Wednesday, December 23, 2020

Expanded tax credits for modern, high efficiency wood and pellet heaters a big step in the right direction

Maine Senators Collins and King were
primary, bi-partisan champions of an
investment tax credit for wood heat.

Update for 2023 - The legislative victory that achieved the 26% tax credit in 2020, has now been upstaged by a law that will give a 30% tax credit as of Jan. 1, 2023.  The only downside to the 30% credit is that is has a $2,000 cap, which makes it of little value for homeowners who want to install very expensive whole house wood or pellet heating systems. Click here for our blog on the 2023 - 2032 wood heater tax credit.

2020 - 2022 - On December 28, 2020 President Trump signed into a law legislation passed by Congress which was the largest renewable energy spending bill in a decade and included incentives for solar, wind, advanced wood heat and a host of other technologies. This marks the first-time modern wood heating systems have been granted an Investment Tax Credit (ITC), rather than the far smaller tax credit wood heating technologies had been receiving.

The incentive provides a 26% tax credit for stoves and boilers that are 75% efficiency or higher. Consumers can easily identify efficiency levels by checking the EPA lists of certified wood and pellet heaters. The credit has no upper limit and lasts for three years, declining to 22% in 2023.

The effort to pass such an ambitious bill was led by the Biomass Thermal Energy Council, who started lobbying for it in 2009. In recent years, another significant push was led by Charlie Niebling, a consultant for Lignetics and former Chairman of BTEC. The Alliance for Green Heat contributed time and resources to both of these efforts, along with many other BTEC members.

As the founding Chairman
of BTEC, Charlie Niebling
was a chief architect of the 
bill and perhaps its most
ardent advocate.

Many Senators and members of Congress signed on to various iterations of the bill over the last decade, but it was Senator Collins and Senator Angus King who provided the final push, along with Chairman Richard Neal in the House of Representatives.

The legislative effort gained momentum as new EPA regulations required wood and pellet heaters to be cleaner and to disclose their efficiencies. “This is an important step forward but it is only one piece of a much larger puzzle to modernize the technology and the test protocols,” said John Ackerly, President of the Alliance for Green Heat.


Wood and pellet heaters that at least 75% efficient are cleaner on average than those that have efficiencies below this threshold. Pellet stoves that test over 75% efficient emit five times less carbon monoxide (CO) than those with efficiencies under 75%. Wood stoves that test over 75% efficiency emit less than half of the CO of their less efficient counterparts.

The 75% efficiency threshold favors pellet technologies, as consistently dry fuel and automated combustion make it far easier to achieve consistently higher efficiencies. Sixty percent of all pellet stove models are over 75% efficient, compared to only 40% of wood stoves. Most catalytic and hybrid wood stove models are above 75% efficient, but only 12% of non-catalytic stoves will be eligible for the tax credit.

The seventy-five percent efficiency requirement was originally chosen about seven years ago, when fewer appliances could meet that level. With today’s technology, 75% efficiency is not a particularly high threshold, but it is much higher than how the 75% threshold was interpreted by industry to meet the previous $300 wood heating technology tax credit. That credit, under Section 25C of the tax code was also pegged to 75% efficiency but Congress did not consistently specify high heating value.

Using efficiency as the sole metric to identify wood and pellet heaters to receive public subsidies is a blunt and imperfect metric but satisfies legislators’ need for simplicity. Particulate matter (PM) emissions from cord wood stoves and boilers are a more important metric for public health. Efficiency is a more valuable tool for pellet appliances since their lab tested efficiencies are a reliable indicator for the efficiency homeowners' get. But wood and pellet appliance manufacturers sometimes purposely lower their efficiency to achieve other goals valued by consumers. Some pellet stove manufacturers use excess oxygen, leading to lower efficiency, to keep the viewing glass clean. Some wood stove manufacturers use excess oxygen to achieve cleaner, faster combustion and to prevent the operator from giving the unit too little air, which causes smoldering. The State of Alaska is currently exploring new metrics to identify cleaner wood heaters, including using the amount of PM created during the first hour of certification test burns.

Using efficiency as a metric does help deploy heaters that will save consumers money with a low-carbon renewable. Since the early 1900s, wood fuel has been the primary way that American households have avoided or reduced fossil heating fuel. An estimated half of American households who heat with wood gather all or most of it themselves, making it a highly sustainable fuel in a country with extensive forest cover.

This bill will help Americans afford to replace older wood heaters or buy higher efficiency ones and have them professionally installed because the tax credit covers the cost of installation. It will also help scores of small pellet mills across the country that mainly use sawdust produced by sawmills. Finally, the bill will also help manufacturers of more efficient wood and pellet appliances and encourage them to redesign heaters to be more efficient.

Benefits of a tax credit do not help everyone equally. Lower income families benefit far more from a rebate granted at time of purchase and many do not have the income level to benefit from a tax credit. And, the 75% efficiency threshold excludes the value wood stoves sold at hardware chains that are affordable to lower income households. Unlike wood stoves, many low cost pellet stoves are at least 75% efficient.

“The Alliance for Green Heat applauds this increased tax credit and calls on Congress needs to do more,” said Ackerly. “We need a dedicated federal fund to switch old, uncertified stove to cleaner heating technologies, similar to the federal program for diesel trucks. We also need increased funding for DOE and National Labs to focus on R&D to develop a new class of automated wood stoves and smart pellet appliances that integrate with solar and heat pumps and reduce electricity demand during winter electricity peak events,” Ackerly continued.

A separate bill included report language that directs the DOE to continue the $5 million grant program for R&D to modernize residential wood and pellet heaters. The Alliance for Green Heat worked with Senator Collins’ office to ensure this report language was included again.

The massive omnibus package included other provisions that could help advance cleaner and more efficient wood and pellet heating:
  • $1.7 billion reauthorization of the Weatherization Assistance Program to support low-income families by retrofitting homes with cost-saving clean energy technologies.
  • Robust funding for EPA “core” programs to protect clean air.
  • Reauthorization of the EPA Diesel Emissions Reduction Act (DERA) program, which is a model for a national wood stove change out program.
  • $200 million timber hauling businesses that experienced a loss of at least 10% of gross revenue between January 1, 2020 and December 1, 2020, compared to the gross revenue earned in the same period in 2019.

 Related stories

Guidance on the 26% tax credit for 2022 and changes for 2023 (Oct. 2022)

AGH urges IRS guidance to recognize efficiencies in the EPA Database (Feb. 2021)

Friday, November 20, 2020

Alaska releases deficiency details on wood and pellet stove test reports

Bryce Ward, Mayor of Fairbanks
North Star Borough.
Alaska posted summary review sheets of nearly every certified wood and pellet stove, exposing issues in a certification system that has been running for decades with little oversight. Of the 131 wood stove models, 130 had major problems in their testing report based on the Alaska classification system.

ADEC is pursuing EPA approval of s smoke reduction plan similar to one in Montana. They said, “Missoula City-County Montana regulations allows installation permits only for pellet stoves emitting no more than 1.0 gm/hr.  Alaska embarked on the certification test review and the establishment of a 1-hr filter pull standard as an alternative to a pellet only program for the nonattainment area as DEC feels this approach meets the communities desire for more device options and is at least equal to the Missoula requirement."  Click here for the full email.)

