Showing posts with label test methods. Show all posts
Showing posts with label test methods. Show all posts

Monday, June 30, 2025

Demand for automation in wood stoves moves forward in Europe, but could be sidelined in the U.S.

Updated July 8, 2026 - The newest type of stove on the market is the automated or ‘smart’ stove that use sensors and computer chips to adjust airflow, instead of relying on the operator. Automated stoves enable the operator to "load and leave," allowing the stove to maximize efficiency and emissions reductions on its own. These stoves are likely to be the next major step towards cleaner residential wood heating because it is well-known that poor operation by the consumer is one of the main reasons for excessive smoke, and often it is the main reason. 

Automation does not just seek to address poor operation by the consumer.  It also can assess variable draft conditions caused by different chimney configuration, the altitude of the home, and the moisture content of the wood.  In addition, automated stoves are often interactive, helping to educate operators through visual prompts or detailed apps on smart phones. 

 

In Europe, automated stoves have been advancing far more quickly and are recognized as by the regulatory community as an important solution.  In the U.S., the EPA and other agencies are focusing on an equally important process - improving test methods for manually operated stoves – with little attention to automation. Improved test methods still leave manually operated stove vulnerable to wildly variable real-world emissions.  

 

Outside of regulatory circles, automated stove technologies have been promoted in the U.S. by the Wood Stove Design Challenge, a series of technology competitions, and by funding from the US Department of Energy in association with national labs.  A 2023 study from Brookhaven National Lab described the technology as “a minimal set of measurement sensors and a heuristic control strategy to actively modulate incoming air to enhance stove combustion performance, thereby eliminating user-error as a factor for emissions production.” More recently, researchers at Oregon State University and Aprovecho Research Center are focusing on automated technologies that show PM reductions up to 95% compared to older models

 

The first such stove on the US market, MF Fire’s Catalyst, launched in 2016, is now off the market. The second, Charnwood, a British manufacturer entered the US market in 2020 with their Skye E2700. The company say, “This stove uses Charnwood I-Blu combustion intelligence that continuously monitors the state of the fire and optimizes efficiency while reducing emissions through real-time adjustments. Air is introduced in just the right amounts, in the right places, at exactly the right time to ensure a cleaner, highly efficient burn.”

 

A number of companies are using passive, partial automation but its unclear how effective it it.  For example, Pacific Energy has added technology to three of their stove models. The Neo 1.6 LE2 and the larger NEO 2.5 LE2, both of which come in freestanding and insert models. Under their True North brand, the TN25 C, they use the same technology on a hybrid stove with a catalyst that is continuously engaged, and does not have a damper control. According to an email from Pacific Energy, they use an “algorithm controlling two sources of supplemental air, working in the background to seamlessly improve combustion.  This patent pending technology uses two probes to monitor the firebox and the flue temperatures. Based on the absolute, delta and the rate of change in temperatures, the combustion is being optimized at all times.”  The operator can still adjust the air damper, which may be then counteracted to some extent by the algorithm depending on combustion conditions. Pacific Energy markets these stoves as regular wood stoves without explaining the details of their automation to the consumer. 

 

The Canadian manufacturer SBI won an award at the 4th Wood Stove Design Challenge for their progress toward an automated stove and they received a grant from the DOE to develop it. A final version of it is expected to be EPA certified and on the North American market later in 2025. 
 
Automated stoves on the European market
In Europe there has been far more R&D and diversity of automated stove technology.  Notably, in Europe, manufacturers highlight the environmental benefits of automation to the public and to the regulatory community. There are now more than 10 models on the market such as: 

 

Hase, Lima IQ (Germany)

Hwam SmartControl (Denmark)

Nordica, Larissa (France)

Rika, Rikatronic4 (Austria)

Scan Zensoric Technology,  (Denmark)

Xeoos Twinfire Blue (Germany)

Wodtke, Stage F (Germany)

Full vs. partial automation.  There are many ways to automate a wood stove and one of the main variables is whether the stove still has air levers that the operator can control.  If the stove has controls for the operator, it is virtually impossible to tell if the automation can override the operator, or vice versa.  Many consumers, particularly in North America, want to at least have the sense that they can control air flow, which is key to heat output.  Otherwise, control of heat output can be with the amount and frequency of wood that is loaded into the stove. Also, there is always the question of whether and how well an automated stove works during a power outage.  Most, if not all, can work, but will do so sub-optimally. 

