At the top of the list of requirements for modern heating systems are energy efficiency and low carbon emissions.

Wood burning stoves meet both criteria and these efficient stoves can help householders meet the current and future energy efficiency requirements.

Wood Logs as Fuel

Wood is a renewable fuel and, when sourced sustainably, is considered by the SIA to be very low carbon.  

Wood logs are categorised as a biomass fuel and biomass is defined by the EU as a renewable energy source (Source:Directive (EU) 2018/2001 on the promotion of the use of energy from renewable sources, see Article 2.1).

The UK government “sees biomass as a low-carbon fuel provided that it is produced from sustainable sources” (Source: National Audit Office) and the Scottish Government defines biomass combustion as producing “net zero carbon emissions at the point of use” (Source:New Build Heat Standard (amended) 2024: business and regulatory impact assessment (see Section 10 and 11).

Fossil fuel carbon originates from ancient organic matter that has been concentrated and buried and transformed into coal, oil or natural gas over millions of years. However, the carbon released when wood logs are burnt is biogenic carbon as it originates from living (or recently living) organic matter.  Wood fuel is therefore part of a relatively short-term carbon cycle. The UK Forestry Standard which sets out the government’s approach to sustainable forestry states that: “Although burning wood generates carbon dioxide, an equivalent amount of carbon dioxide was relatively recently sequestered from the atmosphere as the trees grew.”

Stoves as secondary heating

Many people choose to have a room heater to provide heating when the outside temperatures don’t justify the use of the central heating system or to create a focal point in a living room.

Until now, the most popular forms of room heating have been open fires or room open gas effect fires. Neither of these room heaters is particularly efficient. An open fire has an efficiency of approximately 25% and a room open gas effect fire in the region of 55%.

The low efficiency with the carbon content of the fuel increasingly makes these options difficult to install in an energy efficient house. A wood burning stove ticks all the energy efficiency & carbon saving boxes.

The minimum efficiency of a modern Ecodesign compliant stove is in excess of 75% with the more efficient stoves achieving 80% plus. This level of efficiency combined with the low CO₂ output makes wood burning stoves very environmentally friendly.

Stoves as primary heating

A wood burning stove can also be used as primary heating so long as the stove can heat more than one room.

The SAP energy efficiency software caters for the specification of more than one source of primary heating.

A typical example could be 2 primary heating systems consisting of a condensing boiler, heat pump or pellet boiler, with a linked stove system responsible for heating the living rooms.

This will allow a wood burning stove to provide a significant contribution to the renewable energy sources of the house, while providing house owners with the aesthetic feel they want their house to have.
An oil boiler, for example, will struggle to meet the carbon output requirements of SAP and will need to rely on other features of the house to meet the SAP requirements.

The low level of CO₂ produced by burning wood makes a wood burning stove an ideal and affordable method of doing this.

The Chimney

The chimney plays an important role in the heating system as an efficient heating appliance requires a well and consistently insulated chimney to perform efficiently.

Chimneys are available in a range of materials. Clay and concrete liner systems require insulation to be fitted at the time of installation.

Prefabricated chimney systems in stainless steel, pumice and clay include the insulation as part of the system. Stainless steel tends to be used in existing houses because it is light-weight and does not require a specially constructed foundation.

A new chimney can be easily installed in a house that does not have one and an existing chimney can be relined with flexible stainless steel to create a suitably sized flue for a stove.

Further information on chimneys & flues can be found on the BFCMA (British Flue & Chimney Manufacturers Association) web site www.bfcma.co.uk

Understanding SAP

SAP is the Standard Assessment Procedure used to calculate the overall energy efficiency and carbon output of a house.

The program produces a single value for the energy efficiency of the house and for the amount of CO₂ given out. The energy efficiency and CO₂ output of the components of the house are combined to produce an overall result for the house.

A more efficient or less carbon intensive component can be used to compensate for a less efficient/more carbon intensive one.

This method of ‘carbon trading’ within the house means that a less carbon intensive appliance like a wood burning stove can be used to compensate for a more carbon intensive appliance.