Thermal Mass: A Vital Feature For Tackling Overheating In New Housing

30 Nov 2018

The government has pledged an extra £500 million to the Housing Infrastructure Fund (HIF) in the recent budget, claiming that the extra cash will unlock 'up to 650,000 new homes'. The Concrete Centre is calling for joined up thinking on how this is invested in order to ensure that construction quality and long term performance are central criteria for securing funding.

Government is keen to stimulate the housing market and regularly refers to the target of 300k new homes per year by 2025, but less has been made of the duty that Government and designers have to ensure that we build quality homes and are not creating problems for occupants both now and in the future.    

Tom De Saulles, building physicist at The Concrete Centre, has examined the government’s recent response to the Environment Audit Committee (EAC) report Heatwaves: adapting to climate change  (HC 826) that highlights the importance of tackling overheating and welcomes the promise of MHCLG’s research into overheating in new homes. But he also points out that many reputable studies are already available to assist designers (see listing).

De Saulles adds, “the EAC report was very timely during the hottest summer on record in England and their recommendation was clear “the Government should stop directing financial support to modular housing from its Home Building Fund”.  This recognises that modular housing is typically of lightweight construction and therefore has limited thermal mass. Together with natural ventilation and shading, utilisation of thermal mass is a recognised design strategy for minimising overheating”.  

The Government response published on October 25th reiterates the audit committee’s concerns relating to the risk of overheating on health and productivity, it accepted recommendations such as: “The Department of Health and Social Care should provide guidance to the Care Quality Commission on how to inspect for overheating risk and ensure that overheating risk forms part of its inspection for safety and suitability of health and social care premises.”   

The Government response also reported recent MHCLG research that “investigated the impacts of overheating in new homes on mortality and a loss of productivity due to sleep disruption.”  And that “this research will assist the Government in addressing the issues on overheating raised by the Committee in its forthcoming review of the energy efficiency standards in Building Regulations”.

It is reassuring that we finally seem to be making progress in addressing overheating.  Thermal mass is a key benefit of concrete and masonry, so it is not surprising that it, and hence overheating, has formed a part of The Concrete Centre’s work for some time.  In 2005, we appointed Arup to study the performance of different house types over a 100-year study period to explore the whole-life carbon performance of housing. 

It demonstrated that there is little difference in the embodied impact of a typical timber frame and masonry home (a finding confirmed later by the NHBC Foundation) and that the small difference can be offset by operational savings in just 11 years; a fraction of the building’s lifespan.    

We are confident that the MHCLG research will conclude that thermal mass has an important role to play in minimising risk of overheating and we hope this will inform upcoming revisions to Part L of the Building Regulations in 2019.


Notes to Editor:

Operational and Embodied Carbon in New Build Housing: A Reappraisal”, NHBC Foundation, 2011
Embodied and operational carbon dioxide emissions from housing: A case study on the effects of thermal mass and climate change, JN Hacker et al, Energy and Buildings, 2008 - Elsevier

Independent research on Overheating
There has been extensive work by many organisations to determine how to address overheating and included within this work is the positive role of thermal mass

  • CIBSE TM60: Good practice in the design of homes, 2018
  • The London Plan – cooling hierarchy, 2016
  • Zero Carbon Hub: Overheating in Homes – The Big Picture, 2015
  • Zero Carbon Hub: Solutions to Overheating in Homes, 2016
  • Building Research Establishment - Overheating in dwellings – guidance document, 2016
  • Good Homes Alliance: Preventing overheating, 2014
  • NHBC Foundation: Understanding overheating – where to start, 2012
  • Technology Strategy Board: Design for future climate, 2008
  • Energy Savings Trust – energy efficiency best practice in housing – reducing overheating a designer’s guide, 2005
  • Faber Maunsell: Control of overheating in future housing – design guidance for low energy strategies, 2003

The Concrete Centre:
The Concrete Centre provides material, design and construction guidance. Our aim is to enable all those involved in the design, use and performance of concrete to realise the potential of the material. The Concrete Centre provides published guidance, seminars, courses, online resources and industry research to the design community.

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The Concrete Centre is part of the Mineral Products Association, the trade association for the aggregates, asphalt, cement, concrete, dimension stone, lime, mortar and silica sand industries. It covers 100% cement production, 90% of aggregates production, 95% of asphalt and over 70% of ready-mixed concrete production and precast concrete production.

Each year the industry supplies £20billion worth of materials and services to the Economy and is the largest supplier to the construction industry, which has annual output valued at £144billion. Industry production represents the largest materials flow in the UK economy and is also one of the largest manufacturing sectors.

Issued by:
Kim Hawksworth, 0207 963 8026