Bi-metal springs that have been used for decades in stoves produce a very modest amount of automation to stoves, and they can be used in conjunction with electronic automation strategies.  

Other features. Some stoves have a LED light that will come on when its time to reload the stove.  Some are connected via wi-fi apps and can produce a sound to prompt the consumer when to reload. The Austrian company Rika has a feature where you load firestarter in the tray, add wood, and then you can program the stove to start remotely, as pellet stoves can.


Aftermarket solutions. 
Several companies have built devices that can monitor and/or control the airflow of existing stoves or be integrated into new stoves.  Maxitrol is a leading supplier and makes the battery powered “E-Flame air control system” that drives an actuator to control primary and secondary air flow.  It was designed in part to help companies meet future European EcoDesign Directives.  The Danish stove manufacturer Aduro has had it’s Smart Response on the market for several years. The app-connected thermometer provides feedback to the consumer on their smart phone about whether their stove is burning well, and how to improve its use.  Baltimore-based MF Fire is working on something similar. These technologies do not automate stove functions but monitor conditions and prompt the user to give the stove more air, add wood, clean their chimney, etc. 

Regulations and incentives to automate: In the United States, there is little regulatory pressure or incentives for manufacturers to automate.  The new Integrated Duty Cycle (IDC) test protocols are designed so that all types of stoves can be tested and to our knowledge the test method was not designed so that automated features would help a stove pass, though it is possible that will be the case. It is imperative that the National Residential Heating Task Force test the automated stoves on the market in the U.S. and give them the profile that other stove types are getting.  Currently, the test regimen may show the benefits of catalytic and hybrid stoves in the lab, without sufficient data or attention to how well cat stoves are used and maintained over their 10 – 20 year lifetime.  Automated stoves may also have maintenance issues over their 10 – 20 year lifespan, and it’s important to start assessing which automation strategies are more robust.
Test protocols are perhaps the best way to encourage manufacturers to innovate.  Protocols can make it harder for manually operated stoves to pass by requiring air adjustments that are likely to produce more smoke, unless sensors in the stove can adjust airflow themselves.  Making certification marginally tougher for non-cats to pass, leading to a growing percent of catalyst and hybrid stoves, is not an ideal solution compared to growing the number of automated stoves on the market.

At the state level, change-out and other incentive programs can start to recognize automated stoves and give them higher incentives.  Massachusetts is the only state that sought to provide incentives to automated stoves in a change out program in 2017 but it came too early and automated models were delayed coming on the marketplace.  States and air agencies can start to make consumers aware of this new type of wood stove, along with catalytic, non-catalytic, hybrid and pellet stoves. 

The lack of attention and support for the development of automated stove technology in the United States is connected to similar lack of support for cleaner pellet heating appliances.  Despite the ability of pellet stoves to emit very low levels of PM, the EPA allows them to emit the same level of PM as wood stoves, even though they have a different type of fuel, which should lead to stricter emission standards. In Europe, the EcoDesign Directive of 2022 requires pellet stoves to emit only half of what wood stoves are.  

The lack of “eco” or “green” labels for wood stoves in the U.S. has left manufacturers with little incentive to produce cleaner or automated stoves.  In Europe, some eco labels require pellet stoves, for example, to produce a quarter of the PM of wood stoves, and half of regular pellet stoves.  Manufacturers selling on the US market have mainly focused on achieving 75% efficiency, in order to qualify for the tax credit under IRS Section 25C.  Congress revoked that section, effective Dec. 31, 2025 and its unclear if it will be a permanent revocation or just for several years.  The credit has often lapsed since 2005, when it first began.  In Europe incentives have steered away from residential log heaters and focused on the best pellet stoves and boilers, which is a possible path forward in the U.S.

In Europe, some manufacturers feel that is not if, but when, they will have to start producing automated stoves. There is more urgency in Europe because of more widespread use of wood stoves in cities like London, and densely populated areas of Denmark, Netherlands, France, Germany and other countries. The German Blue Angel label and more local regulatory efforts, such as in Berlin, have also led to far more innovation and R&D on automation.  As in the U.S., lobbying by industry is slowing efforts at national and local levels to pass stricter measures that could lead to quicker adoption of automated stoves and more reliance on pellet stoves.

