Warm sticky nights are becoming more and more common in the UK.
Climate change is raising temperatures, but one factor that adds to that is often ignored. Walk down a city street and you see what would have been front gardens a decade or so ago have now been tarmacked over and turned into driveways.
Individually these changes might seem small, but as more and more gardens disappear this increase in hard driveways can alter the way neighbourhoods heat up during the day and cool down at night. It’s an issue that is suddenly on more people’s minds this summer as they struggle to sleep.
According to a UK’s Royal Horticultural Society (RHS) report in 2025, 42% of domestic garden space is now paved over, including 55% of front garden space.
In 2005, only about 8% of UK front gardens were fully paved. By 2015, that figure had tripled to roughly 24%.
Estimates from the RHS suggest there are 20.6 million domestic gardens (front and back) in the UK, covering around 502,757 hectares. The UK’s domestic gardens together cover an area around three times larger than all national nature reserves combined, giving them enormous potential to support wildlife.
Replacing vegetation with hard surfaces also shrinks habitat for plants and wildlife while increasing surface runoff and the risk of flooding.
The desire for more off-street parking may have contributed to this trend. The shift to electric vehicles could have created another incentive to pave front gardens, as goverment grants helped households finance home-charging points.
How paving stokes heat
Impervious surfaces including asphalt (which many driveways are made of) absorbs heat, raising ground and air temperatures. They both absorb up to 95% of incoming solar radiation during the day, reaching surface temperatures of 50-55°C, compared to 27-32°C for grass or tree-covered areas.
During the day, this heat is stored and slowly released after sunset. This is known as the urban heat island effect. The result is warmer night-time air temperatures, particularly during heatwaves. Unlike vegetation, these hard materials have little capacity to cool themselves through evaporation, and are making cities hotter.
This heat island effect can raise cities’ temperatures by 1-3°C compared to surrounding countryside. That’s why it always feels hotter in the city on summer nights.
Read more: Heatwaves: how to close the UK’s cooling divide
And the result can also cause health problems. The 2018 summer heatwave saw an estimated 399 (of 785) heat-related deaths in the Greater London area attributable to this night-time effect.
Paved front gardens eliminate evaporative cooling (the process by which plants release water vapour), which lowers air temperatures. Plants and trees provide cooling through shading and evapotranspiration (defined as the combined loss of water to the atmosphere through two processes: evaporation and transpiration). In urban environments, green spaces release moisture into the air, which humidifies the atmosphere and significantly reduces air temperature, a mechanism entirely absent in paved areas.
What needs to change?
Changing front driveways back to grass can reduce daytime surface temperatures by 1.5-2.0°C and nighttime temperatures by 0.3-0.5°C. Adding trees doubles the benefit: daytime cooling of 2.0-3.0°C and nighttime reductions of 0.5-1.0°C. Therefore, increasing urban greenery by 10% – particularly planting trees – can lower average air temperatures by around 0.5°C.
Front gardens with plants rather than driveways can also reduce flood risk by absorbing rain, filter air pollutants, support biodiversity and improve mental wellbeing. The RHS estimates that restoring plant cover in one million front gardens could save millions of litres of stormwater run-off annually.
But there are ways to have a driveway that doesn’t create so much heat. London’s De-pave Your Garden campaign offers guidance on replacing concrete with permeable paving, gravel or planting strips, an approach that has since been promoted by London boroughs including Lambeth and Ealing.
Leeds City Council’s front garden design guide encourages householders to retain at least 30% green space.
Other things could help change people’s attitudes to front gardens and their value. Financial incentives, such as council tax rebates for depaving or grants for rain gardens, could accelerate change.
In the future, public policy must recognise private gardens as green infrastructure, not merely private amenities. Updating planning permission rules to encourage a mix of plants and gravel, for instance, would help.
The United Nations identifies urban greenery as a key way to reduce heat in cities. The benefits extend beyond gardens: green roofs and balcony gardens can lower indoor temperatures by up to 11°C.
No single garden will transform a city’s climate, but when thousands of gardens are protected and restored across neighbourhoods, the combined cooling effect would become significant.
As climate projections show more frequent, longer and hotter summers, every square metre of restored vegetation matters. Domestic gardens are frontline defences against intensifying heatwaves.
By not opting for a tarmacked driveway or replanting the existing one, households can help cool their streets, protect vulnerable neighbours and reclaim a piece of Britain’s vanishing green heritage.
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