Why is my electricity bill high in summer?
In summer 2026, the average UK household’s electricity bill can be £40–£60 higher per month compared to winter, even without heating on, according to DESNZ data. You are not alone if you have opened a July or August bill and wondered where the extra usage came from. The answer is not a mystery: it is driven by a small number of power-hungry appliances that run for long hours in hot weather.
Your summer electricity bill is high because cooling appliances such as air conditioning, dehumidifiers and fridge-freezers run for many hours in hot weather, and each kWh costs 32p under the July 2026 price cap, roughly 10% higher than the winter 2025 cap (Ofgem, quarterly price-cap announcement, April 2026). Unlike winter heating, which is often gas at about 7p/kWh, summer cooling is almost entirely electric, so every cooling hour costs four to five times more per unit of energy.
Air conditioning is the biggest single summer power drain
A typical portable air-conditioning unit rated at 2.5 kW running for 8 hours a day uses 20 kWh, roughly £6.40 per day at the July 2026 price cap of 32p/kWh (Ofgem, quarterly price-cap announcement, April 2026). Central air systems in larger homes can double that daily cost, especially if the thermostat is set below 18°C. Many homeowners underestimate the cost because they run units intermittently, but the compressor cycles on and off, not reducing the total daily kWh as much as expected (Energy Saving Trust, “Air conditioning and cooling costs,” 2026).
If you run a portable unit for 12 hours a day on a heatwave week, your monthly air-conditioning cost alone can exceed £190. That is the single biggest factor pushing summer bills up.
Fridges and freezers work harder and cost more in summer
A fridge-freezer in a 28°C kitchen uses up to 30% more electricity than in a 18°C kitchen, according to EST lab tests from 2025 published in March 2026 (Energy Saving Trust, “Refrigeration energy use,” 2026). The average UK fridge-freezer consumes 400–500 kWh/year, so a 30% summer uplift adds roughly 100–150 kWh over June–August, around £32–£48 extra. Older appliances (pre-2015) are significantly less efficient: a 15-year-old model can use double the electricity of a modern A+++ unit (Energy Saving Trust, “Refrigeration energy use,” 2026).
If your kitchen faces south and gets direct afternoon sun, the compressor may run almost continuously on hot days. That is a hidden cost that does not show up on any single appliance label.
Dehumidifiers and fans add hidden costs
A dehumidifier running 12 hours a day at 300W uses 3.6 kWh, about £1.15 per day, or £35 per month (Ofgem price cap, 2026). A standard tower fan uses only 50W (£0.16 per day), but whole-house ceiling fans or multiple units can push the total to 1–2 kWh/day. Many homeowners leave dehumidifiers on 24/7 during humid summer weeks, not realising the cumulative effect on their bill (Energy Saving Trust, “Summer appliance running costs,” 2026).
If you have a basement or a damp ground floor, a dehumidifier running continuously can add £50–£70 to a single month’s bill. That is more than many people expect from a small appliance.
Quick numbers, summer electricity cost comparison table
| Appliance / Activity | Typical power (watts) | Daily usage (hours) | Daily kWh | Daily cost at 32p/kWh | Monthly cost (30 days) |
|---|---|---|---|---|---|
| Portable air conditioner (2.5 kW) | 2,500 W | 8 | 20.0 kWh | £6.40 | £192.00 |
| Fridge-freezer (summer uplift) | , | 24 | +0.8 kWh extra | +£0.26 | +£7.80 |
| Dehumidifier (300 W) | 300 W | 12 | 3.6 kWh | £1.15 | £34.56 |
| Ceiling fan (75 W) | 75 W | 8 | 0.6 kWh | £0.19 | £5.76 |
| Pool pump (1.1 kW) | 1,100 W | 6 | 6.6 kWh | £2.11 | £63.36 |
Source: Ofgem price cap (April 2026); EST appliance power tables (2026); MCS register typical pool-pump data (2026).
The direct answer, why your summer bill is high
Your summer electricity bill is high because cooling appliances (air conditioning, dehumidifiers, and fridge-freezers) run for many hours in hot weather, and each kWh costs 32p under the July 2026 price cap, roughly 10% higher than the winter 2025 cap (Ofgem, quarterly price-cap announcement, April 2026). Unlike winter heating (which is often gas at about 7p/kWh), summer cooling is almost entirely electric, so every cooling hour costs four to five times more per unit of energy. The combination of longer running times and higher electricity unit rates means a typical home can see a 20–40% summer uplift on the electricity portion of the bill (DESNZ, “Seasonal energy use patterns,” 2026).
If you have a swimming pool pump or a hot tub running in summer, that adds another £60–£100 per month on top of the cooling costs.
Eligibility and certification, how to verify your cooling appliance installer
For fixed air-conditioning systems, the installer must be registered with F-Gas Certification (GOV.UK, “F-gas regulations for stationary refrigeration and air conditioning,” 2026). For electrical work (installing new circuits for air conditioning or dehumidifiers), the electrician must be registered with NICEIC or NAPIT (GOV.UK, “Competent person schemes,” 2026). For portable units, no certification is required, but if you buy a unit rated over 12 kW (rare in homes), the installer must hold F-Gas certification.
If you are having a fixed system installed, ask the installer for their F-Gas certificate number and check it on the GOV.UK register before work starts.
Simple changes that cut summer electricity costs by 20–30%
Set air conditioning to 22°C instead of 18°C, this can reduce cooling electricity by 15–25% (Energy Saving Trust, “Air conditioning efficiency,” 2026). Use a programmable timer on the fridge-freezer’s defrost cycle (if available) to run it overnight when ambient temperatures are lower. Replace a pre-2015 fridge-freezer with an A+++ model, the payback on the extra summer uplift alone is roughly 3–4 years (Energy Saving Trust, “Refrigeration payback calculator,” 2026).
If you run a dehumidifier, set it to 50–55% relative humidity rather than “continuous” mode. That one change can halve its daily running time on all but the most humid days. how to reduce energy use in summer
