In this article, Keith Anderson, technical development and regulatory affairs director for Kingspan Insulation Australia explores how adapting the built environment with building insulation can help to tackle the UK’s warming climate
No-one would dispute that the UK is unprepared for extreme heat. As the mercury in thermometers rose last summer, breaking through the 40⁰C barrier for the first time, so did infrastructure failures and admissions to A&E.
Government forecasters have raised the probability of a heatwave this summer to 45 per cent – more than double the usual 20 per cent chance – and this trend is expected to continue in line with rising global temperatures.
How can the built environment support a productive UK population as extreme heat events rise?
I’ve spent my whole career in building and construction, and while I was born in Ireland, I have lived and worked in Australia for almost 40 years.
Here, thermal efficiency – which usually means keeping heat out over much of the year – is central to the work of architects and designers, who work with simple design principles: roof overhang to exclude the high summer sun, and external shading devices along with appropriate levels of insulation.
In the UK, where we get comparatively little hot weather, such solar-control design features would be redundant for the majority of the year and I doubt we will see them being commonly integrated for some time, but it may be time for that to start to change.
Importantly, by designing our homes to keep warm in the cooler weather of the northern hemisphere winter, we also make them better able to keep us at a comfortable, healthy temperature during periods of intense heat.
How can building insulation increase the thermal efficiency of the built environment?
Building insulation might seem like a counterintuitive solution for a heatwave – rather like using your thickest duvet in August – but it is one of the most powerful tools at our disposal.
Put in simple terms: during hot weather, buildings become too hot as walls and ceilings absorb heat from outside and radiate it indoors.
High-performance building insulation is a preventative measure, stopping these internal surfaces from warming up in the first place by stopping heat flow through the fabric of the building.
This is particularly important for walls that are affected by direct sunshine, such as east, west and south facing walls.
Ceilings also need attention, because during a heat wave the direct sunshine on the roof is even more effective at heating up the roof space and subsequently the ceiling.
Even if the ceiling is already insulated but thermally bridged by joists heat from a hot roof space can increase the temperature over much of the ceiling area.
The best way to manage your house in a heatwave
A well-insulated home allows behaviour changes, like opening the windows at night, to be more effective during a heatwave.
The best way to manage a house in a heat wave is ‘night purging’, allowing the house to cool by opening windows once the sun goes down to allow the cooler breeze to circulate through the building.
The internal surfaces of a well-insulated building will quickly adjust to the same temperatures as the cooler night air.
If the night air temperatures remain too high for comfort and safety, then there is no option but to revert to mechanical measures such as fans or air-conditioning – but it is obviously preferable for the planet to keep electricity consumption to a minimum through insulation.
What is the ‘Passive House’ concept?
One idea which has gained traction in Australia, despite actually originating in Europe, is the Passive House concept which takes a ‘fabric first’ approach: if the material of the building is chosen and installed correctly, then comfortable temperatures will follow with much reduced heating and cooling.
As well as appropriate building insulation, houses are designed with no uncontrolled air leakage – so when you shut the door on extreme hot or cold weather, it is truly shut – and having no thermal bridges like steel frames which allow the transfer of heat in and out of a building.
Make no mistake: as a nation, the UK is still woefully under-insulated. The median energy efficiency score in England is 67, or Band D on the EPC, where A-C is considered to be a high standard of energy efficiency.
Government measures to improve efficiency are already in motion to reduce our homes’ carbon consumption – and if these schemes can ensure the elderly and vulnerable, including those in social housing, can be prioritised, then we may be able to alleviate the burden heatwaves place on health services.
Better education needs to be available on how to manage homes in a heatwave
Building insulation isn’t the only measure: the public needs to be better educated on how to manage homes in the heat. I was shocked to hear of friends and family in Britain opening the doors and windows in 40 º C heat last year.
Buildings need to be closed up during the day to keep warm air out, and opened at night to allow the house to cool. A cheap electric fan is then all that is needed to created cooling air circulation.
These measures work best in insulated homes especially as many are heavy weight concrete block or brickwork, so they act as storage heaters and release heat slowly throughout the night.
Moisture and condensation control in buildings
One final consideration: the houses we build today will be affected by climate change in decades to come and the increased likelihood that air-conditioning will be retrofitted, there needs to be a consideration for moisture and condensation control within the building fabric.
Air-conditioned buildings will have cooler than normal internal surface temperatures which increases the potential for condensation to occur behind the internal lining so the type of insulation, use of suitable vapour control layers and sealing of penetrations become an important consideration.
The built environment we have now is the one that we will take into the next decades – in developed economies, eighty per cent of buildings that will be standing in 2050 have already been built – and it is highly likely that we will see significant heat events through the worsening impacts of climate change.
Insulating our homes for hot and cold weather is the right thing to do: for our health, our comfort and for our planet.