In early 2025, the European Commission released draft language of a new directive to take effect in 2027, including language that automation in stoves would be required. This led to strong industry push-back, and work on the new directive has been delayed.  The European Committee of Manufacturers of Domestic Heating and Cooking Appliances stated:

 

“The requirement of for automatic combustion control systems, additional testing, second conformity contradicts Ecodesign principles: it increases costs, energy consumption and maintenance need, limits technological neutrality and makes appliances more expensive.”
 
“Any Ecodesign regulation should not favour specific technologies. It should be technology-neutral and allow manufacturers to choose how to meet the regulation's requirements…. Although not explicitly required, a stove without a built-in catalytic converter and electrostatic precipitator is unlikely to meet the emission requirements. All seven known Blue Angel stoves have these features.”

 

This industry response to the draft of the next European Directive has many valid points which will also be part of the landscape in North America.  Regulators on both continents should shift their focus away from manually operated stoves and address these concerns and others as they move toward next-generation solid fuel heating solutions. One European study found automation reduced PM by 66% compared to one test method.

 

 

More resources on automated stoves



Nordic Energy Research, Nordsyn EcoDesign, Task 2 Report, 2025

Eurocities, Cities call for stronger EU rules on new wood-burning heaters to tackle deadly air pollution,” June 2025

AGH Webinar, “Harnessing Electronics for Cleaner, Smarter Wood Heating,” June 2025

14th U. S. National Combustion Meeting, Forced-draft Airflow Control Tuned to Reduce PM Emissions in a Cordwood Room Heater Under Variable Operating Conditions,” 2025

 

Chemical Engineering Reactions. “Reducing Emissions from Current Clean-Burn Wood Stove Technology by Automating the Combustion Air Supply and Improving the End-User Interaction -Two Important Primary Measures,” 2023

 

IEA Bioenergy, “Design of Low Emission Wood Stoves,” 2022

 

Tarm Biomass, “Automated Wood Stoves: Technology Policies and Barriers,” 2017

 

Technical University of Denmark, “Guidelines for automated controls for wood stoves,” 2017

 

AGH Blog, “Automated stoves entering the marketplace,” 2014

 

AGH Blog, “Nine reasons manufacturers don’t use sensors in wood stoves,” 2013

Thursday, September 30, 2021

The Alaska wood stove regulations – cleaning the air or a proxy war?

On Sept. 26, the EPA issued a resounding victory to Alaska’s strategy for improving the air in the Fairbanks area, rebuking virtually all of industry’s objections.  That victory came from the approval of Alaska’s State Implement Plan (SIP) to reduce wood smoke PM2.5 in the Fairbanks non-attainment area.

In essence, Alaska proposed different and stricter standards for wood stoves to be sold and installed in Fairbanks.  They will not allow cordwood boilers, coal heaters, stoves that emit more than 2 grams, or stoves that emit more than 4 or 6 grams during any hour of testing, and multiple other restrictions.  All of this helps. HPBA and more than a dozen wood stove manufacturers mounted a major effort to beat back the Alaska regulations, making the case that much of Alaska’s approach was arbitrary and capricious, not based on evidence, contradicted federal standards, etc. etc.  EPA’s ruling took the side of Alaska on every issue, often by simply stating that states have the authority to be more stringent than federal standard, rather than addressing the details of industry’s points.

 

Why this is a big deal


What everyone needs to understand is that the little city of Fairbanks Alaska has become a proxy war in a much larger struggle over the future of wood stove testing.  Much of Alaska’s work to review stove certifications did not address air quality in Fairbanks, but it does have major national ramifications.  Alaska developed its own list of stoves that could be installed in Fairbanks that was not based solely on emissions criteria.  Instead, it was mainly based on whether the certification paperwork was complete, and they could verify that the test labs correctly followed EPA stove testing regulations, despite the existence of some grey areas.  This set-in motion an unheralded level of scrutiny on testing done by all EPA approved labs, and sent the EPA into an embarrassing tail-spin, as they showed that the EPA had abdicated its role in effectively overseeing its certification program.

The Fairbanks North Star Borough 
(FNSB) non-attainment map.

