Skylights in classrooms, optimal design for a cold climate through dynamic daylighting and energy simulations

Abstract: Previous studies indicated that skylights can improve the daylight conditions in house or office buildings, decrease the electricity demand for lighting, provide natural ventilation and reduce the heating demand through passive solar heat gain exploitation. This thesis analyses the effect of skylights on the energy use, daylight conditions and thermal comfort in a classroom. The study is performed by dynamic energy and daylight simulations with Grasshopper, DIVA for Rhino and Archsim (EnergyPlus). The simulations were carried out for a single classroom located in Copenhagen, for a Passive construction and a typical Danish construction. The independent variables are: roof tilt, window-to-floor ratio, skylight-to-floor ratio, skylight distribution, amount and position of skylights, and orientation. The dependent variables are: daylight factor, daylight factor uniformity ratio, daylight autonomy, daylight availability and daylight glare probability, heating demand, electricity demand for lighting and overheating time. The results show that skylights can significantly improve the daylight conditions in a classroom in terms of daylight levels and uniformity as well as daylight autonomy while visual discomfort problems can be easily avoided through the use of proper shading devices. The study also shows that the electricity demand for lighting can be significantly reduced while the heating demand is generally increased with the integration of skylights. The results further show that the primary energy can actually be reduced if skylights are placed properly, due to the fact that the electricity use reduction weighs more in the total energy balance when calculating primary energy factors.