r k'.tn lf» r* * * .* W vm w *: | fMF/3u>‘H TAJl vn-tfifrttx mfcHirrtlKmivi 4»vxAirH. c fK .1 Hw w M tv iw h w u fVixy.v* ______ j 91 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. heating and ventilation system be used along with the power required for these systems. It goes to the extent of suggesting on the number of windows on a particular facade and their layout. The site is extremely useful in terms of the technical accuracy and energy advise that it provides. It has been done entirely in javascript and is thus very easy to download. The major drawbacks to this site however, are in the fact that it does little to draw user interest in terms of use of interesting graphics and text. A first time user would easily skip it for just another ordinary site. Besides, again it is useful for a lay person in probably laying out their home or analyzing their energy efficiency but it provides no background on concepts and theories and requires prior knowledge of the subject. ij fh £*• to - b* lr: , 9c*.■ ■ ■ --Hw . ( w w = : ;tfUW ^Chwatr)-TutK»»»r:, ." 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C iif tn u * • f c o d e ) ^ _____________________________ „ _____________ d - - | . _ tP ia & K * v M f lC w lg f e | y j 4 r a c * W to d - ■ ■ > • ■ ■ ■ ■ W o m f t l H W C .. ■ T)Cpntecl.faU‘* -'V23»al - Figure 3-7 Snapshot of the REED site. 92 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. The two tools discussed here afros were web based and required connection to the web while operating. However, the field of building technology has pioneered a number of non-web applications which are independent software’s and are available by payment or for free on the web. Recently, a number of companies and organizations have made these software’s downloadable from the web, either free or for payment of a small fees. Some of these applications are discussed in the following examples. 3. Pow er D O E PowerDOE is a new version of the DOE-2 building energy simulation program. Its primary developers are the Building Technologies Program, Hirsch & Associates, and Regional Economic Research, Inc. PowerDOE has a graphical user interface running under Microsoft Windows, making it easier to use than DOE-2 while retaining DOE-2's calculating power and accuracy. Interface features include menu-driven input, on-line help, graphical results display, building component libraries, links to CAD packages, and the option to generate a building description automatically from type and vintage. PowerDOE has an open architecture to encourage third-party development of specialized performance analysis modules that can be attached to the core program. For example, a planned link to the object-oriented SPARK program will allow users to simulate new HVAC technologies of arbitrary complexity. 93 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. File Edit U tilities View Help 1 C o m m ercial B uildirig‘A n a ly sis;T d o l -P o w e rD O E . v- , ; }liv-^M aln'M enuI£ |:' Sita' f | Builtiin;3 ~~~l ^ li' Run:C alc s: : 1 l :i- Costs I '• t Results I :(BCilid" | £ |jR sftig~l tr^lSVilre1 !^ flFfoor?l:=l: 2bna-iL^'-Y'’l-'Bl5'EqGi^1^liESretsm‘^^M rcnfirrpi5W TI : Building: ■ f . EEBIISEESBI■ N Floor: Main - First 4 S p a c e :' Ml - South 4I f. 4 m Day Lighting Lighting People Equipment t i i Infiltration Furniture S p ace N am e: S p a c e Type: Z o n e T ype: . Sun S p ace: T em perature: M l - South ExtO ff Conditioned No 75.00 deg Air Chngs/Hr: Infil. M ethod: D ay Lighting: Lighting Type: 0.25 Air C hang No Area j P erso n : Light Intensity: Eq In te n sity :; M eat Source:: : 120.00 1.75 2.70 E le ctric SqFt W/SqFt W,'SqFt BTU/Hr Rec Fluor R v , Construction Figure 3-8 T h rough a Schem atic Design Tool th a t incorporates shadow -casting. PowerDOE, however, is still an analytical rather than a design tool, and its primary audience is engineers, energy consultants, and utility staff. 3. B uilding D esign Advisor BDA is the code name for a building design tool that the Building Technologies Program of the Lawrence Berkely Laboratories is developing. BDA will give building designers an integrated view of how well different solutions meet design criteria throughout the building design process, from the initial, schematic phase to the detailed specification of building components and systems. Based on a comprehensive design theory, BDA will be linked to simulation algorithms for energy and other performance considerations, such as cost and environmental impacts, and to databases, such as electronic product catalogs, 94 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. and utility programs. BDA will also provide context-dependent advice on performance improvement. r f ^ 7 F i le , Eclit.: G o tfte rt.; D e s ig n P effp n rn an ce Llbrarie s - D e sig n T e m p la te T otal Energy Case Studies Library • — Average — ..Levrs Plaza ■ ; JFMAMJ J AS OND P e a k D em and — Average • — Levi's Plaza Building:] Levi's Plaza V ie vs Location:| San Francisco, CA Type: | Commercial; O ffice Floor Area: J F M AM J J AS O ND L ife C ycle C ost Average Levi's Pla 2 a Ovner: [Levis Stauas $ Architect: I nellmuth, Obala & Firm:! Kessabaum Liie-Cycle @ 40 Y ears Energy Design Considerations: Side Lighting Skylights Atriums T.lyhr Wellfl O p e ratin g C ost ■ —Average —»Levis:Plaza 'Data J F M.AMJ J AS OND Figure 3-9 The interactive user interface of BDA. The first version of BDA will be linked to PowerDOE and will incorporate a Schematic Design Tool and a multimedia-based Case Studies Database (CSD) to help building designers understand the energy and cost impacts of changing the values of building parameters (such as shape, orientation, and number of floors) using the PowerDOE simulation engine. This database will be the equivalent of an electronic magazine for existing buildings, providing a realistic set of benchmarks for evaluating the performance of proposed buildings. The initial versions o f PowerDOE and BDA were scheduled for combined release in the spring of 1995. However, they are still in the process of developing. These are both downloadable software’s, which though available over the web, need to be operated independently of it. 95 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4. THERM: Two-Dimensional Building Heat-Transfer Modeling Figure 3-10 Snapshot of THERM start The W indows and Daylighting Group's two-year-old computer program THERM 1.0 is a state-of-the-art tool for modeling two-dimensional heat-transfer effects in building components. The thermal property information THERM provides is im portant for the design and application of building components such as windows, walls, foundations, roofs and doors. This Microsoft W indows-based program has great potential to users such as building component manufacturers, educators, students, architects, engineers and others who are interested in assessing the heat-transfer properties of single products, product interactions, or integrated systems. THERM identifies thermal short circuits in components, allowing designers to make more effective insulation technologies and insulating designs. The user can trace imported files in D XF or bitmap format or 2input the 2 References: CBS Newsletter for Building Technologies 96 Figure 3-11 Graphic and analytical ability of THERM H i ' Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. product's geometry from known dimensions. The cross section is represented by a combination of polygons, with material properties defined for each polygon. The user introduces the environmental conditions to which the component is exposed by defining the boundary conditions surrounding the cross section. Once the model is created, the remaining analysis is user-transparent. Results from THERM can be viewed in terms of U-factors, isotherms, heat-flux vectors and local temperatures. This product however, is an expensive state of the art software available to professionals or others for a high price and requires complete knowledge of the subject of heat transfer in buildings , inorder to put it to any use. 97 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3.3 THE NEED FOR A NEW TOOL An analysis of the existing sites on the web - both the existing teaching tools as well as the existing building technology sites and softwares has laid aside certain issues for examination. As aforesaid, there are existing sites and software on the web which are teaching tools as well as web based tools for building energy analysis. However the drawbacks to the existing sites are: 1. The existing teaching tools deal with a variety of topics and subjects. Infact, in subjects like microbiology, they have become an integral part of the teaching medium. However, the few existing tools which deal with the subject of Building Energy or Thermal Processes in buildings are neither comprehensive nor interactive. They are mere extensions of textbooks and do little to arouse user interest in the topic. 