Cooling Demand and Daylight in Commercial Buildings - The Influence of Window Design

An increased window share in general results in an increased use of energy and costs for cooling, but these disadvantages can be reduced with a more careful design. The aim of this paper is to show the influence of window design and room layout on cooling demand and daylight availability in office buildings in Northern Europe. The results in the paper are based on design calculations for two different room types and daylight measurements on two room scale models in a daylight laboratory. Calculations show the influence of window design parameters on the cooling demand. The daylight measurements show the influence of window design parameters on the availability for daylight. The results have then been combined to show feasible window design regarding daylight availability and resulting cooling demand for different window orientations. The results show that, in most cases, it is possible to find a combination of window share and window solar factor that is feasible from daylight as well as cooling point of view. The main finding is that there is a smaller or wider range of feasible design for different window orientations. Here, the product of window share and solar factor is introduced as a guideline to find feasible designs.