As extreme heatwaves expose the limits of active cooling, architects and researchers are looking back to vernacular materials, passive designs and invisible retrofits to build our carbon-neutral tomorrow.
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, i
ts 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. "And now people are just coming around to think about actually, no, we have to deal with the heat as well."
The solutions, she suggests, are deceptively simple and deeply rooted in historical design. The most intuitive is the
physical management of airflow and solar radiation. "Victorian windows in the UK actually work for this principle," Thornley notes. "With the sliding sash, you have a bit at the top that opens and a bit at the bottom to allow air to naturally circulate. We upgraded our windows over the past 20 to 30 years to double-glazed units and stopped doing that. So now we're just trapping all that heat in there."
The same regression applies to
external shading. While southern European streets are traditionally defined by their shutters, northern European architecture has largely abandoned them. "Shutters on the outside stop that energy from getting built up inside," Thornley points out. "If you put shutters on the inside, the heat has already come in. It’s got past the glass, and you're trapped."
This passive intelligence is not a modern theory, but an ancient standard. "When I went to the Alhambra in Granada, I walked through it when it was 36°C outside, but it was still pleasant," Thornley recalls. "That was ancient architecture showing you its best: pulling the air through the buildings, shading, using water and using dense fabric with thermal mass."
Even the surrounding landscape plays a structural role: a single street with a dense tree canopy can drop local temperatures by three to four degrees, stopping the mineral ground from absorbing heat and radiating it back into the houses.
To build the city of tomorrow, however, we must accept that
passive cooling strategies alone won’t be enough if the very skeleton of our cities keeps absorbing and radiating heat. This is where the
structural revolution of mass timber enters the scene. "An ideal city of the future already exists," says Andrew Waugh, director of London-based
Waugh Thistleton Architects, a research-led practice that has spent twenty years pioneering engineered wood. "It's a city that's remodelled, that's rebuilt... where it's as much about architectural surgery as it is about new buildings. Healthy, walking, lightweight, 15-minute cities are our future."
For Waugh, mass timber is the ultimate tool for this "architectural surgery" because it directly addresses both the global carbon crisis and the local microclimates of our warming streets. "Because mass timber buildings have a
far lower thermal mass, you're not creating these heat islands," Waugh explains. "We know that
if you hug a tree in the sunshine, it's not going to burn you. It's not like sitting down on a hot steel bench or a hot stone bench. Timber doesn't heat up our cities in the same way."
Beyond carbon sequestration and thermodynamic properties, building with organic materials restores a
deeply human, biophilic connection to our urban fabric — calming our nervous systems in ways concrete never could. "We're getting increasing amounts of evidence about what it's like to live, work and be educated in timber buildings," Waugh says. "Acoustic qualities, the dynamic of these buildings... unlike very static concrete buildings which are not good for our bodies, timber accepts the minute movements of our bodies through them — the creaking of a staircase, the random patterns of wooden surfaces. It calms the brain, reduces stress levels, makes us sleep better and concentrate harder. In schools and hospitals with exposed timber, children learn better and patients actually get better faster."
Yet,
the construction sector remains notoriously conservative, dominated by heavy, carbon-intensive materials. Waugh attributes this inertia to the massive lobbying power of multinational conglomerates. "These products — steel, concrete, cement, bricks — are run by big businesses that are very good at self-promotion and lobbying governments," he notes. "On the other hand, you have foresters in the countryside who cut down the trees their grandparents planted; they are smaller, often family-owned. There are relatively few national timber associations and no global ones. I was at COP in Brazil last year, and there were fifteen to twenty people from the concrete industry, and no one from the timber industry. Yet timber is the sustainable solution."
But even the most advanced low-carbon materials can’t solve the climate crisis if we keep tearing cities down instead of reworking what we already have —
a shift from a "demolition first" industrial complex to a "repurposing first" philosophy that has become a core battleground of European heritage policy. "We cannot say that cultural heritage is a constraint to sustainability," argues Vanessa Fraga Prol, Advocacy and Partnerships Manager at
Europa Nostra and a key voice in the
European Heritage Hub. "We think that it is really the core asset for achieving climate neutrality, social cohesion and a better quality of life.
The most sustainable building is the one that exists already."
