With a third heatwave hitting the UK this week, portable air conditioning units have become a must-have home accessory. Following record June temperatures of 37.3°C, units at discount supermarkets like Lidl and Aldi are sold out, but savvy shoppers can still find options online with speedy delivery or in-store collection.
How Do Portable Air Conditioners Work?
Portable air conditioners remove heat from a room, leaving indoor air cooler. There are two 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 conditions have a lot more power – one hose to pull in outdoor air and the other to vent this back out.'
Installation Tips
Jamie Hillard of Heatable.co.uk emphasises proper installation: '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 for around £19.98.
Choosing the Right BTU Size
Selecting the correct BTU (British Thermal Unit) rating is crucial. 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.' 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
Running costs vary, but Jamie notes: 'For portable AC units, many models are in the 1–1.5kW electrical input range when running.' Using an electricity calculator, that averages £0.06 per 10 minutes, or 36p per hour – up to £8.64 per day if run continuously. To reduce costs, he 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.' Setting the target temperature to 22–24°C instead of 18°C also saves energy.
Recommended Portable Air Conditioners
Bush 9K Air Conditioner – £375. 9,000 BTU, suitable for rooms up to 18m². Features four modes (auto, cooling, fan, dry), 24-hour timer, sleep mode, LED display, remote control, and castor wheels.
Bush 6.5L Vortex Blade Air Cooler – £85. 2-in-1 air cooler and humidifier with 6.5-litre water tank, three fan speeds, three modes, auto oscillation, and reusable ice packs. Suitable for rooms up to 25m².
Bush 4L 2-in-1 Air Cooler and Humidifier – £110. Evaporative cooling, 4-litre tank, three fan speeds, three modes, 60-degree oscillation, two ice packs, remote control, and seven-hour timer.
Meaco Cool MC 8000CHBTU Air Conditioner – £380. 8,000 BTU, suitable for 16–26m². Provides cooling, heating, dehumidifying, and fan modes. A-rated energy efficiency, app connectivity, remote control, 24-hour timer, castors, and window kits.
Meaco 14000BTU Air Conditioner – £500. 14,000 BTU, suitable for 25–35m². Four modes (Cool, Dry, Fan, Sleep), three fan speeds, 24-hour timer, humidity reduction, window kit, exhaust hose, castors, and A-rated energy efficiency.
Environmental Impact
While portable AC units aren't always eco-friendly, using eco modes and solar panels can help. Andrew Sissons of Nesta says people shouldn't feel guilty, as they are a 'last resort'. Nicole Miranda from the University of Oxford notes they can be vital for vulnerable people. Earth.org recommends setting units to 26°C instead of 24°C to consume 30% less energy, regular filter cleaning, and choosing models with a high Seasonal Energy Efficiency Ratio (SEER).
Are They Worth It?
Despite upfront costs of a few hundred pounds and potential daily running costs up to £8, hot weather poses serious risks. The WHO has linked the European heatwave to 1,300 deaths. Vulnerable groups include those over 65, babies, children under 5, and people with pre-existing conditions. For comparison, a 12,000 BTU wall-mounted unit costs around £750 plus £1,150 installation, making portable units a cheaper alternative.
