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UK Heatwaves: Buildings Under Threat, New Measures on the Way

The UK's rapidly warming climate is posing a growing risk to building occupants' health and comfort. In response, CIBSE (Chartered Institution of Building Services Engineers) is taking action to measure building resilience and develop mitigation strategies.

Overheating in Care Homes: A Pressing Concern

At a recent Futurebuild conference, CIBSE held a session on overheating in buildings. A key focus was care homes, where high temperatures can be especially dangerous for residents.

We can help you select the best overheating strategy for your project by undertaking Dynamic Thermal Modelling Assessments. Using whole building simulation programs, Dynamic Simulation Modelling (DSM). Take a look at our services and recent projects.

  • ClimaCare Project Findings: A study by Oxford Brookes University and UCL found widespread and prolonged overheating in nearly 50 UK care homes. Summer 2022 saw peak temperatures exceeding 35°C and median indoor temperatures around 25°C.

  • Occupancy and Impact: Staff reported feeling hot at lower temperatures (28-29°C) compared to residents (32°C). This highlights the need for measures tailored to different sensitivities.

  • Passive vs. Active Cooling: The project explored interventions to reduce overheating. While passive measures may suffice in the 2020s, modeling suggests a need for air conditioning by 2050 to maintain comfort as temperatures rise further.

New CIBSE Weather Files: Planning for Extremes

CIBSE is developing new weather files based on the latest climate data (UKCP18). These files will be released later this year and will consider extreme weather events in their modelling.

  • Increased Overheating Risk: Case studies using these files show a significant rise in future overheating risks, with more frequent and intense heatwaves.

  • Improved Accessibility: CIBSE is also creating a digital tool to enhance access to weather data. This will allow for long-term planning of building energy systems.

TM59 Update: Addressing Overheating in Homes

CIBSE is updating TM59, a dynamic thermal modelling methodology used to comply with building regulations on overheating mitigation (Approved Document O).

  • Focus on Night-Time Temperatures: The proposed update would shift the overheating criteria from exceeding 26°C for 1% of annual hours to exceeding a night-time mean threshold temperature on a specific number of summer nights.

  • Additional Considerations: The update will also consider:

  • A new gain profile for home offices

  • Modeling of ceiling fans

  • Night-time bedroom window opening profiles

  • Allowing modeling of open internal doors (excluding bedroom doors)

The revised TM59 is expected for release this summer and will be updated with the latest weather files. These changes aim to improve overheating mitigation strategies in new homes.

There is a critical need for buildings to adapt to our changing climate. By implementing these new measures, we can ensure the health and comfort of building occupants in the face of rising temperatures.


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