Are EPA-Certified Wood Stoves Another Emissions Scandal?

New study finds the certification program is dysfunctional

modern wood stove

Kristian Septimius Krogh/ Getty Images

Back in 2015, we wrote "Breathe Easy: Clean-Burning Wood Stoves Are on the Way," marking the introduction of new, tougher regulations set by the U.S. Environmental Protection Agency (EPA). We noted how the EPA standard would lead to a dramatic reduction in the release of volatile organic compounds (VOC) and small particulate matter (PM2.5). While we have questioned whether burning wood for heat was ever a good idea, many have defended it, suggesting that burning wood occasionally in a super-efficient and clean EPA-certified stove wasn't so bad.

However, a new study by the Northeast States for Coordinated Air Use Management (NESCAUM) in collaboration with the Alaska Department of Environmental Conservation (ADEC) reveals a Volkswagen-sized emissions scandal, finding "systemic failure of the entire certification process, including EPA’s oversight and enforcement of its requirements."

Sources of PM2.5

According to the EPA, residential wood heating is responsible for 22% of PM2.5 emissions in the United States. However, it is also concentrated in certain areas: In New England, 21% of households use wood.

Treehugger reported before that PM2.5 emissions are worse than we ever knew — they contribute to cardiac, respiratory, and other diseases affecting everyone from the unborn to the old. This study quotes sources claiming residential wood heating emissions "account for 10,000 – 40,000 premature deaths annually in the US." Gavin MacRae reports that "Health Canada estimates air pollution causes 1,900 premature deaths in BC every year, while total health costs in Canada are pegged at $120 billion annually." This is why switching to the EPA-certified stoves was so important.

However, it appears that the standard was never really implemented at all:

"The unavoidable conclusion of this report is that EPA’s certification program to ensure new wood heaters meet clean air requirements is dysfunctional. It is easily manipulated by manufacturers and testing laboratories. EPA has done little to no oversight and enforcement. Starting in 1988 when EPA first adopted air pollution standards for new wood stoves, it has never conducted a single audit to verify that a wood heater actually performs consistent with its certification test results, a span of over 30 years."

The study was performed at a "screening" level — it is not a full and comprehensive review of test reports — but found enough problems there to raise significant concern.

"The existing program provides no confidence that new residential wood heaters are performing in a manner that better protects public health than the heaters they replace, and at the level required by federal standards. This has critical implications not only for public health, but also for the perceived cost-effectiveness of investments in residential wood heater change-out programs and tax credits given for the purchase of new wood-burning appliances."

Sounding very much like the Volkswagen scandal, it appears that testing agencies "routinely employ atypical burn practices" to improve emission performance, while the manufacturers' instruction manuals describe a completely different way of using the stove. The researchers found prototypes used for testing had different sized fireboxes than the units actually sold.

Examining test reports for 131 certified wood stoves, none had complete reports, 73 had serious deficiencies, and many had different versions of the same report on file. The study found 46% had different firebox volumes in the tests than in the marketing materials and 75% had higher heat output values in marketing materials than in the tests.

But it wasn't just examing paperwork. Lisa Rector, policy and program Director at NESCAUM, tells Treehugger: "The study assessed rule report requirements versus actual tests. The review evaluated if the certification test reports contained all the required elements and if the certification test was conducted according to rule and test method requirements. We found issues on both counts." 

Test results on two stoves

The NESCAUM researchers tested two stoves by replicating conditions in the test procedures and compare them to recommendations from the instruction manuals — they got wildly different results. With one of the two stoves, the emissions were twice as high; in the other, they were 10 times as high in the new test as in the certification test.

Results for pellet stoves and central heaters were all just as bad. And it is not like the EPA was even helpful in this. The agency wouldn't release information, saying: "EPA-approved laboratory inspections and compliance assurance activities are treated as confidential business information (CBI) by EPA and therefore unavailable for public review."

The conclusion of the study is particularly harsh:

"Based on the identified shortcomings in this review, the 2015 RWH NSPS certification program fails to assure that new residential wood heaters are uniformly cleaner than past devices before the new standards went into effect. A flawed testing and review system coupled with a historical lack of EPA enforcement of basic program elements work in tandem to undermine the public health goals of the program. The end result is a program devoid of any credibility to ensure that new residential wood heating appliances are meeting federal emission standards, and that gives every indication that scarce public resources are being misspent on incentive programs meant to encourage the more rapid introduction of cleaner wood-burning appliances that truly reduce emissions."

We read this study after watching a particularly gripping episode of the BS + Beer featuring "engineers Sonia Barrantes, Kristof Irwin, and Brian Ault discussing the topic of indoor combustion—particularly wood-burning—in super-tight homes. Their bottom line? Don’t do it. "

Treehugger reached out to Sonia Barrantes of Ripcord Engineering for comment. At the time of publication, we have only received a preliminary response to our questions of whether they are surprised, with Jacob Staub of Ripcord telling Treehugger: "Surprised?: No. People like their solid fuel fires loosely regulated. It enhances the romanticism of killing yourself slowly."

EPA Certifications Should Be Revoked and Stoves Should Be Recalled

Juraj Mikurcik's wood stove in his passive house
Juraj Mikurcik's wood stove in his passive house. Juraj Mikurcik

When the 2015 EPA regulations were first imposed, many in the United States were outraged, claiming, "Obama is taking away your wood stove!" We wondered what the problem was, noting that "if stoves were clean, then renewable wood might be considered the perfect fuel for many people who have access to it nearby." I know a lot of architects and green building professionals who have used them, for those few days per year that super-insulated homes need a boost rather than burning fossil fuels.

VW's Golf TDI was the Green Car of the Year in 2009
VW's Golf TDI was the Green Car of the Year in 2009--an award since rescinded. (Photo: Wikipedia)

But I also know a lot of passionate environmentalists who drove Volkswagen diesel vehicles because testing showed they were cleaner with lower carbon emissions. Volkswagen cheated on the tests, the government didn't do any oversight, and the company willfully sold cars that put out as much as 35 times the pollution that they were supposed to.

The stove scandal here doesn't seem very different. Now we pretty much know EPA wood stoves are not a whole lot better than the ones they replaced. Manufacturers and the testing organizations — even the EPA — have been complicit in this. It has all been a sham.

In light of this information, all those certifications should be revoked and all those stoves should be recalled and replaced. We know what PM2.5 from burning wood does to people: These stoves were supposed to clean it up, but they are obviously still killing people.

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