Alaska also sought and received approval from the EPA for an IDC cordwood stove test method to be "broadly applicable" which means any manufacturer can choose to use it in a stove's certification test. It also sets the stage for Alaska to potentially require that test for stoves sold in Fairbanks.

Alaska is undertaking this unprecedented review in an effort to find the stoves that they can be assured are the cleanest and meet all the requirements in EPA regulations under the Clean Air Act. AGH first covered this in a October 22 blog. In addition to checking that stoves meet the extremely detailed level of documentation based on emission testing, Alaska has imposed even stricter emission requirements, which do not apply anywhere other than Fairbanks. The primary stricter standard is that stoves cannot emit more than 6 grams an hour of particulates during the first hour of a multi hour test. Ultimately, when averaging the PM of the entire test, stoves must emit no more than 2 grams an hour to meet the Fairbanks standard, even though the federal standard allows up to 2.5 grams of PM if a stove is tested with cordwood.

Part of ADECs summary sheet showing
 the preliminary and initial final
determination and the reasons.
The initiative is being undertaken by the Alaska Department of Environmental Conservation (ADEC). It only impacts which stoves and boilers can be installed in a relatively small area around the city of Fairbanks that currently fails federal air quality limits. That is a very small market for the wood stove industry but the initiative may end up having far reaching implications for the EPA, the stove industry and how stoves are tested in the future.


One reason why so many stove models are flagged with multiple deficiencies is simply because ADEC officials missed data in the test reports or the manufacturer of the model has not yet provided it. Of the 130 stoves with major problems, many will likely meet Alaska’s review in the coming months. Manufacturers who have requested an extension from the State have until April 1 to work with Alaska to provide details, and only after that can the model not be sold in the Fairbanks non-attainment area. In the meantime, the review appears to shpow that only one wood stove model – MF Fire’s Nova tested by ClearStak lab – could be on the market. The data sheets on all stove models can be found here and will be updated at least monthly.

A Step 1 Jotul stove being tested by
Dirigo labs, taken over by PFS-Teco.
The data on pellet stoves is far better in some respects. Rarely do pellet stoves emit more than 6 grams during the first hour of a test like many wood stoves do. Of the 97 certified pellet stoves, only 3, or about 3%, are disqualified for this reason, compared to 31% of wood stoves. However, like wood stoves, the vast majority of pellet stove test reports had missing data. Only 7 had minor issues. As with wood stoves, over the ensuing months, scores more will likely be approved after missing information is found or provided by the manufacturer. Eleven of the test reports could not be found by ADEC. Sometimes links to these reports are hard to find, sometimes the link is broken, and sometimes the report doesn’t appear to be posted.

ADEC has not yet determined which missing items on test lab reports disqualify a stove. Some of the issues ADEC is flagging have to do more with paperwork requirements than the potential cleanliness of the stove. They are engaging in a series of meetings with EPA personnel from both enforcement (OECA) and air quality (OAQPS) offices to determine what is actually required by the NSPS, what isn’t required, and what should be considered significant. One long time technician at an EPA approved lab said that “based upon ADEC’s interpretation of the language in parts of the Federal Register, they have come up with several new requirements” which never existed before.

A 2019 pie chart made by AGH
showing an approximate percent
of stoves tested by each lab based 
on one data set.

For manufacturers, a key distinction is also data that was collected and exists, but was never calculated or reported properly, compared to data that was mistakenly not collected and could only be obtained by retesting the unit. It’s unclear if any of the test reports are so deficient that the EPA would ever considering revoking a certificate.

The scrutiny of certification paperwork by labs by Alaska also comes on the heels of years of effort by the stove industry to prevent stricter emission standards and the possibility of stricter audits. States have become increasingly frustrated that the EPA is not enforcing their regulations governing wood stoves and boilers. While enforcement was explicitly curtailed under the Trump administration, under Obama and previous administrations, enforcement has been regarded as lax or sporadic. In particular, the EPA has never initiated an audit of a wood stove or boiler to determine if it can achieve the emission levels that it got on its initial certification test. There is also no documentation of the EPA denying certification of a stove or boiler based on inadequate lab reports. In addition, there are only a handful of documented cases when a stove or boiler has failed emission tests in a lab even though industry cites very high rates of variability in emissions during testing.

Some of these issues emerged in 2019 when the EPA released hundreds of documents that NESCAUM had requested in a Freedom of Information Act request. But very little has ever been written about the many complex and opaque issues in test labs other than a blog AGH posted in August 2019: Records reveal successes and challenges in laboratory wood heater testing. That article explored issues of conflicts of interest, compliance with testing regulations and suspension of certification tests, all of which are receiving are receiving more scrutiny by ADEC officials and their partner agencies.


An ASTM 3053 test at Omni lab in
May 2020 on a GHP Group stove. GHP
is a company that has not 
requested that ADEC review its stoves.

ADEC’s initiative is also intertwined with concerns about the ASTM E3053 cordwood method and lab tests that showed the method was lax and may have helped some stoves to achieve certification to the EPA’s stricter 2020 standards with few or no modifications to their design. A meeting between EPA and state officials and industry representatives in January of 2020 explored these concerns and ADEC presented their strategy at that time.

ADECs efforts to improve air quality in the Fairbanks non-attainment area go back at least 10 years, starting with traditional stove and boiler change-out programs and a variety of restrictions. But the tenacity of excessive wood smoke in America’s coldest city has frustrated residents and officials alike, leading to this latest effort to understand which stoves are actually cleaner than others. Fairbanks is also spearheading solutions for the other most obvious culprit: unseasoned wood. As of October 1, 2021, only seasoned firewood can be sold in the non-attainment area.

Registration for firewood retailers is
compulsory in Fairbanks and voluntary
in the rest of the state.

It is still too early to tell how much this latest initiative will lead to cleaner air in Fairbanks. There is little doubt that it will bring a new level of scrutiny and integrity to test reports submitted to the EPA, and help the EPA and state agencies better understand how to craft a federal reference method for testing stoves with cordwood.

Postscript: In March 2021, NESCAUM released a report that was largely based off of the reviews of certification reports done jointly by ADEC and NESCAUM.  The scathing report concluded that the EPA process of certifying stoves is "dysfunctional" and recommended a series of aggressive measures.  AGH's initial response that report can be found here.

Monday, November 16, 2020

Alliance for Green Heat calls on President-elect Biden to support and help transform wood and pellet heating

Press release
Contact: John Ackerly

Nov. 16, 2020 - The Alliance for Green Heat congratulates President-elect Joe Biden and Kamala Harris on their 2020 presidential victory and welcome their commitment to scale up renewable energy and energy efficiency.

This change of administration offers the United States a historic opportunity to reduce fossil fuels through a range of renewable heating solutions and energy efficiency measures. We have already begun to decarbonize our electric grid, and now it’s time to also focus on our heating sector which can reduce heating costs for families across the country, buoy economic recovery and create good-paying jobs.

