Extreme heat added an estimated £213,617 to the average property developer’s project costs during the UK’s record-breaking summer, new research reveals.
Shawbrook asked 500 professional property developers to estimate how much the hot weather had cost their businesses across development projects, with cooling requirements, falling productivity and construction delays all taking their toll.
More than half (52%) report higher expenditure on temporary cooling measures including HVAC systems, while 51% experienced lower productivity.
Half encountered technical delays involving building materials and 49% had to temporarily stop work on at least one project. Just 2% report experiencing no negative impact from the hot weather.
DEVELOPMENT DELAYS
The findings suggest developers are already changing how they plan future projects in response to the impact of extreme temperatures.
Some 43% intend to allow more time for projects to be completed, while the same proportion plan to introduce additional health and safety protocols to protect workers during heatwaves.
A further 38% plan to avoid certain building phases during peak summer months, while 37% intend to modify site designs to improve natural ventilation and shading.
Terry Woodley (main picture), Managing Director of Development Finance at Shawbrook, says: “This was an exceptional summer, but an estimated average additional cost of more than £200,000 shows the practical impact prolonged hot weather can have on development projects – affecting day-to-day work, timelines and budgets.
“The bigger picture is housing supply. When projects pause and completion dates slip, that’s homes arriving later in a country that needs more of them.”
CLIMATE RESILIENCE
Developers are also considering how climate risks should be incorporated into the design and cost of future schemes.
Two in five – 41% – plan to invest in climate-resilient building materials or technologies, while 36% expect to increase the proportion of their budgets allocated to climate-proofing.
More than half – 52% – say installing air conditioning or cooling systems will be a priority during the next 12 months.
Other measures include sustainable drainage systems, cited by 47%, water management policies at 46%, making developments compatible with electric vehicles at 41% and solar power at 36%.
PROJECT RISK
Woodley says developers increasingly need to treat extreme heat in the same way as other risks affecting project costs and delivery.
He adds: “The developers adapting fastest are treating heat like any other project risk – pricing it into contingencies, phasing the heaviest work away from peak summer and building resilience in from the design stage.
“And where costs or timelines do move, the earlier that conversation happens with a lender, the more options stay on the table.”
The research was conducted among 500 professional property developers between 14 and 25 August 2026. Respondents were defined as people who develop property as a business or occupation rather than those undertaking occasional or personal development projects.
