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| This award winning Aduro stove accepts wood and/or pellets and can switch between them automatically. |
The Danish stove industry is known for sleek, vertical, expensive stoves. There is a joke that they are made to look like high end furniture that happens to hold a fire. But amidst this new wave of modern design is an industry that embraces innovation, competes worldwide to heat homes and has many budget line models.
Danish stove makers tend to be skeptical of catalysts, very comfortable testing with cordwood, committed to quality and adaptable to the preferences and requirements of different countries. Danish stove manufacturers also have their own EPA-approved test lab at the Danish Technological Institute, one of three European labs that are now approved for EPA certification testing.
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| John Ackerly, AGH President with Jes Sig Andersen and Anne- Mette Frey of DTI. AGH photo |
Danes do not appear as intimidated by sensors and smart control systems as their American counterparts. They may appear on the market quietly, with little fanfare, and possibly without the consumer even knowing what’s under the hood. Since they require very little power, they may just have a couple batteries and don’t have to be plugged into an outlet. The trick is to get those sensors past the 2020 emissions standards with or without using a single burn rate test.
Aarhus – the stove capitol of Europe
No city in Europe is surrounded by as many stove manufacturers as Aarhus, the second largest city in
Denmark. It is located on the mainland, just a few hours north of the German border. Brands well-known to North Americans include Hwam, Rais, Morsø
and Scan, but the city is also home to others that are as big or much bigger, including Aduro, Heta and Termatech. All these brands are present in many if not all European countries.
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Aarhus is centrally located with wind turbines and biomass district heating plants dotting the surrounding countryside. The hundreds of small biomass district heating plants pipe hot water underground to virtually all homes in cities, towns and suburbs. The extensive network of district heating is one of the main reasons that Danish stoves tend to be small. Most homes already have affordable and renewable heat. Rural homes that are not on the district heating grid usually have pellet boilers, made by one of the many Danish pellet boilers companies. Danes also have innovative boilers for farms that use hay bales, another novel technology that could have a market on America’s farms.
EPA’s 2020 emission standards and foreign stoves
Danes have always tested their stoves with cordwood (only Norwegians test with cribs). The ASTM cordwood standard that allows up to 2.5 grams an hour appears to be achievable, according to Danish manufacturers. EPA certification has always been considered the gold standard in Europe and is universally accepted as the hardest test a European stove can pass.
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| Jes Sig Andersen of DTI lab in Aarhus, left, with a technician at the Rais lab. AGH photo |
The 2020 standards make it even harder for manufacturers. Danish stoves “can’t be tweaked, they need to be redesigned,” says Jes Sig Andersen, a senior specialist at the stove test lab at the Danish Technological Institute (DTI). The entire system that delivers primary and secondary air has to be reengineered and optimized to ensure maximum combustion of particulates through primary oxidation, secondary pyrolysis and often tertiary combustion. Getting that just right is a challenge even for seasoned combustion engineers, who have spent their professional lives designing stoves for the laxer protocols required in Europe.
At a seminar hosted by DTI on stove and boiler testing, AGH President John Ackerly presented a powerpoint (PDF) on the current state of EPA regulations, potential changes, and other cordwood test methods that are in development.
At a seminar hosted by DTI on stove and boiler testing, AGH President John Ackerly presented a powerpoint (PDF) on the current state of EPA regulations, potential changes, and other cordwood test methods that are in development.
Danish attitudes toward wood heating
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| The Danish landscape is dotted with small biomass district heating systems, which often use chips or hay bales. |
There is an ambivalence toward wood heating in Denmark that is similar in many respects to attitudes in the US and in many European countries. Wood heating is often viewed as too polluting, a result of too many old stoves and poorly operated new ones. Pellet stoves comprise an even smaller part of the market here but pellet boilers are far more commonplace. In the capital city of Copenhagen, the mayor, like the mayor of London, is cracking down on cordwood stoves and plans to ban their future installation in part of the city. One of the largest crackdowns in Europe is in the Po River valley in Northern Italy where regular inversions trap wintertime pollution.
The Danish government has had national change out or scrapping programs that provide a US $300 grant to simply remove an old stove, or replace it with a newer certified stove (it does not have to carry the Nordic Swan eco-label).
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| Vertical, clean lines and small fireboxes dominate the Danish domestic market. |
Danish automated stoves
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| The Hwam smart controller allows the user to load and leave, and uses sensors to adjust the air. |
Aarhus stove maker Hwam was one of the first to design a fully automated stove, with an Intelligent Heat System (IHS) which competed in the first Wood Stove Design Challenge in 2013 in Washington DC. That stove helped revolutionize the concept of what a wood stove can be, and how it can be assured of operating cleanly in the hands of consumers. Other Danish manufacturers have also used sensors and controllers that will be coming out in future models. The Hwan IHS has held its own in the marketplace, but price conscious consumers still prefer more basic, cheaper stoves.
