The Stove Industry Association (SIA) has reviewed the findings of a recent study by Global Action Plan/Impact on Urban Health Relight my fire? Investigating the true cost of wood burning stoves and makes the following comments and observations:
- The model scenarios used in the study artificially inflate the costs associated with using a wood burning stove and decrease the costs associated with an ASHP because;
- Model B (see page 4 of the study) is based on “Newly1Defra-compliant woodburning stove led heating (80%) with gas secondary heating (20%)”. In footnote 1 at the bottom of the page it reads: “New” includes the cost of purchasing the item and installation, while all options include maintenance and replacement costs.” The SIA questions why if the purchase and installation costs have been factored in for the stove led heating in Model B, they have not been factored in for the gas boiler led heating, Model A?
- Model B also assumes the installation and operation of TWO new stoves (see page 17 of the study). The SIA argues that this is a highly unlikely real-world scenario as a dry stove is a space heating appliance not a central heating sytem.
- Similarly, Model E “Newly installed Air Source Heat Pump (ASHP) providing 100% of heat”underestimates the actual running costs of the ASHP in the reference dwelling used (a Victorian mid-terrace of single skin, uninsulated solid brick construction, see page 15). Heat pumps are not suitable for use in badly insulated housing stock; they will not run optimally in these conditional optimally and therefore won’t give a 3.5 seasonal CoP which the report uses to reach its conclusions.
- The calculations used in the study’s modelling assume that the efficiency and operational considerations of the heating system are met in situ. We know from studies on installed heating systems that the overall efficiency is negatively affected by the system it uses to distribute the heat within the property, e.g. the age and condition of pipework and radiations. The gas boiler and heat pump are affected by this whereas a direct heating appliance like a stove is not. The lack of consideration of this in the energy consumption calculations will positively skew the running costs for the boiler and ASHP against the more accurate running costs of the stove.
- The energy efficiency of the appliance must also be considered when assessing cost-effectiveness. All solid fuel stoves manufactured since 1stJanuary 2022 must conform to the Ecodesign Regulation which, as well as setting emissions levels, also states that the appliance must have a minimum efficiency of 75%. Many of the stoves manufactured by members of the SIA far exceed this, with tested efficiencies of over 80% and some achieving 85%. This is comparable with the most efficient gas roomheaters. While new gas boilers sold today achieve c.89% efficiency in practice, many older models will be less than 70% efficient. Local spaceheating is a key part of many individual’s heating strategy as you do not need to consider heating the whole house, just the space you want heating. Stove owners value the off-grid, low carbon heat that is provided by their stove.
- The SIA uses a range of sources to verify the compariative costs per kWh of various domestic heating fuels including the data presented by Nottingham Energy Partnership which is updated each month. The Partnership’s October 2023 data currently states the price per kWh of an ASHP as 12.37p, kild dried logs as 11.18p, mains gas at 8.64p and electricity at 33.40p. Between November 2022 and June 2023, kild dried wood logs were cheaper than mains gas per kWh.