2025 Update: Progress in Reducing Particulates from Wood Burning Stoves

The issue of particulate emissions from wood burning stoves has been a growing concern in recent years (although for UK not so clear cut see paper). As we enter 2025, it's time to take stock of the progress made in reducing these emissions and improving air quality, both inside and outside the home. This blog post will explore the current state of affairs, legislative changes, firewood supplier improvements and technological advancements in wood burning stoves.

Understanding Micro Particles

Particulate matter, especially those less than 2.5 micrometers in diameter (PM2.5), has been a major focus of air quality concerns. These tiny particles can penetrate deep into the lungs and even enter the bloodstream, potentially causing serious health issues. In the UK, wood burning in homes has become one of the largest sources of PM2.5, surpassing emissions from road traffic.

Legislative Changes

In response to these concerns, the UK government has implemented several legislative changes:

1. Ecodesign Standards: As of January 1, 2022, all new wood burning stoves must meet Ecodesign standards, which set stricter efficiency and emission requirements.
2. Clean Air Strategy: The strategy mandates that wood used in stoves must have a maximum moisture content of 20% or lower.
3. Ready to Burn Scheme: This DEFRA-led certification ensures that only suitable burning fuels are certified for use.
4. Local Authority Powers: Councils now have the authority to issue fines for excessive smoke emissions from chimneys.

The Woodsure System: Reducing Moisture Content

One of the key factors in reducing particulate emissions is the moisture content of the wood used. The Woodsure "Ready to Burn scheme (which we are a full audited member of) has been instrumental in promoting the use of legal, dry, well-seasoned or kiln dried firewood with a moisture content of 20% or less.

Using dry logs has several benefits:

1. Increased Efficiency: Dry wood burns more efficiently, producing more heat.
2. Reduced Emissions: It can cut soot and emissions by up to 50%.
3. Improved Air Quality: Lower emissions contribute to better air quality both indoors and outdoors.

To ensure compliance, homeowners are encouraged to use moisture meters to check their firewood before burning.

Advances in Wood Burner Technology

Manufacturers have made significant strides in improving wood burner technology to reduce particulate emissions. Some of the key advancements include:

Secondary Burning

Modern wood burning stoves often incorporate secondary burning technology. This process involves:

1. Primary Combustion: The initial burning of wood in the firebox.
2. Secondary Combustion: Unburned gases and particles are reignited in a secondary chamber, often at higher temperatures.

This two-stage process results in more complete combustion, significantly reducing the amount of particulates released into the atmosphere.

Improved Airflow Systems

Advanced airflow systems in modern stoves help to:

1. Provide better oxygen supply to the fire.
2. Maintain optimal burning temperatures.
3. Reduce the production of smoke and particulates.

Catalytic Converters

Some high-end stoves now include catalytic converters, similar to those used in cars. These devices help to:

1. Break down harmful gases and particles.
2. Further reduce emissions.
3. Improve overall efficiency.

The Impact of These Improvements

The combined effect of these legislative changes, improved wood quality, and technological advancements has been significant:

1. Reduced Emissions: Ecodesign-compliant stoves can produce up to 90% fewer emissions compared to open fires and up to 80% fewer than older stoves.
2. Improved Efficiency: Modern stoves are typically 80% efficient, compared to 30% for open fires.
3. Better Air Quality: The focus on dry wood and efficient burning has led to noticeable improvements in air quality, particularly in urban areas.

Looking Ahead

While significant progress has been made, there's still work to be done. Ongoing research and development in stove technology, coupled with stricter regulations and public awareness campaigns, will continue to drive improvements in air quality.

For homeowners with wood burning stoves, the key takeaways are:

1. Use only dry, Ready to Burn Firewood with a moisture content of 20% or less.
2. Consider upgrading to an Ecodesign-compliant stove if you haven't already.
3. Follow manufacturer's instructions for proper stove operation and maintenance.
4. Be aware of local regulations regarding wood burning, especially in urban areas.

By working together - stove manufacturers, firewood processors, regulators, and consumers - we can continue to enjoy the warmth and ambiance of wood burning stoves while minimizing their environmental impact. The progress made so far is encouraging, and with ongoing efforts, we can look forward to even cleaner, more efficient home heating in the future.

Sources

https://journal.chestnet.org/article/S0012-3692(18)32723-5/fulltext

https://eeb.org/wp-content/uploads/2021/09/Where-theres-fire-theres-smoke_domestic-heating-study_2021.pdf

https://www.gov.uk/government/publications/the-air-quality-strategy-for-england

https://www.bbc.co.uk/news/articles/cjm9yrgjd3po#:~:text=Under%20the%20new%20powers%2C%20part,offending%20can%20lead%20to%20prosecution.

https://www.gov.uk/government/statistics/emissions-of-air-pollutants/emissions-of-air-pollutants-in-the-uk-particulate-matter-pm10-and-pm25

https://stoveindustryassociation.org/consumer-advice/benefits-of-sia-ecodesign-ready-stoves/

https://www.readytoburn.org/consumers/advice-hub/ready-to-burn-consumer-leaflet/