Another heatwave is coming to the UK, with highs of 32°C predicted across several days next week. This follows last week's record June temperatures of 37.3°C, which triggered health warnings nationwide. If you missed out on buying a portable aircon unit last time, now is the time to get organised.
How Do Portable Air Conditioners Work?
Air conditioners remove heat from a room, leaving indoor air cooler. There are two types of portable air conditioners: 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
Jamie Hillard of Heatable.co.uk shares his tips: 'Installation is key and 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, with heatershop selling them for £19.98. One Metro reader resorted to sealing the gap with taped plastic sheeting, noting the fitting kits are 'quite fiddly'.
Choosing the Right BTU Rating
Figuring out what you need depends on room size, height, window conditions, insulation, room orientation, and room type. A conservatory or loft will need more cooling power than a bedroom of similar size. Jamie warns: 'A really common mistake is buying an undersized unit. 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. Glow Green provides a helpful chart:
- 100–150 sq. ft. / 9–14 sq. m.: 8,000 BTU
- 150–250 sq. ft. / 14–23 sq. m.: 9,000 BTU
- 250–300 sq. ft. / 23–28 sq. m.: 10,000 BTU
- 300–350 sq. ft. / 28–33 sq. m.: 12,000 BTU
- 350–400 sq. ft. / 33–37 sq. m.: 14,000 BTU
- 400–450 sq. ft. / 37–42 sq. m.: 18,000 BTU
- 450–650 sq. ft. / 42–60 sq. m.: 25,000 BTU
Running Costs and Energy Efficiency
'Running costs depend on the size of the space, insulation, glazing, solar gain, tariff, and how aggressively the system is used,' Jamie says. '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.' Using an electricity calculator, that equates to about £0.06 per 10 minutes, 36p per hour, or £8.64 per day if running 24 hours, though continuous 24-hour use is unlikely. Jamie recommends: 'Homeowners can reduce running costs by 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 Brands and Models
AEG Comfort 6000 Air Conditioner – 9,000 BTU, cools up to 21m², Wi-Fi connectivity, LED display, CleanAir filter. Priced from £489.
LOGIK LAC07C25 Portable Air Conditioner & Dehumidifier – 323m³/h airflow, dehumidifier, 24-hour timer, remote control. Priced at £299.
DELONGHI Pinguino AP98 GentleJet – 11,500 BTU, GentleJet airflow, Eco RealFeel technology, quiet night mode. Priced at £799.
MEACO MeacoCool MC12000CHR PRO Smart – 12,000 BTU, 3-in-1 (cool, heat, dehumidify), smart app control. Priced at £479.
Bush 9K Air Conditioner – 9,000 BTU, four modes, 24-hour timer, sleep mode. Priced at £375.
Environmental Impact
Portable air conditioning units aren't always eco-friendly. Eco modes and energy ratings help, and solar panels can power units. Andrew Sissons, sustainable future director at Nesta, says people shouldn't feel guilty for using them, acknowledging they are a 'last resort' for many. Nicole Miranda, sustainable cooling researcher at the University of Oxford, notes they can be vital for keeping vulnerable people safe. Earth.org reports that air conditioners worsen global warming, but advises setting them to 26°C instead of 24°C, which consumes around 30% less energy. They also recommend regular filter cleaning and opting for models with a high Seasonal Energy Efficiency Ratio (SEER).
Are Portable Air Conditioners Worth It?
Despite upfront costs of a few hundred pounds and potential daily running costs up to £8, hot weather can cause dehydration, overheating, and heatstroke. According to the head of the World Health Organization (WHO), the heatwave in Europe has already been linked to 1,300 deaths. People over 65, babies and 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. He says he had it on 'constantly' all last week, and claims it 'pretty much saved my life', though he notes 'I'll find out next month if it's also pretty much bankrupted me'. In comparison, according to Checkatrade, a 12,000 BTU wall-mounted unit costs around £750, plus £1,150 for installation, and air conditioning engineers charge around £280–£720 per day. So a portable unit is far cheaper and keeps you cool, sane, and safe.
Cheap Alternatives Without Aircon
No aircon? Put a bottle filled with ice and a tablespoon of salt into your freezer; the salt lowers the freezing point, creating colder ice. Place the bottles in front of a fan; as the ice melts, the fan blows cool air. Also, keep curtains and blinds closed, especially blackout varieties, and keep windows shut during the hottest part of the day.
