An investigation into future performance and overheating risks in Passivhaus dwellings: Fid-Bau Portal

An investigation into future performance and overheating risks in Passivhaus dwellings

McLeod, Robert S. / Hopfe, Christina J. / Kwan, Alan

Abstract In response to UK government policy mandating the construction of ‘zero carbon’ homes by 2016 there have been significant changes in the way dwellings are being designed and built. Recent years have seen a rapid uptake in the adoption of the German Passivhaus standard as a template for ultra-low energy and zero carbon buildings in the UK. Despite genuine motivations to mitigate climate change and fuel poverty there is a lack of research investigating the long-term performance of Passivhaus buildings in a rapidly changing UK climate. This paper sets out to investigate whether Passivhaus dwellings will be able to provide high standards of thermal comfort in the future or whether they are inherently vulnerable to overheating risks. Scenario modelling using probabilistic data derived from the UKCP09 weather generator (WG) in conjunction with dynamic simulation and global sensitivity analysis techniques are used to assess the future performance of a range of typical Passivhaus dwellings relative to an identical Fabric Energy Efficiency Standard (FEES) compliant dwelling over its notional future lifespan. The emphasis of this study is to understand what impact climate change will pose to overheating risks for Passivhaus dwellings relative to the de facto (i.e. FEES) alternative, and which design factors play a dominant role in contributing to this risk. The results show that optimization of a small number of design inputs, including glazing ratios and external shading devices, can play a significant role in mitigating future overheating risks.

Highlights • Passivhaus dwellings optimized for heating demand may be at risk of overheating. • Future performance of Passivhaus dwellings are compared to a FEES dwelling. • Limitations of existing overheating parameters are discussed. • Enhanced Morris sensitivity analysis is used to rank influential design factors. • The method used is efficient and could improve whole life design optimization.