The Alliance for Green Heat’s supports all renewable heating options as well as strategic pairing of heat pumps, geothermal, solar thermal and solar PV with wood and pellet heat technologies (our specialty). The role of decentralized renewable thermal technologies, including wood, solar thermal and geothermal is essential along with the electrification of heat as our electric grids slowly become more renewable. The electrification of transportation is creating massive demands for new generation and distribution. This combined with very high peak demands in the cold, short daylength northern tier of the country calls for strategic deployment and use of non-electric heating technologies. Rural areas need special attention given the cost of new infrastructure.

Executive Branch

The Biden Administration, through executive action, can immediately begin to drive markets toward beneficial forms of advanced wood heating. It is essential that Biden’s administration analyzes small-scale wood heating as having unequivocal carbon benefits. This includes:
  • Ensuring there is an in-depth, science-based analysis to account for carbon content of wood used for residential and small-scale institutional heating that is separate and distinct from the analysis used for larger scale biomass to electric pathways.
  • Use the power of procurement, as outlined by the Climate 21 initiative, to “bolster markets for climate friendly products such as … heating systems that use wood pellets” in federal buildings, starting with more rural buildings in colder climates.
  • Directing the GSA to require rural federal buildings to consider heating with wood, chips or pellets where it is economically feasible.
  • Prioritize an interagency working group on bioenergy to focus on small scale thermal wood.
  • Include environmental justice considerations in bioenergy projects and expanding employment opportunities for Native Americans and low-income populations in rural areas.



We urge the EPA, under new leadership to give more priority to one of the most popular and commonplace renewable energy solutions in the country. To this end, we encourage the EPA to

  • Invest in the expeditious development and adoption of test protocols that resemble how homeowners use wood heaters (we use the term “wood heater” to include wood and pellet stoves, boilers and furnaces).
  • Prepare the groundwork for a national wood stove exchange program to replace old wood heaters with cleaner alternatives.
  • Put resources into the offices that certify wood heaters so that the process is expedited and includes a full review of all testing requirements
  • Ensure the EPA’s Science Advisory Board (SAB) evaluates the carbon benefits of residential and small-scale institutional wood and pellet heating based on studies of how that wood is gathered and obtained by households and small institutions.
  • Issue a Statement on Scientific Integrity that reaffirms DOE’s commitment to renewable energy pathways that can be deployed in the short term, including wood heating.
  • Expand the focus of the Bioenergy Technologies Office beyond liquid fuels to include biothermal and provide additional grants for automated, next generation wood heating technology.
  • Develop strategies that utilize wood heating as an integrated approach to mitigate grid-load growth risks caused by rapid electrification in the country’s northern tier.
  • Prioritize the utilization of wood thinnings removed from high-hazard forests to be used for local heating of homes and institutions in those areas.
  • Ensure Rural Development Housing programs allow for and encourage the installation of modern, automated wood heating.
  • Increase funding to the Community Wood Energy program.

We urge the Biden administration to work together with a closely divided Congress to:
  • Incorporate the BTU Act into any renewable energy or tax legislation to ensure that the most carbon beneficial pathway for low-grade, bi products of sustainably harvested wood is included.
  • Expand tax credits for energy efficient appliances including the cleanest and most efficient wood and pellet heaters,
  • Expand funding for the DOE to continue the R&D program to modernize residential wood and pellet heating technology
  • Establish a national program to retire older wood heaters in exchange for heat pumps, pellet heaters, and in some cases, new wood heaters.
  • Ensure that weatherizing programs inspect wood and pellet stoves just as they do with gas and oil furnaces for both safety and efficiency and provide avenues for repair or replacement, if needed.

The Alliance for Green Heat promotes wood and pellet heat as a low-carbon, sustainable and affordable residential energy solution. The Alliance works to advance cleaner and more efficient wood heating appliances, particularly for low and middle-income families.  The Alliance runs the semi-annual Wood Stove Design Challenge to encourage innovation and automation in wood stoves. Founded in 2009, the Alliance is a 510c3 non-profit organization based in Maryland.  

Friday, November 6, 2020

Safety recalls of wood and pellet stoves

Updated: July 2022 - There have been at least seven recalls of wood and pellet burning products since 1979 and one certification revocation.  Four of those were in 2015-2016.  While there are few reports of any injuries, recalls are expensive and time consuming for stove manufacturers.

(In addition to stove recalls, the Consumer Product Safety Commission recalled a camping tent sold by Cabellas in July 2022 because the "stove jack ring" where the stove pipe exits the tent, can deteriorate.)

Almost all recalls are voluntary, which is usually to the benefit of the company.  A successful recall effort often reaches about 65% of consumers, and it the case of wood or pellet stoves, it may depend on who sold them and how much effort the company actually made.  Its easier for some stove manufacturers to track down who purchased a particular stove if it was purchased through a specialty retailer compared to stoves purchased through hardware chains.  For the following seven recalls of wood and pellet stoves, there is no data about how effective each recall was.

The dangers posed by some of the stoves subjected to recalls are significant but may pale in comparison to the ongoing dangers of self-installed stoves that never get inspected.  The Consumer Product Safety Commission (CPSC)'s 1982 survey of more than 2,000 households indicates that 70% of stoves in use were installed by the consumer, and half of these "do-it-yourself" installations were never inspected by a building or fire inspector.  A very high percentage of self-installed stoves remains a high probability in the US, in part because of the increasingly high volumes of stoves sold through hardware chains and on-line.  The percentage of self-installed stoves purchased on the second-hand market could be even greater than the 70% figure found in 1982.  In addition to dangerous self-installation practices, the other main cause of stove-related house fires is excessive creosote build-up in chimneys that are not regularly cleaned.


The highest volume recalls have been pellet stoves, which pose less of a fire risk when self-installed, or from lack of chimney cleaning.


1. The recall impacting the most devices was the 2015 recall of the US Stove HomComfort pellet stove that could be mounted in a window or wall.  This recall involved 4,400 units, which provides one of the few insights into volumes of particular units.  The Chinese-made stove was sold at Northern Tool, Rural King, Home Depot and Lowes from 2010 to 2012.  There were 16 reports of fires and property damage, but the recall did not happen until three years after the product run.  US Stove offered $868 cash or $1,200 credit towards the purchase of another US Stove product. Those amounts are still available from US Stove.  An updated version of the stove is 2020 certified but only supposed to be mounted in walls, not windows.


2. The next largest recall was England Stove Works pellet Smartstove.  The US-made unit was only sold for a few months in the fall of 2015. After the company received four reports of incidents and one minor injury, it initiated recall the following year.  Englander sent consumers a free repair kit to remedy the issue.  An updated version of the stove is 2020 compliant and on the market.


3.The next largest recall was for 2,000 Mt. Vernon pellet stoves made in the US by Quadrafire, a subsidiary of Hearth & Home Technologies.  The $4,000 stove was sold for almost a year between 2014 and 2015.  There were eight reports of glass breaking after excessive pressure built up in the firebox but no reports of injuries.  The company remedied the issue by offering to arrange for free installation of an enhanced control board. The firm's dealers contacted known purchasers.  An updated version of the Mt. Vernon is also 2020 compliant and on the market.



