Is It Cheaper to Run a Log Burner Than Central Heating: Winter Budgeting Tips

With energy prices so volatile, comparing logs and gas solely by their cost per kWh does not tell the full story. A log burner delivers concentrated, radiant warmth directly into the living space, while gas central heating distributes heat through water-filled radiators across multiple rooms. In practice, using a stove to heat the main living area can reduce reliance on the boiler and lower the total heating bill.

Log burners have several important advantages over gas central heating. They produce powerful radiant heat as well as warming the surrounding air, creating a comfortable living space without having to heat the entire property. The stove, firebricks, hearth and surrounding surfaces also absorb heat while the fire is burning and continue releasing it long after the flames have subsided.

This thermal mass gives a log burner a lasting warmth that conventional radiators struggle to replicate. Once central heating is switched off, radiators and the water inside them cool relatively quickly. A stove remains hot and continues radiating warmth into the room, while the walls, floors and furniture warmed by the fire also release stored heat gradually.

For an occupied living room, kitchen-diner, holiday let, restaurant or other shared space, a log burner can therefore use heat more purposefully. Central heating may consume less energy per theoretical kWh, but it often uses that energy to heat pipes, hallways, bedrooms and other areas that do not need to be as warm. A stove concentrates its output where people are actually sitting and where the warmth provides the greatest benefit.

Producing the same feeling of concentrated, long-lasting warmth with central heating may require the boiler to run for longer and supply several radiators. This is why the cheapest fuel per kWh is not necessarily the cheapest or most effective way to keep the occupied part of a building comfortable.

Every property is different, so logs and gas are not directly comparable in a purely practical sense. Gas central heating is designed to provide controlled heat throughout a building, whereas a log burner creates a warm focal point and allows the main living space to be heated independently. They perform different jobs and deliver noticeably different types of warmth.

For accuracy and fairness, we will compare the useful kWh output of kiln dried hardwood burned efficiently in a modern wood burning stove with the useful kWh delivered by a gas boiler through water-filled radiators. However, the figures must be considered alongside where the heat is delivered, how long the warmth remains and how much of the property needs to be heated.

We will also examine the one-room heating advantage of a stove, the whole-house role of central heating and the practical benefit of thermal mass. Maintenance costs—including boiler servicing and chimney sweeping—must also be included when preparing a realistic winter heating budget.

Most homes already use more than one source of heat. Central heating may be used in bedrooms, bathrooms and hallways, while a wood burning stove becomes the principal source of warmth in the living room or kitchen-diner. This combination allows the boiler thermostat to be lowered or the heating to run for fewer hours without making the most frequently occupied part of the home less comfortable.

Heat from the stove can also move into adjoining rooms and contribute to the general warmth of the property. By using kiln dried hardwood to provide concentrated and lasting heat in the heart of the home, households can reduce the work required from their gas boiler and potentially lower their overall winter heating costs.

1 Kilowatt Hour of Heat per kwh

As the introduction alludes, there is nuance in the question of whether wood heating reduces your annual energy costs. We can, however, compare the raw heat available from different fuels and calculate how much each kWh costs. Since utility bills show how much we pay per kWh for energy, it is a useful place to start.

Burning wet wood is neither safe nor efficient. Wood should be properly dried before burning, and seasoned wood can be suitable if its moisture content is below 20%, but we only sell kiln dried hardwood logs with a moisture content of 18% or less. Burning scrap wood can create health risks and add to wood smoke pollution, which is another reason we base this comparison on kiln dried hardwood only.

A typical hardwood, such as birch, ash or oak, with a moisture content of 18% or less provides approximately 4.2kWh of energy per kilogram. A stacked cubic metre of kiln dried hardwood logs may weigh around 450kg, although the precise weight varies by species and moisture content, and the average cost of kiln-dried firewood is often around £120 to £140 per cubic metre depending on supplier and species.

A birch crate currently costs as little as £277.51 in the summer sale. If it weighs approximately 450kg, that works out at just under 62 pence per kilogram.

This means that one kWh of raw energy from the logs costs around 15 pence, although broader comparisons often quote kiln-dried logs at roughly 7-9p per kWh of heat before appliance efficiency is applied.

The new UK gas price cap sets the average price of gas at approximately 7.9 pence per kWh. Mains gas is also often quoted at around 10-12p per kWh in broader comparisons, but here we are using the current cap figure for raw gas energy. On the face of it, therefore, energy from the logs costs around 7 pence more per kWh than gas. However, this is before considering the efficiency of either heating system, the gas standing charge and, importantly, where the heat is delivered.

Published estimates often put gas central heating at about £0.10 per kWh of useful heat and a wood-burning stove at roughly £0.10 to £0.20 per kWh, depending on fuel price and stove efficiency.

Useful Heat and Efficiency of Wood Burning Stoves

The raw comparison between gas and logs does not account for appliance efficiency or the amount of useful heat that reaches the home.

A modern stove operating efficiently may deliver approximately 80% of the energy contained in the wood as useful heat. In practice, wood burning stoves often achieve around 70–80% efficiency, while ecodesign stoves are commonly in the 75–85% range. Modern Ecodesign models also tend to have higher efficiency ratings and lower emissions than older appliances. Therefore, each kilogram of logs containing 4.2kWh of raw energy delivers approximately 3.36kWh of useful heat.

