Why UK schools bake in summer and what it means for your home

Half of UK classrooms exceed 28°C during summer heatwaves, according to a 2023 study by the University of East Anglia. That is uncomfortable and a health risk for children and teachers. The culprit? Tarmac playgrounds that absorb heat, windows that do not open, and roofs without insulation or reflective coatings. As reported by The Guardian, the problem is not limited to schools, many UK homes face identical design flaws.

Why overheating matters for your energy bill

The same lack of ventilation and solar control that bakes classrooms drives up summer electricity use in homes. A typical 3-bed semi without shading can see indoor temperatures 5–8°C above outside. To cope, households run fans or portable air conditioners, which cost around 15p per hour to run. Over a two-week heatwave, that adds £30–50 to a bill. Worse, the heat builds up in walls and loft spaces, meaning the house stays warm into the night, forcing even more energy use. The Energy Saving Trust estimates that external shading can cut solar gain by up to 90%, reducing cooling needs entirely.

What your home can learn from school retrofits

Schools are now being retrofitted with external blinds, roof insulation, and mechanical ventilation with heat recovery (MVHR). These measures work for homes too. Insulating a loft to 270mm costs around £350–500 and can save £180 a year on heating, but it also keeps the house cooler in summer by blocking radiant heat from the roof. Trickle vents in window frames, costing about £30 each, allow controlled airflow without losing security. For homes with sealed windows (common in new builds), adding a single room MVHR unit at £500–800 can maintain fresh air without opening windows. Ofgem’s ECO4 scheme covers insulation and ventilation upgrades for low-income households, while the Great British Insulation Scheme offers grants to all households with an EPC rating of D or below.

The ‘but’ that changes everything

But here is the catch: most retrofit programmes focus on winter heat loss, not summer overheating. The ECO4 scheme, for example, prioritises cavity wall and loft insulation. While these help in winter, they can trap heat in summer if not paired with shading or ventilation. The government’s Heat and Buildings Strategy, published in 2021, acknowledges the need for ‘passive cooling’ but has no specific funding for it. Homeowners should therefore ask installers for a whole-house retrofit plan that includes both winter and summer performance. The Retrofit Academy recommends a ‘fabric first’ approach, insulation, airtightness, then controlled ventilation, but always with solar shading as a third step.

What you can do this summer

You do not need a full retrofit to start. External blinds or shutters on south-facing windows cost £200–400 per window and can lower indoor temperatures by 4–6°C. Planting deciduous trees or climbing plants on south walls does the same thing over time. For immediate relief, reflective film on windows costs £10–20 per m² and rejects up to 70% of solar heat. The key is to act before the next heatwave, not during it. Check your EPC report for ‘overheating risk’, it is now a mandatory assessment for new homes. If your current home has no mention, ask a retrofit assessor for a quick check. Grants for shading are rare, but some local councils offer ‘cool roofs’ programmes, search your council’s website for ‘retrofit grant’ or ‘heat resilience’.

Your next move

Book a free home energy advice call through the Energy Saving Trust’s website. They will tell you which grants apply in your area. If you own a home built before 2000, your loft and walls are likely under-insulated, fixing that first will help both winter and summer. For homes built after 2010, focus on ventilation and shading. The deadline for ECO4 applications is 31 March 2026. Do not wait until the next heatwave to discover your home is a heat trap.