4. The following year saw a much smaller recall of a Quadrafire device. This time it was a wood stove, the Explorer III, and involved 650 units.  The US-made unit was sold for about a year and a half for $3,000.  The danger was that the handle of the top lid could disengage and the lid could fall.  There were five reports of incidents, two of which involved minor injuries to fingers. The company offered to fix the problem through its dealer network. The Explorer is off the market.




5. A small recall of 200 Scan Andersen wood stoves made by Jotul occurred back in 2010.  A faulty door hinge led to the door falling off, and of the three reported incidents, one consumer received a bruised foot.  The stove was made in Norway and the fix was a free hinge repair.

6. Going back a bit further in time, there was a recall of 1,300 EPA certified, catalytic Vermont Castings Sequoia wood fireplaces in 2006.  At the time, Vermont Castings was owned by the CFM corporation and the units were made in Canada and the US.  They sold from 2003 to 2006 for about $2,200.  This was a more serious recall, as it involved insufficient insulation or a missing weld, and could cause these fireplaces to pose a fire hazard, though no incidents were reported.  Consumers were advised to stop using the product immediately, and it is not clear if the company offered any remedy after 2008 when they went bankrupt. 



7. The final recall listed on the CSPC database dates back to 1979, and involved glass for stove doors that posed a breaking hazard. The glass doors were in “Hearth-Glo” wood burning circulators made by the Jackes Evans Manufacturing Company. These sold in 1977 and 1978, right before the EPA began requiring wood stoves to be certified. One thousand stoves were involved and customers could get free replacement doors.

8.  While not yet a formal recall, the EPA is taking an unprecedented step of revoking the certification of a wood stove because the lab did not do the test correctly and the EPA certified the stove because it did not carefully read the lab test report.  The stove in question is the England Stove Works Model 50-T tested by Intertek, and the wood they used was too dry. It appears that Englander tried to test it again but couldn't get it under 2 grams an hour. Englander had requested a hearing, but they pulled out of the hearing process and the EPA is finalizing revocation of the model line in April 2022, which apparently will mean those models will have to be recalled from retailers.  

Thursday, October 22, 2020

Alaska building list of properly certified wood and pellet stoves

Lab certification test are designed to
burn as cleanly as possible and all
emission results must now be publicly
disclosed as of 2015.

Alaska Finds widespread deficiencies in EPA wood stove certification process 

Officials in Alaska are in the process of compiling lists of wood stoves and boilers that have met all the requirements of EPA certification and emit fewer particulates during the first hour of the test burn. Alaska regulations requires new wood heating appliances installed in the Fairbanks nonattainment area to meet additional regulatory requirements beyond obtaining a federal U.S. EPA certification. The regulations went into effect January 8, 2020 and Alaska has been working to implement those regulations since then.  The new regulatory requirements involve reviewing certification test reports for deficiencies and collected data regarding additional PM levels and then approve specific models of wood stoves and pellet stoves by updating their approved device list.

The Alaska Department of Environmental Conservation (ADEC) began this process as part of their efforts to address excess wood smoke pollution that contributed to Fairbanks becoming a non-attainment area.  The State’s Implementation Plan (SIP) to improve air quality began including measures years ago to crack down on dirtier wood burning appliances, such as outdoor wood boilers.

The current effort involves reviewing every stove’s certification paperwork to ensure that it includes all the elements that EPA regulations require, such as average CO, the manufacturer’s written instructions to the lab, firebox dimensions, efficiency calculations, burn rate calculations, raw data sheets, documentation of run anomalies, etc. etc. 


If you are not familiar with this brewing controversial initiative, you are not alone.  The first time most people outside a small group of manufacturers and regulators heard about this was a month ago, Sept. 18,  when a group of states weighed in on the litigation between HPBA and the EPA Their brief mentioned that the Alaska Department of Environmental Conservation was conducting a systematic review of wood-burning devices that have been certified to be compliant with EPA standards. The Department found that 59% of the certifications had inaccurate certification data, and that the EPA must have a way to check on manufacturers through audits. 

The start-up phase of a stove in the lab
should be consistent with how it is
described in the owner's manual.

The lists being developed by Alaska officials only pertain to what can and can’t be sold in the Fairbanks Nonattainment Area, a very small market.  But regulators, manufacturers and test labs we spoke to all say that this is having major repercussions.  For the EPA, it’s a wakeup call that they have not been sufficiently reviewing test lab reports before certifying stoves.  Test labs are under more scrutiny for various practices and are already  being asked by manufacturers to help ensure their tests come in under 6 grams during the first hour.  And scores of manufacturers are scurrying to provide additional information to Alaska and showing them the details that were in their test reports that Alaska officials missed.  


One of the main reasons that everyone is paying attention is that most of the people AGH spoke to agree that other states and change out programs could adopt the Alaska lists instead of using the full EPA list of certified heaters.  If more change-out programs, or even states adopt these stricter requirements, the efforts of a small city in Alaska will have greater national ramifications.  Some managers of change out programs that AGH spoke to say they interested to explore ways to identify cleaner cord wood stoves and are uncertain whether the EPA’s reduction from a de facto 4.5 to 2 grams an hour actually resulted in cleaner cord wood stoves. Incentive and change out programs often have adopted stricter efficiency and/or emission requirements and this may represent the next vehicle for those programs to guide how taxpayer dollars should best be used.


The last time state regulators made changes that went on to have national implications may have been in 1995 when Washington State adopted a 4.5 gram an hour state standard, when the EPA allowed up to 7.5 grams an hour.  The 4.5 gram an hour limit soon became a de facto national standard and 20 years later, HPBA insisted it was still the lowest that the EPA should go for the 2015 NSPS.  

Non-confidential portions of emission
test reports made the Alaska investigation
possible for the first time.

Aside from developing new lists of stoves that met all the requirements of the NSPS and emitted less than 6 grams for the first hour of all their certification test runs, Alaska is providing a wealth of information to the EPA, NESCAUM and others who are already in the process of developing a new federal reference test method for certifying wood stoves.  Some regulators the Alliance for Green Heat (AGH) spoke to now acknowledge that they see the current system as “broken” and that no one knew it was so broken.  On November 16, Alaska will be making its data public, showing which requirements in the stove certification process are most commonly ignored or overlooked and which ones are complied with.  


The data to be released on Nov. 16 includes a two-page data sheet on individual stoves, showing any deficiencies in their test lab reports.   Each manufacturer will have had up to 2 months to review their own sheets and provide corrections to ADEC prior to their public release.  The initial sheets prepared by ADEC have numerous mistakes according to several manufactures AGH spoke to and include many of the data points that ADEC initially said were not in their test report.  Test labs have been helping manufacturers find relevant data in their test reports, and ADEC will continue making corrections before and after Nov. 16.


It’s not yet clear if any test lab reports may be so deficient that the EPA could revoke their certification or require that the stove be tested again.  EPA officials are just beginning to grapple with how widespread the problems may be and what they can do moving forward to help fix problems that should have been in plain sight for so long. The EPA has identified and tried to correct some testing deficiencies in the past.  An AGH blog in July 2019 covered an EPA memo asking labs to correct lapses in reports on stoves tested with the ASTM E3053 test method.  This incident may have contributed to greater scrutiny by states including Alaska’s far more in-depth investigation.

