The UK’s building stock is not ready for the heat. As temperatures climb, a Planning, Building & Construction Today editorial warns that most UK homes and offices are ‘too hot to handle’ during increasingly frequent heatwaves. The problem is a health risk, particularly for older people and those with respiratory conditions, and a financial one too.
Meanwhile, a separate CITB and FMB report reveals a new plan to increase the number of workers trained in retrofit skills. The two stories are connected: without enough competent installers, the millions of homes that need cooling upgrades will not get them.
Why UK homes overheat
Britain’s housing stock was built for a cool, damp climate. Post-war homes with large south-facing windows, poor loft insulation, and no external shading trap heat like greenhouses. The Planning, Building & Construction Today editorial points out that new-build homes, designed to maximise energy efficiency in winter, often have airtight construction and high glazing ratios that make them overheat in summer. The Chartered Institute of Building Services Engineers (CIBSE) already recommends that indoor temperatures should not exceed 26°C for more than 1% of occupied hours, but many homes breach that threshold regularly.
For a typical 3-bed semi in southern England, a week-long heatwave can push internal temperatures above 30°C. Running a portable air conditioning unit for eight hours a day costs around £40 a week on current electricity tariffs. That is not a luxury many households can afford.
The retrofit skills gap
The CITB and FMB report is the first coordinated attempt to map the retrofit workforce needed to meet the UK’s net-zero targets. It proposes a national retrofit skills strategy, including standardised training modules, apprenticeships, and a central register of accredited installers. The Construction Industry Training Board (CITB) estimates that the UK needs an additional 50,000 retrofit-trained workers by 2030. The Federation of Master Builders (FMB) warns that without this, the government’s target of upgrading 19 million homes to EPC C by 2035 is unachievable.
The catch is that most existing retrofit training focuses on heating, heat pumps, insulation, draught-proofing, not cooling. Passive cooling measures such as external blinds, reflective roof coatings, and natural ventilation are rarely covered. The new plan aims to broaden the definition of retrofit to include overheating mitigation.
What it means for your EPC and your bill
Energy Performance Certificates currently do not account for overheating risk. That is expected to change. The government’s proposed EPC reform, due in 2027, will include a ‘comfort’ metric that measures summer indoor temperatures. Homes that overheat could see their EPC score downgraded, which affects saleability and rental compliance under Minimum Energy Efficiency Standards (MEES). Landlords face fines of up to £5,000 for non-compliance.
For homeowners, the immediate financial impact is on cooling costs. A typical 3-bed semi using a portable AC unit for 20 days a year could spend £80–£120 annually. Installing a heat pump that also provides cooling (most modern air-source heat pumps can reverse cycle) costs £7,000–£13,000 after the Boiler Upgrade Scheme grant of £7,500. The payback comes from lower heating bills in winter and avoiding separate AC purchase. The ECO4 scheme also covers insulation and ventilation improvements for low-income households.
What you can do now
You do not need to wait for the skills plan to materialise. Start with passive measures: install external blinds or shutters on south-facing windows, add loft insulation to at least 270mm, and plant deciduous trees that shade the house in summer but let light through in winter. These cost a few hundred to a few thousand pounds and can reduce indoor temperatures by 3–5°C.
Check your EPC rating. If it is D or below, you may qualify for free or subsidised insulation through ECO4. Contact your energy supplier to check eligibility. For heat pump cooling, get quotes from MCS-accredited installers and apply for the Boiler Upgrade Scheme grant before the 2027 deadline. If you are a landlord, prepare for the new overheating metric by commissioning a thermal comfort assessment now.
The CITB and FMB report is a step forward, but it will take years to train the workforce. Your home’s comfort next summer depends on what you do this winter.
Frequently Asked Questions
Currently, no. But the government's proposed EPC reform, expected in 2027, will include a comfort metric that measures summer overheating. Homes that exceed 26°C for more than 1% of occupied hours could be downgraded, affecting saleability and rental compliance under MEES.
The Boiler Upgrade Scheme offers £7,500 towards heat pumps that can also cool. ECO4 provides free insulation and ventilation for low-income households. The Home Upgrade Grant (HUG2) covers off-gas homes. Check eligibility at gov.uk.
Running a portable AC unit for 8 hours a day during a heatwave costs about £40 per week. Installing a heat pump with reverse-cycle cooling costs £7,000–£13,000 after grant. Passive measures like blinds and insulation cost £200–£3,000 and can reduce indoor temperatures by 3–5°C.
