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# Proposed Revisions to the NSPS for Residential Wood Heaters – Industry Perspective Presented by the Hearth, Patio & Barbecue Association 1 

# Common Goals 1. Improve Air Quality. 2. Replace uncertified stoves. 3. Continue to work to improve real world performance of certified stoves.
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### • Using data from annual nationwide consumer surveys, Dr. James Houck determined that in 2010 there were more than 6 million uncertified freestanding wood stoves in homes nationwide. 3 

# Freestanding Stoves: Nationwide Inventory - 2010

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

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## • The six million conventional, uncontrolled wood stoves are the problem. • The “common goal” solution is to work to accelerate their replacement! 5 

## • How can we improve the real world performance of certified stoves?

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## • First we have to understand the capabilities AND the limitations of the EPA test methods. • Next we have to understand the relationship between EPA laboratoryemission performance and in-home, realworld emission performance. 7 

### • What variability – precision- can we expect when testing the same wood stove: – In the same test lab? – In a different test lab?
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## We start in the lab.10/11/2012

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### • This is not a new issue in the wood stove regulation. – The assumed “within-the-same-lab” precision when the current NSPS was promulgated was ±1 g/hr. – This determination was based on very limited precision data. 9 

## This assumed precision is represented by a blunt arrow on current hang tags.

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## What are the sources of variability in the EPA Wood Stove Emission Values? 1. EPA Test Methods, including: – Particulate Measurement Methods • Dilution Tunnels Methods (5G-1, 5G-2, 5G-3) • In-Stack Method (5H) 

### – EPA Fueling and Operating Test Method (M28) 

### 2. The Inherent Variability in Burning Wood 11 

### There is a robust database AND a standardized procedure for determining test method precision. • EPA Proficiency Test Data – To obtain and maintain their accreditation, EPA requireslaboratories to conduct “proficiency tests” on EPAprovided wood stove samples. – From 1987 to 2005, five different test stoves were shipped from lab to lab for proficiency testing. • 84 four-run data sets from 12 different laboratories were submitted to EPA. • ASTM E691-09 – “Standard Practice for Conducting an Inter-laboratory Study to Determine the Precision of a Test Method” was used to conduct the analyses. 1210/11/2012

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## Conclusions from Precision Analyses of the EPA Laboratory Proficiency Data • The “within the same lab” precision of the weighted average emissions at the 95% confidence level is at best ~±3 grams per hour. • The “between labs” precision is poorer (at least ±4 .5 grams per hour again at 95% confidence).
13 Source: “**EPA Wood Heater Test Method Variability Study - Analysis of Uncertainty, Repeatability and**  **Reproducibility based on the EPA Accredited Laboratory Proficien cy 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.


### • The dilution tunnel emission measurement methods have good precision and are not major contributors to the high overall variability. – M5H (in the stack) has shown much poorer precision but is still not a major contributor. 

### • Operational and fuel parameter variations (within the specified ranges in EPA M28) are also not major contributors. – Tightening these parameters (moisture content range, for example) would increase costs, would not improve precision and would further increase the disconnect with real world operation. 14 

### Conclusions from the Precision Analyses (cont.)10/11/2012

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### • The high level of variability in wood heater emissi on testing results for any given appliance is most likely a function of the random nature of burning wood , no matter how tightly you try to control the process.
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### Conclusions from the Precision Analyses (cont.)
Source: “**EPA Wood Heater Test Method Variability Study - Analysis of Uncertainty, Repeatability and**  **Reproducibility based on the EPA Accredited Laboratory Proficien cy 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.


### • The 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. • The EPA test methods cannot reliably distinguish emissions performance differences of less than 3 grams per hour. 16 

# What does this mean?10/11/2012

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## Next we compare laboratory results with real world performance. • EPA and State SIP Planners have long recognized that laboratory test values do not necessarily represent in-home performance. – Some states have been calling for test method changes to address this issue. 

### • EPA’s current AP-42 emission factors (g/kg) reflect ~50% emission reduction credit for certified versus conventional stoves. 17 

### • Studies published over the past two decades that were used for determining AP-42 emission factors also show an average 50% reduction for in-situ emission rate (g/hr) for certified models. – These studies show that certified stoves are working. 

