Key Takeaways
- Rising summer temperatures are prompting many UK households to install air‑conditioning (AC), with an estimated 4 million homes now equipped – double the figure from three years ago.
- Portable AC units are common but less efficient; built‑in systems are more effective but costlier to purchase and install, and they consume roughly three times more electricity than portable models.
- Pairing AC with renewable electricity (e.g., rooftop solar or grid‑supplied renewables during peak green periods) can markedly reduce its carbon footprint.
- Heat‑pump‑style air‑to‑air systems provide both heating and cooling, offering a larger climate benefit when they replace fossil‑fuel heating, especially with the forthcoming £2,500 government grant in England and Wales.
- Passive cooling measures—shutters, shading, night‑time ventilation, green roofs, and insulation—can lower or even eliminate the need for mechanical cooling.
- Fans remain a low‑cost, low‑emission alternative; running a fan continuously costs only 15‑31 p per day versus about £5 for a portable AC unit run 24 hours.
- Vulnerable groups (children, older adults, those with health conditions) benefit most from AC during extreme heat, so its use can be justified as a health‑protection measure when deployed responsibly.
Current Heatwave Prompts UK Households to Consider AC
When a heatwave swept the UK this week, software developer Jon Connorton began tracking indoor temperatures in his east Hampshire terrace house, noting that some rooms approached 40 °C. Uncomfortable nights led him to wheel out a portable air‑conditioner, a plug‑in device that extracts heat from indoor air and expels it outside via a hose through a window or door. Connorton runs the unit only when his rooftop solar panels can supply the electricity, yet he still questions whether using AC is environmentally responsible, describing it as a “luxury” that feels “bad for the environment.”
Growing Adoption of Air Conditioning in Britain
Most British homes were not designed for extreme heat, yet the climate crisis is driving a rapid uptake of cooling technology. An estimated 4 million UK households now have an air‑conditioner, a figure that has doubled in the last three years. Portable units with a power rating of about 1 kW are slightly more prevalent than built‑in systems, which can draw as much as 2.7 kW—comparable to an electric oven. The government’s Climate Change Committee estimates that roughly 22 % of homes will require active cooling (such as AC) with 2 °C of global warming, highlighting both a growing need and a potential obstacle to net‑zero goals.
Environmental Impact of Air Conditioning
Because AC units consume more energy than passive cooling methods, they generate higher carbon emissions. The Energy Saving Trust calculates that operating a portable unit for an average of eight hours per day during summer produces about 4.87 kg of CO₂—roughly equivalent to driving 18 miles. Nicole Miranda, a sustainable‑cooling researcher at the University of Oxford, acknowledges the emissions concern but praises Connorton’s strategy of coupling AC with solar electricity as “good thinking” and “really considerate.”
Strategies to Make AC Greener
For households without solar panels, several approaches can lessen the climate impact of AC. Running the unit during periods when the grid has a high share of renewable energy—typically midday sunshine—reduces reliance on fossil‑fuel generation. Pre‑cooling rooms before the evening electricity peak, or using a home battery that stores excess renewable power for later AC use, are additional tactics. Andrew Sissons of Nesta notes that even less‑efficient portable ACs are often employed only as a “last resort,” and that the health benefits for vulnerable occupants can justify their use when deployed thoughtfully.
Heat‑Pump Alternatives Offer Greater Efficiency
Natalie Mathie of Uswitch explains that AC powered solely by grid electricity cannot be considered truly “green” until the entire electricity supply is renewable. In contrast, heat pumps move heat rather than generate it, delivering about three units of cooling for each unit of electricity consumed. Built‑in air‑to‑air heat pumps, which are reversible and provide both heating and cooling, represent a more environmentally sound option, especially when they replace oil or gas boilers.
Cost and Installation Considerations for Built‑In Units
Built‑in air conditioners are substantially more expensive to run than portable versions—nearly three times higher operating costs—due to their greater power draw. A wall‑mounted unit capable of cooling an average British bedroom (≈12,000 BTU) costs roughly £750 for the equipment plus £1,150 for installation, according to Checkatrade. The comparable portable unit is priced at about £350. Proper sizing is crucial; an oversized unit wastes energy, while an undersized one struggles to maintain comfort.
Passive Cooling Can Reduce or Replace Mechanical Cooling
Before resorting to AC, homeowners can adopt passive cooling strategies that limit heat gain. Installing shutters or external shading, opening windows for night‑time ventilation when temperatures drop, adding green roofs, and improving insulation all decrease the amount of heat that enters a dwelling. Miranda mentions using wet towels as makeshift curtains with a fan—a low‑tech method that can provide noticeable relief. Relying on such measures can lower the overall demand for AC, thereby cutting both energy use and emissions.
Fans Versus Air Conditioners: Cost and Emissions
Fans remain the most economical and low‑emission cooling option. The Energy Saving Trust estimates that running a fan continuously for 24 hours in Great Britain costs between 15 p and 31 p, resulting in negligible carbon emissions. In contrast, a portable AC unit operated nonstop for the same period costs about £5—more than 20 times the expense of a typical fan. A 2021 study found that, during hot days between 2007 and 2019, an electric fan alone provided comparable protection against heat stress as an air conditioner, suggesting that fans can be sufficient for many moderate heat events.
Looking Ahead: Balancing Comfort, Health, and Climate Goals
Connorton anticipates needing cooling more frequently as UK summers continue to warm, reflecting a broader societal shift toward accepting mechanical cooling as a necessity rather than a luxury. While the environmental drawbacks of AC are real, thoughtful use—paired with renewable energy, limited to essential periods, and complemented by passive cooling—can mitigate its impact. For those seeking a longer‑term solution, investing in an air‑to‑air heat pump that replaces fossil‑fuel heating offers a dual benefit: winter warmth and summer cooling while advancing decarbonisation. The forthcoming £2,500 grant for heat‑pump installations in England and Wales may accelerate this transition, helping households stay comfortable without compromising the UK’s net‑zero ambitions.