Duraflame, Inc. 

P.O. Box 1230, Stockton CA 95201 

Phone: 209.461.6600 / Fax: 209.462.9412 

info@duraflame.com / www.duraflame.com 

The Secret of Fire®

September 22, 2006 

Larry Greene 

Executive Director / APCO 

777 12th Street, Third Floor 

Sacramento, CA 95814 

Dear Larry, 

I appreciated the opportunity to meet with you and your senior staff recently to discuss 

the emissions characteristics of manufactured firelogs and how our industry might play a 

role in assisting the Sacramento Metro Air District to reduce emissions from residential 

wood combustion. The frank discussions were very useful to clarify the Air District’s 

open questions about the emissions characteristics of our industry’s products. 

As you are aware several independent tests, sponsored both by our industry and air 

quality authorities, have proven that the emission rates of particulate matter, 

Dioxin/Furans and related air toxics for burning firelogs in an open fireplace are far lower 

than those produced from burning a typical wood fire in an open fireplace. In spite of 

these consistent findings from numerous independent laboratory tests your District now 

questions whether the prior test methodologies provided a fair comparison of the 

emissions produced by firelogs and / or cordwood when burned in a non-laboratory, real 

world environment. You also noted that some of the emissions tests you had reviewed 

indicated that firelogs produce greater emissions than cordwood when evaluated on an 

emission factor basis, and therefore feared if consumers were to burn more than one 

firelog at a time the emissions produced would be equal to or greater than those of a 

cordwood fire providing no emission reduction benefit. 

These are certainly fair questions, which we are confident we can resolve with a review 

of the technical facts related to the performance and usage of our industries products vs. 

cordwood. 

1. Real World usage of Manufactured Firelogs and Cordwood in Open fireplaces – 

By design manufactured firelogs have entirely different burn characteristics than those of 

cordwood. Firelogs are made with approximately 55% natural or petroleum based waxes 

and 45% recycled biomass fibers. The wax component of the product provides a far 

higher energy content fuel that generates approximately twice the BTU content per mass 

as natural wood, yet the burn rate of this wax component if far lower than seasoned 

firewood. Firelogs also have significantly lower moisture content than natural wood (2-
Duraflame, Inc. 

P.O. Box 1230, Stockton CA 95201 

Phone: 209.461.6600 / Fax: 209.462.9412 

info@duraflame.com / www.duraflame.com 

3% vs. 20% for seasoned wood), which allows the fuel in a firelog to be combusted more 

efficiently. In fact the burn rate for firelogs is 1⁄4 the burn rate of cordwood burned in an 

open-hearth fireplace. This combination of a higher BTU content fuel which combusts at 

a significantly lower burn rate thereby allows the user to burn far less fuel during a 

typical usage occasion. Hence burning far less fuel per fire occasion results in far fewer 

emissions being emitted. 

During our recent meeting a member of your staff indicated that they feared many of the 

test studies we have presented the District may have utilized an unrealistically high fuel 

charge for an aesthetic cordwood fire vs. burning just one firelog. They speculated that a 

person who was going to burn for aesthetic purposes might burn less wood than the 

recent emission studies indicated. As I mentioned during our meeting the test 

methodology for both the studies recently presented to your District attempted to 

replicate emissions for reasonably comparable usage of the two very different fuel 

products in common appliances. The test protocols and fuel charges for the wood tests 

were designed to represent real world operating conditions for wood burning fireplaces 

and were based on independent user data derived from published studies of fireplace 

usage. 

To elaborate on this matter I am attaching a letter from Dr. James Houck, a PHD scientist 

with Omni Environmental Services who directed the recent fireplace emission tests for 

the EPA, Environment Canada and the Puget Sound Clean Air Agency. Dr Houck is a 

renowned expert in this field, and has conducted significant amounts of residential wood 

combustion emission testing and consulting work for Industry, The EPA and several 

regional Air Quality Districts. 

