Many people leave their heating on low overnight thinking it will save money and make mornings more comfortable. In reality, most UK homes behave very differently once the heating goes off. Whether leaving radiators on overnight helps or wastes money depends on how quickly the house loses heat, not on the thermostat setting itself.
This is why the same approach can work in one home and fail completely in another.
Turning the heating off overnight usually costs less
In most UK homes, especially older or poorly insulated ones, heat escapes steadily through walls, windows and loft spaces overnight. Leaving radiators on low does not stop this heat loss — it simply replaces the lost heat continuously.
As a result, the house still cools by morning, but gas or electricity has been used all night to slow that drop. In these homes, turning the heating off overnight and reheating in the morning is usually cheaper than running it continuously.
Why leaving radiators on low rarely keeps the house warmer
Once the heating output drops below the rate at which the home loses heat, indoor temperatures continue to fall. A low overnight setting often feels reassuring, but it does not change how fast heat escapes.
This is why many homes feel just as cold in the morning whether the heating was left on low or turned off entirely.
When leaving heating on low overnight can make sense
There are situations where overnight heating can help. Well-insulated homes, newer builds, and properties with very low heat loss can retain warmth effectively. In these cases, a low overnight temperature may prevent large temperature swings and make mornings more comfortable.
Homes with underfloor heating or high thermal mass also behave differently, as they release stored heat slowly rather than cooling rapidly.
A cheaper alternative for most homes
For the majority of properties, a timed approach works better. Turning the heating off overnight and setting it to come on 20–30 minutes before waking allows rooms to warm efficiently without running the system for unnecessary hours.
If radiators struggle to heat quickly in the morning, that usually points to a circulation or balance issue rather than a timing problem. This behaviour is explained in why radiators take ages to heat up.
Why overnight heating often feels logical but isn’t
Leaving heating on overnight feels like it should save energy by avoiding reheating from cold. In practice, reheating a cooled house is often cheaper than replacing lost heat continuously over several hours.
The key factor is how well the home holds heat — not how gently the boiler runs.
How this fits into keeping heating costs low
Overnight heating decisions work best when combined with proper radiator balance, stable boiler pressure, and reduced heat loss. When these are in place, short heating bursts are usually more efficient than long low-level runs.
How this approach fits into a full, practical strategy for reducing heating costs is covered in How to Keep a UK Home Warm for Cheap.
