CommunicationPublished on 3 August 2026

BeCool: smart buildings to fight record-breaking heat

Extreme heat is becoming one of the greatest health and development challenges worldwide. While demand for air conditioning is shooting up, Switzerland's approach in its cooperation with India goes in a different direction: ventilation, shading, greening and reflective roofs are designed to ensure that buildings do not heat up in the first place. This protects people, saves energy and avoids fuelling climate change further.

A person is painting a roof white. — Whitewashed roofs are a simple, traditional cooling method gaining new relevance in today's context. — © UNEP

One day in late April, something very unusual happened. All of the Earth's 50 hottest cities on that particular day were in the same country: India. In cities such as Barmer, Churu and Jhansi, temperatures reached almost 45°C. Construction workers and farmers tilling their fields in particular had no defence against the scorching sun. People died.

India is a prime example of a trend that is swiftly gathering pace worldwide, driven by climate change. The World Health Organization reports that the number of people exposed to extreme heat is rising “exponentially” in all regions of the world. Heat-induced mortality is on the rise. It is estimated that nearly half a million people die each year from the effects of extremely high temperatures. This makes heat by far the deadliest of all types of extreme weather event.

Conditioning the air, heating up the planet

In India, where temperatures sometimes surpass the 50°C mark, the pressure to find effective solutions is particularly high. Those who can afford it protect themselves with air conditioners, with the country now one of the world's fastest-growing markets for these units. Currently, about 8% of India's households have air conditioning – a percentage expected to hit 40% by 2038. Over the same period, demand for energy to cool the subcontinent will quadruple, reaching 584TWh – roughly equivalent to the output of 70 nuclear power plants.

And this is right where the dilemma lies: while air conditioners provide short-term relief for people indoors, they simultaneously produce high greenhouse gas emissions and themselves release additional heat into the surroundings. “Air conditioning does protect individuals,” says Frank Bertelsbeck, programme officer of the SDC's Climate, Disaster Risk Reduction, and Environment Section and responsible for the topic of energy efficiency. “But overall, they worsen global warming considerably.” That is why the cooling of homes and public infrastructure must be rethought from the ground up.

One solution is ‘BeCool’

Together with Indian authorities, cities, and international partners, the SDC is thus promoting solutions that keep buildings from heating up significantly in the first place. Shading, ventilation, greenery, reflective roofs, and climate-adapted building materials ensure that interior spaces remain considerably cooler even in extreme heat. This lessens cooling needs significantly, even eliminating additional energy consumption altogether in some cases. Experts refer to this as passive cooling.

In the best-case scenario, passive cooling begins long before the first air conditioning unit is installed, explains Bertelsbeck – namely during the building's design phase. “Those who build wisely today protect people for generations to come, while also saving energy and reducing emissions.” Through the BeCool programme, Switzerland is helping the world's most populous country implement this approach on a large scale. Together with ministries, states, cities, architectural firms, and the private sector, BeCool is developing not only concrete pilot projects but also guidelines, building codes, and financing models. “The goal is not just to cool individual buildings, but to permanently embed passive cooling in urban planning and the construction sector.”

India introduces new building codes

The results achieved so far show that this cooperation is having a tangible impact. Five states and 20 cities are adapting their policies based on the framework that has been established, and are investing in passive cooling. One example of this development is Tamil Nadu. India's southernmost state just introduced a standard operating procedure (SOP) in June 2026 for cool roof coating application. In 12 steps, the SOP covers planning, material selection, application, and quality assurance for the construction of residential, school and public-sector buildings, thereby forming the first-ever uniform norm for the technologies concerned.

“The goal is to anchor such standards throughout India,” says Bertelsbeck. Owing to its size, the country harbours enormous potential for implementing solutions on a large scale. Estimates put the potential reduction in cooling energy consumption in India at up to 20%. In other words, relatively simple measures could save around 200 million tonnes of CO2 equivalents annually. By comparison, that is about five times as much as Switzerland emits each year.

Heat that hampers development

The timing here is crucial. “A lot of the buildings that India will be using in 2050 do not yet exist,” explains Bertelsbeck. Every school, every residential building and every hospital built today to be climate-resilient will save energy in the coming decades whilst also improving protection against extreme heat. Tamil Nadu provides a practicable model of how cities in the Global South can respond to rising temperatures – quickly, effectively and in a socially inclusive manner.

“Heat is becoming one of the biggest challenges to development,” Bertelsbeck says. And it has been more than just a health issue for quite some time now: “Extreme heat puts a strain on agriculture and the food supply, reduces productivity, drives up energy consumption and exacerbates social inequalities.”

Climate change knows no national borders. What works in India also has an impact beyond its borders. If we succeed in significantly reducing energy consumption and carbon emissions in the construction sector in one of the world's most populous countries, the global climate will benefit – and so will Switzerland. After all, every tenth of a degree less of global warming means fewer extreme weather events, fewer heatwaves and a better quality of life – everywhere.

When the sun shines on a dark roof for hours on end, the building beneath it heats up like an oven. In schools, this becomes a particular problem. It's as if people's brains are actually starting to fry. High temperatures make learning difficult, impair concentration and take a toll on the health of children and teachers.
In the Indian state of Tamil Nadu, the Swiss-supported BeCool project is therefore focusing on a simple solution: cool roofs. The project's roofs are painted in a highly reflective colour that reflects a large proportion of the sun's rays and absorbs less solar energy. The effect is remarkable: in pilot projects, indoor temperatures fell by 4 to 8°C. At the same time, the buildings consume less energy for cooling.
These promising results led Tamil Nadu to introduce a uniform cool roofs norm – the first state of India to do so. Up to 300 schools are set to be refurbished this way, which could benefit over 150,000 pupils.
“Even just a few degrees makes a big difference,” says Frank Bertelsbeck, programme officer in the SDC's Climate, Disaster Risk Reduction and Environment Section and responsible for the topic of energy efficiency. “Children can concentrate better, teachers work in better conditions, and schools use less energy.” Solutions like these combine climate adaptation with tangible gains for people.
What works here can be taught elsewhere. Moreover, successful, cost-effective pilot projects become real success stories when their solutions are adopted elsewhere and further developed. “Our aim is not to implement as many individual projects as possible,” explains Bertelsbeck. “We want to create the right framework so that good planning and construction become the norm. Only then will the impact extend far beyond a single building.”