Clean Air Night fact sheet 

Following recent media reports and campaigns, HETAS wanted to provide clarity regarding some burning questions. There is a lot of misunderstanding and some misinformation regarding the solid fuel industry, and it is important that we stay focused on minimising emissions, continuing research, and educating stove users across the UK. 

Statistics are often confusing and can be misinterpreted easily. A key takeaway to consider when reading these headlines is that Annual PM2.5 emissions have continued to decrease – despite recent increases in popularity – across the UK as our industry works hard to innovate and educate. 

HETAS and the wider solid fuel industry are aware that action must continue to be taken to ensure these numbers continue to reduce. Innovation and education continuously takes place across the sector – from professionals to manufacturers – so emissions can be minimised and the best, most efficient practices are encouraged. 

There isn’t –  

• Government is not banning wood burning.¹

• Government have ensured that only appliances that meet emissions limits can be sold in the UK – with industry schemes going beyond this.^2-3

• Only high-quality fuel can be sold across England, requiring sellers to comply and only supply fuel that is scientifically proven to produce less pollution.^4-8 

Campaigning groups create mixed messaging, can misinterpret complex data, and be unaware of the complexities of emissions factors and source apportionment. 

Government’s clear intention to not ban wood burning aligns with the messaging behind the Burn Better campaign. As they will not be banning domestic combustion, they are encouraging the best behaviours. 

Public awareness is low, leading to confusion and negative reactions to anti-wood burning campaigns as the solutions are too brash and not considerate of all users. 

A stove’s heat is dependent on many factors, such as the: 

• Quality of the fuel 

• Efficiency and age of the appliance 

• Airflow 

• Condition of the chimney and appliance 

• User operation 

A modern appliance that is installed by a professional, regularly maintained, and operated effectively using high-quality fuel is an excellent way to heat your home. 

Modern wood-burning stoves can achieve efficiencies of over 80% and are up to 90% more efficient than a traditional open fire. 

Every home is different and not every heating solution may be suitable. Burning solid fuels gives flexibility to households that other forms of heating may not offer; the idea that all wood burners are inefficient is outdated and incorrect. 

Burning wood creates a complex chemical reaction, with the amount of emissions being dependent on a multitude of variables.  

What is important to remember is that wood combustion produces significantly more emissions when wet wood is poorly burned in an old, ill-maintained appliance. High-quality fuel used in an efficient, regularly maintained stove produces significantly less emissions when it burns. 

Combining all the methods of domestic combustion into one broad, overarching statement creates confusion – an old stove or an open fire differs greatly from a modern wood burner. This, in turn, inhibits efforts to educate stove users and downplays the industry’s continuous efforts to minimise emissions. By apportioning each emissions source – as the NAEI estimates do – we can better understand what the most polluting practices are and further our efforts to reduce these. 

The harmful effects of fine particulate matter are well-known across the industry and actions continue to be taken by all groups and stakeholders. HETAS works with all UK governments and devolved administrations, utilising our expertise to provide advice and guidance on the best practices. 

According to official government data, the amount of PM2.5 emissions from domestic burning has been showed signs of a steady decrease – despite the increasing popularity of wood-burning stoves in recent years.  

The National Atmospheric Emissions Inventory (NAEI) gives us insight into how these PM2.5 emissions appear to be primarily from poor burning habits, where users are burning unseasoned wood on old, inefficient appliances. The NAEI shows that high-quality fuel burnt on a modern stove only accounts for less than 0.3% of the UK’s total PM2.5, revealing valuable insights into how the worst behaviours account for the majority of domestic combustion emissions. 

Comparing the best practice recorded under this methodology to the worst practice, the efficiency of a modern wood burner is evident. Using the blanket term of ‘domestic combustion’ diminishes the progress that has been made across industry and puts unnecessary blame on households burning efficiently. 

Industry has responded to the Government’s annual reports, continuously innovating their appliances to increase efficiency and reduce emissions further. Certification schemes, such as the HETAS Cleaner Choice scheme, exist to independently verify that PM2.5 emissions are kept to a minimum, promoting the best appliances to consumers and pushing manufacturers to keep innovating. 

Statistics can often be misinterpreted. Assigning emissions to specific sectors and activities is not easily done, and the methodologies to measure domestic combustion emissions vary.  

The way that specific emissions are estimated vary, and multiple methodologies exist which give differing estimates. The data sources for wood burning remain ‘highly uncertain’ due to a number of variables. HETAS is actively involved in research to improve these estimates, allowing industry and government alike to further reduce particulate matter. 

The data’s uncertainty allows groups to mislead individuals by conflating the different types of home-burning into the wide-reaching term of ‘domestic combustion’.  

The NAEI’s annual figures, stemming from government departments and key data providers, show the stark difference between responsible and irresponsible wood burning: 

• Modern Ecodesign stoves burning dry wood produce 0.174 kt/y of PM2.5. 

• Open fireplaces burning wet wood produce 1.441 kt/y of PM2.5 

This is over eight times more emissions annually. 

Modern Ecodesign stoves burning dry wood produce less than 0.3% of the UK’s annual PM2.5 emissions. Despite this, many groups misinterpret annual emissions statistics and assume that the 29% figure is representative of all households that heat their homes with a wood burner. 

The NAEI statistics apportion based on an informed scientific methodology, and HETAS is actively involved in key research to further such methodologies to establish a clear understanding of how domestic combustion contribute to air pollution in the UK, and how emissions can be minimised. 

Approximately 4.4 million households across Great Britain were estimated to be off-grid in 2021 – representing 15.1% of households.  

