When Yvette Cooper visited an A&E department in Yorkshire this summer, what struck her was not the heat itself but the shape of the pressure it created. Staff described attendances that would be unremarkable in January but felt alarming in July, a mismatch between calendar and crisis that the health secretary now wants the NHS to plan around formally. It sounds like good operational hygiene to follow her advice to approach summer with the same seriousness as winter. It is also, whether intended or not, an admission that the NHS estate was never built for the country it now serves.

The specifics matter more than the framing. Radiotherapy machines and MRI scanners have failed in the heat this summer. Cooling units have broken down. Wards have overheated in buildings designed, in many cases, decades before anyone budgeted for a 40C July. This is not weather disrupting a functioning system. It is heat finding the weakest points in an estate that has been quietly deteriorating for years, and doing so in a way that is now visible to patients rather than confined to an accountant's spreadsheet.

That deterioration has a number, and it is not a small one. The cost of clearing the NHS maintenance backlog in England has climbed past £15 billion, having roughly doubled since the middle of the last decade. Trust estates teams describe a system where deferred repairs become more expensive the longer they wait, where capital meant for new equipment is drawn into keeping old buildings standing, and where a growing share of that backlog sits in the highest risk category, meaning failure is not a hypothetical but a schedule. Cooling failure in a hospital ward is not a separate problem from this backlog. It is what the backlog looks like when the thermometer moves.

The Climate Change Committee's recommendation that all hospitals and care homes have air conditioning within a decade will read, to anyone who has followed NHS capital funding, as aspirational in the way many such recommendations are. Capital budgets in the NHS have a long history of being raided to plug day to day deficits, a habit that hollowed out planned maintenance long before this year's heatwaves made the consequences physical. Promising air conditioning by the mid-2030s means little if the underlying discipline, protecting capital funding from revenue pressure, is not restored first. Otherwise the commitment joins a familiar pile of estate pledges that outlive the ministers who make them.

This is where the politics becomes concrete rather than seasonal. John Healey's Budget on 28 October will be the first real test of whether Andy Burnham's government treats NHS infrastructure as a funding priority or a line to be revisited once other pressures are addressed. Social care reform, immigration enforcement and the cost of living have dominated the early agenda of his premiership, understandably given the pressures on him, but none of those commitments reduces the exposure of a hospital estate that is already failing in ordinary summer conditions. If capital allocation in October does not treat resilience as a distinct and protected category, NHS leaders will be left managing the same annual crisis Cooper has just described, only with a ministerial memo attached rather than a solution behind it.

For NHS leaders themselves, the practical implication is a familiar and unwelcome one. Estates directors will now be expected to produce heat resilience plans without necessarily receiving the capital to act on them, which risks becoming another unfunded expectation layered onto teams already managing a backlog larger than the annual cost of running the estate they maintain. For life sciences and health technology firms, particularly those supplying diagnostic and imaging equipment, the exposure of clinical machines to heat failure is a market signal as much as a safety one.

Cooper is right that the NHS needs to stop treating summer as an exception. But resilience is not a plan or a public health campaign, however well judged. It is a capital commitment, tested every October, and so far the health service has been asked to prepare for a future it has not yet been funded to survive.