Should I get air conditioning in the UK – and can it be green?

An estimated 4 million UK homes now have air conditioning, a figure that has doubled in three years as hotter summers drive demand [1]. Portable units are more common than built-in systems, but their rising use poses energy and emissions challenges [1]. Portable air conditioners, with power ratings around 1kW, are slightly more prevalent than built-in versions, which can consume 2.7kW [1]. About 22% of British homes would require active cooling with 2C of global heating, according to a recent government climate report [1]. Using a portable unit for eight hours a day in summer generates about 4.87kg of CO2 emissions, equivalent to driving 18 miles [1]. Homeowner Connorton, who runs his unit only when his solar panels can power it, expressed a common guilt: “You feel it’s a luxury and that you’re being bad for the environment” [1]. Built-in air conditioners are nearly three times more expensive to run than portable versions [1]. A wall-mounted unit powerful enough to cool an average British bedroom (12,000 BTU) costs about £750 plus installation, compared to £350 for a portable equivalent [1]. Richard Lowes of the Regulatory Assistance Project notes portable units are relatively inefficient because they lower indoor air pressure, drawing warm air back inside [1]. In HVAC systems, ducts are used to deliver and remove air to ensure thermal comfort and air quality, a principle central to built-in systems [3]. Experts suggest strategies to mitigate environmental impact. Nicole Miranda, a sustainable cooling researcher, called pairing air conditioning with solar electricity “really considerate” [1]. Running units during peak renewable energy generation or using a home battery charged during surplus periods can reduce grid strain [1]. Natalie Mathie of Uswitch stated, “Air conditioning that runs purely on grid electricity won’t be truly ‘green’ until the entire grid runs on renewable energy” [1]. For broader decarbonization, Andrew Sissons of Nesta highlighted that homeowners switching from fossil fuel heating to reversible air-to-air heat pumps for both heating and cooling achieve a “big climate win” [1]. The government now offers a £2,500 grant in England and Wales for such installations [1]. Alternatives like fans remain significantly cheaper, with typical running costs of 15p-31p for 24 hours, compared to £5 for a portable air conditioner over the same period [1]. Passive measures such as shading windows, night ventilation, and insulation can reduce cooling demand [1].