July 28, 2022

The eco-friendly alternatives to air conditioners 

Air con and electric fans account for 10% of global electricity consumption – here are the more eco ways to keep cool

Freya Pratty

4 min read

Cooling down is heating up. As summer temperatures climb in Europe, startups across the continent on working on energy-efficient ways to keep buildings — and the people inside — appropriately chilled. 

These companies are working broadly in three areas. First, there’s insulation to limit the flow of hot air from outside. Second, there’s improved windows to limit solar energy entering. And third, ventilation.  

While “insulationtech” (you heard it on Sifted first) might not sound like the sexiest area, founders and investors say these innovations matter. 


Established methods for cooling homes and offices like air conditioners are so energy intensive that, ironically, they contribute to rising temperatures. According to the International Energy Agency, air conditioners and electric fans already account for 10% of global electricity consumption.

Insulation and ventilation

In the insulation world, there are startups like Thermulon, which is developing aerogel insulation (one of the world’s lowest-density and most thermally insulating materials). There’s also Q-Bot, a London-based startup that’s developed a robot to install underfloor insulation in existing houses by crawling under the floor.

An image of the Q-Bot spraying foam-like insulation below the floorboards of a house
The Q-Bot

It’s in ventilation that some of the most innovative changes are happening. Startups are developing new ways to introduce cooler air into buildings without the additional emissions needed to power air con.

British startup Ventive’s system produces cool air as a byproduct of heating — meaning it doesn’t add any additional emissions. 

The system uses a heat pump, which takes heat from the air and transfers it to water to heat it using minimal energy. Heat pumps produce cold air as a by-product — it’s normally pumped outside of the house. Ventive’s system pumps the cold air back into the house when cooling is needed. 

“The cold air supplied into the house is a free side effect,” explains Tom Lipinski, Ventive’s founder. “You're not creating any additional demand on the grid, because your heat pump still needs to supply hot water.”

Lipinksi estimates that the system can offer 3-4C of cooling — not as much as a large air con unit, but enough to make a difference. 

AirEx is another startup working on cooling tech. Every house has "air bricks" built into the fabric of it — bricks with holes in to make sure there’s enough ventilation to prevent damp and mould.

“But,” explains Agnes Czako, cofounder of AirEx, “recent research discovered that actually up to 15% of a home's heat loss can be caused by these air bricks.” 

An image of AirEx's plastic brick next to a traditional terracotta airbrick
AirEx's brick next to a traditional airbrick

Airex has developed a new brick which can let in specific amounts of air at different times — enough to provide ventilation while preventing heat loss in winter and the influx of hot external air in summer. Czako estimates that the bricks can lead to 12% savings on energy bills in winter.


Other companies are working on software tools to optimise the energy that heating and cooling systems in the house use. 

BeeBryte, based in Lyon, has just raised €8.2m for its tech, which forecasts the weather and occupation patterns of the house so it can cool and heat the air in advance of certain behaviours. Turning to a predictive system rather than a reactive one can lead to up to 40% savings, the company says. 

Climate tech founders are keen to stress, however, that alongside tech there are simple solutions everyone can implement: add any shadings possible to windows; turn off heat-producing appliances in the middle of the day, including ovens, TVs and sound systems; close windows in the heat of the day and open them at night to allow the cooler air into the house.  

Freya Pratty

Freya Pratty is a senior reporter at Sifted. She covers climate tech, writes our weekly Climate Tech newsletter and works on investigations. Follow her on X and LinkedIn