Mark Blewitt of ESSE explains why environmental issues attributed to wood burning stoves are not as straightforward as they seem, and the impact of a new eco standard
It is true that recent headlines relating to wood burning stoves have not been particularly positive, following a government paper that some media interpreted as to be identifying them responsible for polluting the atmosphere with harmful particulates. Anyone who cares to dig a little deeper will realise that the research cited in that paper in fact identified open fires burning unregulated fuel as the real culprits. Nothing new there – stoves started to appear back in Victorian times precisely to increase the fuel economy and reduce emissions. At the heart of the design was the principle that stoves burn fuel more efficiently and create less pollution in comparison to open fires where 80 per cent of the heat goes straight up the chimney. Under existing legislation, burning wood in urban areas should occur in a specially designed appliance (or stove). If you live in a clean burning zone as set out by the Clean Air Act, the appliance must meet the higher Defra standard. These are often called ‘Defra approved’ appliances but more accurately they are ‘Defra exempt’. The Department for Environment & Rural Affairs (Defra) exempts certain appliances from the Clean Air Act as they have been designed and tested to burn cleanly when burning dry wood with a moisture content of under 20 per cent. Defra-exempt appliance have become the clean burning choice in both urban and rural areas even when the location is not within a clean burning zone. Wet wood, or wood that has been painted or treated, will not burn cleanly regardless of whether it is being burned on a stove (Defra exempt or not) or on an open grate. Burning wet or dirty wood will result in tar and soot, atmospheric pollution and damage to the installation.
Alternative solid fuel
While we have so far only mentioned wood, What about other forms of solid fuel, namely coal, anthracite and manufactured smokeless coals? Some readers may recall that prior to the demise of British Coal and our mining industry, many homes relied upon a solid fuel stove as a primary heating appliance, except we knew them as ‘room heaters’ rather than stoves. Heating stoves today are direct descendants of such models. In those days, a ‘stove’ was something capable of cooking as well, while some designs would also offer water heating or laundry iron heating too. Anthracite, natures own ‘clean burning fuel’ is still mined today at Onllwyn in South Wales but its popularity is on the wane. Younger generations not brought up on coal find it difficult to light and we might concede that, since we have a diminished capability to mine our own, transporting fuel from distant shores cannot be thought of as an environmentally beneficial option. Customers looking for a manufactured mineral fuel should look for the ‘UK approved smokeless’ label these fuels will have low sulphur content. Petroleum Coke and bituminous ‘house coal’ should be avoided completely.
The environmental choice
Specifying a UK-manufactured stove constructed from UK-made steel and cast iron must surely be an excellent environmental choice. A quality brand that is used and maintained correctly will at least last a lifetime, and well-loved examples could last almost indefinitely. Almost entirely recyclable it may be, such thoughts are almost unnecessary. How different to most manufactured items in the modern world! Burn seasoned, dried logs, again ideally from a local source and you would be hard pressed to imagine a more environmentally friendly, carbon neutral heat source. Meanwhile fuel merchants are also able to offer ‘bio-logs’ made from coffee grounds, heather bracken and compressed wood waste from the forestry and timber industries. Come 2022, all wood burning stoves sold in the UK and Europe will meet a new Eco Design European Standard. Presently stoves sold in the UK are made to meet the European Standard EN13240. In the revision to the standard ‘European Efficiency and Emission requirements EN13240 and 13229,’ Eco Design 2022, all stoves will in due course meet the amended high standards with the aim of reducing emissions when burning wood. The key figures stove manufacturers are working to relate to the efficiency (above 75 per cent), emission of dust or particulate matter (below 40 mg/m3), carbon monoxide (below 1500 mg/m3), NOx – the generic term for nitrogen oxides (below 200 mg/m3) – and hydrocarbons/organic gases (below 120 mg/m3). The challenge we face is to simultaneously meet both the efficiency and emission limits. As a direct consequence of reducing the particulate matter, carbon monoxide and hydrocarbons emissions there is an increase in the emission of nitrogen oxides, while efficiency is adversely affected. Stoves presently available with efficiencies of around 80 per cent will become less efficient as a result of the Eco Design standard as efficiency drops from 80 per cent down to 75 per cent and nitrogen oxide emissions increase. It can be argued that many of our everyday activities damage the environment in some way, as normal as driving a car or buying food packaged in plastic and transported around the world; there is no need for customers to feel guilty at keeping warm with a wood burning stove, which will continue to have a place in green, sustainable and eco conscious developments. Pre central heating, companies made stoves in sizes appropriate to the room which it was to heat, such that a single home might feature multiple stoves in the same way that radiators are specified. Today a stove can still provide a local heat source in a living area in conjunction with other heating systems, a reliable back up and a truly heart-warming, home making focus for the occupants.
Mark Blewitt is sales director at ESSE