### • The average emission rate in these field studies is about 10 g/hr for certified stoves and the average lab value is below 4.5 g/hr. 1810/11/2012

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### • The ability of wood stove NSPS certification values to predict in-home performance was further investigated in a recent paper by Dr. James Houck 1 

### . • As part of the study, real-world emissions from certified wood stove models were compared to uncertified models. 19 1A 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 

### • A robust database comprised of 618 total measurements was used for this evaluation. – For the certified stoves: • 409 emissions tests • 85 wood stoves • 41 individual models 

### – For the uncertified stoves: • 209 emissions tests • 62 wood stoves 2010/11/2012

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# Major conclusions from this study • There is no correlation between certification values and the real world emission rates. • And further, rank orders change. – A stove with a higher certification value may perform better in the field than one with a lower certification value. 

### • Certified stoves perform significantly better than conventional stoves (50% PM reduction). 21

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### • Lowering the NSPS passing grade will not improve the real-world performance of certified stoves. – We cannot reliably differentiate between models performing in the range of interest (i.e., below 4. 5 g/hr), because the precision of the lab test methods is no better than ±3 g/hr. – Even if we could, emission rates from lab testing do not correlate well with field performance. • The rank orders can change, with appliances that perform with higher lab emissions often performing better in the field. 23 

## Conclusions

• Lower standards are also not cost effective.
– New Source Performance Standards (NSPS’s) are “technologybased” standards. Setting them requires EPA to balance two different kinds of inputs: • technological feasibility • cost effectiveness – EPA has determined that standards below 4.5 g/hr are not cost effective. – HPBA is conducting its own cost effectiveness analysis; ou r preliminary conclusions support EPA’s conclusions. – These analyses assume that differences in EPA certification scores are “real”, • that we can meaningfully distinguish between appliances perfor ming within the range of interest based on lab test data, • and that the lab test scores predict performance in the field. – Neither of these assumptions is valid. 2410/11/2012

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## Are lower standards an effective air quality management strategy? • 25 years after the promulgation of the NSPS, there are still MORE THAN 6 million uncertified, high-emitting stoves in homes. • These stoves have real-world emission rates at least 2 or 3 ti mes higher than certified models. • The real air quality objective should be changing-out these old stoves with certified models. • Lowering the passing grade below 4.5 g/hr would slow change-outs by: – increasing the cost of certified models – reducing the numbers of models available to consumers • Lowering the passing grade will produce only the appearance of progress, nothing more, and would not be cost effective even if the marginal gains involved were in fact real. We need to keep our eye on the ball here, and focus on what matters -- facilitating changeouts. 25

## How can we improve real-world, inhome performance? • Would increasing the minimum required burn rate in EPA Method 28 have a beneficial impact?
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# Background: • EPA Method 28 requires a certification test run at a low burn rate of < 1.0 dry kg/hr. • This requirement was based on an analysis of in-situ test d ata during the development of the current NSPS. • Dr. Houck has demonstrated conclusively that this analysis wa s severely flawed. 1 – Test run duration (end of test) was defined very differently f or the field testing (100°F Flue Gas) vs. Method 28 lab testing (100% Test Fuel Bu rned). – The field tests had LONGER durations than Method 28 testing for the same amount of wood burned. – This duration determination difference skewed the in-situ burn rate down when compared to M28 lab testing. This skew was not accounted for when the M28 minimum burn rate was determined. – Dr. Houck estimates that the impact of this error was signifi cant and would certainly have resulted in equivalent M28 minimum burn rates that are appreciably greater than 1.0 kg/hr. 27A 1 Evaluation of Method 28 Wood Heater Burn Rates, James E. Houck, Jeremy Clark, and Thomas Christensen, OMNI Environmental Services, Inc., September 2009 

# Background: • EPA Method 28 requires a certification test run at a low burn rate of < 1.0 dry kg/hr. • This requirement was based on an analysis of in-situ test d ata during the development of the current NSPS. • Dr. Houck has demonstrated conclusively that this analysis wa s severely flawed. 1 – Test run duration (end of test) was defined very differently f or the field testing (100°F Flue Gas) vs. Method 28 lab testing (100% Test Fuel Bu rned). – The field tests had LONGER durations than Method 28 testing for the same amount of wood burned. – This duration determination difference skewed the in-situ burn rate down when compared to M28 lab testing. This skew was not accounted for when the M28 minimum burn rate was determined. – Dr. Houck estimates that the impact of this error was signifi cant and would certainly have resulted in equivalent M28 minimum burn rates that are appreciably greater than 1.0 kg/hr. 27B 1 Evaluation of Method 28 Wood Heater Burn Rates, James E. Houck, Jeremy Clark, and Thomas Christensen, OMNI Environmental Services, Inc., September 2009 Hypothetical Example M28 Test Complete (100% Test Fuel Weight Burned), Fl ue Gas Temp = 300° F 10 kg fuel/8 hours = 1.25 kg/hr burn rate M28 Test Extended to Reach 100°F Flue Gas Temp 10 kg fuel/10 hours = 1.0 kg/hr burn rate (10 hours = time to burn 100% of Test Fuel AND THEN reach 100°F Flue Temp) An M28 test at 1.25 kg/hr is equivalent to a field testat 1.0 kg/hr10/11/2012