Alaska’s scrutiny of certification paperwork was sometimes clumsy, and they found hundreds of details were missing, requiring manufacturers to show them that they often were there, but just difficult to find.  EPA has never provided a consistent format for labs to report data and it has been difficult to get the EPA to confirm which details needed to be included in the certification reports. But usually the details Alaska could not find were in fact missing and they uncovered serious patterns and deficiencies in many certification reports, something that few in industry are willing to admit. Those deficiencies had been in plain sight for years, but nobody looked carefully enough. The EPA, scrambling to show they take wood stoves seriously, began a slow but steady process to figure out what went wrong and how to fix it.  They commenced their own review of certification paperwork and over a year later, they are now sending letters to manufacturers requiring them to provide missing data.  Moreover, they are taking the unique step of requiring some stoves to be retested, similar to the audit testing that HPBA fought against.

 

The significance of the EPA’s ruling on Alaska’s SIP is difficult to summarize, as it has many highly technical themes, each one difficult to assess on its own merits.  Suffice it say that the stove community is in the midst of a historic period of change that had already started with the 2016 EPA decision to design new stove testing protocols, using the Integrated Duty Cycle (IDC) model developed by NESCAUM. Alaska has now tipped the balance of power toward a wider review of EPA’s certification program – and its enforcement and compliance unit.  One manufacturer went so far to say that Alaska had improperly pre-empted the EPA by creating a “de facto federal standard.”  There is the possibility that other states may follow Alaska’s approach, either through regulations or voluntary programs like change outs.  

 

AGH believes the Alaska initiative has had several positive impacts.  First, it’s made labs test stoves more carefully, and properly dot their i’s and cross their t’s.  Secondly, it forced the EPA to take their wood heater certification program more seriously, run it more professionally and better understand the grey areas that they had unknowingly included in the 2015 stove regulations.  

 

The long term view


But the most important outcome is something that all parties can agree on: understanding how to improve test methods so that they encourage engineers to design stoves that will perform better in the hands of consumers.  This is what we all are working for.  Alaska has now brought attention, if not clarity, to scores of issues that make for an effective certification program.  A good certification program needs clear guidance to manufacturers and labs and it needs a compliance program.

AGH is hopeful that this process will lead to genuinely cleaner stoves that get put through their paces in a test lab just as homeowners will use that stove. It’s useful to consider other EPA certification testing programs and the decades it has taken to understand their weaknesses and reform them, so consumers are getting products that work well in the real world.  

EPA auto emission standards
got stricter - and more realistic.
Automobile testing, for example, went through similar stages.  A revolution in auto testing, in the words of one expert, happened when manufactures were “motivated to produce emission controls that not only pass emission certification testing, but also remain functional when vehicles are in real-world use.”  Admittedly, the auto industry is massive and can afford levels of R&D and compliance that are impossible for the tiny, but resilient wood stove industry. Herein lies the rub: how far can the EPA and manufacturers be pushed to make lasting changes? Both are resource constrained.  Will the EPA stay focused on this program?  If they don’t, will other states undertake their own initiatives?  Will some manufacturers just quit making wood stoves and focus on their carbon intensive but profitable gas appliances? And does their industry association have the leadership and vision to steer industry through this, or will they focus more on legal and regulatory battles that may be difficult to win.  Many of the large stove manufacturers, including the biggest three, have already let their memberships lapse, for a variety of reasons.

AGH believes we need a hearth industry that can produce appliances clean enough to help households get off fossil heating fuels.  We are not there yet, except with pellet stoves and boilers which work well in the hands of consumers and can easily be improved even more.  Most New England states have incentives for pellet heating and western US states should adopt those policies as well. The electrification movement and more extreme and frequent weather events may solidify the demand for wood stoves.  Pellet heating deserves far more incentives.

A set-back for federal change-out funding

The Alaska initiative has also been very problematic and in some ways damaging.  A NESCAUM report made the implausible claim that the EPA cannot assure that new certified stoves are in fact cleaner than old, uncertified ones.  Actual lab and field testing has repeatedly found the opposite to be true.  This report helped scuttle federal legislation sought by HPBA that would have provided tens of millions for change-out programs.  The irony is that much of that funding would have helped lower-income families switch to fuels that produce less PM (but maybe more carbon), like gas, pellets, or electricity (heat pumps).  This occurred during the year that Congress increased the tax credit for high efficiency stoves, which benefits higher income taxpayers.  Change-outs also require professional installation which often reduces future PM, whereas a very large percent of stoves bought with the tax credit are self-installed.