In addressing the question of fireplace use for aesthetic vs. heating purposes Dr. Houck 

points out that from an Air Quality planners perspective usually this distinction is made 

by the number of days and hours a fireplace is used as opposed to the amount of fuel used 

during a given fire occasion. Air Quality Planners usually consider a household that 

burns wood frequently in their fireplace to be classified as usage for heating purposes and 

infrequent users as those who burn for aesthetics. 

With regard to individual usage occasions, Dr. Houck notes there is a minimum burn rate 

of wood fuel that must be combusted in an open-hearth fireplace in order for the fireplace 

to function properly. This minimum burn rate for burning seasoned cordwood in a typical 

36” manufactured fireplace that would be most common appliance in more densely 

populated tract home developments in the Sacramento Metro area is 3.3 kg per hour. 

Burning at a rate below this would not sustain combustion and produce a smoldering, 

unacceptable fire that the user would rectify by adding more fuel to the fire. 

Further, Independent studies of fireplace usage in N. California (including the 

Sacramento Area) conducted by UC Berkeley in 2003 for the California Air Resources 

Board indicated the average duration of household burning cordwood in their fireplaces is 

more than 30% longer than the duration of fires burned by households using 

manufactured fires. (See attached excerpt from this study below)
Duraflame, Inc. 

P.O. Box 1230, Stockton CA 95201 

Phone: 209.461.6600 / Fax: 209.462.9412 

info@duraflame.com / www.duraflame.com 

Results of Wood Burning Survey - Sacramento, San Joaquin, and San Francisco Areas, 

University of California Berkeley/ California Air Resources Board - GIS Study, January 

15, 2003 

 

Fireplace Usage, Wood Fires - Average fire duration on weekdays was 4.4 

hours; Average fire duration on weekends was 5.1 hours

 

Fireplace Usage, Wood/Wax Firelog Fires - Average fire duration on weekdays

was 3.3 hours; Average fire duration on weekends was 3.4 hours 

Therefore if one multiplies the minimum burn rate of cordwood for an average size 

fireplace of 3.3kg / hr as noted by Dr Houck, by the minimum average burn duration of 

4.4 hours for wood users in N. California, a wood burning household would consume 

14.52 kg (32lbs) of fuel during a typical fire occasion. In comparison a household 

burning firelogs for the average burn duration reported above would only burn one 5-6 lb 

firelog. 

So, contrary to your staff’s assertion that people who burn wood fires for aesthetics may 

burn less wood than the recent emissions studies utilized, the facts do not support such a 

hypothesis. The average household burning wood in an open fireplace in the Sacramento 

Metro area clearly burns more mass of fuel per fire for a longer period than households 

that burn firelogs, and wood burning households generate far more emissions. 

2. Are firelogs more emissive if mis-used contrary to manufacturers usage 

instructions? 

Another concern stated by staff during our recent meeting was that if the Air District 

began to promote firelogs as a cleaner burning for open fireplaces, traditional wood 

burners might burn more logs than prescribed by the manufactures’ directions and negate 

the lower emissions benefit that occurs as a result of the user burning less fuel with 

firelogs during a typical fire occasion. Again, this is a fair question, but it is again a 

hypothesis for which there is no supporting causal data. 

To give you some background, firelogs are designed to be used one at a time – no matter 

the brand or size. All firelog packaging instructs consumers to use the product in this 

manner. Such instructions are uniform throughout the industry based on compliance with 

a UL safety Classification for our product category. There are different size firelogs for 

different applications / lengths of fires, whether 2 hours or upwards of 4 hours. 

Approximately 70% of the firelogs sold in the marketplace today are the 5-6lb size which 

burn from 3-4 hours. 

As noted in the above-cited 2003 CARB fireplace usage survey the average user of 

firelogs burns their fireplace for 3.3 – 3.4 hours. This is consistent with burning one 5 or 

6lb firelog as prescribed by manufacturers instructions. 
Duraflame, Inc. 