2. The existing web based tools which provide services on the web are based on the user being already aware of the subject or mere novices, who merely want information on the energy spent in their homes. They are NOT designed as teaching tools and do not provide any information of the actual processes going on within the buildings. They are merely different softwares, which are meant to be used once, the user is already aware of the subject. Thus, there exists the need for a teaching tools for architecture students and interested audiences, which provides information about thermal processes in buildings, in an interesting as well as interactive manner. Such that, somebody who is not aware of the subject, can visit the site and leave with a reasonable amount of understanding on the subject. This is precisely what I have set out to do in my thesis. 98 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. PART FOUR THERMBUILDER - THE WEB BASED TEACHING TOOL This chapter discusses the various issues taken into account while designing the site and then describes the basic structure of the site and its contents. 4.1 RESOURCES USED AND NEED In the planning a site, only those technologies that best accomplish the goals, that one has the skills and resources to work with, and that the audience can use, should be selected. My web site uses HTML, Macromedia Director 6, and Javascript to produce files which users can view through Netsacpe4.5 or Internet Explorer4.0. Below are some of the general benefits and constraints of some web technologies and tools that I have used in my site. 1. HTML Hypertext Markup Language (HTML) is the primary technology used to create all web sites Some of the elements in the most recent versions of HTML may not work with older browsers. Benefits o f HTML: • Loads quickly (exception: Netscape waits for all table contents to load before displaying any of the parts) • Can be learned and implemented easily (easy-to-use HTML editors are available) • Can be augmented with sound, video, Java applets, and scripting languages such as JavaScript and VB Script 99 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Limitations of HTML: • Provides only limited control over the way your page will be displayed, and over the appearance of text • Is not programmable and offers only limited response to user interaction events 2. Frames Frames were developed as an extension to HTML 3.2 and are supported by the newer Netscape and IE browsers (3.0 and up). They help provide a sense of place by preserving identity and navigation elements when users navigate or scroll through information. Benefits of Frames: • Segment the browser display area so that parts of the window can be dedicated to specific functions such as providing navigation controls or displaying content • Provide greater control over window layout than HTML without frames • Allow content pages to be developed independently of navigation pages, making development and maintenance more efficient Limitations of Frames: • Present design challenges for tasks such as printing, bookmarking, searching, and using the browser back button • May necessitate a no-frames version of your site to provide accessibility for users with older browsers • Add more complexity Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3. Scripting Language Scripting languages such as JavaScript and VB Script are used primarily for client-side programming, while CGI scripts are often used on the server side. I have primarily used Java Script. Benefits o f Scripting Language: « Allows for interactive, network-aware, and cross-platform applications • Is easier to learn than Java • Adds dynamic and interactive behavior to a web page Limitations o f Scripting Language: • Behaves differently on different browsers and between browser levels ® Can be read by only some browsers as low as 2.0, and not by any 1.0 level browsers • Is difficult to debug • Provides limited functionality compared with Java applets 4. Java applets Java Applets allow you to encapsulate a piece of function and embed it in a web page. Benefits o f Java applets: • Allow for interactive, network-aware, and cross-platform applications • May be used within other applets or applications on the same page Limitations o f Java applets: • M ust be downloaded before they can ran, can be a lengthy wait 101 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. • Provide only limited access to system resources • Function only when the web page being viewed is in a browser window • Often require substantial memory, and the files remain in the browser cache until emptied • Can only be executed/run by Netscape and IE versions 3.0 or later.' Hardware The THERMBU1LDER requires a computer with 64MB Ram or better, 233 MHz. Processing speed, (MMX or Pentium II) Faster machines are recommended, as multimedia scenes will run more smoothly on them. Software Netscape Navigator 3.0 or greater or Internet Explorer is required and also a Shockwave plug-in. The web site has a download center where users can download all the software required for viewing and using the tutorial. To make things better the download center has the whole tutorial in the zipped format which the user can download at one go, and go through the tutorial from his/her hard disk without having to wait for slow downloads. It is specially useful if the user is on a low bandwidth access line. 1 Lemay, L. 1996. Teach yourself Web publishing in a week, 2nd ed. Indianapolis: Sams Publishing Decem ber, J., and N . Randall. 1995. The World Wide Web unleashed. Indianapolis: Sams Publishing University o f Chicago Press. 1982. Chicago manual o f style. 13th Ed. Chicago: University o f Chicago Press. Xerox Corporation. 1988. Xerox publishing standards. N ew York: W atson-Guptill Publications 102 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 4.2 POTENTIAL USERS As much as one may wish it could, one’s site will not appeal to everyone. The best bet is to choose a particular segment of the population and focus one’s efforts on attracting and engaging these users. The basic issues to be considered while selecting a target audience a re : 1. Determine who is likely to be interested in the content provided. At this initial brainstorming stage, you want to look at the full range of possible users. 2. Determine which of these user groups you are equipped to serve. 3. Of the remaining list, determine which users in your list have access to the web. Also, which are most likely to use the web for your intended purpose? Keeping these factors in mind the potential users., my site can be divided into basically three different types of audiences: • This tool is basically designed for anybody interested in the fundamental of thermal processes and the mathematics and physics involved in it. • Anybody who is well acquainted with the subjects, yet uses it to get to new developments in the field through my “LINKS” section. • Students of architecture, who need to clear their concepts taught in the class room. The tool would provide an illustrated and animated study of all the concepts. The site has been designed to cater to the needs and interests of these potential audiences, though it may be useful to other people in various situations. \ Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4.3 WEB CONSIDERATIONS 4.3.1 PLANING AND ORGANIZATION The proposed tutorial uses the web as a medium. To be an effective tutorial it is essential for it to function as an effective web site. More than any other media the web is the easiest platform for anyone to publish or release their work and thus it abounds in good as well as badly presented work. This is because of lack of user behavior predictions as a result of it being a new medium. Another reason is that there is little or no control over what is published on the web. Anyone with access to web space can publish anything, true or not providing a lot of unavailing material. Given below are the basic steps in the design of the web site: 1. The first step in producing an effective web site is to define the purpose. Although this may be redefined after one has received input from representative users, the statement of purpose guides one throughout the process of defining your audience, developing your strategy, and creating the content of your site. Thus, in Thermbuilder, I have taken my sole purpose as to design a web based teaching tool for the purpose of conveying information about the various thermal processes going on within the building, their interaction with the environment and various ways to calculate and estimate these interactions, along with means to control them. 2. The second most important step is organizing and listing all pages into categories. The Thermbuilder, divides the entire content into four broad categories of facts along with glossary and links section as separate. 