The Aduro hybrid that burns both pellets and cordwood uses automation by necessity, so that it knows when the operator has loaded cordwood and when the stove needs to switch back to pellets.
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| Henrik Norgaard, CEO of Rais explaining their upcoming automated stove that gives consumers confidence in clean during technology. AGH photo |
A German company, Thermoelect, is marketing their automated stove in Denmark, looking for buyers who desire heat, domestic hot water and reliable electricity from a very clean burning system. That stove won first place at the 2018 Wood Stove Design Challenge in Washington DC based on its efficiency, emissions, electric output and innovative design.
A key question is whether local and national governments will support the advancement of automated stove technologies that help stoves operate better in the hands of consumers. Automation should be
able to help stoves pass stricter emission standards such as the EPA’s 2020 standards. Otherwise, there may not be sufficient incentives for stove manufacturers to build stoves that do much more than operate well in the test lab.
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| Horst Erichson holds the trophy his automated stove won at the 2018 Wood Stove Design Challenge. Rene Bindig from the German Biomass Research Centre consulted on the firebox design. AGH photo |
European Union 2022 Emission Directives result in weaker emission limits in northern Europe
A weakness of European wide emission standards for wood stoves is that they are the product of a
negotiation between countries with stricter standards, and countries that have no standards at all. One of the key purposes of the Union is to harmonize standards so that goods can flow freely between all EU countries, which means that countries cannot maintain stricter standards than others. For countries like Denmark and Germany, this can result in having to weaken emission standards. The 2020 EU Eco-Design Regulation calls for a maximum of 40 mg/cubic meter for wood stoves and 20 for pellet stoves. Denmark already requires a max of 30 and most stoves are in the 10 – 20 range. Denmark may be able to negotiate keeping their stricter standards which would also result in keeping some stoves made in other countries out of their market. But the more powerful European stove industry associations may block a country’s attempt to keep stronger standards so that they can build stoves to the laxer standards.
One reason that European stove testing protocols are laxer is that they typically only have to test at a nominal heat output rate. They do not have to test at their lowest air setting or heat output rate. They also allow fueling to be based on manufacturers’ instructions and do not require the stoves to be filled with nearly as large loads as EPA protocols. However, there are national variations and the Norwegian national protocols required testing at 4 burn rates and with crib wood.
beReal and IDC testing protocols
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| Round robin testing of the same stove in different labs and settings shows emissions are often double or triple in the real world compared to lab testing. |
Danish stoves for export to the US are much more likely to be tested with the ASTM cordwood method, which should make them somewhat cleaner in the hands of consumers. But using cordwood and including start-up emissions is just the beginning of innovation needed in test protocols. Stricter PM limits only result in cleaner stoves if there is a level of integrity in the test method that does not exist in Europe or North America. On both continents, industry has played a big role in writing the test methods and labs in both continents have a financial stake in making sure their clients pass the test.
The need for more real-life test methods is just as obvious to Europeans as it has become for Americans. Even before NESCAUM began developing Integrating Duty Cycle test methods, European began beReal, a very similar process to understand the weaknesses of existing lab testing and move towards a method that would result in stoves being designed for consumers, not for test labs.
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| An early overview of the IDC protocol under development by NESCAUM. The protocol had early input from HPBA but they have since dropped out of the process. |
A ground-breaking 2018 report, “Advanced Test Methods for Firewood Stoves” by Christoph Schmidl and Gabriel Reichert, concluded that “Real-life oriented test concepts (e.g. beReal) are capable to reflect the real-life performance of the appliances better compared to existing EN standards. An implementation of a real-life oriented test protocol as a quality label or standard should be considered as an instrument to push technological development towards optimized real-life operation and to enable a better differentiation of good and poor products for the end customer.”
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| Marius Wohler, manager of the beReal initiative speaking at the 2016 Pellet Stove Design Challenge at Brookhaven Nartional Lab. AGH photo |
The adoption of more realistic and effective test methods based on the European beReal initiative or the American Integrated Duty Cycle approach will face headwinds. Regulators may not have the time, expertise or motivation to engage in a major test method shift, and industry may resist leaving charted waters that they know how to navigate for seas that may pose tougher challenges. But both continents have persistent stakeholders and face air quality and renewable energy targets that require technologies to operate cleaner in the field, not just the lab.
