Jul 31, 2020

Overheating risk

A few months ago Inside Housing magazine asked us to comment on overheating risk. Here’s what we wrote:

As if Covid-19 isn’t enough, summer is fast approaching and extreme weather events are high on national and international risk registers.  Met Office central projections estimate an average 2oC increase in summer temperatures.  Sounds nice, but it includes heat waves. And remember these are central projections which assume we reduce our carbon emissions enough and the worst effects of climate change do not materialise.

Extreme heat waves cause immense discomfort and lead to excess summer deaths.  So, it’s worth remembering that the Decent Homes standard requires “thermal comfort”.  Although this is widely interpreted as providing winter warmth, I wonder how long it will be before an eagle-eyed lawyer will raise disrepair claims because homes are too hot?

We have been helping social landlords on environmental reporting and strategy building for over 12 years using our SHIFT scheme.  During this time we have found that there are no adequate tools to help landlords identify which homes are at risk.  We ended up devising a simple tool that landlords can use as part of their SHIFT assessment.

We would, however, like to see a national approach, so that landlords are carrying out the risk assessment and doing something about it.  Furthermore, any national approach should incorporate the main risk factors and be cost effective to use.

The methodology for building regulations is demonstrably inadequate.  It has been in place since 2006 and many homes built since then overheat.  The methodology uses historical, cooler, summer temperatures, not projected hotter ones.  Communal heating service pipes are also not taken into account even though they leak heat into homes.  Lastly, the methodology is only used for new build homes, not existing homes.  These are relatively simple fixes that would help landlords improve their stock.

There are a few very detailed simulation models available, but they tend to be costly and not really suitable for mass assessment of existing homes.  They tend to be used mostly in new build care homes where the costs can be absorbed and vulnerable people will be living.

New tools and technologies are emerging, but as far as we’re aware, there is nothing (apart from ours!) that incorporates all risk factors, future projections and is cost effective for landlords.

Even if a national tool emerged and landlords found out which homes are at risk, what should they do?  For new build, the answer is to include passive cooling measures during design stage and ensure they are implemented.  Ensuring adequate ventilation, external shading and green spaces are reasonable interventions at this stage.  There is also evidence that some of this will save money.  For example, communal heating systems are often oversized (hence more expensive) and as a result have larger service pipes running around the corridors.

For existing homes, the story will be different and some kind of retrofit solution will be needed.  And it may be hard to convince finance directors that money is worth spending on preventing overheating because it is hard to demonstrate the counterfactual.  However, we suggest steps that landlords can take that will help.

It may be worth cross checking the list of high risk homes with homes that have condensation problems.  Retrofitting adequate ventilation will help with both issues and save potential disrepair claims where damp and mould exist.

Boosting existing green spaces with more trees will help and is relatively easy to do.  Although the summer cooling effect will only be small, natural habitat will be improved and fit into other environmental policies which are creeping up government agenda, such as biodiversity offsetting.  Plus, it will be a nicer place for residents to live, help with local air quality and provide extra flood attenuation (another climate change risk!).

Landlords may also consider investigating responsive actions.  Ideally, fitting external shading for some properties will give maintenance teams experience of doing so, in readiness for heat waves that occur.  This saves a huge learning curve during a heat wave.  A source of plug-in fans that residents could use would be a second best option.

As this is a comment piece, I’d like to take this opportunity to say what I’d do, if I was in charge.  Firstly, I’d upgrade the current building regulation methodology to include the missing risk factors.  Second, I’d carry out a short research project to calibrate the methodology against more detailed modelling methods and actual overheating homes.  Once this is established for a range of archetypes, I’d release into building regulations.  Then I’d ensure that the methodology was incorporated into existing homes EPC calculations.  Finally, I’d require all landlords to report the number of homes at low risk of overheating as part of an annual environmental performance report.

A fairly straightforward plan which will make our homes and environment much more sustainable.

If you would like to carry on overheating risk assessment for your stock, please get in touch to discuss: [email protected]



* indicates required