Comparative Analysis of Daylighting Systems - Illumination and Structure

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5 EuroSun 98 2 nd ISES Europe Congress E-NET, Centre for Efficient Use of Energy SI-1000 Ljubljana, Ambrožev trg 5, Slovenia Fax.: , e-net@siol.net ABSTRACT FORM Topic : Daylighting Comparative Analysis of Daylighting Systems - Illumination and Structure Levente I. Filetóth Technical University of Budapest, Faculty of Architecture, Department of Building Energetics University : H , Budapest, M egyetem rkp Hungary Tel.:(+361) , Fax: Home Address : H , Budapest, Ulászló u III/2. Hungary Tel / Fax : (+361) or levente@egt.bme.hu Text of Abstract : Investigating the daylighting of roof lights, we can assume, that they are behaving as luminaires - having major role in the lighting features of the interior space. Until now, enough exact and precise information on these daylighting systems does not exist, and because of this - the quality and quantity of illuminance and the light distribution of the space below is not predictable precisely. The exact role of the roof lights are complex, complicated and very sophisticated. Their features are based on the reflectance and geometry of the transparent and translucent surfaces. The effect of these features can not be predicted or calculated using the traditional mathematical methods. I am investigating the effect of these complex roof lighting systems on the interior lighting, using a completely new method: based on series of model measurements in the artificial sky, investigating the roof lights - having different type, form shape and transmittance values. Considering the fact, that the roof light as a complex system, consists of relatively large surfaces - which are different from the point of view of light transmittance and reflectance - have an effect on the large surfaces of the interior space while the size of these surfaces are comparable to each other. Surface effects an other surface. These fields can be determined by the experiments with the roof light models in the artificial sky. Calculating the different fields of the different types of roof lighting systems I will be able to determine the light distribution as well. I have developed a computer software for this purpose. Date: Budapest, 10 th of January, Date : Topic Author s Signature No. : EuroSun 1998, Portoroz, Slovenia, September 14-17, Comparative Analysis of Daylighting Systems

6 EuroSun 98 2 nd ISES Europe Congress E-NET, Centre for Efficient Use of Energy SI-1000 Ljubljana, Ambrožev trg 5, Slovenia Fax.: , e-net@siol.net EL ADÁS KIVONAT Kutatási téma: Természetes világítás Felülvilágítók új természetes világítás analízise Filetóth Levente, doktorandusz hallgató II. év Témavezet : Dr Majoros András, PhD BME, Építészmérnöki Kar, Épületenergetikai Tanszék El adásom kivonata : A természetes világítás felülvilágítás módjánál a felülvilágító játssza a lámpatest szerepét, módosítja, irányítja a küls fényhatást. Ilyenformán a kialakuló világításban meghatározó szerepe van. A felülvilágítás mellett kialakuló világítás mennyiségi és min ségi meghatározásának alapfeltétele ennek megfelel en annak ismerete, hogy a felülvilágító milyen szerepet játszik a világítás kialakításában, milyen módon csökkenti, osztja a küls tér fényét a bels térben. A felülvilágítóknak erre vonatkozó tulajdonságai a szükséges mértékben nem ismertek. E nélkül pedig a felülvilágítás mellett kialakuló megvilágítás-eloszlás nem határozható meg. A felülvilágító szerepe összetett és bonyolult, fényátereszt, fényt át nem ereszt és reflektáló részei geometriai kialakításával együtt alakítják tulajdonságait. Ezek a tulajdonságok egyszer úton nem határozhatók meg, egyszer matematikai összefüggésekkel nem követhet k. A megoldandó feladat annak tisztázása, hogy a bevilágító, mint komplex szerkezeti egység, hogyan alakítja a bels téri megvilágítást. Ezt a problémát, eddig nem alkalmazott teljesen új elképzelés alapján, a következ k szerint oldom meg: A különböz típusú, formájú és fénytechnikai jellemz j bevilágítók kérdéses tulajdonságát mesterséges égboltban, modell vizsgálatokkal tisztázom. Tekintettel arra, hogy a felülvilágító, mint összetett, több különböz fénytechnikai tulajdonságú részb l álló viszonylag nagykiterjedés szerkezet hat a bels tér felületeire és arányaik összemérhet k, a probléma "sík hatása síkra" jelleg, adott felülvilágító, adott geometriai elrendezés melletti hatásmez vel jellemezhet. A hatásmez ket pontosan kialakított felülvilágító modellek segítségével mesterséges égboltban, méréssel határozom meg. Az egyes felülvilágítókra meghatározott hatásmez k felhasználásával, adott felülvilágító rendszer által eredményezett megvilágítás eloszlás meghatározására számítógépes programot dolgoztam ki. A vázolt új eljárás használhatóságát, gyakorlati esetekre alkalmazva mutatom be. Dátum: Budapest, január 10. Dátum: Téma Aláírás : No. : EuroSun 1998, Portoroz, Slovenia, September 14-17, Comparative Analysis of Daylighting Systems