104 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3. The next step is organizing the work into hierarchies and placing matter with in these hierarchies. The basic thumb rule here is to design hierarchies of breadth rather than depth. Research suggests that users begin to lose their bearings within a hierarchical structure once they go beyond the third level. As William Horton notes, "Flat hierarchical structures may cause users to have to scan longer lists o f menu items, but users will get lost less often"1 . Thus, while planning the ThermBuilder, I have taken care so as not to take the user beyond the third level. At every level information has been equally distributed, so as to not produce a dis-balanced site, that goes deep at one end, leaving shallower ends, at other links. In Therm builder, I have kept a balance at each m ajor link and distributing information between these links. TOO SHALLOW Main menu becomes a m assive “ lau nd ry l is t ” of unrelated topics Figure 4-1 Shallow site layout Deep Site Layout Menu pages p r r - = = 2 U s i = t o o d e e p In the examples shown the sites Menus a re num erous and thro u g h arfen d less s e r ie s 3 1 6 e i t h e r tO O S h a l l o w a n d o f nested m enus. spreadout or too deep. The following diagram on the next Content pages Figure 4-2 Deep Site Layout Horton's Designing and Writing Online Documentation for more d e ta il. (1994, p. 170) 105 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 21 ^ page gives the image of a balanced web site and this is exactly how I have arranged my site. u 'M 'J BALANCED MENU STRUCTURE Eiaa E !3 3 EEl'2 B alanced W e Site which has information organised and chunked in a manner so as to keep the user attention and interest, without him getting lost. Figure 4-3 Balanced site Layout THE BALANCED STRUCTURE OF THE THERMBUILDER S(!e Mjp Design Ad/Is or jI o s jjo (Ketmal Coitrols J J j L a L 0 L lo M ! C u 0 u L L Figure 4-4 The structure of Thermbuilder 106 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. 999 4.3.2 ADVANTAGES O V ER A BO O K /CD R O M A Web-based approach has several distinct advantages over the traditional paperback production and distribution CD Rom software First, given the sophistication of W eb development tools, the user interface can be designed (and subsequently modified) with considerably less effort— and thus lower co st- than with traditional methods. The most basic element of using the W eb as a pedagogical instrument is found in its ability to present information clearly, attractively and in doing so providing fo r interaction at the same time. Even though books can provide information in the same manner, additionally on the web one can use hypertext to organize enormous amounts of data in a relatively lucid fashion, using menus, key word searches, even clickable graphics as a means for interaction between the machine and a user. The web technology provides for an interactive medium where the user can make inputs, get results, run simulations, take exams and quizzes and get instant results, something not available with either books or CD-ROMS. Second, the cost to distribute the product is minimal. Anybody who has access to the web, can access this information without incurring any or minimal cost, while the expense of each book is common knowledge to everybody. The cost situation as it stands today, provides a computer at a cheaper or comparable rate to many books and especially the really useful and sought after ones, providing illustrations and graphic content. T hird, future refinements or additions to the program do not require physical redistribution or reinstallation of the software or documentation, changes need only be made to the m aster version (located on the home server) for all users to have the benefit of those changes. 107 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Fourth, Any user with a forms-enabled Web browser, regardless of platform, sees a seamless interface free of most hardware and software compatibility and installation problems. Regardless of the computing resources they have available, users have access to powerful computational engines residing on the host server. Lastly, the Web provides immediate access to all the other relevant information that is constantly evolving on the Web. The world is evolving very quickly and the web provides a means for the common man to stay in step with this evolution. Although networked interactive hypermedia documents do pose novel challenges to information designers, most of the guidance one needs to design, create, assemble, edit, and organize multiple forms of media is not radically different from current practice in print media. Most Web documents can be made to conform to The Chicago Manual of Style conventions for editorial style and text organization. Most of what an organization needs to know about creating clear, comprehensive, and consistent internal publishing standards is already available in guides like the Xerox Publishing Standards: A Manual of Style and Design. Thus, one can easily use, existing conventions and practices to produce a well designed web page, accessible to a large mass, in an interactive manner!2 2 R eferen ce : Xerox Publishing Standards: A Manual o f Style and Design Lemay, L. 1996. Teach yourself Web publishing in a week, 2nd ed. Indianapolis: Sam s Publishing. Decem ber, J., and N. Randall. 1995. The World Wide Web unleashed. Indianapolis: Sams Publishing. University o f Chicago Press. 1982. Chicago manual o f style. 13th Ed. Chicago: U niversity o f Chicago Press. Xerox Corporation. 1988. Xerox publishing standards. N ew York: W atson-Guptill Publications. 108 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4.3.3 NAVIGATION CLARITY One of the most complex aspects of the Web lies in its navigational abilities. Recent statistics suggest that with as many as 10,000 Web sites currently available (and growing at 50% per month, no less), the World-Wide Web is truly beginning to earn its claim as an international informational lattice. And using the Web is a simple matter, even for young children, so anyone with the will (and the time) to explore is bound to discover a variety of fascinating sites and resources. And yet because of the scores of Web sites that may be of use to someone, particularly in education, knowing where to begin, what to look for, and what to ignore can be a daunting task. With the development of what are known as webworms, spiders, and knowbots - computerized search agents which will surf the Internet looking for requested information - it is now possible for a user to connect to a search engine and type in "education technology," for example, and look up all known on-line references to education technology. For example search engines likeYahooligans and Ask Jeeves will literally search out every known document on the Web which uses whatever word you're looking for. So the problem, then, is knowing how to sort through the 1000+ responses the worm might find in its initial search! Clearly, the answer to this dilemma has not been found by throwing in the towel and admitting to an intolerable case of future shock or information overload. Instead, intrepid Web explorers have begun to catalogue the enormous variety of educational resources available on-line. As these individuals compile this information, they relay it back to the educational community in the form of on-line resource guides which may take a variety of forms. Some guides are simply a hypertext list of all known educational resources (some general, others topic-specific). Informational