Issues	with	Wood	&	Pellet	

Stove	Efficiency

John Ackerly

President

A minimum efficiency standard will help consumers 

and industry

National Educational Forum on the Residential 

Wood Heater NSPS, 

Minneapolis, MN November 8, 2012
Alliance	for	Green	Heat

501c3 nonprofit funded by foundations & grants 

A national voice for wood heat consumers

Work for more incentives for the cleanest & 

most efficient biomass heaters 

Call on government to provide R&D funding for 

ultra-clean “next generation” stoves

Work for more common-sense regulation of 

wood stoves, including

No new installs of unqualified outdoor boilers

No new installs of uncertified stoves in 

densely populated areas
Every	Gram	of	PM	Matters

 If neighborhoods like this are to have 10 – 20 pellet stoves, the 

difference between 3 grams and 1 gram is huge. If industry and 

the renewable energy community want more widespread 

deployment of pellet stoves, we need them to be be 

consistently and significantly cleaner than wood stoves.

 EPA should 

propose 2.5 gr/hr

in the NSPS and 

propose as an 

alternative going 

to 1.5 several 

years later.
Wood	Stoves	Must	be	Part	of	

Energy	Audits

BPI Solid Fuel Working Group

Alliance for Green Heat – Chair

EPA

National Fireplace Institute

Chimney Safety Institute of America

Washington State Dept. Ecology

Hearth, Patio BBQ Association

 DOE funded programs have resulted in millions residential 

energy audits that resulted in upgrading hundreds of thousands 

of furnaces and boilers. 

 Wood stoves have been completely left out, indicating a 

widespread lack of interest in government about this technology, 

and its impacts.
The	Grandfather	of	the	US	Wood	Stove

Chose	Viewing	the	Fire	Over	Efficiency		

271 years ago, in 1741, Ben Franklin assembled a stove

far less efficient and dirtier than many other stoves on 

the market. Somehow, it is still hailed as a tremendous 

advance in wood burning.

It undermined the deployment and development of far 

more efficient stove designs.

Why? Anglo culture, led by 

scores of opinion leaders, 

believed an open fire was 

more civilized than the 

closed “Germanic” stoves.
271	Years	Later,	Low	Efficiency	Outdoor	

Wood	Heaters	Plague	our	Countryside	

Wisconsin:	Wood	smoke	PM2.5	capital	of	the	US
What	are	the	efficiency	challenges?

Most wood and pellet stove manufacturers do not report 

reliable efficiency numbers

There are no national minimum efficiency performance 

standards (MEPS) for wood and pellet stoves

Fuel calculators use a wide range of efficiency assumptions 

with little documentation. 

The IRS approved sidetracking B415 and using LHV. 

There is no EnergyStar program for wood or pellet stoves

?
Minimum	Efficiency	Performance	

Standards	are	Widely	Accepted

MEPS are widely supported by the general public

Many consumers buy appliances based on purchase price and 

do not consider long term fuel costs

MEPS save consumers billions each year in reduced fuel costs

MEPS will bolster the reputation of hearth appliances, giving 

consumers confidence that they are all reasonably efficient

MEPS will help conserve wood and pellets, a valuable resource

MEPS are especially important for HVAC systems as annual 

fuel costs can exceed purchase price in several years

MEPS will ultimately even help consumers know that a second 

hand stove is efficient, even when hang tag is long gone

MEPS do not necessarily raise price of appliances
Minimum	Efficiency	Standards	

(MEPS)	are	rapidly	proliferating
Energy	Use	&	Price	Decline	as	

Efficiency	Rises
Efficiency	of	wood	appliances

As	tested	at	High	Heating	Value	(HHV)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Pellet Catalytic Non-catalytic

Best Known

Default (EPA)

Average

Worst Known
Out	of	the	top	24	pellet	stove

companies	retailing	in	the	U.S.

The following is based on a review of 

manufacturer websites: 

7 listed some stove efficiencies

7 make general efficiency claims, i.e. “our 

stoves achieve up to 77% efficiency”

10 do not mention any efficiency numbers

None specified LHV or HHV, that we saw
Pellet	Stove	Advertising	-

Emissions

Of the top 24 pellet stove companies retailing in 

the US,

16 do not list their emissions

8 provide emissions numbers in grams per hour

This may indicate that the market does not easily 

enable consumers to buy cleaner stoves, or avoid 

dirtier ones. 

This may indicate consumers do not know about 

or care enough about emissions.
Efficiency	Confusion	Reigns	

and	No	One	Tries	to	Dispel	it

Which website explains that stoves today are usually advertised 

using LHV and report efficiency in any number of ways, usually 

not B415?

o HPBA

o EPA

o NESCAUM

o WESTAR

o NYSERDA

o Dept. of Ecology, WA

o Alliance for Green Heat

Answer: None of the above. None of these institutions attempts 

to explain how manufacturers advertise efficiency.
Whose	Role	is	it	to	Protect	the	

Consumer?

Last week’s Headlines: “Hyundai/Kia to Correct Overstated 

MPG Claims as Result of EPA Investigation”

How many consumers counted on getting a 75% efficient 

stove with the IRS tax credit? How many actually got a 75% 

LHV stove?

“The IRS sponsored wood stove tax credit program 

allows manufacturers to use a different method of 

determining efficiency. IRS allows laboratories to use 

greater flexibility in determining the thermal efficiency 

rating for tax credit purposes.”

http://www.combustionportal.org/woodstoves.cfm
Fuel	Calculators	in	Disarray

EPA links to a 

calculator that 

doesn’t use EPA 

default efficiencies

Maine appears to

use LHV figure for 

pellet boilers

US Forest Service 

uses extremely high 

numbers

Many exaggerate 

pellet efficiencies

Calculator 

Name

EPA 

Certified 

Non-cat

Pellet

Stove

EPA default 63% 78%

Actual average –

OMNI

72% 68%

Actual average –

Ferguson

71%

EIA 72% 78%

Hearth.com 70% 70%

HBPA 70% 78%

Building

Green.com

70% 80%

Maine 63% 80%

PFI 60% 80%

Oregon Extension 60% 80%

Jotul 70% 70%

US Forest Service 77% 83%

Range 60 – 77% 70 – 83%
What	Consumers	Need	to	

Know:	Pellet	Stoves

Myth #1: Advertised efficiency numbers can be 

relied on.

Advertised efficiency numbers are calculated in many 

different ways and are not reliable. They are almost 

always in LHV, even though EPA uses HHV. We urge

consumers to make sure stove is over 70% HHV or 80% 

LHV using the B415 method.

Myth #2: Pellet stoves tend to be more efficient 

than wood stoves.

Many pellet stoves are fuel-guzzlers with low efficiency 

numbers. Expected savings may never materialize.
Solutions	– Long	Term

Minimum efficiency requirement for biomass 

heaters

An Energy Star-like program that includes both 

emissions and efficiency.
Solutions	– Short	Term

HPBA should urge all members to use B415 and tell 

consumers if they are using HHV or LHV

Stakeholders should take a position on extension of tax 

credit and urge Congress to require B415 efficiency test

Catalytic Stove Caucus request fuel calculators to add 

default efficiency for cat stoves

EPA should urge manufacturers to send B415 efficiency 

numbers to add to EPA list of certified stoves

Manufacturers who provide B415 efficiencies could be 

recognized on the EPA list

EPA & States should educate consumers on stove 

efficiency and warn about misleading advertisements
Thank you!

John Ackerly

www.forgreenheat.org

john@forgreenheat.org

301-841-7755