It seems bizarre and totally incomparable. How can you compare a wood-burning stove to an HGV? It’s not something we had ever thought of, but sadly there has been some misconstrued news that tried to do exactly that with the motive of highlighting how environmentally unfriendly wood-burning stoves are (supposed) to be.
The SIA (Stove Industry Alliance) have provided an insightful look at this comparison to help educate the public about the comparison, and why it is inaccurate, misleading and unfair.
Claims of an Ecodesign Ready Stove producing the same amount of particulate emissions as 750 modern HGVs is one startling headline the SIA has managed to explain away. The source of the original HGV figure was actually from a report by the European Environmental Bureau. This report looked at the amount of PM2.5 emissions given off by generating a GJ (gigajoule) of heat in a stove, compared to the amount generated by creating a GJ of power in an HGV.
The major flaw with this comparison is that these claims are based on very crude calculations using permitted rates of emissions. They did not consider either real-world or non-exhaust emissions. Also, these permitted emission rates greatly rely on differing measurement protocols and techniques.
Comparing the emission rates between sources only tells part of the story. It is important to look at the impact of real-world use, and that paints a very different picture.
A Defra report completed by Kantar shows on average stove users light their appliance for 29hr a week, so around 3.7hr and 4.5hr a day in the winter. In reflection, an HGV can be driven by the same driver for 9hr a day, all year round. Stoves mainly are only ever used in autumn and winter. Over the course of a week, a typical stove will emit 20.16g of PM2.5. A Euro 6 HGV will emit 271g of PM2.5 – so around 13 times the amount of a stove. There are also other points to consider. Emissions from stoves are typically released at over 5 meters, while emissions from an HGV are typically emitted less than 1 meter from the ground.
These comparisons don’t even look at non-exhaust emissions either. PM2.5 from tyres and brake dust is significant, especially so when you consider some HGVs are 40 tones or more and have 18 wheels. That is a lot of tyre wear and brake dust.
Key points for consideration:
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- In the time taken to produce 1GJ (around 14 days’ worth) of heat to a home from a wood burning stove, at typical usage rates an HGV will have emitted 538g of PM2.5, over 7 tonnes of CO2e and similar amounts of NOx as the stove*.
- A Euro 6 HGV produces 13 times more PM2.5 emissions than an Ecodesign wood burning stove over the course of 1 week’s real-world use.
- In 1 hour an Ecodesign stove will emit 0.72g of PM2.5. In that time a Euro 6 HGV will have produced up to 4.3g of PM2.5.