super saturation becomes less of a 109 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. problem when resources are presented in this fashion. More importantly, the average teacher does not have the time to search out on-line resources - in most cases, a teacher would rather stick to traditional curricular methods instead of surfing the Net ad nauseum..3 As the World-Wide Web grows, so will our easy access to useful and interesting information. Providing a rich set of graphic navigation and interactivity links within your Web pages will pull the user's attention down the page, weaning them away from the general-purpose browser links, and drawing them further into your content. By providing your own consistent and predictable set of navigation buttons you also help give the user a sense of your site's organization, and makes the logic and order of your site visually explicit. Here are some issues that are important in web navigation and the following sections show how I have incorporated these in my web pages.4 1. Provide context to the Reader Readers need a sense of context, of their place within an organization of information. In paper documents this sense of "where you are" is a mixture of graphic and editorial organizational cues supplied by the graphic design of the book, the organization of the text, and the physical sensation of the book as an object. Electronic documents provide none of the physical cues we take for granted in assessing information.. Even the view of individual Web pages is restricted for most users. Most Web pages don't fit completely on an standard office 14-inch or 15-inch display monitor, and thus there is always part of the page that the user cannot see. 3 W ilson, A. 1974. The design o f books. Salt Lake City: Peregrine Smith, Inc 4 Apple Computer, Inc. 1992. Macintosh human interface guidelines. Reading, MA: Addison-W esley Horton, W . K. 1994. Designing and writing online documentation, 2nd edition. N ew York: M icrosoft 110 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Thus, web pages need to give the user explicit cues to the context and organization of information, because only a small portion of your site (less than a page) is visible at one time. Screen 6 4 0 x 4 8 0 screen area Figure 4-5 Visible area of the screen The screen shot below from Thermbuilder shows the use of attractive graphics as clues where care has been taken that the entire graphic fits on the screen and the user is able to get a complete view of the factors before going on to each one separately. <3 NUMCniCS - BA^IC.THEQRy. r Micro>oUlotcinct'Explotc»ptovidt;<i by MSN- ' H E E 3 radiation basic theory Factors affecting beat conduction iJ gain/loss in buildings people convection lighting appliances Vi Figure 4-6 Use of attractive graphics for linking M icro so ft Corporation. 1 9 92. The W indow s interface: An application design guide. R ed m o n d , W A : 111 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2. Going back" and going to the previous page All hypertext systems share a common problem that has no direct precedent in print media: going "back" through a series of links you have previously visited is not the same as paging "back" through the F irst Web site I IS ! H ypertext li nk “Go back” Second Web site (a sequence of pages) “ Go fo rw a rd ” preceding pages of an ordered sequence of pages. When users click on a hypertext link in a Web “ P re v page” “ Next page” document they often are transported from one Web site to another, perhaps even from one country to another. Once made the hypertext link is bi-directional; you can "go back" to the Web site you just left by clicking on the "Back" button of the viewer. Having hit the "Back" button, the "Forward" button lets you move to the new Web site again. Thus, it is very important to provide for and create attractive links to guide the user back or forward within the site. In fact, these hyperlinks are of extreme importance as they prevent the user from getting lost within the site or being aware of their exact position . These buttons give the user a sense of power over technology. Thus, I have provided these links on my own, which the user can navigate in a controlled manner, over riding the links of the browser, which can lead to the user getting lost and losing touch with the site. M icrosoft Press.W iley. 1 1 2 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. This screen shot shows the global the back buttons named after the sections and placed right at the top for clarity.5 4-7 Use of global back buttons in each page. Here the same "B ack L in k " has been provided by the main graphic link which is the characteristic of each section. 4-8 Back Link provided by graphics 3. Always let users know w here they are in the site Because web sites often contain several or even hundreds of pages, users can easily become disoriented and even lost. To inform users where they are in a site: 5 U n iv ersity o f C h ica g o P ress. 1 9 8 2 . The C hicago m anual o f style. 13th ed., C hicago: U n iv ersity o f C h ica g o P ress 113 a C L I M A T I C .F A C T O B S I H tH E n M ^ U P P H P ItlO N S T > l°< ?cfe thermal comfort ■ h u m a n F A C T O R ■ R E L A T IV E ; . -H U M ID IT Y ■ M E A N ■ - R A p l A N T ’ f :v. ■ •T E M P E R A T U R E ■ C O R R E L A T I O N r/.tA am& T M C O H V iT H C H M A L p O M r O B T ^ r 1 — '— ^ correlation of factors and thermal Comfort fV rrtiriy atcK^cTufXi. n '. ^ * rc ,T < » x n ^ • ratuio; t* M itij *t j Va n d tu)ih,dal;a:AWpr.d>n«- '*-t.lo dos.tgn • an f e s-if.to * R i-e i p i c . 1 wV If> 6; c oinf#rr.c ^ n‘ e t s ‘ p? e^44cT 5 ? ; • 1 - "; Qo(t<litif-ni can r lt ti m j ) Comfort c a n b o d rtc rib fe rf m lb* « titiJln tth lc tiih « ;o .l* eomplt»»twiLflat» b » h « « n lh ® v B ri0 ii* m « th o d * o tb e Jilt« ittte r« rK n b e l* m p e rH irt« B c b e h rtd lrn W e tfie • : j .bblldrng (couch flhatjhoff.ta n e n t i d f o r *f7y»rtfcflcfol.ninr«eJ hMtto® o f cooling. It b o - .j / - « * !• cf,conTpl*l* h « r m o h y b th w tn th » WOtflnfl *rtdiH oirtriiJ« s e M iO f tm o o tlo o ch o h rt'.v j conttftform imfoe ' j : 1 _;Bi’ /tho:tnBttll 4yt!lilT1 ( V -V'-V '//{-V .V^y;' V: ■ ' :• •; ;; A p o H c r ^ i^ 'c ^ V tT tiM s ic r ^ y s i > i o f - • i X f-f t la ciij ai-l-Ll.» putiiii.o ^cridti&hv CfVtK* . ! 0 J V ^ < ^ 4 't h ^ i . y s > > u f c i 0 1 i i ^ r w t ^ e . ^ & q i S J t V n r > « C h - ^ » i r A l K c ?, '. \"f f rt < * rfj r7<' rt f 1 o m r% * f"i fi -v a k m t fa'lilM * k u * n H fi> (ilt'o iifo iV j* 1hA f f t n & if i ? n f\* ' » r I fed r r i ti **< : . \ Dl R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. • Provide easy access to some form of table of contents, from where users can link to any other place (the table of contents may be the home page itself, or another separate page) • Always provide an immediate way to return to the home page • Make the resident section heading clear As shown below, the main page at the back and the smaller window infront clearly shows that the user is in the subsection of the site. •T m c 'pim aC ■ aduA 'n' :-~r* &i q h 4-9 Use of smaller windows for different subsections 4. Provide visual and audio feedback Good feedback design supports users' understanding of events on the screen by confirming actions they have just taken. Thorough feedback in the design of links includes visual and possibly audio changes that occur in stages. 114 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. The picture of the solar factors subsection gives a very clear feedback on the subsection. The margin on the side provides link to the various subsections of this part, while that on the top takes the user back to the home site. Figure 4-10 Use of a clear margin for sub-sections links 5. Decide whether to design links as icons or as text Studies have shown that experienced users, if given the choice, tend to rely more on icons than labels because icons can be processed faster. However, designing icons that clearly convey their meaning is not easy, and users often rely on labels until they "learn" the interface. A link that includes both an icon and a label will satisfy both new users and those who are experienced with the interface, but labels take up more screen real estate. Another option is to use a scripting language such as JavaScript to create a text label that appears when the user moves the mouse pointer over the icon. If you use text in your links, use the minimum amount of text necessary for users to identify the link. I& .S 0U B FACTORS IH IHEHMAli COHDJTIONS - M dicapa solar factors ■ S O L A R B A S I C ■ - g O L A R -------- .R A D IA T IO N ■ S H A D I f J G: A N D □ V C R H A N G S Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. As the screen shot of the site, clearly shows, here a combination of text as well as graphics has been tJJMitaniWhi?