At 62 pence per kilogram, this makes the cost of useful heat from the logs approximately 18.5 pence per kWh.

A complete gas central heating system may achieve a real-world seasonal efficiency of around 80–85%. Some heat is lost through the boiler and flue, while some is released through pipes or into parts of the property where it is not particularly useful.

At 7.9 pence per kWh and 80% system efficiency, useful gas heat costs approximately 9.88 pence per kWh.

In the UK, we also pay a daily standing charge for gas, including during the summer when the heating may not be used. Standing charges vary by region, but in the South West the standing charge is around 28.68 pence per day.

If we attribute the annual standing charge entirely to a six-month heating season, it is equivalent to approximately 57.36 pence for each heating day. However, this would not be a fair allocation where gas is also used throughout the year for hot water or cooking.

When a gas boiler starts, it heats the water circulating through the pipes and radiators. Some heat begins entering the rooms fairly quickly, but it takes time for the complete system—and then the rooms themselves—to reach the required temperature.

Most modern boilers are modulating. They initially operate at a higher output and then reduce the flame as the property approaches the desired temperature. A boiler rated at 24–28kW will not normally consume 24–28kWh of gas during every hour it is switched on. The headline rating is its maximum output, and many combination boilers require that capacity primarily to provide hot water.

The actual cost of an evening’s central heating depends on the property, insulation, thermostat setting, weather, boiler controls and the number of radiators being heated. These are among the other factors that can materially change the real cost from one home to another. Nevertheless, central heating often uses energy to warm bedrooms, hallways and other spaces when the occupants are spending most of the evening in one room. That is why log burners are usually most economical when heating a single living space rather than trying to replace whole-house heating.

By contrast, a stove concentrates its heat in the room where people are sitting. If you burn 7.5kg of firewood during an evening, the logs contain approximately 31.5kWh of raw energy and cost £4.65 at 62 pence per kilogram. At 80% stove efficiency, they provide approximately 25.2kWh of useful heat.

The kWh cost of the logs remains higher than gas, but the practical use of that heat is different. Wood fuel can still work out cheaper than electric heating, which is often around 25–30 pence per kWh, even though it is often not cheaper than mains gas. A stove creates a concentrated source of radiant and convected heat in the room being occupied. Central heating distributes its output across the radiators and rooms connected to the system. Electric stoves can reach 95–100% efficiency, but the unit price of electricity is usually far higher.

When it comes to keeping one main living space comfortably warm, there really is no substitute for a real log fire.

Practical Advantages of Thermal Mass in Heating Systems

A wood burning stove does not stop heating the room the moment the flames die down. During combustion, its metal body, internal firebricks and surrounding hearth absorb some of the energy released by the logs. This stored energy is then gradually released into the room after the fire has subsided.

This is known as thermal mass. It does not create any additional energy—the heat released later is already included within the log’s useful heat output—but it changes how that energy is delivered. Instead of disappearing as soon as the fuel stops burning, some of the heat is stored within the stove and released steadily over a longer period.

A radiator has much less thermal mass. Once the boiler and circulation pump switch off, the relatively small quantity of water inside the radiator cools quickly. The stove, by comparison, may remain noticeably warm for hours, particularly if it is made from cast iron or incorporates substantial firebrick or stone.

There is also an important difference between radiant and convected heat. Radiators predominantly warm the air, which then circulates around the room. A stove also produces strong radiant heat, warming people, furniture, walls and floors directly. Those surfaces absorb some of the heat and release it gradually, helping the room continue to feel comfortable even after the fire has reduced.

This is why comparing logs and gas solely by their cost per kWh can be misleading. A kWh remains the same amount of energy, but its practical value depends on where, when and how it is delivered.

Gas central heating is highly effective when the aim is to warm an entire property evenly. A stove is particularly effective when the aim is to make the room being occupied warm and comfortable. The stove avoids deliberately heating every radiator in the house, provides immediate radiant warmth and stores part of its output in its own thermal mass and the surrounding room.

Logs may therefore cost more per theoretical kWh while still helping some households spend less overall. That is mainly true when the stove is displacing heat in one occupied room rather than trying to warm multiple rooms or the entire house. The saving does not come from firewood magically producing cheaper energy than gas. There can also be hidden costs with a stove, especially upfront installation and ongoing maintenance that do not appear in a simple fuel-only comparison. In practice, installation costs are significant: fitting a log burner typically ranges from about £700 to £3,500, with an existing chimney often keeping it nearer £700 to £2,000, while a new chimney can push the total up to about £3,500. Labour alone is often around £250 to £800, and annual chimney sweeping adds roughly £50 to £80. Published annual costs also vary widely with use and buying habits, with estimates for wood burners ranging from about £260 to £1,170 a year, fuel-only figures around £420 to £490 in some cases, and daily running costs around £2.00 to £9.00. Buying logs in bulk can help reduce running costs, while expensive bagged logs push them up. Some comparisons suggest a stove can cost about 13% less than gas heating or save up to £720 a year, but that depends heavily on usage patterns and the installation already being in place. It comes from using concentrated heat where it is most useful, allowing the thermostat to be lowered and reducing the time for which the whole-house central heating system needs to operate.