Social landlords should be estimating the risk of overheating in their stock now, to prepare for heatwaves to come, says Richard Lupo
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 two-degree increase in summer temperatures by 2050 and possibly three or four degrees by the end of the century.
Sounds nice, but that includes heatwaves. And remember that these are central projections that assume we reduce our carbon emissions enough and the worst effects of climate change do not materialise.
“The methodology included in building regulations is demonstrably inadequate. It has been in place since 2006, and many homes built since then overheat”
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 more than 12 years using our SHIFT scheme, which measures the sustainability of social landlords. 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 assessments.
We would, however, like to see a national approach, with all landlords carrying out a 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 included in building regulations is demonstrably inadequate. It has been in place since 2006, and many homes built since then overheat. This 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 used only for new build homes, not existing homes.
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.
For each home we take build date, build form and heating type from asset management systems. We also use postcode information to decide whether flats are single aspect, in a hot region and in an urban heat island.
We’ve calibrated the number of risk factors per home against the likelihood of homes overheating using a corrected version of building regulation methodology.
“Boosting existing green spaces with more trees will help and is relatively easy to do”
If landlords do find out which of their homes are at risk of overheating, what should they do next? For new build, the answer is to include passive cooling measures in the design, 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.
However, it may be worth cross-checking the list of homes at high risk of overheating 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 the solution will fit into other environmental policies that are creeping up the government’s 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. Fitting external shading for some properties will give maintenance teams experience of doing so, in readiness for heatwaves that occur. This saves a huge learning curve during a heatwave. A source of plug-in fans that residents could use would be a second-best option.
I’d like to take this opportunity to say what I’d do, if I was in charge. First, 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 update building regulations.
Then I’d ensure that the methodology was incorporated into existing homes’ Energy Performance Certificate calculations. Finally, I’d require all landlords to report the number of homes at low or high risk of overheating as part of an annual environmental performance report.
A fairly straightforward plan that will make our homes and environment much more sustainable.
Richard Lupo, managing director, Suss Housing
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