During 2017, I had wanted to test the robustness of the Passive House modelling software on my own house. From January until December, I set the thermostat to 20 degrees and monitored actual internal and external air temperatures. The results from PHPP modelling had predicted I would use 6,267 kWh for space heating and hot water (based on adjusting the climate data to reflect actual temperatures in 2017, as well as reducing internal temperature to 19 degrees in the model, which was the actual measured internal temperature).
The result? So my actual gas usage ended up being 5,622 kWh, which indicates that PHPP estimates on the conservative side of things – but still, it’s only 10% out. So in my books, PHPP is a great tool for robust energy analysis prior to retrofit!