The use of electric lighting in homes and at workplaces represents a significant portion of the societys electric energy consumption. At the same time as the electricity flows through lamps inside houses, an overflow of light flows down from the sky and hits the exterior of the same houses. At almost any day the daylight is superior in both the illumination level and the quality compared to the artificial light that is being used for everyday tasks. So why not utilize the daylight instead? And this is actually happen. Daylight and sunlight is let into our building through windows designed both for view and for lighting purposes. Until electrical
See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/215448141 Advanced Daylight Technologies For Sustainable Architectural Design Article · January 2010 CITATIONS READS 2,890 author: Ossama Omar Beirut Arab University 41 PUBLICATIONS 55 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Zero Energy Home View project All content following this page was uploaded by Ossama Omar on 01 June 2014 The user has requested enhancement of the downloaded file Advanced Daylight Technologies For Sustainable Architectural Design Osama Mohamed El-said Omar Architecture Department, Alexandria University, Egypt, Senior Architect in Technical Office, Engineering Department, Bibliotheca Alexandrina Abstract Daylighting has been a part of built forms throughout architectural history Interest in using daylighting as a major design element has varied with the social and economic forces of the time Since 1973, interest in daylighting has increased as a result of oil embargo and the understanding that electric lighting represents a major energy consumer Energy savings achieved through the use of daylight also translate into energy cost savings from reduced electricity consumption for lighting and cooling as well as from reduced needs during peak demand periods in many building [ Fikry,2000] The objective of this paper is to explain the great importance for daylighting and the role played in design process for the building and the participation in the design from the first step which effects the designer decision for dimensions, position for the opening and the building orientation, etc Which give the psychological comfort for building user and how to control the heat transfer throw opening by using different materials and using simulation programs which give to the designer a clear image for what will be a situation all the year around? Keywords: Daylighting, Simulation, Sustainability, Daylighting Calculation Background The use of electric lighting in homes and at workplaces represents a significant portion of the society's electric energy consumption At the same time as the electricity flows through lamps inside houses, an overflow of light flows down from the sky and hits the exterior of the same houses At almost any day the daylight is superior in both the illumination level and the quality compared to the artificial light that is being used for everyday tasks So why not utilize the daylight instead? And this is actually happen Daylight and sunlight is let into our building through windows designed both for view and for lighting purposes Until electrical lighting became efficient and cheap enough in the mid 20th century, the major changes in architecture aimed at letting more light in This was the objective of the Roman and the Gothic groin vault as well as 19th century Crystal Palace [Lechner, 1987] In order to fully replace the electrical lighting with the daylight during daytime one step must be taken further than windows and other architectural solution The question is how to get the light into the building, when windows and skylights cannot this? [Whitehouse, 1999] Problem definition & importance of research difficult issue in the design is the determination of openings design aspects that influence amount and distribution of the daylight in the space The main Internal lighting has ever been a problem facing architects who try to provide the natural lighting in the space without depending on artificial lighting which is energy consuming So the most mistake in the design process is the inconsideration of the natural lighting of the space in the initial design stages As we suppose to take into consideration the orientation of the building in the land to get the best lighting in places needing light at all hours of the day, without being exposed to the glare We have to consider that sometimes the natural lighting causes some increase in the temperature inside the space and one has this problem wasting energy and money Another important element for the reflection of the natural lighting is materials used inside the space as it may have a positive or negative action in the resultant light in the space Eventually, it can be concluded that the kind of glass and the material used in the finishing of the ceiling and floors and walls of the space plus the location and dimension of the openings all these act together as an equation to give the last result for the space and how it may be designed in the first location In this research we will discuss the design considerations which have to be taken in the determination of size and location of the openings and its material to assure the permanent purpose of the building in hot areas of the world and maintaining it by using the new renewable resources instead of the obsolete consumed ones (And this will be done by making application methods by supplying some examples and simulating them by simulation programs as "Ecotect"… ect.) As these programs enable us to determine the size and the dimension of the opening and its location, in the initial