* E* La 'tom 3 S i a i l s t rf II ' \J * f K k m m t' A S Thermal oroces r i t ^ s r s l used as links, which have been further enhanced by mouseovers. Figure 4-11 Use of a combination of graphics and text for linking 6. Design links so users clearly understand their function Following the wrong links wastes users' time, so clear representation of the destination and resulting action of each link, is of utmost importance. Sometimes users have difficulty distinguishing between navigation items and static images. This problem can be overcome by clearly and consistently separating areas used for navigation from those used for content. Provide visual cues to represent clearly the function of linked items. These are examples of mouseovers used to describe the function of links in the site. Each Figure 4-12 Use of mouse overs J * at • . * if 4 1 Theory 116 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. section is long and informative and for a user with a slower modem would require sometime to download. Thus, these mouseovers, use text as well as graphics to lead the user on and provide queues to the section content.6 Figure 4-13 Use o f m ouseovers in subsections 7. Provide clarity in adhoc links Relationships between content items do not always fit neatly into the categories of hierarchical, global, and local navigation. In practice, this usually involves representing words or phrases within sentences or paragraphs (i.e., prose) as embedded hypertext links. This approach can be problematic if these ad hoc links are important, since usability testing shows "a strong negative correlation between embedded links (those surrounded by text) and user success in finding information. Apparently, users tend to scan pages so quickly that they often miss these less conspicuous links. One can replace or complement the embedded link approach with external links that are easier for the user to see. As you can see, embedded links are surrounded by text. Users often miss these links. One Solution to the Embedded Link Problem is to give links their own separate lines within the paragraph. 117 ■ B Q U K M tlA aiC l ■ QOLAR ... .N A O lA tlO N je o ts i tn * ire t t tAe <* '■ 4 i q h a o in o Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. iS S a U fl BASICS M dicj® c The approach one uses should be determined by the nature and importance of the ad hoc links. For non-critical links provided as a point of interest, embedded links can be an elegant, unobtrusive solution. The diagram shows, how an adhoc link surrounded by text has been highlighted to make it very clear , yet aesthetically pleasing. Use of graphics as adhoc links, so that the user is attracted by them and stops to follow the link to the Hdl site. '-•geographic lo c'al* p n ;; ;w^?cqr ' aifajifny.afijl a y S 0 ^ a r ‘ |>3!.b • d i irjjr a : a I i or«^jd ijri 5 irs t ^ C y f r ' 1 h ^ 'r r r * “ , “ . ‘ suji'i p o litic^ syrt;W thln the;'sfcj Viu^ik'prdj*ct«d. on so’i/hwiionfii• -A '; je/huuoikv cm tt.i*: ri w .,, v- * ?y- \ r a d ia tio n basic theory ra tte r* aTfettm o h eat Figure 4-14 Example of adhoc links in the web-page. .In the following screenshot from the Thermbuilder Site, it's fairly conduction J obvious where the link will take. However, if text were underlined, one would be hard pressed to guess where those links would lead. Thus, in designing web sites for clear navigation - Content is king. Figure 4-15 Another example of 2 3 adhoc links 6 Shneiderman, B. 1992. Designing the user interface: Effective strategies f o r effective human-computer interaction. 2nd ed., Reading, Mass.: Addison-Wesley. 118 Qbifl/MiI id p e o p le convection l ig h tin g rtp ftH rM k C e * Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4.3.4 DOWNLOAD TIME The other important issue while designing web based tools or web pages is the download time of each page along with animations , graphics, programs or any other material that has been embedded in the page. Research has shown that most users visiting a site are not prepared to wait too long for a site to download. The basic reason for this is the availability of abundance of information over the web, which reduces the significance of any one medium considerably. Furthermore, a large part of the population still has slow modems, operated from homes. Making a very huge file, completely rules out this large population ever having access to any site, however well designed. While designing the Thermbuilder, I have taken care not to make any graphic greater than 72dpi in resolution and 400*400 pixel in size. Also, the applets and movies have been kept small, reducing one into two where the file was becoming too large. A “doc” version of the entire site, along with a zipped version which includes all graphics, is available for all users. The movies which require shockwave, will automatically link the user to the download site, incase the required version is not present. Besides, there is a an information center in the beginning which gives information on various required and desirable downloads for the site. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4.3.5 PRINTING CONSIDERATIONS Since some users prefer to read hardcopy, providing an easy way for users to print related sets of pages is important. If your site is divided into sections, you may want to give users controls so they can print these sections as well as individual pages. Most of the site has been done in a separate window, where each window can be printed separately. All the graphics are clear and printable. The printing can be done as a complete section, or as individual pages. Only a section i.e the theory section has been done with a dark background which can always be inverted for printing without in any way, losing the content of the site. Also, as already mentioned, a “doc” version of the entire site, along with a zipped version which includes all graphics, is available for all users. The “doc” version provides, the theory while the zipped version provides the animation and graphics as well. Yet again, here the document version is available in sections or as the complete set, which ever is desired by the user. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4.4 SCOPE AND LIMITATIONS The task of putting together a site which gives complete information on the various thermal processes in buildings, their interaction with the outside world, the ways to control these interactions and the ways to estimate and calculate these interactions, is certainly too large for a masters thesis. The subject of thermal processes is so immense and deeply related to various factors that even a sub section of the “Theory” section, can be a thesis in itself. However, my attempt has not been to put together all the information available on the subject. My thesis, is to put together a teaching tool which gives basic information about these processes in an interesting and interactive manner, such as to arouse user interest. In this, I have limited myself, by making my guideline very close to that of Architecture 215, the basic theimal environments class, taken by Professor Schiler at the School of Architecture at the University of Southern California. I was a teaching assistant for this class for two semesters and thus have found, that this much information is good enough to arouse interest in the subject as well s give a very good estimate and rules of thumb in the subject. Yet, again while defining the users, I have catered to only the three set of audiences described earlier, thus making all the web decisions based on these audiences. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4.5 STRUCTURE OF THE SITE The “Thermbuilder” site begins with an introduction page which leads gives the user two choices. The Then the index page leads the user to two choices: 1. Information and downloads This section, as the name suggests, gives the user information about using the site. It does three very important and useful things a. Has a plugins and requirements section, which specifies the hardware/ software requirements for using the tutorial, as well as links to where these plugins in software’s can be downloaded. b. The printable version of the entire tutorial in “doc” format. c. The download version of the entire tutorial in zipped format. 