Sarah stares at her energy bill, the numbers glowing accusingly on her phone screen. £247 for January alone. Her flatmate Jake swears by leaving their heating on low all winter—”keeps the place steady, no shock heating costs.” But Sarah’s been switching it on and off, cranking it up when she gets home from work, then killing it before bed. Now they’re both wondering who’s been burning through their money faster.
This scene plays out in millions of homes every winter. You’ve probably had this exact argument with family, flatmates, or that little voice in your head when your thumb hovers over the thermostat. The heating on and off debate isn’t just about comfort—it’s about whether your next energy bill will make you wince or cry.
The answer might surprise you, because what sounds logical often isn’t what physics actually does in your living room.
Why turning heating on and off usually wins the money game
Here’s what really happens when you leave heating on low versus switching it on and off. Your home is basically a leaky bucket. Heat escapes constantly through walls, windows, doors, and every tiny gap your builders left behind. The warmer your house compared to outside, the faster that heat runs away.
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When you keep heating on low, you’re topping up that leaky bucket for hours and hours. Your boiler works steadily, replacing every degree that sneaks out. It feels gentle, but those hours add up fast.
“Most people think constant low heating is efficient, but they’re paying for 12-16 hours of continuous heat loss,” says energy consultant Michael Chen. “With intermittent heating, you’re only paying for maybe 6-8 hours of active heat replacement.”
The physics is straightforward. More hours at higher temperature equals more total energy lost. Your boiler doesn’t get to rest just because it’s set to “low”—it keeps working whenever the house cools even slightly below your set point.
The real costs: what the numbers actually show
Multiple studies from energy agencies across Europe consistently point to the same conclusion. Switching heating on and off typically uses 10-30% less energy than leaving it on low, depending on your home’s insulation and outside temperature.
Here’s how the costs break down in a typical UK home:
| Heating Method | Daily Hours Active | Average Daily Cost | Monthly Estimate |
|---|---|---|---|
| Constant low (16°C) | 14-16 hours | £8-12 | £240-360 |
| On/off (20°C when needed) | 6-8 hours | £6-9 | £180-270 |
| Smart scheduling | 5-7 hours | £5-8 | £150-240 |
The savings get bigger when outside temperatures drop. During cold snaps, leaving heating on low can cost nearly twice as much as strategic on/off heating.
But here’s where it gets interesting. The type of heating system you have makes a huge difference:
- Gas boilers: Turning on and off almost always saves money
- Heat pumps: Work better with steadier temperatures, but still benefit from some scheduling
- Electric heating: Massive savings from on/off approach, especially with time-of-use tariffs
- Storage heaters: Already designed for intermittent heating cycles
When leaving heating on low might actually make sense
Before you rush to reprogram your thermostat, there are specific situations where constant low heating could work better for your wallet and comfort.
Older homes with terrible insulation sometimes behave differently. If your house loses heat so fast that it takes hours to warm up again, you might spend more energy on those big reheating cycles.
“In poorly insulated homes, especially those built before 1970, the reheating penalty can sometimes outweigh the savings from intermittent heating,” explains heating engineer Lisa Rodriguez. “But even then, better insulation pays for itself faster than accepting high heating bills.”
Heat pumps also prefer steadier temperatures. These systems work most efficiently when they don’t have to work too hard, so dramatic temperature swings can hurt their performance. However, even heat pump owners usually save money with some temperature scheduling rather than running constantly.
If you’re away for just a few hours, the energy needed to reheat might exceed what you save by turning off. The sweet spot seems to be around 4-6 hours. Shorter than that, keep it on. Longer than that, turn it off.
Vulnerable household members change the equation too. If someone in your home has health conditions affected by temperature changes, comfort and safety matter more than optimal energy savings.
Smart scheduling beats both traditional approaches
The most efficient homes don’t choose between “always on low” or “manually on and off.” They use smart scheduling that heats different zones at different times based on actual usage patterns.
Modern programmable thermostats can learn when you’re home, which rooms you use most, and even factor in weather forecasts. This beats both old-school approaches because it heats spaces only when and where you need warmth.
“Smart heating systems typically save 15-25% compared to basic on/off heating, and 30-40% compared to leaving everything on low,” notes energy researcher James Park.
Simple improvements that boost any heating strategy:
- Set temperatures by zone: Heat bedrooms to 16-18°C, living areas to 18-21°C
- Use timers aggressively: Heat 30 minutes before you wake up, turn off 30 minutes before bed
- Close doors: Keep heat in the rooms you’re actually using
- Bleed radiators annually: Trapped air makes systems work harder
- Seal obvious draughts: Even small improvements help both strategies work better
What this means for your next energy bill
For most UK homes, switching to strategic heating on and off will cut energy bills compared to leaving heating on low. The savings typically range from £50-150 per year, depending on your home size, insulation, and local energy prices.
The biggest wins come from combining smart scheduling with basic efficiency improvements. Seal the worst draughts, use thermostatic radiator valves, and heat rooms based on when you actually use them.
Your heating system doesn’t care about your comfort myths—it just responds to physics. More hours at higher temperatures means more energy used, regardless of whether that feels “gentler” on the system.
Start with simple changes: set timers for morning and evening heating periods, drop nighttime temperatures by 3-5 degrees, and turn off heating in unused rooms. Track your usage for a month and compare bills. Most people find the savings obvious enough to stick with smarter heating habits.
FAQs
Is it cheaper to leave heating on low all day?
No, for most homes it’s more expensive because you’re paying for continuous heat loss over many hours. Turning heating on and off typically saves 10-30% on energy bills.
Does turning heating on and off damage the boiler?
Modern boilers are designed for regular cycling and won’t be damaged by normal on/off use. Constantly running on low actually creates more wear over time than intermittent heating.
How long should I leave heating off to save money?
Generally, if you’re away for more than 4-6 hours, it’s worth turning heating off. For shorter periods, the reheating cost often exceeds the savings.
What temperature should I set for maximum savings?
Aim for 18-21°C in living areas when occupied, 16-18°C in bedrooms, and 15°C or off in unused rooms. Each degree lower saves about 6-8% on heating costs.
Do heat pumps work better left on constantly?
Heat pumps are more efficient at steady temperatures than gas boilers, but even heat pump owners usually save money with some temperature scheduling rather than running constantly at the same level.
Should I heat unused rooms?
No, close doors and turn off radiators in rooms you don’t use regularly. Heating empty spaces wastes money regardless of your overall heating strategy.