7 COMPARATIVE ANALYSIS OF DAYLIGHTING SYSTEMS - ILLUMINATION AND STRUCTURE LEVENTE FILETÓTH Technical University of Budapest, Faculty of Architecture Department of Building Energetics H Budapest, M egyetem rkp. 3. Hungary Tel.: , Fax.: : levente@egt.bme.hu ABSTRACT. Investigating the daylighting of roof lights, we can assume, that they are behaving as luminaires - having major role in the lighting features of the interior space. Until now we do not have enough exact and precise information on these daylighting systems, and because of this, we can not predict precisely the quality and quantity of illuminance and the light distribution in the interior. The exact behavior of the roof lights are complex and sophisticated. Their features are based on their geometry and reflectance, transmittance of their non-transparent, transparent and translucent surfaces. The effect of these features can not be predicted or calculated using the traditional mathematical methods. I am investigating roof-lighting systems taking account the complex effects of their parts, using a completely new method based on series of model measurements in the artificial sky. Investigating the rooflight as a complex system which consists of relatively large surfaces - as the effects of surfaces on other surfaces. Considering the different fields of the different types of roof lighting systems I will be able to determine the light distribution and efficiency of the system as well. The results are given by a new computer software has been developed for evaluate the measured data. 1. PROBLEM : TOO COMPLEX FORMULAS Daylighting in interior space results of a large exterior surface, the sky in relatively small room and the light is moderated by the top-light. It is difficult to describe and predict the exact behavior and efficiency of various roof-lights. The most important features of top-lights are: their geometry, transparent and reflecting surfaces and their structural obstructions. The main problem is to investigate all the effects of all these interior Effect of roof-light exterior EuroSun 1998, Portoroz, Slovenia, September 14-17, Comparative Analysis of Daylighting Systems 1.

8 features on the illuminance distribution and efficiency. To describe the problem by mathematical formulas is far too complicated, so far only rough calculations has been developed up to now. None of the existing methods are considering all the components (what happens exactly with the light getting through the structure of toplight). 2. SOLUTION : MODEL MEASUREMENTS The most convenient, reliable and precise solution to describe and follow the illuminance distribution and efficiency of the top-light is to make model measurements in the artificial sky. I have developed a modeling system, where the headroom of the interior can be changed, and also the transmittance of the light well can be modified. On top of the well the 700 model of the investigated roof-light can be placed. Its geometry, structural y obstructions, transparent and translucent surfaces are designed and A A built according to the previously decided parameters. 700 m m h Plan of the model m A-A Section of the model x x 27 The research - with the help of model measurements - is able to follow all the necessary and required characteristics. As the following figure and matrix shows, I am considering the angle and type of the applied glazing, all the existing obstructions, the transmittance and the depth of the wall of the lightwell, and the headroom of the interior space as well.? ~1 ~1000 Incommensurable quantities EuroSun 1998, Portoroz, Slovenia, September 14-17, Comparative Analysis of Daylighting Systems 2.

9 a α t a d r m (unit) h Structural Components of Top-light r ρ t τ m[cm] unit d [cm] well d. h [cm] headr. matte white simple glazing 6 shiny white double glazing matte black RESULT : ILLUMINANCE VALUES Series of model measurement in the artificial sky are providing illuminance values. With the help of these data the distribution of daylight factor can be determined by an x-y coordinate system of a reference plane. This surface of daylight factor represents all the effects of the top-light in a given case. The same time it is also suitable to determine the efficiency of the top-light and the resulting illuminance from more top-lights, which are having the same characteristics and positioned by the same way. The resulting illuminance is the outcome of superposition. The above mentioned results are taking into consideration the effects of the different structural elements of the roof-lights without separating all the various effects of the components. EuroSun 1998, Portoroz, Slovenia, September 14-17, Comparative Analysis of Daylighting Systems 3.

