To cool or not to cool? As extreme heatwaves grip the European continent, the debate over air conditioning has reached a boiling point, transforming a technical necessity into a fierce cultural and political battlefield. In France, where only about one in four households is air-conditioned, localised blackouts — like the massive transformer failure in Finistère that left over 100,000 homes in the dark during a June canicule — have exposed the fragility of an ageing energy grid under thermal stress. The climate control divide is continent-wide: while Spain has normalised cooling in over 40% of its homes, and Italy absorbs nearly a third of the EU’s cooling power, Germany and the Low Countries remain structurally unprepared, still well below 20% of dwellings equipped. Yet, while active cooling is a medical necessity for vulnerable people, from the elderly in care homes to pregnant women, its environmental feedback loop is devastating — fuelling the very urban heat island effect it tries to escape, and accounting for a massive spike in power demand and associated emissions. How to break this thermal deadlock? The answer might not lie in the high-tech, energy-guzzling promises of tomorrow, but in the forgotten, passive wisdom of the past. "Architects have been talking about this for years; it's just that this is the first time anyone is bothering to listen," says Christine Thornley, a chartered architect based in the northeast of England and founder of Grove Studio Architecture. To resolve the modern cooling crisis, Thornley argues that we must first deconstruct the errors of 20th-century construction, which relied on cheap fossil fuels to bypass the natural environment. "We spent a long time focusing on how to make buildings more energy efficient to heat them in winter, and then we forgot that there's a converse side to that," Thornley explains.