design stage Objective Reaching the design standards in the determination of the sustainable design aspects in the hot areas Taking into consideration the dependence of new resources and not the obsolete ones Discussing methods of using the natural lighting in Egypt and how to use the latest technology in this field Advanced Daylighting for sustainable architecture The design of a daylighting space is both an art and a science The biggest challenge facing the lighting designer is to admit only as much light as necessary and distribute it evenly throughout the space without introducing glare or heat In hot / warm climates, it has become common practice in windows spaces to specify blinds and glazing with high shading coefficients to control glare and minimize heat gain However, this practice reduces the effectiveness of lighting systems that dim automatically Improved systems are needed to capture natural daylight and distribute it uniformly throughout a space while controlling heat gain and glare One such system is the light shelf Light shelves shade the space from direct sunlight and reflect this sunlight onto the ceiling for a deeper and more uniform Classification of daylight elements In order to classify the daylighting components it is important to distinguish between two main groups which are "Conduction components ","Passthrough components" and " Control Elements " The conduction component can be defined as a space designed to guide and / or distribute daylight towards the interior of a building from one passthrough component to another Basically, there are two groups of this type: A Conduction Component: A.1 Intermediate light space A.2 Interior Light space Daylighting calculation distribution While this is not a new idea, little unbiased empirical data has been collected, outside the laboratory that compares the performance (energy savings, uniformity, and level) of an automatic daylighting system [Aboulnaga, 2003] B Pass-through Components are identified as three groups as follows: B.1 Lateral passthrough component B.2 Zenithal passthrough component B.3 Global passthrough component B.4 Control Elements These three groups component may incorporate C control elements such as C.1 Separator surface C.2 Flexible screens C.3 Rigid screens C.4 Solar filters C.5 Solar obstructers Recently in the last century the calculation method has been developed to the daylight factor In the past it was dependent on the tables and equations which used to know the required ratios to be achieved in the space, also the lighting reflections on the different surfaces, opening size, and other influential elements on the daylight factor Although this operation requires precision and much attention, its error rate “factor” was in a very high percentage This is because of the large and complex mathematical operations significantly, which increase the error percentage for the person who uses such operations By time, the mathematical operations and equations which used ”aimed” to reach the daylight factor value have been represented by flow charts and counter maps This facilitates the way for the designers and architects to discover the darkest places in the space to design its openings Although that, this drawings contain some errors, this because of the many inaccurate readings Also its non-successive “non-sequential” in short periods Accordingly this doesn’t result into more coordinates so we can connect between them to reach to more accurate and clear curve but it is surely less than the calculation which had a higher error rate “factor” With the rapid evolution of the technology and the achieved breakthrough in the simulation programs” the new inventions in the simulations programs” , many programs has been invented to help the designer in his designs of the buildings internal spaces, also the openings designs in these spaces These programs are distinguished from the others in the two previous methods because of the existence of important factors which are the speed and the accuracy These programs are characterized with their speed in the daylight factor calculations, Also their ability to obtain highly accurate flow chart in a recordable time This is helpful for the designer to achieve his work in a short time Through this introduction we can conclude that the calculation method of the daylight factor consist of three phases “stages” which are the calculation method, the graphical method, and the simulation methods which is considered a combination of the two previous methods but with less error rate and high speed The following programs are considered examples of the simulations programs: Ecotect, Daysim, Radiance, & Skyvision” The following will explain each method separately, and its pros, & cons “its advantages, & disadvantages” The most obvious and important aspect of daylighting calculation and design is the Variable nature of the source The results are tied to a prediction of external conditions that vary with the time of the day, the day of the year, and with the weather In some countries sufficient daylighting is seldom available during the whole of the daylighting working hours throughout the year It is necessary to decide the percentage of working hours for Which adequate lighting is to be provided? By statistical evaluation of long term illumination records, for a given location an outdoor illumination level can be established which is exceeded in 90% or 85% of the time of daylight hours This is taken as the "design sky" illumination value for the particular location As mentioned before, daylight Illumination in an interior can be expressed either in absolute terms or as a percentage known as the daylight factor