Clean Air Night fact sheet 

Following recent media reports and campaigns, HETAS wants to provide clarity regarding some burning questions. With so many mixed messages and apparently conflicting statistics, it is important to focus on the things we can do to minimise the effect of burning on our environment.  

The fact is that the Government has not said it intends to ban domestic burning. Research and consultation have revealed that the consequences of attempting to ban burning at this time are not acceptable to many vulnerable groups; as well as being almost impossible to enforce at this time in the development of clean heat and sustainable use of heat generating fuels and technologies. It is important that we stay focused on minimising emissions, continuing research, and educating stove users to burn as cleanly as possible across the UK. 

A key takeaway to consider when reading headlines is that government-published reports show annual PM2.5 emissions have continued to decrease – despite recent increases in popularity of stoves across the UK. Our industry works hard to innovate, and organisations like HETAS work with our registered installers, approved sweeps, servicing companies, and retailers to educate users across the UK. Similarly, Woodsure continues to promote the use of better, cleaner, higher quality fuels to reduce emissions. 

HETAS and Woodsure, alongside many manufacturers, retailers, and other trade professionals continue to push for the use of the cleaner burning stoves, better fuels, regular and professional appliance maintenance, chimney sweeping, and the best-practice use of appliances in the home. Maintaining these efforts will help to ensure emissions continue to reduce. Innovation and education are integral to ensuring emissions can be minimised and the best, most efficient practices must continue to be encouraged. 

There shouldn’t be –  

• 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 lower moisture wood fuel, and low smoke, low sulphur mineral fuel can be sold across England, requiring sellers to comply and only supply fuel that is scientifically proven to produce less pollution.^4-8 

As there is no intention to ban domestic burning, we must all encourage the best practices to ensure wood stoves across the country are used optimally and safely.

Calling for a total ban on any widely used heat technology divides opinion and fails to consider those who rely heavily on that heat source or technology – as was the case with the recent reversal in Scotland.

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 can be an excellent way to heat your home.

Many stoves are used as secondary heating appliances especially in late autumn and early spring when using a stove can alleviate the need to turn on whole heating systems fuelled by fossil fuels – therefore displacing another undesirable heating source with one that forms part of a more sustainable fuel chain. In winter, stoves are used to supplement poor and often inefficient heating systems and in many rural areas may be the only source of heat in smaller dwellings. 

Modern wood-burning stoves can achieve efficiencies of over 80% and are up to 90% more efficient than a traditional open fire, reminding us of the importance of not conflating all solid fuel burning methods and technologies.

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. 

To answer this question, we must first understand that there are different solid fuels. These split into two main groups, although there are also more modern and innovative fuels which span both types.  

Solid Mineral Fuels  

House coal is the sort of soft coal that was utilised over many years in open fires. So-called ‘smokeless fuels’ are either natural anthracites or manufactured mineral fuels that produce significantly less smoke and sulphur, and have replaced house coal for domestic burning.

The Government in England has banned the sale of house coal since 1 May 2023, allowing only authorised smokeless fuels to be legally purchased. It seems likely that Wales and Scotland may follow with similar legislation, which will further contribute to eliminating the most polluting fuels. The removal of house coals and any other similar fossil fuels with high smoke emissions is a very positive move for clean air, and another step towards minimising our annual emissions.

More action may be taken in due course to assess the viability of coal-derived heating fuels in the UK. HETAS will support government with creating just, reasoned legislation that supports the solid fuel heating industry and appliance users across the UK.

Wood burning 

It is important to remember that the combustion of dried wood causes significantly less emissions when wet wood combustion. Fuel with a higher moisture content (above 20%) will struggle to burn and burn poorly, producing much less heat and significantly higher emissions than dry wood.

High-quality fuel used in an efficient, regularly maintained stove produces significantly less emissions when it burns. 

The harmful effects of fine particulate matter are well-known across the industry and action continues to be taken by stakeholders. HETAS works with all UK governments and devolved administrations, utilising our expertise to provide advice and guidance on the best practices, and will continue to work diligently towards a cleaner, safer, and more sustainable environment.

According to official government data, the amount of PM2.5 emissions have showed signs of a steady decrease – despite the increasing popularity of wood-burning stoves in recent years, with estimated PM2.5 emissions from domestic combustion decreasing by 15% since 2018.

The National Atmospheric Emissions Inventory (NAEI) and supporting documents give 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 be misinterpreted. Assigning emissions to specific sectors and activities is not easily done, and the methodologies to measure domestic combustion emissions vary.  

It is often the case that different types of home-burning are grouped 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. 

Looking at apportioning the source of emissions more accurately allows us to concentrate on the worst emitters and further discover ways to minimise the UK’s PM2.5 emissions. ‘Home burning’ encompasses many different types of burning, such as:

• Open fires (possibly the worst polluters for indoor burning) 
• Old stoves with low levels of control (may be multifuel) 
• Older stoves with moderate levels of control (may be multifuel) 
• More modern stoves complying with current regulations  
• Innovative new stoves that burn controlled fuels in more technologically advanced ways (the least polluting appliances) 
• Central heating boilers – often highly efficient and low emissions 
• Outdoor burning – BBQs, firepits, chimineas, bonfires, pizza ovens, etc. (often very smoky and high emitters of PM 2.5)

Approximately 4.4 million households across Great Britain were estimated to be off-grid in 2021 – representing 15.1% of total 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 modern heating technologies, such as 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. Assessing this official government data reveals that steps can be taken to address London’s consistently higher exposure rate, as revealed by IFS. Upgrading London’s open fires to modern, highly efficient stoves will help the city’s air quality improve and its exposure rates get closer to the rest of the UK, which have fell by 54% since 2003.

Further, 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, drive consumers towards modern appliances, and encourage best practices. Only the most efficient burning appliances and highest quality fuels should be burnt in smoke control areas to ensure emissions are minimised.

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 solid fuel appliance: 

• 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 – furthering innovation in appliance manufacturing and reducing emissions. 

• Smoke control areas (SCAs) limit which fuels and appliances can be installed and used by homeowners, and provide local authorities with the legislative powers to fine those burning irresponsibly – with recent funding from Defra enabling 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 and installation to 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 that are 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/