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Responsible Wood Burning...

Cozy feet in front of a responsible, efficient wood burner

...and the bad press.

My customers, especially those that read The Guardian, often ask my opinion regarding the bad press that wood burning stoves get in the media and whether burning wood in their stoves does really affect the local air quality as much as the media would like us to believe.

 

So I thought it would be good to idea to share my thoughts on the matter here and at the same time clear up some myths.

I guess I should start by saying that I am biased. Of course I am, I make my livelihood from sweeping appliances that burn wood. But I am also educated (I studied environmental science at university and worked for the Environment Agency doing air and water quality analysis) and well read on the subject. I would also say I am probably less biased in favour of wood burning than others are biased against it!


A lot of people are also unsure about the regulations that surround burning wood and coal in cities, so I thought it would be good to idea to clear up some misunderstandings...

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Legality | Pollution | Indoor air quality | Reduce my PM emissions

Bristol DEFRA smoke control area with lots of chimney pots

Are wood burning stoves legal in Bristol and can you burn wood in them? 

Yes, and mostly.

 

All of Bristol City Council and parts of South Glos are in a DEFRA Smoke Control Area, which means you can only legally burn wood in a “DEFRA smoke exempt appliance”, more commonly known as a DEFRA approved stove.

 

Most stoves are DEFRA approved, especially newer ones and ones that have been fitted by a HETAS installer. DEFRA approved stoves are different to non-approved stoves in that they have a permanently open air supply in an attempt to stop their users from slumbering their stoves.

 

Turning a stove right down and smouldering the wood inside it produces a lot of smoke and very little heat. You might be able to find out if your appliance is DEFRA approved by following this link . Alternatively get in touch and I should be able to help.


It is worth mentioning that if your stove is not DEFRA approved you can still legally burn smokeless fuel in it, also known as anthracite.

Can I burn wood in an open fire in Bristol?

No. Open fires are not DEFRA approved, and therefore if you burn wood in a Smoke Control Area on an open fire you could be subject to a fine of up to £300.

 

Bizarrely, you can be fined £1000 if you buy an unauthorised fuel (wood) to burn in an appliance that is not approved by DEFRA. So if you have an open fire you must only burn smokeless fuel. This only applies to domestic appliances that emit smoke through a chimney in the roof of a building.

 

Barbecues, chimineas, outdoor fireplaces, pizza ovens and even bonfires can happily burn wood in a smoke control area. Likewise, being an industrial appliance, the coffee roasters just down the road from me in St Werburghs can release as much smoke as it likes from its chimney.

Are they going to ban wood burners in Bristol?

I don’t think so. Certainly not in the near to medium future.

 

In the Clean Air Strategy of 2018, and again in the Environment Improvement Plan published by the government in January 2023, it clearly states that the government is not considering a ban on domestic burning of wood in England. The aim is to regulate the sale of fuels, by banning the sale of house call and unseasoned firewood. And to tighten the emissions of new wood burners being sold. 

Chimneys and ballons on the Bristol skyline

Are wood burners as polluting as the media makes them out to be?

No. They are not nearly as bad as the press would have you believe, or at least there has yet to be a study that credibly links air pollution with wood burning stoves.

 

We have all seen articles in the media that state that such and such a scientific study has shown that wood burners are awful for the environment and flood our homes with deadly toxins. But if you actually read those studies it quickly becomes obvious that all they are really saying is that burning wood may have a negative impact on air quality but that it is hard to determine.

 

It also becomes obvious from the way the media quotes the studies out of context and warps and sensationalises their findings that the British media has a anti-woodburner agenda or just doesn’t understand the difference between “burning wood” and “burning wood in a modern wood burning stove”.

Why, when discussing wood smoke’s effect on air quality, should we differentiate between generic wood smoke of an unknown source and smoke coming from a wood burning stove?

This distinction is very important and is, in my opinion, key to this debate.

 

Without going into the combustion physics of wood, it is important to know that the hotter wood burns, the cleaner and more efficient a combustion it has. In other words, if you burn a log on an open fire, where there is a lot of air flowing through the fire and limiting how hot it can burn, it will produce a modest amount of heat and a large amount of smoke, and in that smoke are a whole host of toxic gases and particles such as soot and tar. If you burn that log in a woodburner, the fire will burn considerably hotter (because it is in an insulated box, with limited air cooling it) thus producing considerably more heat and a lot less smoke and the smoke will contain much fewer polluting gases and particles.