Daylight design considers two basic stable conditions:A The completely overcast sky which may be considered either of uniform luminance, or having a given non-uniform luminance distribution, such as the CIE sky With such a sky, it is practical to think of light admitted as a percentage of the total light available from the hemisphere of the sky Orientation and location can be ignored The design is based on light reaching the window from two sources, the overcast sky and the exterior surface's contribution of reflected light B The clear blue sky, with or without sunlight, for which a luminance distribution for the sky may be obtained from knowledge of the sun's position and the relevant scattering constants for the atmosphere The luminance of the ground and vertical surfaces may be found from knowledge of the luminance from the sun, sky and the reflecting properties of these surfaces With clear sky conditions it is possible to work with actual values of illumination that will vary considerably with orientation, location and season The design is based on light reaching the window from three sources, direct sun, clear sky and reflected light from ground or exterior surfaces In case of the clear sky without sunlight, the direct sun's contribution is omitted Fig 6.1 Diagram of daylight calculation classification Fig 6.1 example of daylight factor contours on horizontal working plan [source / Dr.Nagwa zaki, PHD thesis] 6.1 Calculation Methods This method depends mainly on two elements to calculate the daylight factor which are the spread sheets & the mathematical equations The spread sheet can be used to obtain the required value of daylight factor to be achieved in the design of space According to the required purpose It also used to obtain the lighting reflections values on the different materials So these values can be used in the mathematical equations to find the daylight factor value in the space and compare it with the estimated values in the spread sheet The main equation to find daylight factor is: DF = SC + ERC + The sky component (SC) The external reflectance component(ERC) The internal reflectance component (IRC) 6.2 Graphical Methods Diagrammatic methods There exist a number of diagrammatic methods which enables the daylight factors to be evaluated, among them are: 1- B.R.S Daylight Protractors: Which are devised primarily to simplify the calculation of the sky component to enable daylight measurements to be made From architect's drawings, In this respect they are not design methods but merely an aid to design Fig 6.2 BER SC protractor number for a vertical glazing under the CIE overcast sky [source / L.Robbins,1985] 6.3 Simulation Methods A number of daylight simulation methods, have been developed over the past 50 years, making use of simulated or artificial skies and building models Simulation techniques have the advantage of allowing for unique buildings shapes and room’s Configurations In the last 50 years, the method of the daylight simulation has been developed to calculate the daylight factor These programs use the different conditions of the sky which it are already entered in the program according to the different locations, longitudes, latitudes which specify the estimated location where the model will be built in it Based on this information, in this part, we will preview quickly 2- Half Cube Method: This gives the sky component and the externally reflected component under CIE sky and uniform sky It is particularly useful when the external obstructions are complex 3- The Waldram Diagram: This gives the sky component and the externally reflected component under CIE sky and uniform sky It is particularly useful when the external obstructions are complex [Dr.Nagwa zaki, PHD thesis] Fig 6.2 Simplified Waldram diagram for glazed apertures under the CIE overcast sky [source / L.Robbins,1985] three programs and how they operate or function Also the input & output format, and the result that we can get when we use these programs [Dr.Nagwa zaki, PHD thesis] We have chosen this program based on the recommendation of the Canadian supreme institution of the daylight as it recommended those programs as the best three programs in 2006 We will review and talk about the following programs (Ecotect, Daysim, Radiance) ECOTECT Interface:ECOTECT v5.20 is the most comprehensive and innovative building analysis software in the market today It features a designer-friendly 3D modeling interface fully integrated with a wide range of performance analysis and simulation functions What really sets ECOTECT apart is the visual nature of calculation feedback and its support for very early stage conceptual design as well as final design validation Designers can start Generating vital performance-related design information before the building form has even Fig 6.3 Ecotect Interface [source / http://www.Eco tect.com] As ECOTECT deals with many different aspects of building performance, it needs a wide range of data to describe the building To reduce the burden on the designer, ECOTECT uses a unique system of progressive data input Initially only simple geometric details are needed As the design model is refined and more accurate or detailed feedback is required, the user makes more choices and enters more data as it becomes important This means that you can be analyzing sun penetration, shading options and available light after only a few mouse clicks [http://www.Ecotect.c om] • • • • You can use ECOTECT to the following: Display and animate complex shadows and reflections Generate interactive sun-path diagrams for instant overshadowing analysis Calculate the incident solar radiation on any surface and its percentage shading