An ADEC official taking
air quality readings on top
of a school.

The EPA certifies stoves based on the weighted average of the entire burn but requires labs to also report the amount of PM in the first hour.  Like efficiency, its data that must be collected and reported by the lab to the EPA, but there is no regulatory limit.  The Alaska initiative is making everyone ask whether the first hour of emissions may be an equally important indicator of a stoves cleanliness than the entire burn cycle.  


Currently, the way EPA approved test labs test stoves is by using the standard Method 28 or a variation of it. Lab technicians load stoves with an amount of wood based on the size of the firebox and let the fire go until all the wood is burned, which usually takes anywhere from 4 – 9 hours but can be longer.  During the last several hours of the burn, known as the “tail”, there is virtually no particulate matter being released, but those hours are still averaged into the overall calculation, with much be less than 2 grams an hour with cribs, or 2.5 grams an hour with cordwood. 


AGH reviewed scores of test reports and found that single PM reading from the first hour could be as high as 20 grams an hour and the average of all the first hour burns could be as high as 10 grams an hour, but it would be less than 2 grams when the cleaner parts of the burn and especially the tail end of the burn was included.  For Alaska, if any single run went over 6 grams, it was rejected.  Since start-up is the dirtiest part of the burn, identifying stoves that have cleaner start-up may help airsheds improve air quality.


Test labs that AGH spoke to noted that this will likely have the result of disqualifying a greater proportion of larger fireboxes.  The average firebox size is 2.2 cubic feet and an initial small sample of stoves with average first hour emissions over 6 grams was 3 grams an hour.  One test lab also said that this could disadvantage catalytic stoves that have no secondary combustion during start up prior to engaging the catalyst, which often occurs 20 – 30 minutes after lighting the fire.  Hybrid stoves, however, that use both air tubes and a catalyst are likely to have cleaner start-up, according to test labs.


Some manufacturers are angry that a state is using a brand-new emission metric – first hour emissions – that they could have designed for, if they knew it would be used in some markets to regulate stoves.  Now that it has been flagged, manufacturers certifying stoves going forward can try to meet that – or at least urge the lab to build  the type of start-up fire that will come in under 6 grams.  One of the primary goals of a lab is to familiarize themselves with the stove being tested so they can “optimize stove operations during certification testing.” Some regulators fear that this will just become another factor that manufacturers and labs will use to “game the system.”


The Alaska initiative will have a far greater impact on wood stoves than pellet stoves.  Extremely few pellet stoves emit more than 6 grams in their first hour and the testing regimen is more straightforward.  Ultimately, only a dozen or fewer pellet stoves may be disqualified by their review, out of the 98 models that are currently certified. Of the 144 currently certified wood stoves, up to a quarter to a third could be impacted.   New outdoor wood boilers are not allowed in Fairbanks already.  They will be reviewing pellet boilers for compliance.

An inversion in Fairbanks that traps
wood smoke close to the ground.,

Next steps


As of Nov. 16, Alaska will publish its review on virtually every EPA certified stoves.  On December 1, only those stoves that ADEC found had complete test reports will remain on the approved device list and be allowed to be sold in Fairbanks.  If a manufacturer needs more time to address potential report deficiencies, they can contact ADEC and if they commit to working to correct the deficiencies, their device may remain on the approved device list.  The first hour emission of 6 grams on each test run requirement, went into effect on September 1, 2020, and those devices have already been removed from the approved device list. 


Other jurisdictions, incentive and change-out programs will likely begin assessing whether the Alaska list represents better stoves for public funding.  Consumers who really care about a cleaner stove could also check that list before buying a stove.  For now, there are more questions than answers but the bottom line for everyone in the industry and the wider renewable heating community is that this is a story to watch.

Related stories

Veteran lab technician challenges Alaska's wood stove criteria (March 2021)

Alaska releases deficiency details on wood and pellet stove test reports (Nov. 2020)

Friday, September 25, 2020

EPA and states vigorously defend wood stove audit testing

States share more variability test data and raise serious problems with certification process 

Updated on Oct. 20 - The EPA responded to HPBA’s lawsuit, saying that it is recycling old arguments and using a flawed analysis, and that its lawsuit should be dismissed. Eleven states and one air agency also filed a brief in agreement that provided compelling new data about testing variability and asserted that recent stove certifications are full of errors and deficiencies.
The states’ brief may be influential as it provided recent test data in an arena where very little publicly available data exists. Beyond showing that many stoves can provide repeatable emission data, states say that the ASTM 3053 cord wood method, “an industry-developed test … produces more variability than Method 28R,” the standard EPA crib wood method. The brief also cited recent testing that shows “manufacturers could generate more reliable ASTM 3053 test results by conducting certification tests in a manner that was more representative of consumers’ ordinary use of the stoves.”

We provide a brief analysis and then provide excerpts of key parts of legal briefs by the three parties: EPA, states and HPBA and also the NESCAM memo with variability test data. The briefs are long and parts are technical, but we encourage stakeholders to read these excerpts as they provide important details and context on federal wood heater regulation and the final stages of the much anticipated HPBA lawsuit.

The strong response from the EPA shows that while enforcement has not been a high priority recently, it is heavily invested in maintaining its ability to conduct audits, even though it may have only done so once or twice since the first NSPS in 1988. The 1988 and 2015 NSPS give the EPA the right to retest a stove after it has been certified, known as an audit. However, none of the three briefs ventures to discuss what circumstances could or should give rise to an audit, or whether they would be completely random.  More routine audits every 2 - 5 years for the higher volume stove models could be an option.

HPBA is the one litigant in a larger case that has gradually dissipated to one narrow issue: audit testing.  The EPA appears to be on solid ground and is backed by many states and non-profit interveners.  The data relied on by HPBA is now very old and no manufacturer is offering newer data showing high testing variability.  

The variability of emissions testing with pellet stoves or boilers had barely been mentioned in the past. For the first time, data was submitted about pellet stove variability by NESCAUM and cited in the states' brief.  AGH believes data like this is important to build greater confidence in and support for pellet technology as a core part of residential renewable heat policy. 

These briefs also come on the eve of the EPA sell-through announcement. Stuart Parker, a reporter for Inside EPA filed a story that noted “many of these same states are also threatening EPA with a lawsuit if it as expected finalizes its sell-through of wood stoves not compliant with step 2 emissions standards. The eleven states closely coordinated their response and highlighted the more notable restrictions that they have enacted to “to mitigate the risks of wood-burning devices.”

Next in the litigation process will be the September 28 filing of briefs by the non-profit intervenors, who include the American Lung Association, Clean Air Council, and Environment and Human Health, Inc.  Then, HPBA will have a chance to respond to the EPA and states by October 9, when they can rebut, if they so choose, the validity of the new testing data submitted by NESCAUM. Only after that will the DC Circuit Court schedule oral arguments which will almost certainly be virtual.  Finally, the three person panel of judges from the DC Circuit could either be more liberal or conservative and may give some indication of what arguments they may be favorable disposed to rule on.  The full briefing schedule can be found here.

