Deliberately defining overheating – Part two

October 29, 2015

This blog piece is part of a series by Sustainable Homes and the Zero Carbon Hub.  We will explore some of the policies and solutions being developed to address overheating in homes.  In part one of this article we outlined the various definitions of overheating. In this second part we examine the approaches taken by housing providers to define and tackle overheating in homes.

What definitions are being used by Housing Providers?

A survey of 75 housing providers carried out by Sustainable Homes and the Zero Carbon Hub in November 2014, suggested that, as would be expected, Housing Providers are using different definitions of overheating within their organisations.

Respondents were asked “How does your organisation define ‘overheating’ in residential properties?”

Approximately two thirds of the 75 organisations who provided information defined overheating in general terms, and these definitions related to the “thermal comfort” of occupants rather than health-related definitions.

For example, one organisation said overheating is “A condition found in a domestic property whereby the indoor temperature is too high and cannot be controlled, to provide comfort to the occupants.”

Eight organisations referenced SAP Appendix P as the basis for their definition. The remainder said they defined overheating using quantified criteria including CIBSE’s Guide A Environment Design (2006) or criteria developed specifically for Passivhaus designs.

Going forward

The question is whether an agreed definition or “standard” is needed and what form it would take?

A number of recent reports highlighted some of the consequences that the lack of an official definition can have. For instance, the Zero Carbon Hub’s June 2015 report “Overheating in Homes – The Big Picture” shared industry concerns that:

  • Housing associations and housebuilders lack clarity on what reasonable steps they must take and rules they should apply to safeguard their current and future occupants from overheating; and
  • Professionals tasked with assessing the risk of a property overheating may choose differing criteria to judge the performance of buildings, limiting comparison between them and generating anxiety about what the ‘right’ test to apply is.

If the goal is deliver high quality, energy efficient homes which are thermally comfortable in winter and in summer, then agreeing what we are aiming for is probably a useful thing. However, we must also be certain that any future requirements are very carefully developed to avoid creating unintended consequences. Protecting the health of potentially vulnerable occupants must also be a consideration.

Thankfully, research done to date provides a solid foundation for agreeing a sensible and pragmatic way forward, and the Zero Carbon Hub intends to bring together a group in the coming months to coordinate thinking on next steps.

In the meantime, it is worth thinking about the different ways of measuring and assessing overheating and deciding which are most relevant for your organisation. Which allows you to feel confident that you are genuinely taking reasonable steps to limit the risk of overheating in your stock? What are the common sense design solutions you can adopt now to help prevent homes overheating?

To see the Zero Carbon Hub’s Big Picture report go to http://www.zerocarbonhub.org/recent-publications

Read part one of our blog here.

 

Daniel Navarro