Are the energy savings of the passive house standard reliable? A review of the as-built thermal and space heating performance of passive house dwellings from 1990 to 2018

摘要

The Passive House (PH) standard is a voluntary quality assurance standard focused upon maximising the health and wellbeing of occupants, whilst reducing space heating demand to a very low level. To meet the PH standard, well-defined criteria have to be met. However, given literature that suggests a 'performance gap' for energy savings, the question remains, how well do PH dwellings perform in situ? This paper presents results from in situ building fabric thermal performance measurements, along with a comparison between the design intent and the measured space heating energy used by over 2000 newly built and retrofitted PH dwellings. The results reveal the in situ thermal performance of the building fabric is close to the design predictions. Within space heating measurements, a standard deviation of up to 50% has to be attributed to the broad spectrum of user behaviour; this is not specific for PH, but a general observation. Despite this, the average values for the PH developments ranged within the uncertainty of the demand calculations. With over 2000 PH dwellings averaging a space heating energy consumption of 14.6 kWh/(m~2a), the in situ performance is close to the original design intent and extraordinary low compared to the consumption in ordinary buildings. The results suggest the PH standard is capable of producing dwellings in a verifiable manner. This means, on average, the in situ thermal performance of the building fabric and the energy consumption for space heating match the design intent, i.e. there is no significant 'performance gap'.