2. The second part leads to the actual tutorial or the Teaching Tool. The second part is organized into four basic sections, each of which opens into a separate smaller window. It also has three smaller sub sections, which open within the main window and can be accessed at the same time as the sections in the main window. These are : • Links Section • Glossary • SiteMap The primary reason for keeping these in the main window was to provide simultaneous access to the theory as well as the glossary, information, link information or site map for that section. It is very possible for example that a user is in the theory section, within the Solar factors and needs to know the meaning of a word without having to exit the site, 122 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. which he can do so through the main window. A brief description of the main sections follows. fto Qo ^gwwr.nr * ' y a 4 2 a A t£ si Ciel fijiotd H r* U«cK to n e* * Pirt 5*vj+/ X iW'?t **• > v * » ,r Thermal process ! C w u h e * d . 'D < ^ * ' The site m op, links and g lo ssary a s part of th o main p age. Figure 4-16 Snapshot of the first page which has separate links to sitemap, links and glossary section 123 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4.5.1 THEORY This section forms the theoretical background for all the processes involved, the factors affecting them, the interactions of building with the outside world and the terms and conditions related to these. Each of these sections also contains a quiz in the end to check, whether how much the user has grasped after going through a section. This sections has been further subdivided into four broad categories: w m ss& im V T H fin W A L I ,COM r.O«T. ■ solar . • • '.'.V actoho ..•r/tC T Q U C Figure 4-17 Snapshot of theory main page a. Processes of heat transfer This section provides information on the four basic processes of heat tranfer. These can be categorized into: • Conduction • Convection • Radiation • Latent Heat 124 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. • Quiz Each section contains a definition of the process, the basic factors affecting the transfer along with the basic formula for calculating them. Each process can also be learned through a movies as well as small calculator programs which not only calculate the amount of heat lost or gained but also give the user a chance to enter their input and check to see, if their answer is correct or not. Given below are screen shots of this section. & T H E FtM A l-G U ID E • N cU cap o ■ C O N D U C T I O N ■ CONVECTION- ■ r a d i a t i o n Figure 4-18 Snapshot of processes page. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. & H A P IA IIU H - N e ts c a p e B B D S I T H E O R Y |P R D C C a O C O - radiation ■ "Racliajioo; is;th ^ jp rb tsssj oiliWaf1 flow.W fel e t f f ojrn agen eti E r . wave s-fr brti^a. Kpt't e/; s uirfii q e to: ! > is the-'0 f\Jyme.lhod- ofhe3l.1rens.fer w hich does not- require £ medium.tor h e st transfer i * £ & * ' * V s ’ Figure 4-19 Snapshot of radiation page uchon ’ N etscape.- . r ; ' : T ' • SB onvectiori Figure 4-20 Snapshot of convection movie starting shot 126 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Coriryeoiiph;'Me^l.-flcriv:'iri:a buildiVtii t^ikoc'p laco: belv<i>ort .llio apt eriQrbr:lH4;^«i^fAg!'tH« pot Gido~3ir7 It /^COM VECTIDN CALCUI-ATlift - M ic m io jjJ n td n c lE x a to ie i ptQ V fJcdb^M S fJ :V p ^ p jlE 3 .A i Changes [ S “ : FocmVdui (678 TemgCut [S6 Tmrpln : [45 Q y 165300 Check .Cefcvlale) Re«* ■ Figure 4-21 Snapshot of the ventilation calculator in a room b. Thermal Comfort This section provides an explanation of all the various factors affecting thermal comfort conditions in buildings, along with a section which correlates these factors and explains, the meaning of thermal comfort conditions. This section has been divided into: • Wind • Human Factor • Relative Humidity • Mean Radiant Temperature « Correlation of factors • Quiz 1 27 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Given below are screen shots of this section. g-CllM A TICFA CTO nS IH THERMALCONDlTIQHS'yHcUMpo: ::..-;v. :;;i i o ^ ^ thermal comfort ■ : W I N D ■ R E L A T I V E " • H U M I D I T Y ■ MEAN R A D IA IS |T T E M P E R A T U R E ■ C O R R E L A T I O N Figure 4-22 Snapshot of the Thermal Comfort Main page & W I N D N eticap c 0 0 E 3 | ■ T H e O R Y l T H E R M A L C O M F D R T SB wind and air movement m Wind a ir n to v e m e o i air m ovem ent in l) iM A i:e s 'l> 6 d iiy .:h « i> i tialm ce^riil h e ric p T tb e rM ir c o r* ig « t . ^ o c f 'c - o n w ^ tT S s e ^ B t^T ^ rv sifeT 'b etjy eeo :fh s p s k T n ; ah d . v - A - ’ . W . .- X h if r fo r m er is .9 f f V # r o :e < i I byiairorybulb; : t S i n r i p e r a it U r'e ,tn V ;e ^ ^ fig .th « ‘ a J r ’ -sp6 ;^ ^ - -ih e r f fa i'je 's ;: th e T ^ t.< ? '.o f lie ^ c tf a iV a f e r i; b u ’ tif t^ i‘ d irip lip ri'; pf heat (lo w d ^pends iijp 'n n ^ ^ elh er.th e/T 'em p ^ r'at.tjfe.if tlie '.a ir js/y E ^ a t^ r'o rjIe ss'th a n 'th e 's.k i'n .-V -V i' V fe if e c t i’ .a s i h o u 9 h ; ;a f -h ' ah. ! . ;^pocr p re i? w 'e s V < h ¥ i;o v « ra ire ff& c i n V a y ;ie ;srri-i(l. T h ' s u g g fe s lfo ij te m i) e r h 'i m ie 's ;: i'B -tH e t a b fe '/e p ti e ^ « p it '.^ u id e lja f r t.e v ; C lic k h e i e lo r s u g g e s t e d lo o m l e m p e i a l i n o s l o r v a r i o u s s p a c e s : ^Tti'e: c o m fo rt /''aip .w ld cfly ;' lill Figure 4-23 Snapshot of the wind and air movement page 128 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. S&.THERMAL COMFORT^.* w M ij it? •N etscape T H E O R Y I T H E R M A L C O M F O R T co rrela tio n o f factors and thermal Comfort T h erm al C om fort c a n b e described a s the state in w hich th e re is c o m p le te b a la n c e . hotM raon th a v a rio u s m e th o d s of haal tram rforafld th e la m p a ra tu re n c h o iv e d in sid e th o . : building Is s u c h th a t th e re Is no n eed for an y arHlicinl m e a n s o f h e a tin g o r cooling. II is a s ta te of c o m p le te h arm o n y betw een.the building an d its oufeid o .o m riro n m en l.to ad ieiv B id ea l c o n d itio n s I n s i d e ------- — ---------------- — --------------------- *- * .;; .V ;X V s wll>;iTianyfacfef&Qf aYcH'itectura!sigiri'.-.the,:Surit» ,6f.th«; pari i':ar.clirna'tic'Ta'rt i;'/''p g n sid ered ;sim u h a:n e!p u s.l^^ ^ :,^ : p o r're L a tiQ ris ;can-X .r'^ Psychom etric chart 1 yV 'fjsychpM eirii.;eh3iffecrii#£tH eietato^ joT ihejtlim ate-enV eJgpe.o'o'. |H e trfetnc^cfiii jt lylflll^iridtcat. pSh e 'r ®&s\^r,^ K |3 r i \ s t - v ;-'-'' i.cDhdjtjci'nS ofterrip^ratu'rg^aQd ?9 lal^IhUfhi^y.J&ll-'i>ut!^e’ T^^6 iBr!nf(^'£pnd/.c^pe^^*T»*eas6 resiic-j.'1 *^i; winds; sonstnne:, or moiiimi>.cturpioiJuC(ii:criinlortab[(!Mndit[Ons:.PrevJilin(jcontiilons. are plolied on- the chart to find * tu t corrective m easures are needed \ ■ C llc ^ fiia fe ; o V ii ie tM ^ f f c lic ifi; ;--y v ; . '. - . '■ Figure 4-24 Snapshot of the Thermal Comfort correlations page '3'HcirttansfeM h*bugfyconduction ».