New Rules for New Houses
Wood Burning Stoves, Even More Environmentally – The Outworking of the New Document L
A real fire is an essential part of most people’s dream house. With the focus on energy efficiency and low carbon homes a wood burning stove can help fulfil this dream and make a significant contribution to energy efficiency and lower CO2 emissions.
The new Document L, which came into effect in October, increases the role a wood burning stove can play in the overall heating of a house. Under the old version of Document L a stove could only be used as a room heater and contribute a maximum of 10% to the heating of the house. With the new Document L a wood burning stove can be used as primary heating and be responsible for up to 100% of the house heating.
One of the most significant developments in Document L is the ability to use a wood burning stove as primary heating so long as the stove can heat more than one room. The new SAP 2009, which will apply initially to new homes, 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.
In recent years, when the cost of oil & gas was spiralling upwards many home owners were turning to linked stove & boiler systems to reduce their heating costs. Stove manufacturers have reported that stoves with an integral boiler is the fastest growing product sector. The changes in Document L should give greater momentum to this trend.
There is no longer a requirement to specify secondary heating in a house if the house can be heated adequately with the primary heating source. When secondary heating is specified it accounts for 10% of the overall heating of the house, if the house is on the gas main and 20% if the house is in an area without natural gas. Secondary heating is defined as a room heater, so a stand -alone stove can also contribute to the efficiency of heating the house and lower the CO2 emissions in this way.
Burning wood in an efficient stove is the key to achieving the carbon savings. Wood is the most environmentally friendly fuel that can be used. It is a renewable energy and virtually carbon neutral. The carbon factor for wood has been significantly reduced in the new SAP2009 to 0.007kg of carbon per kwatt compared with 1.98kg for gas, 0.274kg for oil and 0.517kg for electricity.
The amount of carbon produced by an appliance is a combination of the appliance efficiency and the carbon content of the fuel. This means that a 70% efficient wood burning stove will produce 200kg of carbon less than a 100% efficient electric fire, because of the high carbon content in electricity.
As we move towards carbon zero houses wood burning stoves will play an increasing important role. For many low energy houses a stove will be sufficient as the sole primary heating system. In others the fact that the house can have 2 primary heating systems will mean that the use of a stove in a linked system will overcome the weaknesses of more carbon intensive systems.
