Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Energy demand of cooling system is not always correlated to the U value. For example, in some tropical places most of the year the outdoor temperature is lower than the cooling setpoint. Solar heat gains and internal loads increase internal temperature generating the need to cool down spaces. If you use a lower U value, the heat cannot go to the outside through the window as easy than a window with a higher U value.
I think one of the main purposes of energy simulation is to evaluate different parameters such us envelope, internal loads, shading, orientation, weather etc and how they interact with eachother. low U values usually is good where you have extreme weather conditions or seasons. I have found examples where a high U value can give better results. I hope it helps.
