Wood Stove Market Impacts

Including Efficiency and Emissions Standards

Hearth, Patio & Barbecue Association

Prepared and Presented by: 

Robert Ferguson

Ferguson, Andors & Company

1
Wood Stove Market Factors

• The wood stove market is driven by many factors. 

– The influence of these factors is not the same for 

every potential purchaser or for every locale. 

• Some of those factors:

Positive Factors

• Increasing Conventional Energy 

Costs

• Self-Sufficiency Motivation

• Firewood Availability and Cost

• Tax (or Other) Incentives

• Capital Outlay/Investment 

Payback (ROI) 

• Efficiency/Emissions Performance

• Aesthetics

Negative Factors

• Lower (or Stable) Conventional 

Energy Costs

• Inconvenience and Extra Work

• Firewood Availability and Cost

• Capital Outlay and Investment 

Payback (ROI)

• Safety Concerns

2
Wood Stove Efficiency

• IRS Tax Credit

– In 2009, IRS approved a tax credit program that 

included biomass heating equipment as long as 

minimum efficiency requirements were met.

– Both HPBA and EPA worked to get a standard 

efficiency determination protocol included as part 

of the IRS program.

• This effort was unsuccessful other than getting 

clarification that the Lower Heating Value of the fuel 

could be used for determining efficiency.

3
Basics of HHV v. LHV

• HHV (Higher Heating Value) assumes that the water vapor 

produced when the solid fuel is burned can condense and therefore 

the heat released if that occurs is treated as “available” heat as part 

of the total heat input from the fuel.

• LHV (Lower Heating Value) assumes that the water vapor produced 

when the solid fuel is burned will never be allowed to condense, 

and therefore, that potential heat recovery shouldn’t be counted as 

part of the heat input from the fuel. 

• Since efficiency is heat output divided by heat input, using LHV 

(smaller denominator) results in higher efficiency values. 

• LHV is generally used in Europe for solid-fuel fired heaters.

• HHV is the general norm for rating all heating equipment in North 

America and allows direct comparison of efficiency of heaters 

burning different fuel types (gas, oil or wood).

• Since there are already condensing designs for gas and oil, and 

there is always the possibility of someone inventing a condensing 

system for solid fuel, HHV is the better way to rate ALL heaters.

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How did this affect the IRS values?

• IRS allowed self-certification by manufacturers 

including using previously available efficiency data.

• The standard practice adopted by manufacturers in the 

absence of IRS guidance was to base the efficiency 

value on a single heat output category rather than the 

weighted average over the full operating range of the 

stove.

• In combination with the LHV, this resulted in “IRS”

efficiency values that can be significantly higher when 

compared to the weighted average HHV efficiency.

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• HPBA supports the determination of the average 

overall efficiency using a standardized weighted 

average HHV efficiency test method (CSA B415.1-10) so 

the playing field is level for everyone.

• HPBA also supports determining the precision of the 

efficiency test method.

• Standardized efficiency values (including precision) 

should be disclosed to the buying public to aid their 

purchasing decision.

– on hang tags 

– in advertising materials 

• Marketplace pressures will ultimately drive 

manufacturers to improve efficiency levels for their 

lower performing models. 

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Wood Stove Efficiency
Wood Stove PM Emissions

• EPA Wood Stove Particulate Emissions are 

determined using a laboratory test procedure 

that consists of burning Douglas fir fuel cribs

in at least four test runs that span the 

operating range of the stove.

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• The EPA test methods have limitations and a 

comprehensive evaluation of the precision1 of the 

EPA test methods has shown that they cannot 

reliably distinguish emissions performance 

differences of less than 3 grams per hour. 

• This means that EPA test methods are certainly 

capable of reliably distinguishing between good and 

bad performance, but they cannot reliably 

distinguish between “good, better and best”

performance.

1

“EPA Wood Heater Test Method Variability Study - Analysis of Uncertainty, Repeatability and Reproducibility based on 

the EPA Accredited Laboratory Proficiency Test Database”, R. Curkeet and R. Ferguson. Submitted to EPA on October 6, 

2010. The report is available upon request. The report was also summarized in Hearth and Home Magazine, March 2011 

Issue.

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• The emission test results from the EPA 

laboratory-based test methods are also not a 

reliable predictor of in-home PM emission 

performance2.

• In-home PM performance is generally higher 

and stove rankings can change.

– A stove with a higher EPA emission certification 

rating may perform better in the field than a stove 

with a lower EPA number.

2 

“A Comparison of Particulate Emission Rates from the In-Home Use of Certified Wood Stove Models with U.S. EPA 

Certification Emission Values and A Comparison between In-Home Uncertified and Certified Wood Stove Particulate 

Emissions”, Dr. James Houck, February 2012

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• Tightening performance standards will have

definite impacts:

– Stove prices will increase due to re-design costs, 

certification costs, cost impacts in manufacturing, 

and marketing and sales costs as well as the actual 

material cost increases for each stove produced -

to name some of the elements.

• In the simplest terms, when stove prices 

increase, stove demand decreases.

– Each 1% increase in retail price results in 1.6% 

fewer sales. 

– Impacts on replacement stoves may be even 

greater.

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11

8% Decrease in 

Sales Volume

5% Increase in 

Retail Price
0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 2017

U

nits

S

old

Year

EPA Certified Wood Heater Historical Sales Data, 

1987 - 2010, and Projections through 2017

Historical Data - Freestanding Only

Linear Fit & Projection

Freestanding Stoves Only

Estimated & Projection

Freestanding Stoves 

plus Fireplace Inserts

Sources

1. The Fraction of Freestanding Wood-Fueled Stoves in Current Use 

That are U.S. EPA Certified Cordwood Stoves and Wood Pellet Stoves

James E. Houck, Ph.D., July 23, 2011

2. Estimated Fireplace Insert Sales as an Average Percentage of Total 

Certifed Stove Sales 1999-2010, Hearth, Patio & Barbecue Association

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EPA NSPS Phase 2
• Current trends show a modest 1% average 

increase in sales volume without added costs 

due to new regulation.

• With new or tighter regulations, that trend is 

likely to reverse -- with fewer sales than today.

• For PM emissions, lowering the passing grade 

will produce only the appearance of progress–

nothing more. 

• It will slow the rate of change-outs, by increasing 

the cost of new stoves and reducing the number 

of models available to consumers.

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2010 National Particulate Emissions by 

Freestanding Stove Category

Certified NonCat: 15,188 

Tons, 10%

Certified Cat: 

5,016 Tons, 3%

All Pellet: 1,445 

Tons, 1%

Conventional 

135,420 Tons, 

86%

14

6 Million + 

Stoves - 86% of 

Total PM

~3.3 Million

Stoves – 14% 

of Total PM Total PM Emissions –

2010: 157,069 Tons

Source: The Fraction of Freestanding Wood-Fueled Stoves in Current Use That are U.S. EPA 

Certified Cordwood Stoves and Wood Pellet Stoves, Dr. James Houck, July 2011
Conclusions

• Wood stove demand is volatile, can have regional 

differences and is influenced by many factors. 

• Economic Factors are Primary Drivers for Consumers

– Conventional Heating Costs 

– Availability and Cost of Firewood

– Capital Investment and Payback (ROI)

• Tightening standards is a meaningless numbers game 

-- nothing more. It will however, drive up stove

prices and reduce demand.

– This reduces change-outs as consumers opt to keep 

their old stoves. Pre-certification era stove models 

produce the vast majority of PM from residential 

wood combustion.

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