AGH is an independent non-profit that has worked with all stakeholders to advance cleaner and more efficient wood and pellet heaters that can help reduce fossil fuel use and compliment solar panels, heat pumps and other renewable technologies. AGH sided with industry in supporting a limited sell-through of Step 1 heaters and has sponsored a series of technology competitions to demonstrate innovative solutions to reducing emissions in real world settings. AGH supports the audit provisions in the 2015 NSPS to provide important safeguards to determine potential flaws and lapses in certification testing and better understand emissions from different stove designs in real world settings.

To download the full briefs, click here for PDFs of the EPA brief, the States' brief, the HPBA brief, the Intervenors' Brief and the NESCAUM memo. The excerpts below have only been altered by removing citations, footnotes and subheadings.

1. Excerpts of EPA brief

Simi Bhat, Senior Trial Attorney, DOJ
Residential wood heaters generate small particles of pollution that can cause difficulty breathing, heart problems, and even premature death. These emissions are so pervasive that EPA estimates that residential wood heaters account for nearly twenty-five percent of cancer risks from toxic air pollution and fifteen percent of noncancer respiratory risks.

After conducting its own analysis on variability and considering other data on newer heaters, EPA concluded that variability was not as high as HPBA supposed, but still present.

HPBA now recycles the same argument about variability, but applies it only to the compliance audit process. Oddly, HPBA ignores its own success—the final standards reflect variability. EPA did not need to adjust the audit provisions because EPA adjusted the standards themselves, both by allowing a margin for variability in the emissions limits and by improving precision in testing.

While HPBA may be concerned that EPA may not administer the audit provisions fairly, this concern is unripe. EPA has not yet conducted an audit under the 2015 Rule. A hypothetical failed audit test by unknown margins with unknown context does not lend itself to judicial review at this time. If EPA revokes certification, that decision can be challenged. This petition should be dismissed.

Residential wood heaters collectively emit hundreds of thousands of tons of particulate matter throughout the country every year. At times and places of high use, wood heaters can contribute over fifty percent of daily particulate matter pollution. Because residential wood heaters are located in residential areas and emit pollution at low heights, even a small amount of pollution from these devices can cause disproportionately high exposure. This exposure is not fleeting because residential wood heaters are often used around the clock.

The manufacturer Woodstock Soapstone submitted comments comparing HPBA’s data to Woodstock Soapstone’s more recent data for three room heaters. Woodstock Soapstone attributed the difference between the variability it observed in test results of its heaters and the variability HPBA described to the “deep[] flaw[s]” in HPBA’s dataset.

Puget Sound concluded that HPBA “disregarded basic questions of data quality and representativeness.” For example, HPBA relied on results from the highest emitting wood heaters, which can have large differences in test results, instead of analyzing the entire dataset. But the variability of the “worst performing” device does not represent the variability across the board. Puget Sound further observed that HPBA’s data reflected “different sampling methods, locations, testing protocols, testing locations, span many years, and do not include data from a balanced or representative cross spectrum of the stoves and independent variables.” Even if HPBA’s dataset were representative and reliable, which Puget Sound did not believe, the real variability was far less than HPBA calculated. Puget Sound discovered that HPBA simply used the wrong statistical measurement to express variability as ± 4.5 to 9 gram/hour. The correct value for the (problematic) dataset of old heaters would be approximately ± 1.5-2 gram/hour.

EPA contracted with the Brookhaven National Laboratory to investigate, among other things, the repeatability of results from hydronic heater tests. Brookhaven tested the heaters by burning wood at three different rates, as specified in the test method for hydronic heaters. At the highest burn rate, results for three replicate tests were within 15% of each other. At the two other burn rates tested, the results were within 3% and 10% of each other. EPA concluded from this study that the “repeatability of cord wood test method” for hydronic heaters can be “very good.” 79 Fed. Reg. at 37,261. Before seeing the results of the Brookhaven study, HPBA had postulated that precision in hydronic heater testing would likely be similar in precision to other wood heater testing

The final 2020 standards are less stringent than initially proposed because EPA incorporated a margin of variability in the standards. EPA concluded that if “precision” in testing “is no better than 1.0 [gram/hour],” the final emissions limit of 2.0 [gram/hour]” for room heaters tested with crib wood would adequately reflect the emissions reductions achieved by stoves that tested at 1.0 gram/hour

The differences between the 1988 and 2015 audit provisions are slight. In the 1988 Rule, EPA required that the audit test be performed at the same laboratory that performed the certification test, until EPA could determine overall test method precision. Test method precision can be broken into two components. There is variability in test results when the same device is tested in the same laboratory multiple times (intralaboratory precision), and there is variability in test results when the same device is tested in different laboratories (interlaboratory precision). Under the 1988 Rule, once EPA determined test method precision, EPA would allow an additional margin equal to only interlaboratory precision when determining whether a device failed the audit test.

EPA did not need to make special allowance for variability in the audit provisions because EPA had already accounted for variability when setting the standards. Even the outdated analysis championed by HPBA does not support the need for any further buffer in the audit provisions.

Manufacturers will have a further opportunity to submit evidence on variability should any of their devices fail an audit test. EPA will consider any relevant evidence manufacturers present during an audit hearing, including evidence on variability. No other mechanism is necessary to address variability in audits.

EPA left the audit process in the 2015 Rule largely unchanged from the original 1988 Rule. Variability has never before been an issue in the implementation of the audit provisions, and HPBA offers no good reason to think it will now.

If EPA revokes certification following a failed audit test, a manufacturer can challenge that decision at that time. HPBA’s challenge to the possibility that EPA might revoke certification based on an unknown test result in the face of unknown rebuttal evidence in a future audit is unripe.

HPBA does not once mention in its brief that the audit process includes the opportunity for manufacturers to present additional evidence. Given that variability is already incorporated into the standards, as discussed above, and that EPA will consider any relevant evidence presented in an audit hearing, EPA did not need to make yet another allowance for variability in the audit provisions.

The only circumstance in which consequences are automatically triggered without a hearing is if a wood heater fails the audit test by 50% or more of the standards. If a device fails so egregiously, then EPA will suspend the certification after giving the manufacturer 72 hours’ notice of the suspension. This suspension may be withdrawn by EPA, and the manufacturer will still have the same opportunity to present any relevant evidence at a subsequent hearing to avoid final revocation.

The 50% exceedance trigger for suspension allows for even greater variability than HPBA itself calculated based on its old and flawed dataset.

2. Excerpts of States brief

Nicholas Buttino, Assistant Attorney General for NY


The amici States have a compelling interest in protecting their citizens from the emissions of wood-burning devices, which produce multiple pollutants that cause serious health effects. To advance this compelling interest, the amici States have enacted their own measures to mitigate the risks of wood-burning devices, and have participated in efforts to reduce wood-burning device pollutants at the federal level.

The state studies described in this brief confirm that there is no merit to petitioner Hearth, Patio & Barbecue Association’s objections to the audit-testing provisions in the 2015 Rule. As the States’ analyses demonstrate, the audit-testing provisions are necessary to ensure compliance with the Rule’s emissions standards. Petitioner’s testing variability concerns are overblown: those concerns are based on flawed statistical analysis and avoidable testing choices made by the manufacturers themselves. Accordingly, the States urge this Court to uphold the Rule in full, and reject the petitioner’s challenge.

