We’re designing buildings for the climate we had, not the climate we’re going to live in
The UK has just experienced another series of summer heatwaves. Schools have closed classrooms, offices have become uncomfortable, hospitals have implemented heat plans and thousands of buildings have struggled to maintain acceptable indoor temperatures.
Yet our national conversation about building decarbonisation remains almost entirely focused on one subject: heating.
Heating is only half the equation
Over the past two decades, the construction industry has transformed the way buildings
retain heat. Better insulation, improved airtightness, higher-performance glazing and low-carbon heating technologies are all helping to reduce winter energy demand. This progress should be celebrated.
However, in solving yesterday’s problem, we risk creating tomorrow’s.
Today’s highly insulated, airtight buildings are increasingly susceptible to overheating. Internal gains from occupants, lighting, IT equipment and solar radiation are becoming more difficult to remove, while hotter summers mean conventional cooling systems are working harder than ever.
Cooling demand is no longer confined to prestige offices in London; it is becoming an essential design consideration for schools, hospitals, residential developments, laboratories, manufacturing facilities and commercial buildings across the UK. The uncomfortable truth is that we are designing buildings for the climate we had, not the climate we’re going to live in.
Every building completed today is likely to remain in service well beyond 2080. It should therefore be designed for the environmental conditions it will experience throughout its lifetime, not simply against historical weather data. Building Regulations, design standards and planning policy must evolve accordingly. The time to do that is now.
Government policy has rightly invested billions in decarbonising heat through initiatives such as the Green Heat Network Fund and the wider transition away from fossil fuel heating. These programmes represent significant progress towards net zero.
But they address only one side of the thermal equation.
Buildings require energy for both heating and cooling. Physics does not distinguish between the two, and neither should our long-term energy strategy.
Perhaps the most overlooked consequence of rising cooling demand is its impact on the electricity network. Heatwaves create significant daytime electrical peaks as air conditioning systems operate simultaneously across offices, retail, healthcare, manufacturing and residential buildings. These peaks drive network reinforcement, increase infrastructure costs and ultimately determine the capacity required to support an increasingly electrified economy.
The electricity grid is not constrained by average demand. It is constrained by peak demand. Reducing cooling loads therefore becomes just as important as improving heating efficiency.
Conventional air conditioning rejects unwanted heat into the outside air. Unfortunately, the hotter the air becomes, the harder these systems have to work. It is an inherently inefficient approach, asking equipment to reject heat into an environment that is already hot.
The solution beneath our feet
There is, however, an alternative that has existed beneath our feet all along.
Just a few metres below ground level, temperatures remain remarkably stable throughout the year, typically around 12C–15C across much of the UK. Instead of rejecting heat into 30C or 35C summer air, ground source systems reject heat into this naturally cooler environment.
The thermodynamic advantage is significant. Using the ground as a heat sink can reduce the electrical energy required for cooling by around half compared with conventional air-cooled systems, with a corresponding reduction in operational carbon emissions as the electricity grid continues its journey towards decarbonisation.
In many buildings, the opportunity goes even further.
Where cooling loads are modest, the ground can often provide passive cooling. Rather than operating refrigeration compressors, cool water is simply circulated through the building using the naturally low ground temperature. Only circulation pumps consume electricity, providing exceptionally low-energy cooling while improving occupant comfort and reducing strain on the electricity network during periods of highest demand.
Even more importantly, the heat extracted from buildings during summer is not wasted. It is stored within the ground, becoming a valuable thermal resource for the following winter. Heating and cooling cease to be independent systems and instead become part of a continuous annual energy cycle. The building effectively recharges the ground during summer before recovering that energy months later.
This is not simply efficient engineering; it is intelligent thermal infrastructure.
“Yet our national conversation about building decarbonisation remains almost entirely focused on one subject: heating.”
Perhaps it is time we stopped thinking purely about heat pumps and started thinking about thermal assets. Every development excavates the ground. Every foundation transfers structural loads into the earth. Yet once construction is complete, we largely ignore one of the largest renewable thermal resources available on the site.
Whether through boreholes, energy foundations, diaphragm walls or ambient ground loops, the opportunity exists to transform the ground beneath our buildings into long-term renewable energy infrastructure capable of providing highly efficient heating and cooling for generations.
The construction industry has become exceptionally good at keeping heat inside
buildings.
The next challenge is becoming equally good at removing unwanted heat.
A new phase for net zero
History may well look back at this period and wonder why we spent billions improving winter heating performance while giving comparatively little attention to summer overheating. Future generations may conclude that designing a new building without considering the thermal potential of the ground was as short-sighted as constructing one without insulation.
The UK’s journey towards net zero is entering a new phase. Decarbonising heating remains essential but it is no longer sufficient on its own.
Heating and cooling are simply opposite sides of the same thermal equation.
If we continue designing buildings for yesterday’s climate, we will continue solving only half the problem. By embracing the renewable energy resource beneath every development, we have the opportunity to create buildings that are not only lower carbon but also more resilient, more comfortable and better prepared for the climate of the future.
The solution has been beneath our feet all along.
The post Britain has a cooling crisis. We’re still talking about heating appeared first on Planning, Building & Construction Today.