Like America, the stove community has become even more divided, making the process of developing new test protocols more contentious.  It is unclear what individual or entity has the leadership to bring the sides together to hash out the scores of issues in a truly productive way that could reduce the bitter and litigious atmosphere. The Alaska initiative did not help but it could set the stage for more collaboration, if someone can facilitate it.  Up until a few years, 90% of the expertise in stove testing was within industry and the test labs they work closely with to certify their stoves.  This process has changed that dynamic, forcing more people at EPA and state agencies understand the regulations and the science behind stove testing.  

This NYT image shows extremely
slow growth of renewables in our
electric supply, an impediment
to the electrification movement.

There is also little consensus about the future of wood and pellet heating in America.  This process is being driven by air quality agencies who usually don’t take carbon into consideration.  Thus, even if a pellet stove fueled mainly by residuals from sawmills has higher PM than a gas stove, these officials may lean more heavily on the gas scales.  In the US, there is scant leadership that there is in most of Europe promoting certain types of high efficiency wood and pellet heating as part of the renewable energy solution, at least until our grids have a majority of renewable electricity on them.  The EPA – and Alaska – often claim to work under a technology neutral rubric, although neither is technology neutral, nor should they be.  They both need to more aggressively promote cleaner, lower carbon appliances.  The EPA and Alaska even struggle to officially tip the scales more towards pellet appliances, even though their air quality mandate should make that an obvious policy direction. Luckily, while EPA works on how to test stoves, the DOE is funding a complementary process – building innovative, next-generation wood stoves.

Industry has vital expertise that must go into the process of developing new stove testing protocols.  Many individual manufacturers also will be gathering vital test data from internal testing that they could share with the EPA.  NESCAUM is also developing data which they should share at some point. We need thoughtful leadership on both sides to make sure we get genuinely effective test methods that incentivize manufacturers to do the kind of R&D that will lead to stoves that work well in homes.  Industry sometimes seems to think the rule making process should still be a "reg neg" - a negotiated rulemaking that emerged in the 1980s and was used in the first wood heater NSPS.  Reg negs were supposed to reduce the overly adversarial process of traditional rulemaking.  This is not a reg neg but still, effective cooperation and communication can be extremely beneficial.

The lengthy process that led to the 2015 NSPS regulations did not lead to a new generation of cleaner stoves, like the 1988 regulations did.  But we are now asking the right questions and we better understand the nature of beast that we are trying to control.  Who will step forward and reset the relationship between industry and air quality agencies?

Monday, September 1, 2014

EPA provides brief summary of NSPS comments

At a wood smoke conference at the University of Montana last month, the EPA did a presentation of
the status of the NSPS that included one slide that summarized stakeholder comments on the NSPS.  This summary is the first one, to our knowledge, that gives some insight into how the EPA views comments from stakeholders and which topics it regards as some of the most important.

The conference was a major gathering of wood smoke experts, air pollution agencies and a few representatives of wood stove manufacturers.

The frequent reference to states infers that their views are playing a significant role, along with industry.  The multiple references to “some manufacturers” indicate that they are paying attention to issues where industry is not united.   The reference to “electronic reporting” is about the move from paper to electronic submissions of test and compliance data from the EPA approved test labs to the EPA.  

Larry Brockman, who represents the EPA's voluntary wood heat programs, was at the Montana conference and gave the presentation:

* Environmental/health organizations, almost all states, most of the public and some manufacturers are very supportive.
* States oppose allowing the full 5 years for current certifications at 1988 NSPS levels.
* Industry wants grandfathering plus sell-through of inventory.
* States want standards for visible emissions, right-sizing (energy audits), hangtags and proper installation and operation.
* Industry and states want electronic reporting.
* Stakeholders agree that compliance test methods should use real world conditions, e.g., cord wood but some manufacturers question the adequacy of the current database.”

The full EPA presentation and the other presentations at the conference can be found on the EPA website. For our summary of stakeholder comments to the NSPS, click here.


The conference sponsors included the University of Montana Student Chapter of Air & Waste Management Association, Montana Department of Environmental Quality, American Lung Association of the Mountain Pacific, Missoula City-County Health Department, and the Center for Environmental Health Sciences. For more about the conference.