Emerging research shows that long term exposure to PM2.5 increases the mortality rate from COVID-19, including in minority and low-income communities.

The health effects of wood-burning devices are acute in the amici States. The amici States have hundreds of thousands, if not millions, of residents who rely on wood-burning devices for heating. New York alone contains nearly 150,000 homes that use wood as a primary heating source and 500,000 homes that use wood for supplemental heat. In Vermont, 22% of homes use wood as a primary heating source, and 35% of households burn wood for at least some heating.

The amici States agree with EPA that petitioner’s challenges to the Rule are meritless, for the reasons stated in EPA’s brief. The States file this brief to inform the Court of the States’ own research, which underscores that the audit-testing provisions challenged by petitioner are necessary to ensure compliance with emissions standards, and that petitioner exaggerates testing variability as an impediment to reliable auditing.

The Alaska Department of Environmental Conservation has conducted a systematic review of wood-burning devices that have been certified to be compliant with EPA standards. The Department found that 59% of the certifications had inaccurate certification data, and 64% had certifications based on non- representative testing methods—i.e., methods that were not consistent with ordinary consumer use. What is more, three certifications lacked certification test reports altogether. These results suggest serious problems in the certification process. And those problems in the certification process in turn demonstrate why EPA must have a way to check on manufacturers—and hold them accountable—through audits.

The Curkeet study suffers from three main defects. First, the Curkeet study incorrectly applied statistics applicable to a normal distribution to data that was not normally distributed. Second, the Curkeet study improperly divided its dataset and drew conclusions from data that were not representative of the dataset as a whole, allowing particularly extreme values to be highlighted and taken out of context. Finally, the Curkeet study conflated absolute difference in values with a confidence interval, leading to a dramatic overestimate of uncertainty. Based on these problems with the Curkeet study, EPA reasonably discounted Curkeet’s conclusions.

NESCAUM’s analysis shows that testing variability may be minimized if manufacturers use a reliable certification test and scrupulously follow that test method. In issuing the Rule, EPA required labs to follow a certification method designated Method 28R, but allowed for approval of alternative test methods. At the request of manufacturers, EPA approved ASTM 3053, an industry-developed test, as an alternative test method. But using ASTM 3053 produces more variability than Method 28R because ASTM 3053 contains fewer specific instructions. To illustrate, where Method 28R states that manufacturers should use fuel logs that are no less than 5/6 the length of the firebox, ASTM 3053 contains no such limitations.

A NESCAUM study shows the testing variability that may result from ASTM 3053. NESCAUM tested six wood stoves, including five that used ASTM 3053 for their certifications and one that used Method 28R. NESCAUM replicated the results of the stove certified using Method 28R—in other words, there was no substantial testing variability using that method. However, two of the five stoves using ASTM 3053 had high variability between the certification test results and NESCAUM’s results. NESCAUM determined that these stoves used non-typical fueling approaches, such as by burning short logs or logs stacked in unusual ways, which likely explained the variation in test results.

NESCAUM noted that manufacturers could generate more reliable ASTM 3053 test results by conducting certification tests in a manner that was more representative of consumers’ ordinary use of the stoves. For example, the manufacturer of one of the stoves in NESCAUM’s study used the ASTM 3053 test for certification, but with a representative testing technique (by loading the stove as a consumer would). NESCAUM found that that stove emitted almost exactly the amount in NESCAUM’s test that the stove was certified to emit.

3. Excerpts of HPBA Brief

David Chung, Counsel to HPBA

In the 2015 Rule, EPA set very low particulate matter (“PM”) emission standards for wood-fired residential heaters. Not only did EPA require manufacturers to achieve compliance with those low standards during the certification testing process, EPA also promulgated audit testing requirements that allow the Agency to require a manufacturer to retest an EPA-certified appliance either at the same laboratory that conducted the initial certification testing or at another laboratory unilaterally selected by EPA. These requirements are problematic because EPA did not account for the long and well established facts that: (i) the results of repeatedly testing an appliance at a single laboratory often vary significantly (intralaboratory variability); and (ii) there is even greater variability among the results of testing the same appliance at different laboratories (interlaboratory variability). This is generally referred to as “test method imprecision” or “testing imprecision,” but is sometimes also referred to as “test method uncertainty” or “test method variability.”

EPA tried to address test method imprecision in its prior (1988) new source performance standards (“NSPS”) for wood stoves in two ways: promulgating higher emission limits that assumed and accounted for a certain level of intralaboratory variability; and conditionally restricting where and how audit testing could occur, at least until EPA studied and better understood interlaboratory variability. Together, these safeguards helped divide the risk of test method imprecision between EPA and manufacturers, the overwhelming majority of which were—and still are—small businesses. This risk sharing was sensible in light of the inherently variable nature of wood burning and the many potential sources of variability given the complexity of wood heater test methods and the fact that testing can span nearly a full week.

EPA inexplicably proposed to make no such accommodations to account for variability in developing the 2015 Rule. HPBA thus commented at length about testing imprecision, urging the Agency not to require audit testing at all given the demonstrated magnitude of both intralaboratory and interlaboratory imprecision. HPBA also reminded EPA of the need to account for test method imprecision when setting emission standards if the Agency insisted on finalizing audit testing requirements. EPA’s proposal placed manufacturers in the unfair position of not only having to meet very low PM emission limits but having to achieve results that leave a large enough margin below the applicable limits to account for testing imprecision in the event their appliances are audited.

Faced with significant objections to its proposal to effectively ignore testing imprecision, EPA improperly dodged those objections by offering conclusory or illogical responses or (worse) ignoring them altogether. And EPA entirely failed to explain why, in the 2015 Rule, it abandoned the more sensible approach to audit testing and addressing test method imprecision it had codified in the 1988 Rule.

4. Excerpts of the NESCAUM memo

Lisa Rector, Policy & Program Director, NESCAUM

TO: NESCAUM Board of Directors

FROM: Barbara Morin and Lisa Rector, NESCAUM

RE: Reproducibility of Test Results in Step 2 Stoves

DATE: September 4, 2020

Development of new test methods for residential wood heating appliances has been part of Northeast States for Coordinated Air Use Management’s (NESCAUM’s) research agenda for the last eight years. As part of that initiative, NESCAUM purchased and tested several Step-2 certified appliances at contracted research laboratories during the past two years. The primary intent of that research effort was to determine how testing procedures affect emission performance measurements. To establish a foundation for this research, baseline particulate matter (PM) emission performance testing was conducted on the study devices using current certification test procedures. Note that the research lab did not attempt to replicate certification results, nor did it follow the detailed instructions manufacturers provide to the labs, which are sometimes identified in test reports.

The results of the NESCAUM baseline tests are also useful for informing discussions regarding the compliance audit specifications in US EPA’s 2015 New Source Performance Standards (NSPS) for Residential Wood Heaters.

Step-2 Pellet Stoves

The NESCAUM study evaluated three Step-2 certified wood pellet stoves with differing heat outputs and pellet delivery systems, identified here as Stoves 11, 13, and 14. The study tests were conducted according to the ASTM 2779 method, which is the Federal Reference Method (FRM) used to certify the compliance of pellet stoves with NSPS emission standards.

