Daylight optimization versus energy consumption for NordicEcolabelling of a residential building

Sammanfattning: This project, in collaboration with The Nordic Swan Ecolabel, deals with optimization of daylighting as well energy usage within a residential building for the purposes of Nordic ecolabelling/certification. One of the main purposes of this study is to understand the fundamentals of daylighting and to explore commonly used methods of daylight optimization and how these affect the energy consumption of the building. The other purpose of this study entails a comprehensive study of the evolution of daylight regulations within the Swedish building standard.In order to achieve the above intended aims of the project, a literature review was done on the fundamentals of daylighting as well as a review of the Swedish building standard. In order to evaluate the daylight optimization methods and how they affect energy usage, a mathematical model of a residential building was used within IDA ICE software. The simulated model was built based on certain requirements by the Nordic Swan Ecolabel.Due to time limitations, the study was focused on simulation of metric of daylight factor, and this limited the scope of the study. More realistic simulations with regards to control signals for internal shading were not possible within IDA ICE software. Therefore, simulations were done for only two extremes, that is, always drawn window blinds and never drawn.The window size, presence, and type of internal blinds as well as light transmittance affected both the average daylight factor as well energy consumption the most. The use of large windows with venetian blinds and light transmittance of 0.71 were the best alternatives for both average daylight factor and energy use. Increase in window size increased both the average daylight factor as well as the operational energy used within the building.