An industry case study using parametric modelling to facilitate Passive House design

A Passive House’s airtight, well-insulated building envelope can lower operating energy use but also increase the possibility of overheating during the summer. The Passive House Planning Package (PHPP) Excel modelling tool for Passive Houses treats the entire structure as a single thermal zone; this simplification may be in part to blame for the instrument’s poor capacity to forecast the risk of overheating. The current study offers new information on two subjects. First, we compare PHPP’s overheating evaluation method to that of the Chartered Institution of Building Services Engineers’ (CIBSE) ‘TM59’ standard, which involves conducting dynamic energy modelling at the room level. Our results support the idea that PHPP underestimates overheating. In the analysed case, glazing solar heat gain coefficient, and air change rate were some of the most crucial factors affecting compliance. Second, we highlight the usefulness of parametric design for compliance.