P.O. Box 1230, Stockton CA 95201 

Phone: 209.461.6600 / Fax: 209.462.9412 

info@duraflame.com / www.duraflame.com 

The retail cost of firelogs also creates a disincentive to burning multiple logs in one 

occasion. The average retail price of a single 5-6 lb firelog today is between $3-$4. 

Burning two logs would cost $6-$8 per fire which is more than the homeowner who uses 

their fireplace for secondary heating purposes would be willing to spend. 

Due to the high energy content per mass of fuel burning two firelogs at a time, or adding 

a second firelog to an existing fire will produce a very aggressive fire that could be 

unsafe, which is why our industry recommends against this practice. Attached you will 

find some photos of two (6 pound / 4 hour) firelogs burned in a standard 36 inch 

manufactured fireplace, the most common size wood burning fireplace installed in 

densely planned subdivisions in the Sacramento Metro Area. One set of photos show two 

logs that were ignited at the same time, and the other shows the fire produced when one 

firelog was added to the fire after the first log had been burning for about one hour. You 

will note that burning two 6lb logs produces a raging fire that would produce too much 

heat and flame that would alarm the average homeowner. They would likely only do this 

one time before learning that burning two logs at a time is not necessary and may not be 

safe. 

While, people could burn more than one log in a large masonry fireplace, these are not 

the standard in most homes today. If a consumer were to choose to burn more than one 

firelog it is likely the would do so by burning one log in succession to the other. This 

would extend their burning time to 6-8 hours, depending on when the second log is added 

to the fire, which would be contrary to the average burn durations for fireplace according 

to the CARB 2003 Fireplace usage study. 

Even in the event that the minority of households with large masonry fireplaces in the 

Sacramento Metro area decided to burn two firelogs their fireplace, firelogs would still 

produce fewer emissions than burning and a wood fire for an equivalent time period in an 

open fireplace. 

1. Firelogs 

2 x 2.72kg (6lb) = 5.44kg of fuel consumed over 5 hours 

5.44kg x 14.2 g/kg pm1

 = 77.25 g particulate matter emitted 

77.25 g-pm / 5 hours = 15.45 g-pm / hour

2. Cordwood 

3.3kg / hr (minimum functional burn rate for a fireplace) 

3.3kg / hr x 5 hours = 16.5kg of fuel consumed over 5 hours 

16.5kg x 13 g/kg pm2

 = 214.5 g particulate matter emitted 

214.5 g-pm / 5 hours = 42.9 g-pm / hour

 

1

 Mean emission factor of Total Particulate emissions for manufactured firelogs cited from 2005 

Environment Canada / EPA region 5 study “Content and emission characteristics of Artificial Wax 

Firelogs” 

2

 Mean EPA method 5H emission factor of total particulate emissions for Cordwood from 167 fireplace 

emission tests – Source January 2005 Omni Environmental Services “Development of a Fireplace Baseline 

Particulate Emission Factor Database” 
Duraflame, Inc. 

P.O. Box 1230, Stockton CA 95201 

Phone: 209.461.6600 / Fax: 209.462.9412 

info@duraflame.com / www.duraflame.com 

This example clearly demonstrates, that even a household chose to burn more firelogs 

than manufacturers prescribe, or that independent usage studies indicate to be normal, 

they would still produce 64% fewer particulate emissions than burning cordwood for a 

comparable time period. So again the Districts concerns that increased usage, or misusage 

for firelogs would increase emissions and negate the emission reduction benefits of 

burning firelog are without merit. 

3. Do firelogs emit more air toxic compounds than burning cordwood? 

During our recent meeting you pointed out that your review of the recent tests conducted 

for the Puget Sound Clean Air Agency to compare the Dioxin / Furan Air emissions of 

manufactured firelogs vs. cordwood indicated that such emissions for firelogs were 

greater than those of cordwood. You were correct that when looking at the emissions 

data on a grams of pollutant emitted / kg of fuel combusted basis firelogs produced 1/3 

more dioxin / furans emissions than cordwood. However the grams of pollutant emitted 

per hour of a comparable fire duration data from the same test demonstrated firelogs 

produced 3/4 less toxic emissions than burning cordwood. 

