The Advertising Standards Authority (ASA) has banned two advertising claims by the Stove Industry Association (SIA) after ruling that the trade body misled consumers about the environmental impact of modern wood-burning stoves.
The ASA upheld two complaints against statements made on the association’s website in May 2025. The site claimed that ‘choosing a modern stove and dry wood fuel can significantly lower emissions and improve efficiency compared to an open fire or older stove’ and that, when used correctly, ‘a modern wood burning stove is a very low emission way to heat the main living space in your home.’
Both claims were found to be misleading and unsubstantiated.
The SIA, which represents stove manufacturers, suppliers and retailers across the UK, argued that the statements were based on data comparing modern, Ecodesign-compliant stoves to older models and open fires.
These newer appliances, the group said, met strict efficiency and emission limits set out in EU and UK legislation and performed best when used with properly dried wood.
The association submitted evidence including government guidance, scientific reports and research datasets, suggesting modern stoves could reduce PM2.5 compared to open fireplaces.
However, the ASA found that the data did not consistently demonstrate lower emissions across all key pollutants, such as carbon monoxide and sulphur dioxide, and in some cases, showed increases.
The ASA assessed the most recent data for GHG emissions and other pollutants, from 2023, in relation to burning dry wood in the older stove types, a modern stove and an open fireplace.
They found: ‘The data showed modern stoves emitted significantly less PM2.5 than open fireplaces. However, it showed modern stoves emitted more PM2.5 than the older stove types listed. It showed a comparative decrease in some emissions, such as methane, nitrogen oxides, and black smoke.
‘However, it also showed that other emissions were higher, and in some cases significantly higher, for dry wood burned in a modern stove as opposed to an open domestic fireplace, such as sulphur dioxide, carbon monoxide and several other toxins.
‘Between modern stoves and older stoves, the data showed increases in pollutants such as carbon monoxide, methane, and sulphur dioxide. The data therefore did not show a significant decrease in all relevant GHG and other air pollutant emissions between older stoves and open fireplaces, and Ecodesign stoves.’
On the second claim, the ASA said consumers were likely to interpret ‘a very low emission way to heat the main living space’ as meaning stoves produced minimal indoor air pollution compared to other heating methods. Yet the evidence provided – including studies from Imperial College London and trade reports – did not demonstrate that wood stoves were low-emission in real-world indoor environments.
The ASA ruled that the basis of these environmental comparisons had not been made clear and that both claims breached the CAP Code’s rules on misleading and environmental advertising.
The authority ordered that the adverts must not appear again in their current form and instructed the SIA to ensure future marketing avoids making broad environmental claims without robust evidence. It also told the organisation to clarify the basis for any future comparisons between stoves and other heating methods.
The full ASA ruling can be read here.
Leave a Reply