With workers and children spending more time at home during lockdown, there has been an increase in the number of people thinking of purchasing a portable air conditioning unit this summer.

According to Uswitch.com, Google searches for portable air con units rocketed 133% in the last week of May compared to the previous year.

But calculations by the price comparison website show that air con devices can increase home energy bills by up to £28 a week.

The warning comes as temperatures are expected to soar above 30°C this week.

Uswitch found that portable air conditioning units use 2.7kW of power on average. This is equivalent to constantly running a washing machine or tumble dryer.

People who already own an air con unit say they use them for 4 hours 18 minutes on average during the day when temperatures are high, and 4 hours 48 minutes at night. According to Uswitch, this means weekly energy bills could rise by £28 during a hot spell.

A further 2.2 million consumers are considering buying an air cooling system — which uses water rather than a coolant to reduce temperatures — to help them stay cool this summer. Another 2.2 million are planning to purchase an electric fan.

The cost of running different devices varies dramatically. Air con systems use an average of 2.7kW of power, compared to a standard desktop fan consuming just 120W.

With many homes planning a summer at home instead of abroad, there are also warnings about the potential impact of other seasonal feel-good gadgets on energy bills. Searches for hot tubs, which can use 3kW for the heating element alone, have shot up by 775% in the past three months and electric patio heaters searches have soared by 790%.

Sarah Broomfield, energy expert at Uswitch.com, says: “In normal times, millions of workers would be spending this heatwave in a perfectly chilled air-conditioned office. Now an open window and a desk fan is the best that many of us can hope for.

“With temperatures creeping above 30°C and people set to spend the hottest times of the day at home, it’s no surprise that so many of us are investigating what we can splash out on to make things more bearable.

“Portable air conditioning units are an effective way to keep a room cool, but they consume a lot of power and could well bring about a nasty surprise when the next energy bill arrives.

“There are plenty of cheaper ways to control your temperature at home, such as placing a bowl of ice cubes in front of an electric fan. The fan will create a refreshing breeze as it blows the ice-cooled air around the room.

“Also, keep your curtains shut during the day. It may be tempting to let a breeze through the house, but the sunshine will heat up every room it can reach, turning your home into a greenhouse in no time at all.”