Passivhaus Affiliate

Sweltering summers? No Sweat!

Are you basking in the summer heatwave? The soaring mercury makes it more pertinent than ever that we need buildings which do not guzzle energy to keep us warm in winter or stay cool in summer. Recently, overheating buildings is a growing concern in the UK, exacerbating health risks to the elderly & vulnerable and potentially increasing the strain on the NHS. The Environmental Audit Committee warns of 7,000 heat-related deaths every year in the UK by 2050.

A simulation of maximum temperatures on 21 July. Photograph: Climate Reanalyzer/Climate Change Institute/University of Maine

Delivering summer comfort can be a challenge in the UK because, whilst there is always a heating system to control winter temperatures, there is no source of active cooling available in the summer. Other European countries with typically hotter summers than the UK manage to maintain comfortable temperatures in their low-energy buildings without active cooling, so it follows that active cooling should not be required in the UK. 

Typically, in warm-hot climates, buildings have always had to be designed to cope with hot summer temperatures and the building’s occupants have learned how to keep a building cool using shading and night ventilation. Where this is not possible (e.g. in noisy environments) cooling may be specified.

John Talyor TweetNicola Albert Tweet

Although a warming climate is sometimes blamed for the increase in overheating, the real issue is the change in our building specifications. The insulation we use to keep us warm in winter also retains heat from the sun and internal gains in summer. If this heat gain is not removed, we become uncomfortable. Also, high performance glazing allows us to install more glass in our buildings without winter discomfort or high heating bills. However, the increased glazing could raise the risk of overheating. It is therefore very important to consider both winter and summer comfort levels when designing buildings. 

Whilst it is well documented that Passivhaus buildings deliver excellent winter comfort in the coldest of climates, the Standard also includes targets for summer comfort (including humidity) and the Passivhaus design software (PHPP) provides increasingly powerful tools to consider this. For further design advice on summer comfort please download our Good Practice Guide and read our How to build a Passivhaus: Rules of thumb guidance.

Juraj Mikurcik tweet

How is your building coping? Hear the latest exemplar Passivhaus case studies discuss effective solutions to ensure summer comfort at the 2018 UK Passivhaus Awards Ceremony on the 24th October in London. Tickets are free, registration essential, so join us for an informative afternoon.

2018 UK Passivhaus Awards Ceremony at London Build - 24th October


Further Information

PHT Good practice guide on designing for summer comfort

The hidden problem of overheating: Committee on Climate Change – 8 August 2018

UK ‘woefully unprepared’ for deadly heatwaves, warn MPs: The Guardian -  26 July 2018

The impact of the heatwave on our daily lives at home: 19 July 2018

Passivhaus Overheating: Design it out: Elrond Burrell – 11 August 2016

7th August 2018

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