 

It is also important to note that when testing for particulate matter (PM) it can be possible to tell if that particulate matter is coming from the combustion of wood, but it is not possible to tell how and where that wood was combusted, whether in a wood burner, an open fire, a bonfire, the coffee roasters in St Werburhgs or Drax Power station. This is relevant, because when DEFRA published their Emissions of Air Pollutants in the UK-Particulate Matter (PM10 and PM2.5) and claimed that whilst PM in UK air has declined massively since the 1970s and is at the lowest since records began, the PM from the domestic combustion of wood accounted for a 16% increase in overall PM in 2021. A slight increase from 2020 but not exactly a huge source of it.

 

And what The Guardian and others don’t tell you is that “the domestic combustion of wood” includes open fires, old unregulated and unapproved wood stoves, and outdoor fires, as well as modern efficient wood burners. But the media pin those emissions on wood burners, when in actual fact only 1.3% of all PM2.5 emission are attributable to modern Eco-design ready stoves. See SIA response.

So why does the British media have a anti-wood burner agenda?

I honestly don’t know.

 

But if pressed my answer might contain certain bits of information, such as that it all started in the tabloids, as part of their anti-middle class and anti-woke narrative. And that many energy companies advertise heavily in the tabloids. And that gas companies must have felt the effects of all those wood burners that have been installed in the last twenty years, many of them replacing gas-guzzling gas fires, thus reducing their sales of gas. 

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But I can’t account for The Guardian and their anti-wood burner agenda. That makes no sense to me. And not just because wood, as a carbon-neutral and potentially locally and sustainably sourced fuel, has its part to play, at least for the time being, in moving away from fossil fuels.

Wood burner with low PM emissions for indoor air quality

What about indoor air quality, will my woodburner increase the concentration of PM into my house?

Yes, but a lot less than cooking will.

 

A non-peer reviewed paper published in 2020 by a member of the structural engineering department of Sheffield University and a criminology academic from Nottingham University gave rise to a flurry of anti-wood burner articles when it was released. It claimed that using a wood burner tripled the concentration of PM2.5 in the room whilst it was lit and there could be peaks of up to four times the baseline amount.

 

This study failed however to provide any data on any of the wood burners tested, the quality of wood being burned, or the condition of their chimney. Nor did it give any data on how long the increase in PM in the room lasted, or how these peaks compared to PM released from other activities and products inside the studied homes.

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A large number of other studies, often from more reputable sources, have repeatedly shown that there is as yet no evidence of adverse health impacts from exposure to the indoor air typically associated with modern enclosed wood burning stoves. 

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Other studies show that whilst wood burners do emit some PM2.5 and PM10 into homes, on the whole they emit less PM than other sources of PM in the home such as cooking (in particular frying and roasting), the burning of incense, oils and candles, hair spray and other beauty products, as well as cleaning products.

 

And it is worth noting that wood burners act as extractor fans, taking air from the room and sending it up the chimney, so any spikes in PM that occur when a wood burners is opened to refuel are fairly rapidly removed, contrary to what occurs in the rest of the house.

Cosy couple if front of low pollutant wood burner

All that be as it may, but what can I do to reduce my fire’s PM emissions both inside and outside my home?

Burn well seasoned wood in a modern woodburner and have your chimney swept regularly.

 

It has been well documented that modern wood burning stoves emit significantly less pollutants than older designed stoves and massively less than open fires. As mentioned, the hotter wood is burnt, the cleaner and more efficient a combustion it has. And wood burns much hotter in a modern wood burner than in an open fire. Also a woodburner generally draws better than an open fire, thus evacuating the smoke from the room better.

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A good draw also allows the fire to burn hotter, which is why if you keep your chimney clean by sweeping it regularly, your appliance will burn hotter and cleaner, reducing its emissions.

And the same goes for the quality of wood that you burn. If your wood is well seasoned and has a low moisture content, it will burn hotter, thus producing more heat and less emissions.

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Feel free to call me on 07581 506570 or contact me via email if you'd like to discuss in (even) more detail!

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