Aligned with the principles of the
New European Bauhaus (NEB) and the
Faro Convention — the Council of Europe’s treaty that reframes heritage as a living resource for communities —, Europa Nostra campaigns to prove that
preserving our history and protecting our climate are not competing agendas. On the contrary, she argues that
exempting historic buildings from modern energy performance targets actually hinders progress. "Heritage is normally exempted from these rules and this has not led to innovation," Fraga Prol observes candidly. "Let's say that when you exempt heritage, then there is a kind of laziness. And so there are no innovative ways to think about how we could adapt historic buildings to the new rules."
When innovation is forced to meet the strict aesthetic and physical boundaries of heritage preservation, the results are often extraordinary. The European smart city project
POCITYF has spent years proving exactly this,
turning some of the most highly protected historical fabrics on the continent into active laboratories for the future.
In Évora, a Portuguese UNESCO World Heritage site cradled inside medieval walls, the conflict between heritage preservation and renewable energy was managed on the ground by Site Manager Humberto Queiroz and Project Manager Nuno Bilo. "Our main concept in a nutshell was to
install technologies for producing, storing and managing energy in a way that a bystander is not even aware they are there," explains Queiroz.
Rather than deploying standard, highly visible solar panels, the Évora team worked closely with heritage authorities to design
invisible, integrated solutions. On the roof of the historic City Hall, they replaced ancient clay shingles with photovoltaic tiles that mimic the traditional local texture. "Despite a slight difference in colour, they are equal," Queiroz says of these PV shingles, which are made of epoxy with solar cells embedded inside. Inside the building, the intervention went even further. "If you enter the City Hall and look up today, you will see a normal skylight," Queiroz describes. "But we replaced some of the glasses with glasses that have thin, grey strips of solar cells. It filters the light to generate electricity with no visual impact."
This physical alchemy was accompanied by an equally
complex bureaucratic negotiation. "We had a lot of difficulties from the beginning with the national culture and heritage authorities," admits Nuno Bilo. "It is not allowed to implement conventional panels. But this project showed that the coexistence of new technologies and heritage is possible. We had very close contact with them, we negotiated, we found solutions. We must go forward and not give up."
This painstaking integration of modern clean tech into medieval stone is not just a technical victory; it is a social one. By turning municipal buildings, car park covers and local schools into positive energy nodes, Évora is laying the foundation for a
localised energy community. This community will eventually share its clean electricity with the residents of the historic centre, shielding them from market volatility.
"In the last few decades, we have been accused of becoming more and more individualistic," Bilo reflects. "But through these community solutions, we are going back to a shared scale of living — bringing back that old sense of community that was lost."
This, ultimately, is the real alchemy of time. Securing our urban future does not require a blank slate, nor does it mean abandoning historical centres to build afresh on greenfield outskirts. Instead,
the city is a living, breathing entity that heals itself through architectural surgery, utilising the low-carbon, biophilic materials of our ancestors while weaving invisible modern technologies into its ancient stone. By combining the passive, natural designs championed by Thornley and Waugh with the institutional vision of Europa Nostra and the on-the-ground proof of projects like POCITYF, Europe is showing that we can only survive the climate storms of tomorrow if we are brave enough to anchor our future in the deep, shared memory of our past.
Suggested reading:
- Mario Cucinella, "The future is a journey to the past. Ten stories about architecture"
An account of ten journeys through places and cities across the world (from Iran to the Maghreb, from Cappadocia to Ireland) to rediscover the wisdom of spontaneous and vernacular architecture. Not a nostalgic tale, but a pragmatic reflection on how the passive and ecological climate management of the past can offer solutions for designing the future.
An exploration of how traditional earth architecture and mud-brick building techniques are being re-engineered for modern high-rises in India, providing passive thermal insulation to adapt to extreme urban heatwaves.
Article by Selene Verri
Photos by Selene Verri, EDP and
Jon Tyson from Unsplash
Contacts:
Project coordinator:
João Cravinho – EDP
joao.cravinho@edp.pt
Communication Secretariat:
info@pocityf.eu
Project website: https://pocityf.eu
LinkedIn: https://www.linkedin.com/company/pocityf/
YouTube: https://www.youtube.com/channel/UCfINly2sme7pxYOm8n2Z1Dw?view_as=subscriber