Again for the reasons outlined above, namely firelogs contain a much higher energy 

content that is combusted at a much lower burn rate than cordwood, it is not realistic to 

attempt to make apples vs. apples comparisons of emissions on a mass of emissions per 

mass of fuel basis, when the fuel products being compared are apples and oranges. 

What you may have overlooked from reviewing the recent test reports though is that the 

Dioxin / Furan emissions for both firelogs and cordwood were extremely low in relative 

terms. Further, most of the air toxic components used to calculate the total Dioxin / Furan 

emissions of firelogs were non-detectable, and therefore the approved EPA protocol for 

measuring dioxin emissions requires that 1⁄2 of the detection limit must be added to the 

calculation for a non-detectable component, thereby resulting in a potential overstatement 

of the real total volume of such emissions. Finally, since the emissions of Air Toxic 

components including Dioxin / Furans for firelogs is so low, the test laboratory had to 

burn two firelogs in succession in order to collect enough emission material to allow 

them to detect any level of air toxic components from firelog emissions. Thus when used 

according to the manufactures instructions, that is burning one firelog per fire occasion, 

the Air Toxic components of firelog emissions are extremely low, if not undetectable. 

4. If the District promotes manufactured firelogs as a clean burning alternative for 

fireplace use will it confuse households about what is acceptable to burn and 

undercut its goal to reduce residential wood combustion emissions by advocating 

less or no burning of solid fuel in fireplaces? 

At our recent meeting your Communications Director pointed out that even if firelogs are 

cleaner to burn than cordwood in an open fireplace, they still produce emissions greater 

than not burning at all. She went on to state that since the District is just beginning to 

intensify its efforts to educate the public about the need to reduce residential wood 
Duraflame, Inc. 

P.O. Box 1230, Stockton CA 95201 

Phone: 209.461.6600 / Fax: 209.462.9412 

info@duraflame.com / www.duraflame.com 

combustion emissions it was important to keep the message simple and advocate that 

converting a fireplace to natural gas fuel or not using fireplaces at all are the lowest 

emission alternatives. We won’t argue that firelogs don’t generate emissions, but we do 

disagree with the strategy of not advocating all clean burning options available to 

consumers. 

There appears to be a double standard in the Districts policy on what it will advocate as 

clean burning and what it will not. In the case of wood burning stoves the District is 

advocating that consumers change out old wood burning appliances to newer, cleaner 

burning wood or pellet fueled heating stoves. These appliances still produce particulate 

emissions but far fewer than old wood fueled stoves. A gas fueled stove produces even 

fewer particulate emissions vs. a wood-burning stove, yet it still encourages cleaner 

burning wood stoves or pellet stoves as an alternative. If the district is willing to 

advocate cleaner burning solid fuel options for wood heating, than it should be consistent 

and advocate proven cleaner burning fuels such as firelogs for aesthetic use in wood 

burning fireplaces. 

What is even more confusing with the Districts policy, is that it does advise households 

that plan to burn cordwood in fireplaces to burn seasoned wood, which certainly is 

cleaner than burning “green” wood, yet in spite of numerous independent tests that 

demonstrate firelogs burn significantly cleaner than even seasoned wood, the District has 

decided to discontinue its prior policy of advocating firelogs as a cleaner burning 

alternative. We fail to accept the logic in this policy change as a fair and reasonable 

approach when the District is willing to advocate other uses of solid fuel as clean burning 

options. 

While we can appreciate the District’s desire to present a simple message to the public, 

even the simplest most concise message will have little impact if it is not a message that 

the public is receptive too. A simple message of “do not burn in your fireplace” will not 

be as readily accepted as a message that indicates there are options to burn cleaner in 

your fireplace. The public today is more environmentally aware than ever, and while they 

are not ready to give up their everyday comforts, they are willing to make incremental 

changes in their behavior. The overwhelming demand and growth in sales of expensive 

hybrid fuel vehicles is a good example of this trend. The public is still not willing to cut 

back the amount they drive in their vehicles, but they are willing to purchase vehicles that 

will use less fuel for economy and environmental benefits. The fact that a growing 

number of people are willing to pay more for fuel efficiency than will ever be paid back 

by the efficiency gain is a demonstration that more people see the need to do the right 

thing for the environment, particularly when it doesn’t require them to drive any less. 

