Following last week's record June temperatures of 37.3°C and widespread health warnings, the UK is bracing for another heatwave with highs of 32°C predicted over several days next week. For those who missed out on buying a portable air conditioner during the previous hot spell, now is the time to prepare.
How do portable air conditioners work?
Air conditioners remove heat from a room, leaving indoor air cooler. There are two main types: single hose and dual hose. Katie Lillywhite, air treatment expert at AO.com, explains: 'Single hose air conditioners have one hose to vent hot air from the appliance. This works by drawing air from your room, cooling it through its system then venting this out. [They] lack a bit of power to cool particularly hot rooms. Dual hose air conditioners have a lot more power – one hose to pull in outdoor air and the other to vent this back out.'
Installation tips for portable AC units
Proper installation is crucial. Jamie Hillard of Heatable.co.uk advises: 'The exhaust hose must be sealed properly at the window to prevent warm air from coming back in. The exhaust hose needs the shortest, straightest route possible to the outside. Long, kinked, or poorly positioned hoses reduce performance because the hot exhaust air can radiate heat back into the room. The window opening also needs to be sealed properly. A proper window sealing kit or rigid panel makes a noticeable difference.' Most units come with a kit, or you can buy window sealing kits online, such as from heatershop for £19.98. One Metro reader resorted to sealing the gap with taped plastic sheeting, noting that fitting kits are 'quite fiddly'.
Choosing the right unit: BTU sizing
Selecting the correct size depends on room dimensions, window condition, insulation, orientation, and room type. Jamie warns: 'A really common mistake is buying an undersized unit and if the unit is too small, it will run almost continuously, using more electricity but still struggling to bring the room temperature down.' Use a BTU calculator to determine the required British Thermal Units. Glow Green provides a helpful chart: 100–150 sq. ft. (9–14 sq. m.) needs 8,000 BTU; 150–250 sq. ft. (14–23 sq. m.) needs 9,000 BTU; 250–300 sq. ft. (23–28 sq. m.) needs 10,000 BTU; 300–350 sq. ft. (28–33 sq. m.) needs 12,000 BTU; 350–400 sq. ft. (33–37 sq. m.) needs 14,000 BTU; 400–450 sq. ft. (37–42 sq. m.) needs 18,000 BTU; 450–650 sq. ft. (42–60 sq. m.) needs 25,000 BTU.
Running costs and energy savings
Running costs vary based on room size, insulation, glazing, solar gain, tariff, and usage. Jamie notes: 'The biggest mistake is setting the target temperature too low. Trying to cool a room to 18°C during a hot spell will use far more electricity than maintaining it at around 22–24°C. For portable AC units, many models are in the 1–1.5kW electrical input range when running.' At average electricity rates, this equates to about £0.06 per 10 minutes, 36p per hour, or £8.64 per day if run 24 hours. To reduce costs, Jamie recommends closing blinds on south- and west-facing windows, keeping windows shut during the hottest part of the day, and cooling rooms before they become overheated.
Recommended portable air conditioner models
Several models are available to suit different needs and budgets. The AEG Comfort 6000 Air Conditioner (£489) offers 9,000 BTU for rooms up to 21m², with Wi-Fi connectivity and a CleanAir filter. The LOGIK LAC07C25 (£299) is a compact 2-in-1 unit with a 323m³/h airflow rate, 24-hour timer, and remote control. The DELONGHI Pinguino AP98 GentleJet (£799) provides 11,500 BTU with GentleJet technology and Eco RealFeel for larger rooms. The MEACO MeacoCool MC12000CHR PRO Smart (£479) is a 3-in-1 unit with 12,000 BTU, smart app control, and heat pump technology. The Bush 9K Air Conditioner (£375) offers 9,000 BTU for rooms up to 18m² with four modes and a 24-hour timer.
Environmental impact of air conditioners
Portable AC units can be eco-friendly when used wisely. Andrew Sissons, sustainable future director at Nesta, says people shouldn't feel guilty for using them as a 'last resort'. Nicole Miranda, sustainable cooling researcher at the University of Oxford, notes they are vital for protecting vulnerable people. Earth.org reports that setting AC to 26°C instead of 24°C consumes around 30% less energy. Regular cleaning and replacing filters, and choosing models with a high Seasonal Energy Efficiency Ratio (SEER), also reduce environmental impact.
Are portable air conditioners worth it?
Despite upfront costs of a few hundred pounds and potential running costs up to £8 per day, hot weather can cause dehydration, overheating, and heatstroke. The World Health Organization has linked the European heatwave to 1,300 deaths. People over 65, babies, children under 5, and those with pre-existing conditions are especially vulnerable. Steve Charnock, Audience Writer for Metro, recently bought a 9,000BTU Ariston unit from B&Q for £225, describing it as 'pretty much saved my life' during last week's heatwave. In comparison, a 12,000 BTU wall-mounted unit costs around £750 plus £1,150 installation, making portable units a far cheaper option.
Cheap alternatives if you don't have air conditioning
If installing AC isn't possible, try freezing a bottle filled with ice and a tablespoon of salt, then placing it in front of a fan to create a cool breeze. Keep curtains and blinds closed, especially blackout varieties, and avoid opening windows during the hottest part of the day to prevent hot air from entering.