Work out daylight factors and artificial lighting levels either spatially or at any point • Calculate monthly heat loads and hourly temperature graphs for any zone • Generate full schedules of material costs and environmental impact • Trace the paths of acoustic particles and rays within any enclosures of any shape • Spray sound particles around an enclosure and watch the rate of decay • Quickly calculate statistical and raytraced reverberation times in any space • Export to VRML for interactive visualisation and presentation to clients • Read and write a wide range of CAD and analysis file formats [http://www.Ec otect.com] The application The need to provide climatic control inside buildings to improve comfort levels and hence productivity is very desirable However, the cost of design or redesign to achieve the desired comfort levels has to be economically evaluated With the on going energy/greenhouse emission reduction campaigns and in accordance with Environmental and Ecologically Sustainable Development (ESD) principles, the relevance of implementing sustainable energy technologies is now gaining the attention of building designers around the world The problems associated with energy consumption such as cost, material depletion both renewable and non renewable and greenhouse gas emissions have provoked an increased awareness and willingness to strive for technologies that provide ameliorative measures which increase the sustainability of building stock Fig 7.1 Plan For Fourth Floor in Admi nistra tion Buildi ng [Facu lty of Engin eerin gArchit ecture Depa rtmen t] An area of this application will be a classroom located in Alexandria University, Faculty of Engineering, Architecture Department, in Administration building, fourth floor This classroom has several problems such as low daylight level in space depth the classroom leading the users to close the windows and use the electrical lighting Fig 7.2 Classroom plan [Faculty of EngineeringArchitecture Department] Also the unequal distribution of natural illumination due to the space, the daylighting cannot reach in to big depth in the space so the daylighting covering small areas and users (Fig 7.2) (Fig 7.3).The question is how to increase daylighting level in the space? How to reduce heat Load for lighting? The drawing to be entered into the simulation program “Ecotech” mentioned before in the background part to know the classroom behavior for the daylight throughout the year, it also can be reviewed throughout the different seasons In every season the sun paths, the lighting rate and directions in the space will be reviewed and compare it to the other seasons to know the best and worst time for the daylight in the space, informing about or determining the space location is one of the required data in this application or program to the simulation process accurately or appropriately in order to determine the sun movement paths in this region throughout the year The Tables explains that the daylight factor percentage should be less than % and for each drawings table These are the required percentage to achieve the visual comfort & clarity to the user helping in doing his functions and work in proper and comfortable way The simulation program will be used in this study to know the places which have poor and high lighting levels to find out the weakness points which need treatment and increase the daylight percentage and how to it The second step in this application after collecting data about the case study and problems facing it is to prepare This application works by entering the longitudes and latitudes and specifies the city location from the list of cities that lies in this region In order to have an accurate simulation process, all the input data like the drawings must be correct This application or program doesn’t deal with the complicated models while it deals with the simple models through studying the lighting behavior in the space This model should reflect the dimensions, height, length of the expected location or places of the openings & its dimensions which give the designer the contours plan of the lighting in the space This contours plan enable us to specify the strength and weakness points of the classroom and determine the ways to increase the daylight rate in the places that suffer from lack of lighting through the modern techniques like (“HLP” Horizontal Light Pipe Technology , “VLPs” Vertical Light Pipes Technology ) Fig 7.3 Photograph for Classroom [Faculty of EngineeringArchitecture Department] Simulation results in September:- Fig 7.4 Daylight Analysis for classroom in September [Ecotect output] Fig 7.5 Contours plan for classroom in September [Ecotect output] Simulation results in March:- Fig 7.6 Sun path for classroom in September [Ecotect output] Simulation results in December:- Fig 7.7 Daylight Analysis for classroom in December [Ecotect output] Fig 7.10 Daylight Analysis for classroom in March [Ecotect output] Fig 7.11 Contours plan for classroom in March [Ecotect output] Fig 7.8 Contours plan for classroom in December [Ecotect output] Simulation results in June:- Fig 7.12 Sun path for classroom in March [Ecotect output] Fig 7.9 Sun path for classroom in December [Ecotect output] Fig 7.13 Daylight Analysis for classroom in June [Ecotect output] Fig 7.16 Horizontal light pipe technology (HLP) [source / http//www.ask.com] Fig 7.14 Contours plan for classroom in June [Ecotect output] While well known to domestic applications that have roof space to floor area available, vertical light pipes (VLPs) and skylight technologies are now playing a part in rooftop locations such as supermarkets and where substantial savings in lighting have