At a glance
- Colder weather increases the heat needed to maintain an indoor temperature, often raising consumption even when your thermostat setting stays the same.
- Shorter days, occupancy and hot-water habits can add to the change.
- Compare kWh, prices and billing periods separately; a higher winter bill does not automatically mean waste.
- Protect warmth, ventilation and essential equipment while checking controls and avoidable use.
For many homes and workplaces, winter brings a larger gap between indoor and outdoor temperatures. Heating must replace heat escaping through the building, so energy demand can rise even when daily routines appear unchanged.
Understanding that change helps you investigate costs without assuming every extra kWh could safely be avoided.
On this page
- Why the same thermostat setting can cost more
- Separate consumption, price and payments
- Other winter changes
- Understand different heating systems
- Review controls and heat loss
- Keep health and safety central
- What changes in business premises?
- Use winter information well
Why the same thermostat setting can cost more
A thermostat sets a target indoor temperature. In cold weather, the building generally loses heat more quickly than on a mild day. The heating may therefore run longer or work harder to maintain the same target.
Two homes with the same thermostat setting need not use the same energy. Size, insulation, exposed surfaces, draughts, occupancy and heating-system performance all matter. A neighbour’s bill is not a controlled test of your efficiency.
Energy Saving Trust explains how buildings lose heat and the role of insulation and other measures. A colder spell can reveal heat loss that is less noticeable in summer.
Separate consumption, price and payments
Look at kWh as well as pounds. A higher bill can reflect more energy, a different rate, a longer period or an account adjustment. Calculate daily consumption to make billing periods more comparable, while still allowing for weather.
For example, 1,000 kWh of gas over 30 days averages about 33 kWh/day. Using 1,500 kWh over 30 days averages 50 kWh/day. Investigate the change in heat demand or use before concluding that the gas price explains the whole increase.
A fixed monthly Direct Debit can stay level while seasonal energy costs change. Credit may build during summer and be used during winter. Ofgem explains this seasonal account pattern. The payment collected is not a direct measurement of that month’s consumption.
Other winter changes
Shorter daylight hours can increase lighting use. More time indoors can mean more cooking, entertainment or home working. Hot-water use and the temperature of incoming cold water can also affect energy demand.
Check what actually changed in your household rather than assuming every explanation applies. An extra person at home, a heated garden office or a portable heater may matter more than a small change in lighting.
Compare actual readings where possible. If one period used estimates and another used an actual reading, some apparent seasonal increase may be a billing correction.
Understand different heating systems
A resistance electric heater drawing a steady 2 kW for five hours uses 10 kWh. At an illustrative 30p/kWh, that costs £3 in consumption charges. The example assumes continuous full-power operation; a thermostatically controlled heater may cycle.
Several portable heaters can therefore create a substantial electricity load. Whether heating one occupied room costs less than a whole-home system depends on the system, rooms, tariff and safe temperature requirements.
Heat pumps are different from simple resistance heaters: they move heat and their efficiency depends on operating conditions. Do not apply a boiler-style on/off schedule without checking the system guidance. Energy Saving Trust answers common heat-pump control questions.
If a heating system seems to be operating incorrectly, get the appropriate installer or service support rather than changing unfamiliar technical settings.
Review controls and heat loss
Check schedules against when rooms are occupied and whether controls match the type of heating installed. Avoid overheating, but do not assume a long overnight shutdown suits every building or system.
Look for unintended draughts around external doors and windows. Appropriate draught-proofing can help comfort, but required ventilation must remain. Energy Saving Trust distinguishes draught-proofing from blocking necessary airflow. Do not seal air bricks, flues or ventilation openings needed for safe operation.
Insulation and other building work need to suit the construction and moisture conditions. A generic energy-saving tip is not a substitute for suitable advice on a particular property.
Keep health and safety central
Reducing heating until a home becomes dangerously cold is not an energy-efficiency improvement. Older people, young children and people with some health conditions can need particular protection.
UK Health Security Agency guidance for England recommends trying to keep regularly occupied rooms at least 18°C, with individual comfort and health needs considered. Some people need warmer conditions. Seek appropriate advice for the people living in the home.
Maintain suitable ventilation and do not use an oven, barbecue or other unsuitable appliance as room heating. If costs make adequate warmth difficult, contact the supplier and use independent household support.
What changes in business premises?
Businesses can have higher winter demand from longer heating hours, frequently opened doors, heated warehouses or extra lighting. Compare opening hours, weather and activity before judging performance.
Check for simultaneous heating and cooling, schedules left on after closing, and controls that do not reflect occupied zones. Protect stock, frost-sensitive equipment, required ventilation and safety systems.
The Carbon Trust’s office energy guides provide general ideas. For closures, use an agreed shutdown and restart plan instead of an instruction to switch everything off.
Use winter information well
Keep a short record of readings, weather, occupancy and major changes in equipment or controls. Compare similar periods and record whether readings are actual or estimated.
Lower spending can result from a tariff change without any fall in consumption. Lower kWh can result from milder weather without a building improvement. Environmental claims also need an appropriate emissions method, not simply a lower bill.
Related guides
- Investigating an unexpectedly high bill
- Five common household energy myths
- Understanding energy, cost and emissions
Sources and further reading
- Energy Saving Trust: reducing home heat loss
- Ofgem: how your electricity or gas bill is calculated
- Energy Saving Trust: heat-pump questions answered
- Energy Saving Trust: draught-proofing and ventilation
- UKHSA: keeping warm and well in cold weather
- Carbon Trust: office energy-efficiency resources
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