Compliance audit testing or "market surveillance"
Regulators on both continents also realizing the need for compliance audits, called “market surveillance” in European parlance. Without effective oversight of test lab results, a culture of artful, possibly legal, manipulation of test protocols can grow in labs. Once the culture exists in one lab, other labs need to follow to keep their clients from going to labs who can help stoves pass more easily. The Alliance for Green Heat wrote about this danger in 2015 in the wake of the Volkswagen testing scandal. That scandal involved a emission testing defeat device, but it also uncovered an old boys network that stayed quiet about a culture in labs that is driven more by client pressure and expectations than government-approved test protocols.
Under the U.S. Clean Air Act, the EPA has authority to conduct compliance audit testing of stoves
and revoke a certification if the particulate matter exceeds the original lab test by 50% or more. That provision is under litigation by HPBA and other stakeholders agree that if the PM is below 1 gram per hour, 50% is too strict given the variability of solid fuel testing. European countries have similar compliance laws, and Belgium has begun to conduct audit testing and cracking down on stoves that it believes may have exaggerated test numbers. They issued a seven-page document, "List of devices tested in the laboratory" (pdf) that banned the sale of nine mostly Spanish Panadero stoves in Belgium based on discrepancies in PM or CO between the certification lab and the audit lab.
Panadero is a family run, mass market value stove manufacturer that like many other companies
claims to have met the 2022 standards for all its stove in 2018. In addition, some Panadero stoves carry the French Flamme Vert and British HETAS and other eco-labels. They apparently do not qualify for the Nordic Swan or Blue Angel. Most of the stoves found to have a large PM and/or CO variation in 2017 Belgian audit compliance tests appear to be out of production as of 2019. One that is still in production, the Luis, does not claim to meet any European eco-labels.
Regulators on both continents also realizing the need for compliance audits, called “market surveillance” in European parlance. Without effective oversight of test lab results, a culture of artful, possibly legal, manipulation of test protocols can grow in labs. Once the culture exists in one lab, other labs need to follow to keep their clients from going to labs who can help stoves pass more easily. The Alliance for Green Heat wrote about this danger in 2015 in the wake of the Volkswagen testing scandal. That scandal involved a emission testing defeat device, but it also uncovered an old boys network that stayed quiet about a culture in labs that is driven more by client pressure and expectations than government-approved test protocols.
Under the U.S. Clean Air Act, the EPA has authority to conduct compliance audit testing of stoves
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| A page from a 2017 Belgian list of stoves whose sale was banned after audit testing was performed. |
and revoke a certification if the particulate matter exceeds the original lab test by 50% or more. That provision is under litigation by HPBA and other stakeholders agree that if the PM is below 1 gram per hour, 50% is too strict given the variability of solid fuel testing. European countries have similar compliance laws, and Belgium has begun to conduct audit testing and cracking down on stoves that it believes may have exaggerated test numbers. They issued a seven-page document, "List of devices tested in the laboratory" (pdf) that banned the sale of nine mostly Spanish Panadero stoves in Belgium based on discrepancies in PM or CO between the certification lab and the audit lab.
Panadero is a family run, mass market value stove manufacturer that like many other companies
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| The Panadero website shows the eco- labels that some of its stoves carry. |
Can Danish stoves gain traction in the US market?
Vertical, stylish European stoves led by Danish companies have been slow to catch on in the US market. But the entry of Danish value stove makers could change that. They already make more horizontal style stoves with larger fireboxes for the British and other markets. Danes could have a real advantage with sensor-equipped stoves that have sensors that take some or all of the “idiot factor” away from the operator. If tests can better show the value of these stoves, then it will be up to federal, state and local jurisdictions to find ways to help pave the way for them to proliferate. The recent funding opportunity from the US DOE is clearly looking for R&D in automation, and that may be a tipping point for automated stoves. Danish companies are not eligible for that, but they are well-positioned to benefit from any trend in that direction.
European stoves may also be a beneficiary if the trade war between the US and China escalates.
Tariffs on steel and parts such as fans could impact American manufacturers far more than European ones, which could benefit Italian pellet stove manufacturers, for example.
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| Many Danish export stoves are more horizontal and have larger fireboxes for Eastern European and British markets |
Regardless of their share of the US market, Danish stoves represent an enduring aesthetic. They are also expanding into Eastern Europe, where some of them are manufactured, and where cleaner, more efficient stoves are needed far more than North America and Western Europe. It is difficult to know how regulations, innovation and energy demands will impact wood stoves, but Danish stove makers are likely to be on the forefront of those changes.
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