10 All the information of the illuminance distribution curves, representing the characteristics of the top-light will be traced, translated and stored in matrixes. The final goal of my research is to provide a computer software, which is developed for design purposes. Using various matrixes of various measurements, completing interpolation in between the values, it is easy to calculate the illuminance and its distribution considering all the various features of the daylighting system. The computer software is going to be a user-friendly, easy-to-use program both for scientific researchers and for architects. AKNOWLEDGEMENTS I would like to express my sincere thanks to my professors, Dr. András T. Majoros and Dr. Andás Zöld, who has supported my efforts throughout all my studies and researches. REFERENCES [1] Majoros, A. T. (1998) Daylighting Design Tools and Techniques, PLEA Note Series, Queensland, Australia [2] Majoros, A. T. (1993) Daylighting, EESP, London, GB. [3] Szokolay, S. V. Solar Geometry, PLEA Notes [4] Robbins, C. L., Daylighting - Design and Analysis [5] Baker, N. Fanchiotti, A. Steemers, K. Daylighting in Architecture [6] Moore, F. Concepts and Practice of Architectural Daylighting [7] Egan, M. D. (year) Concepts in Architectural Lighting [8] Goulding, R. Owen Lewis, J. Steempers, T. C. Energy Conscious Design [9] Hopkinson, R. G. Petherbridge, P. Longemore, J. Daylighting, UCL [10] Crisp, V. H. C. Littlefair, P. J. Cooper, I. McKennan, G. Daylighting EuroSun 1998, Portoroz, Slovenia, September 14-17, Comparative Analysis of Daylighting Systems 4.

11 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 1 EuroSun 98 The Second ISES - Europe Congress September 14-17, Convention Centre Bernardin Portorož, Slovenia COMPARATIVE ANALYSIS OF DAYLIGHTING SYSTEMS ILLUMINATION AND STRUCTURE LEVENTE FILETÓTH PhD student Technical University of Budapest Faculty of Architecture Department of Building Energetics H-1521 TUB Hungary Consulting Professor : ANDRÁS T. MAJOROS PhD. Dr. Habil.

12 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 2 Problem : Large Exterior, Small Interior? ~ 1 ~ 1000 What is the effect of the top-light? Features : exterior 1. Geometry 2. Transparent surface 3. Obstruction 4. Reflecting surface interior What effects do these features have on illumination distribution and on efficiency of lighting system? So far only rough calculations has been developed.

13 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 3 a.) Point b.) Line P L E = I r 2 E = Lab 2 h P 1(d,h,l) c.) Plane (Zijl-Larg Diffusor) z a h j x y b = y 1 M x E F M B x x + h arctg y + y x + h arctg y1 y + y 1 x + h 2 2 x - a b arctg b y 1 arctg b y + y 1 x a - x 2 2 arctg 2 arctg h + ( y + y ) h + ( y + y ) h + ( y + y ) y 1 h + y 1 2 a - x arctg 2 2 h + y 1 arctg 2 2 x h + y 1 2

14 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 4 d.) Top-light Even much more complex formulas are required. Top-lights are consisting of large surfaces, so the case is: Surface effects on an other surface. Solution: model measurements in the artificial sky. b a "a" and "b" are incommensurable working plane h b These dimensions are already commensurable with each other.

15 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 5 Model measurements in the artificial sky Plan of the model: 700 y A 700 m m x A A - A Section of the model: h m x 27

16 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 6 Structural Components of Top-lights : a t d r m (unit) h a α r ρ matte white shiny white matte black t τ simple glazing double glazing m [cm] unit 6 d [cm] well depth h [cm] headroom

17 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 7 Perspective Views of the Model in Section

18 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 8 Pictures of the Artificial Sky

19 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 9 Pictures of the Built Model

20 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 10 Pictures of the Built Model

21 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 11 Illuminance Distribution Date of Measurement : lx X [cm] S6 S11 S16 S21 S26 S31 S36 S41 S1 S46 S51 S56 Y [cm] E h = 414 lx, E control = 354 lx, α = 45, d = 1.6 cm ρ = matte black, τ = simple glazing, h = 2 M (12cm) IEC OVERCAST SKY Longitudinal Axis [lx] X [cm]

22 Comparative Analysis of Daylighting Systems - Illumination and Structure D - 12 PROBLEM : SUMMARY Investigating the daylighting of top-lights: their structural parts are depending on four major components : 1. Geometry 2. Transparent Surfaces 3. Structural Obstructions 4. Reflecting Surfaces It is far too complicated to describe the illuminance distribution and efficiency by mathematical formulas. SOLUTION : The best and most convenient reliable and precise way to describe, follow and investigate all effects of these components are the model measurement in the artificial sky. These measurements are providing illuminance distribution curves, which are incorporating all the characteristics of the current top-light. Using various curves of various measurements, interpolating in between their values, it is simple to calculate the illuminance and its distribution - considering all the different features of the daylighting system. RESULT : With the help of the illuminance distribution curves the efficiency of lighting can investigated, in a much more exact way, than before - with the help of the existing numerical methods. Final outcome: computer design software for scientific research and for architectural design.