For example, if you mainly use your living room during the day, should you have the central heating off and just heat that room?
As it turns out, the main method you use to heat your home has the biggest influence on whether it's worth heating a room individually or not, but the size of the room in question – compared to the size of your whole house – is also key.
If you have a boiler
If you have a modern gas or oil central heating system and a well-insulated home, it's probably best to use your central heating to heat most of your home, rather than just heating one room individually.
Features like a balanced flue - which draws in air from outside to feed the burning process, as well as expelling the fumes - heat exchangers and condensing technology mean that all in all, the modern boiler is the most efficient way of heating the home.
If you have central heating radiators with temperature controls
If you have an up-to-date heating system, you probably also have temperature controls on your radiators — also known as thermostatic radiator valves or TRVs.
They allow you to vary the temperature of different rooms in the house, which means you can use the main heating to keep a reasonable background temperature around the home, while at the same time using the radiator controls to increase the temperature in one particular room when you need to.
If you have central heating radiators without temperature controls
If you don't have the option of using radiator controls you may want to use a gas fire or electric heater in a room where you spend a lot of time — although it's still a good idea to use your main heating to keep a reasonable background temperature around the home.
If you do this, however, make sure your thermostat isn't in the room with the additional heating, otherwise it will disrupt control of the main heating system. If you have a wireless thermostat, move it out of the room you're locally heating.
If you have storage heaters
If the main method you use to heat your home is a storage heater, the considerations are different.
A storage heater is designed to predominantly use off-peak electricity, but it's generally assumed that you will need to top this up with some peak-rate electricity usage to provide extra warmth when and where it is required.
In this case, it may be worth heating a small room separately, but if you do so, remember to close the door of the room to keep the heat in.
If you have a gas fire
If your living room has a gas fire, it would only be worth using this rather than your central heating if the room is less than a third of the size of your home.
While a modern central heating boiler might have an efficiency of 90%, a gas fire might only be around 50% to 60% efficient, and an open flame gas fire as little as 30% efficient or lower. This is because a lot of heat is lost up the chimney or flue.
A gas fire also needs a supply of fresh air to provide oxygen for the gas-burning process. That fresh air is drawn into the room through a ventilator or air-brick. Unfortunately, this ventilation works all the time and can lead to the loss of warmth and warm air, even when you're not using the fire.
For some homes, flueless or catalyst gas fires are more practical to install, but from an efficiency perspective they still need ventilation - more than with a traditional gas fire - whether the fire is on or not.
A balanced flue gas fire could be a good option - they don't need ventilation and although they are expensive to buy, they are cheaper to run than other options as they can be as energy-efficient as condensing central heating boilers.
If you have a portable heater
Portable heaters and small heating devices don't tend to be particularly energy-efficient. They don't use the cheapest fuels and it's also very easy to end up overheating the room, so avoid using them if you can.
Movable bottled gas heaters (known as liquid petroleum gas or LPG) are the same, as a lot of ventilation is required to avoid fumes and condensation.
If you have a smaller home
In smaller homes, it's rarely worthwhile heating an individual room and is generally better to heat the whole house.
If you have a larger home
In larger homes, a small room may be worth heating individually if it's less than a quarter of the size of the whole house, although there's less benefit if your house is well-insulated.
If your home is open-plan
If, like many modern houses, you have an open-plan layout, perhaps with your stairwell, hall or dining room merged with your living room, then it won't be energy-efficient to try and heat just one room. If you have high ceilings the same rule applies.
Other things to consider
There are other factors when it comes to deciding whether or not to try and heat a room individually.
From a health point-of-view, it's better to err on the side of caution when you're considering heating just one room, especially if you're elderly or disabled, or there are young children in the home. As far as basic comfort is concerned, heating one room is not helpful if it means you have to go from a warm room to a cold room.
Safety is another important consideration. Open-fronted gas and solid fuel fires can be hazardous to children and other vulnerable people, as there's a risk of falling into or against them.
It's far safer - and more energy-efficient - to opt for a glass-fronted fire or stove, but care is still required. If you have a gas fire it's important to have it serviced regularly; in rented homes, this is the landlord's responsibility.
Is it cheaper to heat one room with an electric heater?
It might be cheaper to heat one room with an electric heater, but it depends on the size of the room and the length of time you need to heat it for. Gas costs significantly less than electricity per kWh, but will usually be heating more than one room via the central heating system, so it will often work out more expensive overall.
