Enjoy Victorian air conditioning! Homeowners with sash windows can use them to keep homes cool

Brits are desperately search for ways to cool down amid the soaring temperatures, but there could already be free ‘air conditioning’ hiding in your home. 

And you have the Victorians to thank for it! 

Victorian sash windows are designed to suck in cool air and push out warm air if you position them correctly. 

Opening both the top and bottom sashes equally separates the air flow into the room. This causes cooler incoming air to flush out the warm air. 

The warm air inside the room tumbles out of the top opening and the cooler air from the outside comes in through the lower opening.  

Victorian sash windows are designed to suck in cool air and push out warm air if you position them correctly. Opening both the top and bottom sashes equally separates the air flow into the room. This causes cooler incoming air to flush out the warm air

Sash windows were carefully installed by the Edwardians and Victorians to improve the circulation of air within your room, cooling down your property in the hot weather, experts say.

In fact, sash windows are so successful at providing air conditioning that the University of Cambridge studied how they work to learn how best to design the low energy ventilation systems of the future. 

But this isn’t a secret to everyone, as some savvy Brits have already been sharing their sash window ventilation tips on social media.

Sharing the Cambridge University study on Friday, one Twitter user wrote: ‘Annual hot weather reminder that if you’ve got sash windows and open them equally at top and bottom, you can enjoy some Victorian ‘air conditioning’ that ventilates and removes heat.’

People replied expressing their gratitude, with one saying: ‘Thank you! It’s working!!!!’

Another person said: ‘Yes! I’m always banging on about how sash windows work.

‘My south-facing bedroom sash window currently has the top sash down to let the heat out. The Victorians were amazing!’ 

And in 2021, another Twitter user shared a picture of their sash window with both sashes positioned equally, saying: ”The humble sash window … working its wonder today to ventilate the home office in the 29 degree heat.’ 

In a video shared by the university, researchers explain how sash windows provide ventilation. 

The scientists identified three different flow regimes that may occur when a sash window is open. 

These are a bidirectional flow at the upper opening, a unidirectional flow, and a bidirectional flow at the lower opening. 

Gaël Kemp, PhD student and study co-author, said: ‘The primary purpose of ventilation is the removal of pollutants and heat. 

‘If used correctly, sash windows can be very effective sources of ventilation.’

But this isn’t a secret to everyone, as some savvy Brits have already been sharing their sash window ventilation tips on social media

The study added that calculating the natural ventilation flow rate is important for informing smart and low energy building design.

As well as reducing heat, the researchers say effective ventilation can also improve indoor air quality and limit the risk of transmission of airborne infections by circulating fresh air in the room.

The tip comes as the UK’s heatwave is set to continue, with temperatures reaching as high as 32C.

However, forecasters also warned thunderstorms in some areas could cause flash floods. 

Saturday was the hottest day of the year with highs of 32.3C in Surrey. 

But the Met Office said there was a chance homes and businesses could be flooded quickly on Sunday.

Floodwater, lightning strikes, hail and strong winds could also been seen, with difficult driving conditions expected and a slight chance of power cuts, 

It predicted delays and even cancellations to public transport because of floods or power cuts.