Atrium spaces have the potential to make vital contribution to the sustainable strategy and consequently eco-dynamics of a building. The environmental benefits in terms of daylight, natural ventilation, and heating that an atrium offers are widely recognised. Daylight availability in an atrium space is generally high; however, this may not necessarily be true for the adjoining spaces. Previous studies indicate that the daylight performance of the adjoining spaces can be improved through the design of atrium facades, whereby there is a progressive increase in the fenestration from the upper to the lower floors. Therefore, this paper seeks to systematically investigate the effects of different atrium façades design characterised by varied distribution of fenestrations on daylight (DFs) in an atrium and horizontal penetration of daylight in its adjoining spaces under overcast sky conditions for a four sided, top-lit, square atrium building of Well Index (WI) 1.25. Studies were undertaken using computer simulation software programs ECOTECT and RADIANCE with the objective of understanding the influence of facades and providing guidelines for facade design to create optimal daylighting conditions in the adjoining spaces. Three main curves were developed, each of which included five options of 20%, 30%, 40%, 50% and 60% openings on top floor with a progressive increase in openings and 100% opening on the ground floor. Results demonstrate that façade compositions have a very limited influence on daylight in the adjoining spaces offering very little benefi ts to the lower floors, where daylight is critical. But increase in opening on the top floor may increase DFs significantly on the top two floors. For this study, the option of 60% opening on top floor with progressive increase to 100% opening on ground floor provided the best results.
Adjoining spaces, atrium, daylighting strategies, facade design, fenestration distribution
 The Chartered Institution of Building Services Engineers, CIBSE Code For Interior Lighting, CIBSE: London, 1984.
 Letherman, K.M. & Wright, J.C., Illuminance in Atria: review of prediction methods. Lighting Research And Technology, 30(1), pp. 1–11, 1998. doi:10.1177/096032719803000101
 Aizlewood, M.E., Butt, J.D., Isaac, K.A. & Littlefair, P.J., Daylight in Atria: A Comparison of Measurements, Theory and Simulation LUX EUROPA, Amsterdam, pp. 571–584, 1997.
 Sharples, S. & Lash, D., Daylight in atrium buildings: a critical review Architectural Science Review, 50(4), pp. 301–312, 2007.
 Oretskin, B.L., Studying the effi ciency of lightwells by means of models under an artifi cial sky. Proceedings of the 7th Ases Passive Conference, Knoxville, TX, pp. 459–463, 1982.
 Navvab, M. & Selkowitz, S., Daylighting data for atrium design. Proceedings, 9th National Passive Solar Conference, Columbus, pp. 495–500, 1984.
 Cartwright, V., The use of lightwells as a daylight strategy. Proceedings ‘85, American SES, Raleigh, NC, pp. 115–118, 1985.
 Aschehoug, O., Daylight design for glazed spaces. Proceedings From The International Daylighting Conference 2, Long Beach, CA, November, pp. 237–243, 1986.
 Liu, A., Navvab, M. & Jones, J., Geometric shape index for daylight distribution variations in atrium spaces. Proceedings of the 16th National Passive Solar Conference, American Solar Energy Society, Denver, 1991.
 Cole, R.J., The effect of the surfaces enclosing atria on the daylight in adjacent spaces. Building and Environment, 25(1), pp. 37–42, 1990. doi:10.1016/0360-1323(90)90039-T
 Boubekri, M., The effect of the cover and refl ective properties of a four sided atrium on the behaviour of light. Architectural Science Review, 38(3), pp. 3–8, 1995.
 Willbold-Lohr, G., Daylighting in glazed atria. Proceedings of the 2nd European Conference on Architecture, Paris, pp. 16–20, 1989.
 Iyer, R.U., Daylighting in atrium spaces. Architectural Science Review, (37), pp. 195–208, 1994.
 Matusiak, B., Aschehoug, O. & Littlefair, P., Daylighting strategies for an infi nitely long atrium: an experimental evaluation. Lighting Research And Technology, 31(1), pp. 23–34, 1999. doi:10.1177/096032719903100105
 Sharples, S. & Mahambrey, S., Refl ectance distributions and atrium daylight levels: a model study Lighting Research & Technology, 31(4), pp. 165–170, 1999. doi:10.1177/096032719903100405
 Samant, S. & Sharples, S. & Surface refl ections distributions and their effect on average daylight factor values in atrium buildings. Architectural Science Review, 47(2), pp. 177–182, 2004.
 Littlefair, P., Daylight prediction in atrium buildings, Solar Energy, 73(2), pp. 105–109, 2002. doi:10.1016/S0038-092X(02)00038-5
 Sharples, S. & Lash, D., Refl ectance distributions and vertical daylight levels in atria Lighting Research & Technology, 36(1), pp. 45–57, 2004. doi:10.1191/1477153504li103oa
 Matusiak, B., The impact of lighting/daylighting and refl ectances on the size impression of the room. Full-scale studies Architectural Science Review, pp. 47(2), 2004.
 Calcagni, B. & Paroncini, M., Daylight factor prediction in atria building designs. Solar Energy, 76 (6), pp. 669–682, 2004. doi:10.1016/j.solener.2004.01.009
 Samant, S. & Yang, F., Daylighting in atrium: the effect of atrium geometry and refl ectance distributions. International Journal of Lighting Research and Technology, 39(2), pp. 147–158, 2007. doi:10.1177/1365782806074482
 Lau, B. & Duan, Z., The daylight benefi t conferred upon adjoining rooms by specular surfaces in top-lit atria Architectural Science Review, 51(3), pp. 204–211, 2008.