Victorian ‘hack’ gives you free air conditioning with the right windows

Summer is in full swing and large swathes of the UK are experiencing very warm temperatures. Saturday (10 June) saw the country record the hottest day of the year so far after the mercury reached 32C in Chertsey, Surrey.

As Britons search for ways to keep cool at home, one trick may have been hiding in plain sight this whole time – if you have sash windows.

Sash windows are a common feature of Victorian-era homes and involve a window that can be slid open vertically to create openings at the bottom or the top.

However, some people have recently discovered that sash windows can be opened in such a way that it creates openings at the bottom and the top at the same time.

The tip was recently revealed by journalist Jess McCabe, who tweeted recently: “Annual hot weather reminder that if you’ve got sash windows and open them equally at top and bottom, you can enjoy Victorian ‘air conditioning’ that ventilates and removes heat.”

She added in a separate tweet that she had lived with sash windows for four years and “suffered every summer until we found this out”.

According to the University of Cambridge’s Department of Engineering, the act of opening the top and the bottom of a sash window allows for better ventilation as lighter, warmer air escapes through the top, while denser, cooler air enters the building from the bottom.

A number of people thanked McCabe for the revelation, as many did not realise it was possible to use sash windows in this way.

“This is life-changing, thank you,” one person said.

“I did not know this. Have just opened the bottom pane. Thank you!” another added.

Others pointed out that they are unable to take full advantage of their sash windows since they are renting a home in which the top window has been painted or nailed shut.

Another summer hack involving windows is to aim a fan so that it faces the outside through the open window. While this sounds counterintuitive, the trick has been hailed as “the best, low-cost, highly effective technique to keep a home cool” by New Zealand eco design adviser Nelson Lebo.

Pointing a fan to the outdoors through an open window as soon as the temperature outside drops lower than the temperature inside can create cross ventilation.

This brings cooler air from outside the house indoors, while forcing the warm air out.