Passivhaus Affiliate

Feeling the heat?

Today the UK temperatures have topped 40C. A recent Guardian article says that experts warn the UK’s housing stock must be resilient to rising heat levels, with retrofitting of older properties also needed. The health implications of summer overheating in our homes are significant. It is estimated that there are currently around 2000 heat-related deaths in the UK every year. The BBC reported that this could triple by 2050.

2022.07.19 EU heat map

Energy-efficient Passivhaus buildings use high-performance components and contain lots of insulation which helps maintain stable temperatures & comfort levels all year round.

Three of the main issues contributing to overheating in new homes are:

  1. Inadequate ventilation
  2. Unshaded glazing
  3. Heat loss from building services such as hot water systems.

The Passivhaus design software, PHPP, includes checks to limit all three of these factors to help reduce overheating risk. All certified Passivhaus schemes must meet summer comfort criteria – which include modelling and assessing heat gains from occupants & appliances, and a dedicated shading & ventilation strategy. Different facades of a Passivhaus building are optimised, carefully assessing where windows are placed, what size, and how they are shaded (windows are where large heat gains in summer or heat losses in winter can occur.) New stress tests have also been introduced over the last few years to ensure that Passivhaus buildings are resilient to higher occupancy levels and that ventilation strategies are workable, for example in areas where noise and security might make night-time cooling more difficult.

When outside temperatures are higher than inside temperatures, it’s difficult to cool a building down. A Passivhaus should let in less heat during a heatwave, because of the insulation and shading, so should stay cooler for longer, which should help keep occupants comfortable until night-time temperatures return to a lower level. We’re just starting to get some evidence as to how Passivhaus buildings cope in these extreme conditions as some people are sharing their buildings performance on social media:

Discover more in our free resources:

Keeping cool: avoiding overheating risks Passivhaus Benefits Guide Retrofit Masterclass lecture series: on-demand


Further Information  

Passivhaus Benefits Guide

Keeping Cool: avoiding overheating.

Passivhaus Retrofit

BBC: Climate change: Heat deaths could triple by 2050 - 18 July 2022

The Guardian: ‘A lot of challenges’: can housing industry build homes habitable in high temperatures? - 19 July 2022

19th July 2022

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