18 • The ASTM committee that developed the replacement for EPA Method 28 tried to solve this problem. The “fix” was to modestly increase the low burn rate requirement by 15%, from <1.0 kg/hr to <1.15 kg/hr. • This is not a matter of trying to game the system. – Every certified stove model has satisfied the <1.0 kg/hr burn rate requirement. – The minimum burn rate tested is the lowest burn rate achievable by the stove design. • Stove designs with burn rate capabilities lower than 1.15 kg/h r will be tested at their lowest burn rate. – Increasing the lowest air setting would help homeowners to more consistently achieve expected levels of emissions performance with real world installations and with real wo rld fuel. – We believe that the current M28 low burn rate requirement is frustrating the implementation of BDT, not reflecting it. 28 

### Colville WA Wood Stove Low Burn Rate Project • To show the impact of the EPA M28 minimum burn rate requirement, two identical non-cat stoves were run in several series of comparison tests. • In one series, EPA M28 test conditions were run with the exception that one stove had EPA fuel cribs and the other was fired with D. fir cordwood. Emissions were measured using a dilution tunnel. • The comparison of the crib fuel to cordwood fuel is shown on the following slide. 2910/11/2012

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# Test Fuels

30 EPA M28 Test Fuel Crib – 7 lb/ft 3 D. fir Cordwood Test Fuel – 7 lb/ft 3 Note: The steel bars represent the interior side walls of the stove. 

### • The stoves and their chimney exits were video-taped to create both a data and visual record. • A visual evaluation of smoke opacity was also made by experienced technicians at regular intervals over the course of the test runs.
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# 1 8

32 399.6°F 407.4°F 

# What are we looking at? Run #’s View of Fire Chimney Exits Run Time from Start of Test Ave. Stove Temp. at Start Opacity Chart

Video Cue Ave. Stove Temp. at Start

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### • Additional comparative test runs were conducted under conditions better representing homeowner use. – ~21 feet of chimney height, vented though the roof, to create more realistic draft conditions. – D. fir cordwood was used. – Start-up times were increased from the five minutes allowed in EPA Method 28. – Fuel load density was increased from 7 to 10 lb/ft 3 

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### • One test series included 15 minute start-up times (to allow the fuel load to become more fully ignited) before the Primary Air Control (PAC) was set to the run position. • At the end of the start-up, one stove’s PAC was set at its minimum setting while the second had a partially open PAC. • A video synopsis of the first two hours of that series is shown on the next slide along with a plot of the opacity readings. 3510/11/2012

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### • The results of this test series were as anticipated. – The stove with the PAC at its minimum setting smoked for most of the test. – The stove with the partially open PAC ran with little or no smoke for most of the test run. 3710/11/2012

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### • In another test series under the same conditions, a different result was achieved. – The emission performance of the stove with its PAC at the minimum setting was exceptionally good – better even than the stove with the partially open PAC.
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### • A plot of the opacity readings for the first two hours for these runs are shown below. • This result shows that under favorable inhome conditions, the stoves can perform well.10/11/2012

24 • Additional test runs were conducted comparing wet and dry cordwood and shorter start-up times. • This example shows the opacity readings for a wet cordwood test run.

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## Other Test Runs

• A wet crib run was also conducted. • A summary of all the test runs plus video and test run data can be made available upon request.
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## What did the Colville project show? • To achieve a cleaner burn more consistently, there are significant differences in the minimum combustion air settings required for EPA crib fuel compared to cordwood. • The current minimum burn rate requirement in EPA M28, is negatively impacting real-world low burn rate performance. • Modest increases in the minimum combustion air setting will allow homeowners to achieve better, more consistent performance. • Wet wood performance was worse than drier wood even when given a longer start time. No surprise! 42 

## Industry’s Concerns about EPA’s Proposed Efficiency Standards
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## Is Overall Efficiency a Surrogate for Carbon

Monoxide? • The short answer is no! CO like PM correlates with combustion efficiency, not overall efficiency. – Overall efficiency is the combination of combustion efficiency plus heat transfer efficiency. These can work in opposite directions. 

