Record September heat reopens Switzerland’s air-conditioning debate

Temperatures reached 30.1°C in Basel-Binningen during the final weekend of September, setting a late-season record north of the Alps and pushing heat protection back into the political spotlight. Delémont reached 29.6°C on Sunday, while MeteoSwiss reported readings of up to 30°C in other locations. Forecasters expected another stretch of 25°C to 29°C in the following days.

Meteonews said no hot day had previously been recorded so late in the year on the northern side of the Alps. The reading followed a summer in which Basel-Binningen reached 39.7°C on July 30, matching the northern Alpine record set by Geneva-Cointrin in July 2015.

The timing matters for public health. Hospitals, care homes and schools face risks when indoor temperatures remain high, particularly for older people, patients with existing conditions and others who cannot regulate body heat easily. Switzerland’s summer of 2026 was the hottest and driest since national measurements began in 1864, according to related reporting by Swissinfo.ch. That pattern is forcing planners to examine how buildings can remain safe as heat arrives earlier, lasts longer and extends deeper into autumn.

Heat already kills more people in Switzerland than road traffic accidents, according to ETH Zurich professor Arno Schlüter. His warning gives the air-conditioning debate a public-health dimension that extends beyond household comfort.

During heatwaves, hospitals and care homes must keep patients and residents within safe temperatures while continuing to operate medical equipment and essential services. Older people and those with chronic illnesses can be especially exposed. Schools also need rooms where children and staff can work safely when nights fail to cool buildings.

Schlüter expects air-conditioning to become more important for vulnerable groups in hospitals, care homes and schools. He also rejects the idea that every Swiss apartment and office should simply receive a cooling system. That approach would increase electricity demand and could transfer heat outdoors, depending on the technology and its power source.

The practical task for health providers is therefore broader than buying more machines. Building operators need heat plans, shaded outdoor areas, effective ventilation, access to drinking water and procedures for identifying people at risk. Mechanical cooling may be essential in some wards and rooms. In others, passive measures could reduce the need for it. The debate is moving from seasonal comfort to clinical safety.

Air-conditioning remains unusual in Swiss homes, hospitals and care homes because installation is tightly regulated. In many cantons, a split system with an indoor and outdoor unit must satisfy energy, environmental and town-planning requirements. Permits can be required, and outdoor units may face scrutiny because of noise, appearance, energy use and their effect on the building or neighbourhood.

Those rules reflect Switzerland’s long-standing approach to energy efficiency and its preference for limiting unnecessary cooling. Many buildings were designed around winter heating rather than prolonged summer heat. Traditional responses include shutters, blinds, cross-ventilation, thick walls and night-time cooling. They can work well when nights become cooler, but their effectiveness falls during persistent heatwaves.

The regulatory system is now facing a harder climate calculation. A cooling system can consume electricity and add pressure to the grid during periods when many buildings need it simultaneously. Yet refusing cooling in a hospital room or care facility can carry direct health costs.

Swiss planners are consequently weighing building orientation, external shading, insulation, ventilation and district cooling alongside air-conditioning. The choice will vary by building, canton and user. A server room, an intensive-care unit and a family flat do not have the same cooling needs.