Passivhaus Affiliate

Technical Guidance - Keeping Cool: Avoiding overheating risks

Category: Guidance

Avoiding Summer Overheating

MVHR Maintenance - Good Practice Guide
Published: May 2021

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 tests to demonstrate robustness.

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PHT Summer Plugin for PHPP

PHT Summer plugin

The PHT Summer plugin for PHPP provides summary guidance on design strategies, an interactive analysis of risks, limitations and constraints, a dynamic generator of key indicators of overheating risk pulled from your PHPP data, and also (PHPP 9 version only) a series of stress tests that apply to all users.

The plugin is available free to download for both PHPP 9 and for PHPP 10. In PHPP 10.x, the stress testing element of the plugin has been incorporated into core PHPP, so that has been removed from the PHPP 10 version of the plugin.

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Summer Comfort Statement for Passivhaus Certification

Summer Comfort Statement for Passivhaus Certification

To ensure summer comfort, Passivhaus certification requires written documentation of the strategy for thermal comfort in summer, signed by the building owner. This should be issued to the building certifier as part of the certification documentation, alongside the relevant section of the handbook for the building user.

The sample Summer Comfort Statement provided here has been put together by the Passivhaus Trust and the UK Certifiers Circle to be used as a template for this purpose. The statement identifies the critical assumptions that underpin the design, and the summer comfort strategy, as well as overheating risk results and stress testing.

This template can also be used for buildings with active cooling, presenting the expected results for active cooling instead of overheating risks.

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You may also like

MVHR for single dwellings
  Passivhaus for Social Housing
  How to build a Passivhaus: Good practice guide

 

 

PHT Patron Member logo whiteThanks to our Patron members

We are grateful to our Patron members, whose ongoing support has
funded this publication.

 

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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