Many off-grid households rely on their wood burners to heat their homes and do not have the means to use another form of heating, either due to funds, reliability, or fuel poverty. 

This is not to say that wood burners do not exist in properties on the gas grid. Wood burners are also a viable supplementary heating solution for properties with a heat pump, allowing for homes (particularly poorly insulated homes) to be sufficiently heated during winter months. 

Every household is different and benefits from different heating solutions. The Scottish Government’s recent U-turn demonstrates how many households across the UK rely on their wood burner to stay out of fuel poverty and blanket legislation negatively impacts individuals that are not the root of the problem. 

Modern wood-burning stoves are a highly efficient heating solution suitable for households in both rural and urban areas.  

On average, 40% of appliances across the UK are open fires. However, 68% of appliances in London are open fires – the highest in the UK. Lowering the number of open fires across London by upgrading them to modern, highly efficient stoves will address the recent PM2.5 exposure disparity highlighted by IFS. Whilst exposure has fell by 54% since 2003, London has consistently had a higher exposure rate 

Many urban areas, like much of London, are smoke control areas. These areas prohibit the burning of wood in non-exempt appliances, such as open fires, in an effort to reduce emissions and drive consumers towards modern appliances. 

Government and industry have been working together for a long time to reduce emissions and limit the worst burning practices. Legislation exists to combat the poorest, least efficient, most polluting ways of heating your home with a wood-burning stove: 

• Ready to Burn certification ensures that consumers purchasing firewood to burn at home are only able to purchase dry firewood, enabling a cleaner and more efficient burn.^4-8 

• Ban on traditional house coal in England for use in homes made it illegal to sell coal, preventing the use of a highly polluting fuel from 1 May 2023.⁹

• Competent person schemes ensure solid fuel installations are professionally installed by a trained expert, preventing poor installations and setting industry safety standards that are constantly evolving.¹⁰

• Regulations and standards will continue to strengthen and evolve over time for all solid fuel appliances and installations – this will be further innovation in appliance manufacturing, reducing emissions. 

• Smoke control areas (SCAs) limit which fuels and appliances can be installed and used; and provide local authorities with the legislative powers to fine those burning irresponsibly, and recent funding from Defra has enabled cities to consult on expanding their SCAs, widening enforcement powers.¹¹

• Legal emission reduction targets require government to meet ambitious targets, incentivising effective, decisive action that will continue aiding emissions reductions from all sources – including domestic combustion.¹²

When combined with expert-led user education, this legislation prevents the worst, most polluting burning practices.  Every aspect of a stove – from manufacturing to installation, fuelling and maintenance – is held under scrutiny to ensure regulations, legislation, and best practices are followed.  

The entire solid fuel industry has responded to this scrutiny, taking accountability and tirelessly working to innovate – reducing emissions, improving efficiency, and educating consumers on how they can do their part, too. 

Smoke control areas (SCAs) exist to prohibit the most polluting domestic burning and grant local authorities the legislative powers to fine individuals burning poorly. This encourages the best, least polluting burning practices and promotes the use of modern, efficient appliances as opposed to open fires or old, inefficient stoves. 

Find out more about smoke control areas in our article in light of expansions. 

As an industry-leading certification body, HETAS is uniquely positioned to provide expert guidance to government departments, professionals, and consumers. It is easy for complex datasets to be misunderstood or misinterpreted, and it is vital that we stay vigilant to investigate beyond headlines. 

1. Department for Environment, Food & Rural Affairs (2023) Environmental Improvement Plan 2023. Available at: https://www.gov.uk/government/publications/environmental-improvement-plan 
2. Department for Energy Security and Net Zero & Office for Product Safety and Standards (2021) Regulations: ecodesign of energy-consuming products. Available at: https://www.gov.uk/guidance/placing-energy-related-products-on-the-uk-market#full-publication-update-history 
3. HETAS, HETAS Cleaner Choice. Available at: https://www.hetas.co.uk/consumer/services/products/. 
4. Department for Environment, Food & Rural Affairs (2021) Selling wood for domestic use in England. Available at: https://www.gov.uk/guidance/selling-wood-for-domestic-use-in-england 
5. Price-Allison, A. et al. (2021) ‘The impact of fuelwood moisture content on the Emission of gaseous and particulate pollutants from a wood stove’, Combustion Science and Technology, 195(1), p. 133–152. 
6. Holubčík, M. and Jandačka, J. (2018) ‘The effect of moisture content of firewood on the energy efficiency of fireplace insert and emission production in the combustion process’, Acta Facultatis Xylologiae Zvolen res Publica Slovac, 60(2), p. 189–197. 
7. Rau, J. A. (1989) ‘Composition and size distribution of residential wood smoke particles’, Aerosol Science and Technology, 10(1), p. 181-192. 
8. Price-Allison, A. et al. (2019) ‘Emissions performance of high moisture wood fuels burned in a residential stove’, Fuel, 239, p. 1038–1045. 
9. Department for Environment, Food & Rural Affairs (2023) Selling coal for domestic use in England. Available at: https://www.gov.uk/guidance/selling-coal-for-domestic-use-in-england 
10. Ministry of Housing, Communities and Local Government (2013) Competent person scheme – current schemes and how schemes are authorised. Available at: https://www.gov.uk/guidance/competent-person-scheme-current-schemes-and-how-schemes-are-authorised 
11. HM Government, Smoke control areas: the rules. Available at: https://www.gov.uk/smoke-control-area-rules 
12. HM Government, The UK’s plans and progress to reach net zero by 2050. Available at: https://commonslibrary.parliament.uk/research-briefings/cbp-9888/