Passivhaus Affiliate

Technical Guidance - Keeping Cool: Avoiding overheating risks

Category: Guidance

Technical Guidance - Avoiding summer overheating

Recent summer heatwaves have made us more aware than ever that the risk of overheating in both new and existing buildings demands attention - and is likely to become even more of a concern as our climate warms.

As a comfort driven approach, the Passivhaus standard includes a summer overheating criterion which requires that internal temperatures do not exceed 25ºC for more than 10% of the year. However, as with all models, the assessment is highly dependent on the assumptions that are made during the modelling process. We need to ensure that the result remains robust when those assumptions vary, for example as occupant behaviour changes, or as the climate warms.

To meet this need, the Passivhaus Trust has developed detailed guidance accompanied by a PHPP plugin covering design strategies to reduce risk, limitations and constraints that may have an impact, key indicators of the likelihood of risk, and a series of stress test to demonstrate robustness.

The stress testing element of the Trust's overheating PHPP plug-in has been integrated into the new iteration of PHPP10. If you are a PHPP9 user, the stress testing feature is still included in our freely available plug-inOther features of our plug-in including the detailed risk log and overheating heating key indicators designed for use with PHPP9, can now be run with PHPP10, by downloading our free PHPP10 compatible plug-in. Our detailed guidance, covers design strategies to reduce risk, key indicators of the likelihood of risk, and a series of stress tests that apply to all users.


Avoiding summer overheating [PDF]                 

Download (high quality print version)





 Overheating PHPP plugin  

Download PHPP plugin



Further information

Keeping Cool: avoiding overheating risks - On demand short-course

Previous PHT story: Sweltering summers? No Sweat! - 07 August 2018

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