been achieved (Fig 7.17) Fig 7.15 Sun path for classroom in June [Ecotect output] The previous results of the simulation process in the classroom, and the counter maps show the main problem that face the classroom which result from the low rate of daylight especially in the middle of the classroom which is clearly obvious in the counter maps resulted from the simulation process and which is the current fact The usage of the simulation programs output result in the desired objectives These programs have proved their effectiveness & efficiency for the designer in this field although such programs are usually used in the earlier stages of the design process and the implementation stage Accordingly new two techniques will be displayed These techniques increase the daylight rates in the classroom, and the places that suffer from the lack of daylight One of the daylighting devices that have been evaluated involves a solar hood shading device to stop incident radiation from striking the south facing glazing but reflects light through a horizontal light pipe (HLP) above the suspended ceiling and then redistributes that light into the classroom place (Fig 7.16) [http//www.ask.com] Fig 7.17 Vertical light pipes technology (VLPs) with and without reflectors [source / http//www.ask.com] Final conclusions The following points can be concluded from the previous results, the comparisons between different methods to calculate the daylight factor, and the theoretical analysis of sustainability term:1- The realization of the sustainability concept in the design process preserves the electrical power for the future generation which is the common trend of architecture in the whole world to reserve the non-renewable resource, make use of the renewable natural especially daylight 2- The entering of the daylight in the early stage of the design process help the designer to make use of much daylight, directing & choosing the places, and the dimensions of the openings and windows 3- The more awareness of the architect is important as sustainability concepts in the design processes which contributes to a strong continuous architecture for many years 4- The using of modern techniques and architecture processing that would increase the daylight rate in the space are very important to reduce the energy consumptions with the use of natural ventilation reducing thermal loads transmitted through openings 5- The comparison between different methods to calculate daylight factor shows the benefit of using simulation programs in these calculations in space because of its highly accurate performance and the comprehensive or integrated look of daylight behavior provided to the designer throughout the years 6- Designers knowledge or analysis of the daylight behavior in the space throughout the year is helpful to choose the appropriate solution to reduce the problem arise after the implementation from lack of daylight rate in the space which will be cheaper and easier to address if it is discovered through the designing process using the simulation programs 7- The simulation programs give accurate, clear, comprehensive results for the daylight rate in the space throughout the year These results can be displayed in different forms like the counter maps, tables & flow charts which mainly direct the designer in the design process 8- These programs are capable of doing the simulation process for any space anywhere around the world by entering the longitude and latitude of this place to simulation the sun paths or tracks in this place to get the a correct, and the most likely results 9- It is not difficult for the designer to learn how these programs work because of the available tutorial on the internet Also the speed of these programs in performing the simulation process enhance the designer to learn these programs to save the effort lost or consumed in the linear algorithms or mathematical operations to get the same results but with less accuracy and high error rate 10The more awareness of the designers is as important as the simulation programs in the early stages of the design process to define the problems that might arise after implementing the design in order to solve these problems quickly to reduce the costs, energy consumption, to rely on the daylight as much as possible 11Both daylighting and natural ventilation are critical climatic control components that should be considered for all building sticks in efforts to reduce energy consumption and to increase the sustainability 12Increasing the different daylight rates in the 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pp 454-460, (1998) William-Olsson, Margarela, "Solbrist kan orsaka benbrott", pp 210- 220, (2002) Christoph Reinhart , " Ecotect, Daysim, Skyvision program " , (2005) http:// www.greatbuildings.com (Access Date 207-2005) http://www.arch.mcgill.ca/prof/reinhart/software/ Radiance.htm (Access Date 12- 8-2005) http:// www.radiance-online.org (Access Date 128-2005) http://groups.google.com/group/daysim Date 15-8-2005) (Access http:// www.ecotec.com (Access Date 15-8-2005) http:// www.Daylightinglab.com (Access Date 308-2005) View publication stats ... its support for very early stage conceptual design as well as final design validation Designers can start Generating vital performance-related design information before the building form has even... technology in this field Advanced Daylighting for sustainable architecture The design of a daylighting space is both an art and a science The biggest challenge facing the lighting designer is to admit.. .Advanced Daylight Technologies For Sustainable Architectural Design Osama Mohamed El-said Omar Architecture Department, Alexandria