### • EPA found 25 years ago that separate standards for CO were not needed. – PM controls that require improvements in combustion efficiency would also improve CO. 44 

## Are the proposed efficiency standards

supportable? • Adding “Overall Efficiency” standards to the NSPS occurred late in the process. This presents several issues: – EPA has done NO technological feasibility or incremental cost effectiveness analysis that include BOTH PM and Overall Efficiency standards. – Without that required analysis, EPA attempted a short cut, by selecting efficiency standards it believed could be met by the vast majority of appliance models that met the PM standards. 4510/11/2012

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### • The Hearth, Patio & Barbecue Association (HPBA) undertook an efficiency data gathering effort for wood heaters in response to EPA’s initiative. The study was completed in 2011. • CSA B415.1-2010 overall efficiency data, along with corresponding EPA emissions certification values for 68 currently produced non-cat* models that meet Washington State emission limits were obtained. *Too little data were obtained to allow any meaningful an alysis for catalytic wood heaters. 46 Figure 1 is a bar chart showing the distribution of overall weighted ave rage efficiencies by efficiency range for the 68 non-catalytic heater models. Figure 1

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### • Of the 68 non-catalytic wood heater models in this database, 21 models have weighted average overall efficiencies that are below the proposed level of 70%. This represents 31% of the heater models in the database.
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• The relationship between weighted average overall efficiency and weighted average particulate emissions for the 68 non-cat models was evaluated using standard statistical practices 1 . • The poor R 2 value (0.05) for the linear regression line and the corner score analysis show there is no correlation or association between these parameters. 1 Mark’s Standard Handbook for Mechanical Engineers, Eight h Edition, 17-22 A linear regression line was fit to the data and a corner score analysis conducted. 4910/11/2012

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### • These analyses clearly show that EPA’s proposed overall efficiency standard doesn’t meet their “low bar” design criteria and is also inappropriate for regulating CO. – About 1/3 of this significant sub-set of current non-cat models meeting a 4.5 g/hr PM standard won’t meet EPA’s proposed 70% weighted average overall efficiency standard. • The actual percentage, if all heaters meeting 4.5 g/hr are considered, could be even greater. – CO and PM correlate with combustion efficiency, not overall/delivered efficiency. 50 

### • There is, however, a sound alternative to what EPA is proposing: – require efficiency testing using CSA B415.1-10, but don’t set enforceable efficiency standards. 

### • The efficiency values would 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. 5110/11/2012

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# Restating the Common Goals 1. Improve Air Quality 2. Replace uncertified stoves. 3. Continue to work to improve real world performance of certified stoves.
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# Final Conclusions • Certified stoves work in the field! • There are over six million uncertified wood stoves still in American homes. These uncontrolled stoves have emission rates at least two or three times higher than EPA certified stoves. • 86% of Wood Stove PM emissions (~135M Tons) are from uncertified stoves. 5310/11/2012

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### • Lowering the NSPS passing grade will not improve the real-world performance of certified stoves. – The precision study shows that that we cannot reliably differentiate between models performing in the range of interest (i.e., below 4.5 g/hr), based on lab testing. – Even if we could, Dr. Houck’s study demonstrates that the emission rates from lab testing do not correlate well with field performance. 54 

# Final Conclusions (cont.) • Even if we could differentiate between stoves with lab emissions in the range of interest and if the lab testing correlated with field performance, EPA has determined that standards below 4.5 g/hr are not cost effective.
– HPBA’s independent analysis is coming to the same conclusi on. • Lowering the passing grade will produce only the appearance of progress in improving the in-home emission performance of new stoves – 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. 5510/11/2012

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### • Increasing the minimum tested burn rate will have a beneficial impact real world performance. – The Colville Project demonstrates that increasing the minimum burn rate in EPA M28 will result in new stove models with more robust in-home performance over a wider range of real-world conditions. 56 

# Final Conclusions (cont.)

• EPA’s proposed efficiency standards are not a sound way to lower carbon monoxide emissions. – CO and PM correlate with combustion efficiency, NOT overall efficiency. – Overall Efficiency is therefore a very poor choice as a regulatory surrogate for CO. PM is the better choice. 57 

# Final Conclusions (cont.)10/11/2012

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### • The proposed efficiency standards are not supportable. – EPA’s effort to shortcut NSPS decision criteria for efficiency standards doesn’t work. 

### • There is a better option: Don’t regulate efficiency. Require testing and reporting of efficiency for point of sale use. Let the marketplace provide the pressure to improve efficiency ratings. 58 

# Final Conclusions (cont.) What is our most important common

goal? • Changing out the more than six million uncertified stoves still in American homes because this will improve air quality. – Lowering the passing grade below 4.5 g/hr will slow change-outs and produce only the appearance of progress – nothing more. 59