Across Europe and the UK, plenty of households argue over whether it is sensible to leave radiators ticking over all day on a low setting. With gas and electricity costs climbing, the approach can feel reassuring - almost like a careful, common-sense choice. An industrial engineer who focuses on domestic energy, however, says it is a comforting idea that should be binned.
The myth of “always on” heating
The pitch is simple and sounds plausible: if your home never gets the chance to cool down, the boiler will supposedly “work less”, and overall energy use will fall. The message is repeated across social media, and some landlords even pass it on to tenants as a money-saving tip.
From an energy perspective, keeping your heating constantly on at low temperature to save money is false, says industrial engineer Jorge Morales de Labra.
Morales de Labra, a Spanish industrial engineer and a familiar commentator on energy consumption, recently unpacked the logic on the radio. His point is rooted in basic physics: any heating system consumes energy for every minute it is operating. Keep it running for longer, and it will use more - even if the thermostat is set to a modest temperature.
He also argues that it usually makes financial sense to turn the heating off completely when you leave the house, even if it is only for a quick errand. If you nip out for a few minutes to buy bread, he says, switching the boiler off and then on again still generally uses less than leaving it idling in the background.
Why “low and constant” doesn’t add up
Heat loss never stops
A home is always shedding heat through walls, roofs, windows and the small gaps around doors. The bigger the difference between indoor and outdoor temperatures, the faster that heat escapes. So if you hold the inside at a steady 20°C while it is 5°C outdoors, warmth will leak out minute after minute, all day long.
To keep that 20°C constant, a boiler or heat pump has to keep topping the heat back up, repeatedly. By turning the heating off, the indoor temperature can drop a little, narrowing the gap with the outside air and lowering heat losses during the time the system is off.
The moment the heating stops, heat loss slows. Less time running usually means less energy burned over the week or the month.
Short breaks still matter
A common belief is that switching off only pays off for long periods away from home. Morales de Labra disputes that. Even 20–30 minute breaks can deliver noticeable savings because the system is doing nothing during that time, and no fuel is being used.
Modern boilers and heat pumps also restart efficiently and do not suffer the same drawbacks as some older systems. In most reasonably insulated homes, the “start-up cost” - the brief burst of energy as the system comes back on - does not outweigh the energy saved during a modest off period.
Thermostats, not intuition (Jorge Morales de Labra’s advice)
In real houses and flats, heating rarely behaves as tidily as it does in theory. Some rooms warm up faster than others, radiators can trap air, and people open windows at awkward moments. A programmable thermostat brings more order to that reality than relying on gut feeling.
- Aim for a comfortable daytime range of about 19–21°C in living areas.
- Keep bedrooms and corridors a little cooler.
- Drop the setpoint by several degrees overnight and when the home is empty.
- Use timed schedules so heating matches your actual routine.
Energy specialists often repeat a key rule of thumb: each extra degree on the thermostat can increase consumption by roughly 6–8%. That small nudge upwards can add up to a significant cost across an entire winter.
Practical ways to cut winter heating costs
Temperature, timing and behaviour
Morales de Labra’s view is that sensible heating is not about tolerating discomfort; it is about using energy only where it improves comfort, and avoiding waste that delivers nothing in return.
The goal is not “spend less at all costs”, but use energy better and avoid waste that never improves comfort.
In most homes, bills are mainly driven by three levers: the temperature you choose, the hours the system runs, and how well the building holds on to heat.
| Action | Typical impact |
|---|---|
| Reduce thermostat by 1°C | About 6–8% less energy use |
| Turn heating off when away | Cuts runtime, lowers total fuel burned |
| Improve window and door sealing | Reduces draughts, slows constant heat loss |
| Use daily schedules | Heating only when the home is occupied |
Insulation and simple fixes at home
No control strategy performs well in a property that leaks heat from every surface. In poorly insulated flats, warmth can disappear so quickly that the boiler ends up cycling frequently even when you are aiming for modest temperatures. Proper insulation upgrades bring long-term savings, but it is often worth starting with inexpensive basics.