The emission results (ERs) measured in all of the pellet stove study runs were lower than 3.0 g/h, the audit test level that would trigger the initiation of revocation procedures. All of the softwood runs were also lower than the 2.0 g/h NSPS emissions limit for Step-2 stoves.

The results indicate that compliance audits are a reasonable requirement for assuring compliance with emission standards for pellet appliances. While ERs were substantially higher in runs with hardwood pellets than with softwood pellets, replicate runs with the same fuel produced reproducible results.

ASTM 2779 does not include specifications about the physical parameters of the pellet fuel used for testing. Because the composition of the pellets has a marked effect on the ERs, it is crucial that test reports include an elemental analysis of the pellets used in the test to enable a fair comparison with audit results. EPA should also consider requiring the use of pellets that are representative of the range of wood pellet types in typical consumer use, including hardwood pellets, in certification tests for these appliances.

Step-2 Cordwood Stoves

The NESCAUM research included the assessment of six Step-2 stoves. One of those stoves was certified using the EPA Method 28R (M28R) crib wood test, and the other five stoves using the ASTM 3053 cordwood method.

The ERs measured using the IDC alternative protocol for Stove 7, 12, 15, and 17 would not trigger the actions required when audit testing shows results greater than 150 percent of the standard. As in the baseline testing, however, the IDC ERs for both Stove 9 and 16 were substantially above the certification values and would trigger revocation proceedings. The considerably elevated emissions measured in those stoves, using both the baseline and alternative testing protocols, is evidence that the poor performance is attributable to poor combustion design rather than test method variability and precision issues.

Although the variability in the Stove 16 test runs was within acceptable parameters, the ERs in all runs in that stove were consistently elevated, suggesting that certification values for this appliance are not representative of in-use performance. Stove 9’s run variability was an outlier in the study, and its highly variable performance across testing methods supports the need for replicate testing and compliance audits.

Conclusions on Cordwood Stoves

The results of the baseline and alternative testing of cordwood stoves provide evidence that compliance audits are reasonable and necessary for assuring that those appliances conform with emission standards. Baseline and alternative test protocols measured ERs for four stoves was consistently below levels that would trigger revocation actions. The study identified two stoves with substantially elevated and, in one, highly variable emissions that would trigger further compliance activity. Analysis of additional data from the study indicated that elevated or variable emission levels did not result from test method precision or variability issues but instead were an indicator of elevated emissions performance. Problems with the certification testing procedures and operation of those two stoves would likely have been detected by compliance audits.


Taken together, the results of NESCAUM’s analysis indicate that the compliance audit requirement is reasonable and would be an effective tool for compliance assurance if fully implemented. The study was able to reproduce certification test results in both pellet and cordwood stoves according to the audit criteria specified in the NSPS, when those certification tests were conducted appropriately. Furthermore, the analysis demonstrated that an audit would likely identify substantial issues associated with unrepresentative operating and fueling procedures and with appliances that have highly variable performance.

The compliance audit requirement in the NSPS rule provides a mechanism for avoiding the inappropriate certification of high-emitting stoves. NESCAUM’s research indicates that replicate testing, such as is used in compliance audits, provides critical compliance assurance procedures necessary to maintain the integrity of the regulatory program. The data also suggest that the emissions measured in audits of well-designed appliances that have been certified using appropriate testing procedures will be acceptable within the tolerances specified in the current 2015 NSPS for Residential Wood Heaters. 

5. Excerpts from Intervenors' Brief

Respondent-Intervenors American Lung Association, Clean Air Council, and Environment and Human

Timothy Ballo of Earthjustice, counsel
for Intervenors

Health, Inc. (collectively “Intervenors”) embrace, but do not repeat, EPA’s argument that the rule under review reasonably accommodates testing variability, through both the emission standard levels EPA selected and the compliance audit process it prescribed. 

Petitioner Hearth, Patio, and Barbecue Association (“HPBA”) seeks to eliminate EPA’s ability to enforce the updated emission standards. HPBA does not contend the emission standards are themselves unlawful, nor does it attack the test methods EPA has adopted and through which HPBA’s members certify that their products comply with the standards. Instead, HPBA asserts that there is too much variability in test results for EPA to rely on audit testing to find that a wood heating device does not comply with the standards. In sum, HPBA’s position is that although the test method is accurate enough to identify products that HPBA’s members can sell, it is not accurate enough to identify products that they must stop selling. 

If this Court is persuaded that EPA has failed to explain aspects of its decision to adopt the audit testing regulations included in that rule or to respond to comments opposing that decision, vacatur is not the appropriate remedy. This Court should instead remand the matter to EPA for additional explanation. 

It is clear that EPA could take lawful action on remand to retain the compliance audit provisions HPBA has challenged. The more recent studies of variability discussed in EPA’s Brief show there is sufficient evidence to support a determination to retain the existing regulations. 

Supporting Amici have detailed the widespread problems with manufacturers’ certifications of compliance with EPA’s wood heating device standards and how manufacturers have implemented EPA’s test procedures in ways that yield favorable outcomes. Nor are Amici alone in recognizing that manufacturers have made choices when conducting certification tests that achieve compliance at the risk of generating unrepresentative values. For example, the lead author of the study HPBA relies on to claim EPA’s audit testing provisions are unreasonable has suggested the ratings achieved for certification purposes “are biased toward low values,” in part because labs select favorable start-up procedures and “may have imposed significantly tighter controls of fuel selection and arrangement than required by [EPA].”

6. Excerpts of HPBA's Corrected Reply Brief (filed on Oct. 15)

Amanda Shafer Berman, an
attorney for HPBA
The U.S. Environmental Protection Agency’s (“EPA”) brief is an exercise in post hoc rationalization. The Agency failed to provide a reasoned basis for its audit  testing requirements in the 2015Rule, which barely mentions—much less adequately explains—major changes in those requirements from the 1988 Rule. 

Nor did EPA analyze the key issue of interlaboratory variability, e.g.,by making findings on the magnitude of such variability, in promulgating the 2015 Rule.

EPA nonetheless asks this Court to uphold its decision to allow wood-fired heaters to be audit tested at any federal or private laboratory of EPA’s choosing— without making any allowance for interlaboratory variability—based on a combination of conclusory statements and its belated assessment of record data. These are not acceptable bases to uphold agency action. But even if this Court entertained EPA’s post hoc justifications, the information EPA now highlights does not support its decision, and this Court therefore should vacate (not merely remand) the challenged audit testing provisions given the seriousness of the errors and the lack of disruptive consequences that would result from vacatur. 

Having failed to support the 2015 Rule’s audit requirements on the merits, EPA attempts to avoid review on ripeness grounds. EPA argues that it intends to audit manufacturers rarely, so judicial review should await some future enforcement action. But the Clean Air Act (“CAA”) commands that pre- enforcement, facial challenges to EPA rules be brought within sixty (60) days of promulgation. And this Court has repeatedly held that legal issues such as whether the 2015 Rule’s audit provisions are reasonable and supported; whether EPA responded to comments; and whether EPA explained why it abandoned the 1988 Rule’s approach to auditing should—and indeed must—be adjudicated now.