Common Household Devices That Push Up Electricity Bills During a Heatwave

Portable air conditioners, fridges and freezers running harder, and continuous fan use are among the household devices that push up electricity bills during a UK heatwave. The Energy Saving Trust publishes typical running costs by appliance, and on the new Ofgem cap level from 1 July a few common devices can add tens of pounds to a monthly bill if used heavily.

Portable air conditioning units

Portable air conditioning units typically draw 700 to 1,500 watts. At a unit rate of around 27p per kWh under the new cap, running a 1,000-watt unit for eight hours a day costs about £2.16 a day, or £65 over a month.

Newer inverter units operate more efficiently than older equipment and modulate output based on the room temperature. Energy Saving Trust analysis suggests inverter portable units cost roughly 30 per cent less to run than equivalent older models.

Fridges and freezers in the heat

Fridges and freezers work harder when ambient temperatures rise because the temperature difference between the inside of the appliance and the kitchen is larger. Energy consumption can rise 20 to 30 per cent during a sustained heatwave.

Keeping the appliance away from direct sunlight, leaving space behind for air circulation and not opening the door unnecessarily all help to limit the extra usage. Replacing rubber door seals that have stiffened with age also reduces leakage.

Electric fans and tower fans

Electric fans draw far less than air conditioning, typically 40 to 90 watts depending on size. Running a 60-watt fan continuously for 12 hours a day costs about 19p a day under the new cap, or under £6 a month.

Tower fans, pedestal fans and ceiling fans differ in air movement and noise level rather than in fundamental electricity use. Energy Saving Trust ratings are not provided for fans because consumption is low compared with larger appliances.

Other heat-related cost drivers

Garden hosepipes, paddling pool pumps and outdoor lighting all draw modest power but add up over a sustained warm spell. Hosepipe bans set by water companies can affect garden use rather than electricity consumption.

Dehumidifiers run more during humid weather, which often follows heatwaves as the system breaks. A typical 250-watt dehumidifier costs about 7p an hour to run on the new cap.

How to manage usage during the cap rise

Smart meter data, accessible through the supplier's app or in-home display, shows half-hourly consumption. A spike in usage during the heatwave is normal but the data identifies which appliances are driving the rise.

Households who can shift consumption to off-peak hours, including running washing machines, dishwashers and dryers in the evening, save against the cap on time-of-use tariffs. Standard variable tariffs charge the same rate at any time of day.

FAQ

How much does running a portable air conditioner cost?

About £2.16 a day for a 1,000-watt unit running eight hours, or around £65 over a month under the new Ofgem cap from 1 July. Inverter units cost roughly 30 per cent less to run than older models.

Do fridges use more electricity in hot weather?

Yes, by 20 to 30 per cent during a sustained heatwave. The appliance has to work harder to maintain the internal temperature when the kitchen is warmer. Keeping it out of direct sunlight and with airflow behind reduces the extra usage.

Is a fan cheaper than air conditioning?

Substantially. A 60-watt fan running continuously for 12 hours a day costs under 20p a day, compared with around £2 a day for a typical 1,000-watt portable air conditioner.

How do I see my real-time electricity usage?

Through the supplier's app, your smart meter in-home display or your online account. Smart meters show half-hourly consumption, which makes it easier to identify which appliance is driving usage.