Wood stoves: blessing and curse at the same time

Created: 09/12/2022, 12:43 p.m

By: Matthew Schneider

Wood-burning stoves are becoming increasingly popular in light of the energy crisis.

But the heating method also has its negative aspects.

Munich – Because of the horrendous energy prices, a crackling stove is a winter refuge for many people.

But what gives warmth to one's own family can give the neighbors asthma and a heart attack: "According to calculations by the European Environment Agency, fine dust is responsible for around 53,000 premature deaths a year in Germany," explains Felix Pötschke, spokesman for the Federal Environment Agency.

That is why the authority subordinate to the Federal Ministry for the Environment is targeting wood heating systems.

Heating with wood: Fine dust can have serious consequences

Because while the fine dust values ​​at the traffic hubs of the big cities make the headlines, fireplaces often get out of focus: "Overall, the fine dust from wood combustion is about the same size, more than tire abrasion or exhaust gases on their own," according to the Federal Environment Agency.

And that can actually be a big problem, explains Stefan Karrasch, research doctor in occupational, social and environmental medicine at the LMU-Klinikum in Munich: "Possible consequences are an aggravation of the narrowing of the airways, for example in COPD or asthma, but also heart attacks or strokes .

This is particularly true for people with previous illnesses.” Because the particles are smaller than ten micrometers, they are too fine for the body’s own protective mechanisms and thus get into the organism: “There, among other things, the fine dust can activate inflammation and coagulation mechanisms that lead to blockages in the arteries being able to lead."

In addition to cardiovascular diseases, particulate matter is said to be able to trigger a number of other diseases: "There are indications that particulate matter can also cause diseases such as diabetes mellitus or impair the brain," says Stefan Karrasch.

Every single particle is harmful to health.

But is the fine dust from wood stoves more dangerous than others? 

Wood stoves: Lack of care from owners becomes a problem

"The effect of various fine dusts has not been researched well enough to make a statement here.

However, there are indications that particulate matter from combustion processes is particularly harmful to health,” explains the doctor.

But while the Federal Environment Agency criticizes the use of wood stoves on the basis of medical findings, the Federal Office of Economics and Export Control supports the installation of biomass heating with lavish subsidies.

A shield prank?

"The problem is primarily the comfort fireplaces, i.e. the fireplaces that stand for the cozy warmth in the living room," says Felix Pötschke from the Federal Environment Agency.

The main problem is the lack of diligence on the part of many stove owners: "The wood may still be too damp or not suitable for burning at all - the fine dust pollution is correspondingly high."

Instead, Pötschke advocates combustion-free heating systems such as heat pumps or solar thermal systems.

However, the technologies reach their limits when there is a high energy requirement – ​​for example in poorly insulated buildings: “If wood heating is required, you should consider replacing the old system with a more efficient one.

Pellet stoves – which heat the whole house – are far more efficient and produce fewer emissions than comfort fireplaces.” Because the standardized wood compacts provide the whole house with heat in a central heating system.

In contrast to a stove, a pellet boiler replaces an oil or gas heating system and is therefore climate-neutral.

Wood stoves are becoming increasingly popular.

But the heating method also has its downsides.

© Angelika Warmuth/dpa

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There is also an ecological advantage: no tree has to be felled for pellets, explains Sabine Hiendlmeier from the CARMEN research center: “The pellets usually consist of 90 percent by-products from the sawmills, such as sawdust.

The remaining ten percent is made from round wood that cannot be sawn.” The Federal Environment Ministry is aware of the conflict of objectives between clean air and climate protection, as a spokesman explains.

An attempt is therefore made to do justice to both sides: "Germany successfully implemented the last EU directive in 2017 with the clean air program.

One of the measures was the funding program for more efficient heating systems, including pellet heating systems," said the spokesman.

Ovens: limit values ​​will probably be tightened soon

Increasingly strict limit values ​​have been in force for all types of stoves for several years.

As a result, many old ovens had to be replaced with newer, more efficient models.

The emergency situation is currently being taken into account: Bavarian authorities are allowed to suspend the statutory shutdown if the wood stove can replace a gas heater.

Exactly how this is done is a matter for the district offices.

At the end of this year, the EU air quality directive is to be amended.

It can be assumed that the Commission will tighten the guideline values.

The federal government would then have to enact this regulation in a law.

However, there is still room for maneuver at the lowest decision-making level, according to the Ministry of the Environment: “The municipalities implement EU law with a view to local conditions.

In doing so, they take into account the local exposure to air pollutants.” Because the fine dust emissions in a sparsely populated village are different than in a big city.

Accordingly, every household can emit more particulate matter until the limit values ​​are reached.