^ iict6^ p fjl;in tfe|n ef-E ^ > lp i^ ‘ ’ p < o y id 'cd by H S .N . ' . ! JffifjllQ L r: /..v. safefcteaawaal W r ! .M ! J « _ f ? l W t.A ! C r L t! 0 ,ti W ! F a c to r s in t h e r m a l c o m f o r t Figure 4-25 Snapshot of the Thermal Comfort movie start page R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. b. Solar Factors This section provides basic information on solar factors and controls which affect thermal conditions. It begins with a section on solar basics which describes the useful terms and facts about the sun. It then provides an estimation of the heat received from the sun. The third and fourth part provide for various means of controlling the sun entry into the building. The overhang design section provides basic thumb rules, for designing overhangs, along with a program which provides a rough estimate of it. Given below are screen shots of each part. The basic parts in this section are: • Solar Basics • Solar Radiation • Shading • Overhand design • Quiz ___ _______ ffjS q L A B E A C tC IR S IN THERMAL C O N D ITIO N S'. N c U c o p c solar factors ■ B O L A R - RAD I ATI O N ■ S H A D I N G D E V IC E S ■ S H AD I N G AN □ O V E R H A N G S Figure 4-26 Snapshot of solar factors main page 130 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. *3-$Q L A R nA D lA T lO M - H iC :fO to H lrv«:inet £xp)loiei piavided ItytySN B B S solar radiation T H E O R V | O 0 L A R F A C T O R 3 'I A 3 R U L I* B U U 1 a if t « J I M 1 1 U t niixttioim 1 3 mw' w cuuj. ■ sw w ftc w n tjflj u Figure 4-27 Snapshot of solar radiation page [^;Hfeat-tran5fef;ihr6ugh-conduct<on^M icfoyoft-lnternelfEKpTlrrr-E9l»IJ&| THE SUN PATH ' start Figure 4-28 Snapshot of the Sun Path movie start shot Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ' ■ ' j H c jt tianafcrihipL lO h co n d u clian - MibrosQft ln tc m c t E xptbicf pr ov ide d@ 0 Q T he b a sic sh a d in g d e v ic e s are: fan*) Horizontal shading devices m m (II® Vertical shading devices Imfa Egg-crate devic‘ es’ Shade from surroundings Figure 4-29 Snapshot of the shading device movie c. Climatic Factors The climate and micro-climate also affect thermal conditions inside buildings immensely. This section provides an overview of the basic climate types in the US, the built forms particular to each type, the mother micro-climatic conditions which affect thermal conditions and hence, design decisions and a small movie which provides an overview of the principles of vernacular architecture. Thus, the basic parts to this section are: ® Climate Types • Building shapes and forms ® Micro-climate • Vernacular architecture. • Q u iz Following are screen shots of each part. 132 R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. S ir C LIM A TIC F A C T O F IG IH TIIEnM Aj. C O N D IT IO N S ' • Nrlicapc H H B | climatic factors ■ - B .U I L T ,: F 0 R M ' A N O S H A P E ■_MJ£^RO-__ C L I M A T E FACTORS ■ V E R N A C U L A R ' ' A B C H I T E C T U H 'N f f ia tf o T * 1 ? .... . i i i ji" J )ij, £ 2 i I i 2 r t H Figure 4-30 Snapshot of Climatic factors main page BUILDING FQHM AND SHAPES - N clscabc. T H E O R Y I C L IM A T Ij: F A C T O R S building form and shapes ; 'if''/puiidfrjg ferpjaiiy'.shiijje:1ar^i^'p<^ant-^if^i3c^ii[lerlag;H&puiq#9-dV-^ain.-ln buildings. Jhsy'pl.ay "ir rja.rT.trji'fjorlgnt roj e - in. t jj e ;,tli eirria I proc]^s^^s^caT<uii g'pjace:.withifa/tHf'’ i6uiJ.di'r^;'as!y^il^^-'vrt^jHS-";:''yu^i:'rv[■ ; ::;-^|-'-ti.uilditrg ahdits;§ij(foyndmgs.A.:squafd;;andl£cfangle;^ e .;ih g l^ ysuSily.ribuiidir|ig^witb..rnoresurf9C.^ »?-;■^ ;> it!tte ? ^ S y ifg d e 'a r^ ;i f e s u i ^ c on jditioirinsTtiS; pf buildln g S :;.,if; a ^ byildingiiiSSiailai^ jhsideipf iTuiJidi^s^ |fL % bul[dih^T^ % : i - ;k'.'^surfac’ ® areSv: thi e. \oiffTh:al cghbiliort'iSiTn.o'fe! fnfluenc;ecT;b'y;'ihe sjiteVnairclim^ p'ne ;iw rth .le s ^ , ; :v. ^^f^'®hrface»'areas^S'^aJI^:buftiSir^’ ^^aViBMsirger}slqii^p5i!jrTie-rsiti o . . ; t h ain'-ia rg e id ul tding sv-Arfcuifd in^;W ft|Y' v.'ift.SjgsSsi^iiiiic& 'atea^sidotanjate'cliy^ v ^ : . 'i j - : b p tim liW tK s ,u s a ig e .-b C th B ;e rttir^ re a i: .e s ja te ;..F ) jg H ;'i;f s e .'b u j! ^ ::curtain/Wal!safe;iTi6stTy,.gfass-.wf!ich; On'ths';.bTKsr/b'artciy.:;^ . .' .. . -cijlain via Is.act as v/r'aa: .:o seal the whole K.uildinn’ard thus tlVey seal ths.ivhs'e buildlric n^kind it ■ de'.^ndsnf.Dr; a niecli.aricai coclng s y s te n y - V - i; .' -,1 • • '• '.• • • ^ /is R E L A T I O N S H IP R tT W rE N 7 W L I 1 1 A S I O rO H M S i ^bteay^'ddnclustons;^for/basc; liujldjng;;Tortyis^ce; Figure 4-31 Snapshot of building form and shapes page Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. - 3 H e a t liansfcr th rb u g h co n d u ctio n - M icrosoft Internist E kpiorcf p io v id cd by MSN ■ @ B E 3 P rin cip les o f v e rn a c u la r a rc h ite c tu re Figure 4-32 Snapshot of Vernacular architecture movie page CLIMATETYf’ES t M icroioll Internet Explaici provided b ; MSN h e p ■ ■ . : ' A ■ ■ ■ ■ ■ ■ . . ■ ■ • ■ - ■ ' ..../ ■ • / - l,\. '■(. The basic cfim atfc.regions o f th e united s t a l e s o f am erica ' T H E O R Y I C U M A T I P F A C T O R S basic climate types ty ^ e .: h a 5 L ii& th e .f o llb Y Y in g .' C s g t i e lift! I 4 m e : ^ e ; d i a § i 5 m ' b % w c l i j w a i i t i p g fo n s .o f.' • M t K e;iibr1 ftd-s t ^ es .V y it h a .b/Vtf ties C T fp1 .'1 ? f?’o f e a tiv c lim a l^ iy p & a if t.f h s ^ ;^ . u:4irth uj* o rtlir>L' /in <|-. • ■ ' . • • • • •. ;• .. » ;';\,Th.e purj^Q ^ecategbfU ihqp' ^epgraphjca^amsis'.by- climSiVe is tp**idev«IOp:a-mria^eabje numb'er.6f;; j - -gu idejinesiTO T^nbigyioyisciaUs .rffes.i^.;TKesiaVf^-4¥pijaT 9w^®!j/tS-B:..ans:iSspefc tally' u steiui 'arhjd^ hjeJpiSiiy-' iy i;iv ih P '''|rrd g E a m m ;i< jg v P ^ : ;/.T34<V c!ly'.^ller ih e '-'re g ia n g L g U i'd e Jiire s;-T p e th a p ^ ; jh 'fe^ rn o 'st:^ ^ 'it.'ik iio y in ;c a ^ '. h a s t h 'f e m a i n 'c a i e g p r i e s 'a s . ■ ■ !" v : .3:. Y '?- Y / ■ ■ ■ / ■ ■ ■ " ■ Figure 4-33 Snapshot of climate types page Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4.5.2 NUMERICS This section provides an overview of the basic heat loss and heat gain calculations. It begins with theoretical background on all the factors that affect heat gain or heat loss, then it provides a small animation for the same. There are two worked examples, one of each type followed by a program which calculates each factor and then sums it together to calculate total heat gain or heat loss. Thus, the basic parts to this section are: • Basic theory • Animation • Worked examples • Calculator • Quiz The snap shots of each section follow. THEBMAL-GUlbE - N e ttc jp 'e numerics lAtCUUiTIO 0 O L Figure 4-34 Snapshot of NUMERICS main page 135 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. * 3 NUHEp}C^:>BASiC THEORy;r''Micfo»oU tMeii>elg«ftlofef, piQvrid(?d by MSN ; E 3 S E 3 basic theory Heat Soss calculations r : p s s s s s s ^ Hoat toss Is usually calculated for the design of a heating installation. Heat toss rate for a condition which is the coldest for 90% of die time, Is calculated and the heating retaliation is designed, then la prodjce h e at a t the sam e rato. Under less severe conditions, n the rom am ng 10% of the time, this peak normalfy occurs In short spoils and ma>t» t r i c e d by the thermal inertia o f the building, GENERAL GUIDELINES: Figure4-35 Snapshot of Basic Theory page /3:K U iM C R lC $ypnK tp'r €X^pl:£S. ; ^ worked examples in d U f a a tKiteun Traugli rails wrCuctlyi he*t B 4l thrwighgtaij r«NIWWWIMBIJJjtlL li |.ll» illllli|i,IIILil J I Ji Figure 4-36 Snapshot of Worked examples page 136 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4.5.3 THERMAL CONTROLS This section provides the various active and passive means available to control the thermal conditions inside buildings. The major chunk of it would be the HVAC systems which has only been mentioned while other non-conventional systems that are available today have been discussed in greater detail. Most of these system definitions have been done on the basic principles and theory. This section also includes a quiz in then end. The basic parts to this section are: • Active Systems • Passive Systems The snap shots of these sections are given below. < 3 THERMALBUILDElR • CQHl H O IS - Mi.ciotdH Internet E iy lo iet piovidcd b y MSH ! _ ' H B B f thermal controls 4-36 Snapshot of Thermal Controls main page 137 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ■3 THERMAL COWinOLS - PASSIVE SYSTEMS ^ M icro io fH n icm el £ uplw er provided by M SN-' 'M ■ J 3 B E 3 passive system s D ire c t g c l n l w o y c h ™ w in d o w s 4.- Shading rrn e e d e d to reduce h eat gam in Hie sum m er Overhangs.iawnrngs, tre llise s,: * J Zl 4-37 Snapshot of passive systems - direct gain page 3 THERMAL CONTROLS IfoSStyfrSY STE M S :,HicmtofHntrioeV^ ISJSJX passive systems A p a s siv e sy stem is a non-m echanical heating and cooling sy stem . A passive heating sy stem will u se building com ponents - windows, wails, and floors - to capture, store and distribute the energy gained from various natural p ro c e sse s. The energy required to achieve heating or cooling in passive sy stem s is also obtained from natural m ean s. It is not produced or convened using the com m on active elemts. In passive s y ste m s there are no m echanical collectors to convert natural energy into heat nor pum ps or fans to distribute the heat. The energy is used directly. A passive cooling sy stem will u se the building com ponents, su c h as roof overhangs, awnings and window insulated curtains to im pede the heat gain during th e sum m er. 3v SOLAR ENERGY Wind energy ' ■ . - * 5 S - Insulation Figure 4-38 Snapshot of passive systems main page 138 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. • ilT H E R MALCONTFI0 LS - PAS SFVESYSTEM S* Mictojofl Internet Explorer provided by MSFEv'''/C'-v-V;' 0 E E 3 passive systems • The cunspace ac is a s a buffer zone betwsen the outside and the primary space. j*J f e 4-39 Snapshot of passive systems- isolated gain page 4.5.4 DESIGN ADVISOR The main emphasis of my thesis has been the first three sections. The design advisor actually is supposed to take all the factors discussed in the first three sections and then provide the user with design decisions. This in itself would be another thesis and I have left it to be carried through by any other person interested in the same. References Center for Advanced Instructional M edia (C/AIM ), Y ale University. Xerox Corporation. 