Effects of air infiltration modeling approaches in urban building energy demand forecasts

The air infiltration rate is a highly sensitive variable that influences heating and cooling demand forecasts in urban building energy modeling. This paper analyses the effect of two different simplified modeling techniques of air infiltration - fixed air change rate vs. a model based on wind pressure and air temperatures - on the heating and cooling demand in a district. The urban energy simulation toolbox City Energy Analyst (CEA) is used to simulate a case study in Switzerland, comprising of 24 buildings of various functions. Results indicate that despite the large differences for individual buildings, a fixed infiltration rate model could be sufficient for early design studies of district energy systems, as the impact on the sizing of district energy systems remains relatively low. This comparison will contribute to the continued development of urban energy simulations that are robust, as well as computationally fast.