Without any major renovation work, households can tackle several simple points:
- Seal gaps around windows and doors using adhesive strips.
- Use thicker curtains and shut them at night to trap heat indoors.
- Put rugs on cold floors to reduce how chilly rooms feel.
- Keep internal doors closed so heat stays in the rooms you actually use.
By slowing heat loss, these measures give the heating system longer rest periods and reduce how often it needs to fire.
Using free solar heat wisely
Even in northern climates, winter sunshine provides free warmth. South-facing windows can work like passive radiators when curtains and blinds are left open during the day. Once the sun goes down, closing them promptly helps keep some of that gained heat inside.
Think of curtains and blinds as a second, temporary layer of insulation you control daily at no extra cost.
In smaller living rooms especially, the gap between a home that captures solar gain all day and one kept shaded behind closed blinds can be several degrees.
A couple of extra low-cost checks that support timed heating
It also helps to make sure your system is delivering heat efficiently when it is on. Bleeding radiators that have cold patches (often at the top) can improve heat output and reduce how long the boiler needs to run. Likewise, keeping furniture away from radiators and ensuring curtains do not drape over them allows warmth to circulate properly rather than being trapped at the window.
Annual boiler servicing and correct system pressure are not glamorous money-savers, but they can prevent inefficient operation. For heat pumps, asking an installer about appropriate flow temperatures and weather compensation can make a noticeable difference to running costs while still following the same principle: avoid unnecessary runtime, and heat the home only when it brings comfort.
Rethinking common heating habits
Comfort versus habit
A lot of heating routines are driven more by fear of feeling cold than by real evidence. People leave radiators on “just in case”, or warm rooms no-one uses simply because “it’s what we’ve always done”. When energy prices rise, those habits become expensive very quickly.
Energy engineers often suggest a straightforward exercise: walk through your home one evening and ask, room by room, when and why it truly needs heat. A spare bedroom, storage area or corridor may require far less warmth than the sitting room or a child’s bedroom.
That kind of review typically leads to smaller heated zones, fewer operating hours and reduced bills - with very little change in day-to-day comfort.
When “always on” might feel tempting
There are limited situations where near-continuous low-level heating can seem attractive: very old buildings with thick stone walls, homes with persistent damp, or people with particular medical needs who struggle with temperature swings. Even in these cases, engineers usually prefer controlled setbacks rather than genuinely constant operation.
Rather than running a boiler 24/7, a specialist might recommend a smaller overnight setback, a moderate daytime setpoint, and targeted improvements to the most exposed windows or walls. The underlying principle remains the same: keep runtime in check and avoid large indoor–outdoor temperature gaps when the space is not being used.
Looking ahead: smarter, not harder, heating
Smart thermostats and connected radiator valves add another layer of control. They can learn occupancy patterns, spot open windows and adjust temperatures room by room. For many households, this is a practical way to break the “always on” heating myth, because the system automatically trims output during absences.
For example, a family could set the home to sit at 17°C during working hours, climb to 20°C about an hour before everyone returns, then drop again at bedtime. The boiler runs for fewer hours, the house still feels pleasant on arrival, and costs fall across the season.
It can also be worth matching your heating schedule to how you are billed. If you are on a time-of-use tariff, the cheapest hours may not line up with when you currently heat the house. Checking a smart meter (where available) and shifting some heating to align with occupancy - rather than running “low and constant” all day - can make the savings more visible and easier to stick with.
If you are unsure how your own property responds, a small test over two cold weeks is often convincing. Keep the same comfort level, but compare two patterns: one week of constant low heating, and one week of timed heating with small setbacks. Watching actual consumption on your meter frequently changes minds faster than any technical explanation.
Underneath the debate is a wider challenge: staying comfortable through colder months without wasting money and energy. Engineers such as Jorge Morales de Labra argue that the solution is not to keep systems quietly humming in the background, but to choose when warmth genuinely matters - and cut everything else.
Comments
No comments yet. Be the first to comment!
Leave a Comment