1988. Xerox publishing standards. N ew York: W atson-Guptill Publications. 139 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. PART FIVE INTO THE SUNNY FUTURE “The woods are lovely dark and deep but I have promises to keep and miles to go before I steep and miles to go before I sleep...................................' " The Web-Based Teaching Tool on Thermal Processes in buildings has been developed in response lo the need for an easy to use, interactive tutorial for beginners as well as interested audiences. In doing so it reaches out to very wide audience all over the world who can benefit from this site. The environment fulfills the requirements for such a tool because of its graphical vocabulary, which is familiar to the designer, “user friendly” features, interaction, which provides instant response and extensive database. However, it is also true that it remains a broad overview, and does not deal with any topic much in detail. The subject of thermal processes is so immense and deeply related to various factors that even a sub section of the “Theory” section, can be a thesis in itself. However, my attempt has not been to put together all the information available on the subject. My thesis, is to put together a teaching tool which gives basic information about these processes in an interesting and interactive manner, such as to arouse user interest. The way each section has been organized, anybody interested in developing a part can easily carry it through with out in anyway, disturbing the structure of the site. Some useful additions to the site, would be a search tool allowing for information on any particular topic without having to tediously go through each section. The Design advisor itself would be a very useful and integral element of the site once it is done, as it would provide the culmination of all the information provided in the previous sections. Other 1 Robert Frost, Stopping by the Woods on a snowy evening. R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. ways would be to provide more vivid and animated puzzles and quizzes, not only for the purpose of providing interesting information but also for the purpose of generating interest of o user in this critical as well as challenging subject matter. The controls section could present the working of a photo voltaic cell as well as turbines etc in a “game like” as well as animated manner with the use of more sophisticated animation tools. Organizing and presenting information about the materials o f a building, could form a part of the design advisor as well as provide an excellent materials and energy teaching and information tool. I have designed the site with existing hyperlinking, animation and programming tools. However, the world of computers and the World Wide Web at large is growing everyday, with leaps and bounds. Technology, which was a limiting factor in many decisions today maybe the pioneer of the decisions of tomorrow. Thus, the future is sunny and bright for this kind of tool. Teaching over the web and that too in the field of architecture and building science is as yet new and the sites of tomorrow would certainly be miles ahead, not only providing information in an interactive manner but also advising on energy design issues! The important thing in designing the site has been that it has pioneered information in this field in a manner not provided by any other site and in doing so it provides a good overview of Thermal Processes, along with small tools, games and interactive softwares. The site is comprehensive and informative in its present form and performs what it set out to do in the first place. However, the future is bright and new technology and ideas along with aforesaid enhancements could increase the scope and use of the site. R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. BIBLIOGRAPHY Allis, L., Inside Macromedia D irector 6 with Lingo, N ew Riders, 1997 Leary, M ichael, Web Designer's Guide to Typography, Hayden, 1997 Mulder, Steven, W eb Authoring D esk Reference: Html, Stylesheets, Javascript, Vbscript, Hayden, 1997 W eb D esign Consortium, The Web Design Annual., B ooks Nippan, 1999 W ebster, Timothy, Web Designer's Guide to Graphics: PNG, GIF and JPEG, M acm illan Computer Publishing, 1997 Benjamin Stein and John S. R eynolds, Mechanical and Electrical equipment fo r buildings, S1 * Edition. W atson, Donald FAIA, The Energy design Handbook, The American Institute o f Architects press, W ashington D.C. Egan, Design fo r Thermal Comfort, M cGraw Hill, N ew York(1983). P. O. Fanger, Thermal Comfort- Analysis and Applications in Environmental engineering, M cGraw Hill, N ew York(1972) California Energy Com m ission. E fficiency Standards Office, Energy efficiency standards fo r residential and nonresidential buildings. California Energy Commission, Efficiency Standards O ffice, Energy E fficiency Division. Hastings, S. Robert, Passive Solar commercial and institutional buildings: a sourcebook o f examples and design insights, Chichester ; N ew York : J. W iley, cl9 9 4 . Balcom b, J. Douglas, Passive solar buildings, Cambridge, M a ss.: MIT Press, c l9 9 2 . Anderson, Bruce, 1947, Solar building architecture, Cambridge, M a s s .: MIT Press, 1990, c l9 8 9 Vance, Mary A ., Solar architecture : a bibliography o f monographs, M onticello, 111. : Vance Bibliographies, 1981. Shurcliff, W illiam A., Solar heated buildings o f North America : 120 outstanding examples, Harrisville, N .H .: Brick H ouse Pub. Co., c l9 7 8 . Tuluca, Adrian, Energy efficient design and construction fo r commercial buildings, N ew Y o r k : McGraw- H ill, c l9 9 7 . Sick, Friedrich, Photovoltaics in buildings: a design handbook fo r architects and engineers, L o n d on : James & James (Science Pub.), c l9 9 6 . Thumann, Albert, Energy conservation in existing buildings deskbook., Lilburn, G A : Fairmont Press ; Englewood Cliffs, NJ : distributed by Prentice-Hall, c l9 9 2 . Ternoey, Steven., The Design o f energy-responsive commercial buildings, N ew York : W iley, c l9 8 5 . 142 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
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Asset Metadata
Creator
Tandon, Geetika
(author)
Core Title
Thermbuilder: A Web-based teaching tool to study thermal processes in buildings
Degree
Master of Building Science / Master in Biomedical Sciences
Degree Program
Building Science
Publisher
University of Southern California
(original),
University of Southern California. Libraries
(digital)
Tag
Architecture,Computer Science,education, technology of,engineering, mechanical,OAI-PMH Harvest
Language
English
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Digitized by ProQuest
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https://doi.org/10.25549/usctheses-c16-289937
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1409661.pdf (filename),usctheses-c16-289937 (legacy record id)
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289937
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Thesis
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Tandon, Geetika
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texts
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University of Southern California Dissertations and Theses
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The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...
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University of Southern California Digital Library
Repository Location
USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA
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education, technology of
engineering, mechanical