Building Climate-Resilient Cities

When one participant was a child in Milan, apartments there had no air conditioning. Now every apartment has it. This year the city had its hottest summer on record, with temperatures of 38°C, and the candidates for mayor are debating how to turn it into something closer to a forest, with white roofs, new paving and shade. The participant, a corporate investor, did not believe private, technology-led solutions would change the city's buildings. Only mass public investment would, on the scale of the public housing programmes of the 1960s, and city councils and states have no money. At this Ripple on climate-resilient cities, nobody much doubted the tools. The argument was over who pays for them, and how fast.

Matt Stanley of BDC Capital said most of the technology needed to decarbonise cities is already mature. "We could probably achieve close to net zero in most cities today by just deploying what we know today that's already available, but doing it better and doing it faster," Matt said. What is missing is financing. Retrofits of single homes need pooling into vehicles that measure results before and after and can move capital at scale, so that a household does not face a $30,000 bill. Today's urban capital stack is a patchwork of grants, utility incentives and municipal or national schemes.

Tanja Huohvanainen of Kiilto Ventures said a Finnish geothermal company the firm had backed carried no technology risk at all. Its innovation was letting customers pay for the energy they used, with no large upfront cost. Another participant recalled IKEA's move to LED lighting from 2012. Once the supply chain made LEDs cheaper and better, customers bought them whether or not they cared about sustainability.

The city as convenor

A city innovation official said their city has no trouble finding solutions or companies. The hard part is working with start-ups, suppliers and investors at the speed they need. Tallinn's head of innovation, the official said, counts moving fast as the city's best trait. A municipality acts as an authority, as a buyer and as a facilitator, and the official saw most promise in the last. Their city runs a programme with 40 to 50 property owners that together hold over half of its building mass.

A founder applying for an EU LIFE grant with a city said agreeing who pays for what took six months. A participant decarbonising factories said cities are well placed to curate the network of start-ups, corporates and investors that a retrofit needs, because start-ups rarely have the runway to build that trust themselves.

We could probably achieve close to net zero in most cities today by just deploying what we know today that's already available, but doing it better and doing it faster.

Heat reaches the north

Tanja said Nordic buildings are insulated for cold but not prepared for overheating. Heat also divides neighbours. One participant said an air-conditioning unit on one house makes it hotter for the neighbour who cannot afford one. Satellite images of North American cities show far more tree canopy in wealthier districts, Matt said. Nature should come first, paid for with public funds, and private capital can deploy the rest.

A participant who had worked on a heat wave plan for Malmö had a surprise to report. Malmö has a simple rule that everyone should live within 300 metres of a green area, and the team mapped the socially vulnerable districts with the least greenery. When they interviewed residents, some said they came from the Middle East and found Sweden too cold. Coping with heat is partly behaviour and culture, the participant said, and people in the Nordics could be taught simple ways to deal with it.

Old answers to new heat

An architecture educator from India said many projects there are returning to traditional building methods, which dealt with heat long before air conditioning. Such buildings are not expensive, the educator said, "but the ideas are only with the people with the money." Others offered their own. In Brazil, tiled floors keep houses much cooler. In Malmö, glazed balconies trap welcome heat in winter and unwanted heat in summer, and openings that can be changed with the season would help. Nordic district heating networks could be decarbonised with large heat pumps and perhaps one day run in reverse to cool.

Design can matter more than devices, Matt said. The aim of mobility is to move people and goods, not cars. Amsterdam was bumper to bumper in the 1950s and has spent 60 years remaking itself. Urban infrastructure works on 10- and 20-year cycles, while venture capital wants returns in five to seven, so much of it needs other kinds of capital, even if some mobility businesses scale across many cities.

A founder who works on EU policy urged start-ups to join in. A new EU standard for social housing, which covers heating, has been under discussion for a year and a half, with around 100 people in the room, and founders inside the process can plan products and fundraising around it. Speed was the problem there too. One of the hosts closed on new buildings, where the stakes are longest. Whatever cities build now will stand for 80 years or more, and if they do not get it right now, there is no chance to adapt it later.

This Ripple was hosted by Matt Stanley (BDC Capital) and Tanja Huohvanainen (Kiilto Ventures) at The Drop 2026 on 16 September.