UK schools have seen classroom temperatures exceed 40°C this week, according to a report from Hertfordshire. Harry Paticas, an architect and founder of Retrofit Action for Tomorrow, explains why schools struggle with heat and what can be done.
Why schools overheat
Modern schools often feature large expanses of glass with insufficient shading or ventilation. Post-war designs prioritized natural light for public health, but windows often have safety restrictors limiting opening. Glass atriums, common in schools built under the Building Schools for the Future programme in the early 2000s, act like greenhouses, intensifying heat.
Victorian school buildings, originally designed with passive cooling and cross ventilation via tall sash windows, external shutters, and awnings, have lost these features through refurbishments, safety changes, or painted-shut windows. Single glazing lets up to 37% more heat into buildings than double glazing, while outdated heating systems and poorly insulated hot-water pipes radiate extra heat.
Tarmac playgrounds worsen the problem
Playgrounds, mostly tarmac and treeless, absorb heat all day. Research at a school in Catford, south London, found dark surfaces can reach 60°C during heatwaves, making outdoor play uncomfortable and unsafe.
Scale of the issue
Retrofit Action for Tomorrow, a non-profit community interest company, engaged with 80 schools across England. 68% reported overheating, with over a quarter describing it as “significant”. Teachers report pupils fainting or vomiting due to heat, and schools closing, exams cancelled, and study time lost. Heat increases task-completion time and errors, reduces cognitive performance, and harms test results.
Quick fixes and long-term solutions
Simple measures include shading windows externally with fabric (twice as effective as internal shading) or even coating glass with yoghurt. Guidance on window and blind management: close windows and blinds when outdoor temperatures are higher than indoors, open them when cooler (overnight and morning). Use stack ventilation by opening high-level windows at night, and cross ventilation by opening windows on opposite sides and internal doors.
School investments in planting and passive cooling show benefits. At Dalmain primary school in Lewisham, south London, solar shading, rain gardens, and outdoor learning spaces kept staff and children comfortable, while attracting butterflies and bees, linking climate adaptation with biodiversity and wellbeing.
Need for national investment
Harry Paticas calls for national investment and collaborative action guided by a clear plan. The Department for Education’s new 10-year modernisation strategy signals a shift toward resilient learning environments through retrofit and estate improvement. Schools must adapt to provide healthy, safe, and productive spaces for children to learn and thrive.