We suggest that advocating manufactured firelogs as a clean burning alternative to 

burning cordwood for the hundreds of thousands of open fireplaces in the Sacramento 

Metro Area could be your hybrid vehicle strategy for cutting residential wood 

combustion emissions. People are going to continue to use their fireplaces regardless of 

your messaging but if you give them an option to use them in a cleaner burning fashion 

people will begin to change their burning habits and you will see a real reduction in 
Duraflame, Inc. 

P.O. Box 1230, Stockton CA 95201 

Phone: 209.461.6600 / Fax: 209.462.9412 

info@duraflame.com / www.duraflame.com 

residential wood combustion emissions from open fireplaces. We know it will work 

because the strategy has been proven in the Puget Sound area, which was once a nonattainment area for PM 10 emission. The Puget Sound Clean Air Agency achieved PM10 

attainment without ever banning the installation of a wood burning fireplace, but instead 

by creating meaningful partnerships with all stakeholders to cooperatively implement a 

multifaceted strategy of educating the public about how to burn cleaner with tools such as 

new clean burning appliances and clean burning fuels such as manufactured firelogs. We 

are confident the Sacramento Metro Air Quality Management can achieve this same level 

of success. 

We aren’t asking the District to carry all the burden of communicating this message 

either. All we ask is that you change your recently modified neutral strategy regarding 

burning of firelogs to one that advocates them as one of several simple cleaner burning 

tips for open fireplace use. With your support our industry will take the initiative of 

spreading this message to the public, and to the extent you are willing to engage in 

cooperative communications we are ready and willing to partner with the District in 

promoting its residential wood combustion emissions reduction messages. 

Larry, we trust we have addressed all of the concerns expressed by your staff at our 

recent meeting. We really desire to be a partner of the Air District instead of an 

adversary. We hope that your review of our comments herein will once again open a path 

for your District and our industry to pursue a win / win strategy to reducing RWC 

emissions. 

Best Regards, 

Chris Caron 

Vice President, Brand Development 

cc; Bob Cline, Cline & Dupliessea 

 Erika Schmidt, Frause PR 

Attch; 
OMNI Environmental Services, Inc. 

Consulting 6 Engineering 6 Testing 

 5465 SW Western Avenue • Suite G • Phon Phone: (503) 643-3788 

 Beaverton, Oregon 97005• USA Fax: (503) 643-3799 

 Email: houck@omni-test.com 

September 13, 2006 

Chris Caron 

Duraflame, Inc. 

2894 Mount Diablo Blvd. 

Stockton, CA 95203 

Dear Chris, 

In response to your question regarding the burn rate of cordwood in fireplaces used to compare 

the air emissions from commercially available wax/fiber firelogs that were part of the two recent 

testing programs sponsored by Environment Canada (EC), I offer the following information. 

The first EC testing program (administered by U.S. EPA Region 5), which focused on a number 

of key pollutants (NOx, VOC, PM2.5, PAH, CO, benzene, and formaldehyde), made 

measurements of these pollutants for five firelog brands. Direct measurement of emissions from 

cordwood was not funded. Comparison with cordwood was accomplished by using literature 

values compiled in a refereed Air and Waste Management Association publication, which in 

turn, compiled test results from a broad spectrum of fireplace operations and cordwood fuels 

(multiple fireplace models and nine tree species were used for fuel). These data were from work 

conducted for the Oregon Department of Energy, work conducted for Duraflame, Inc., work 

conducted by the Canadian Combustion Research Laboratory, work conducted by Shelton 

Research, Inc., and work conducted by B.C. Research. The second Environment Canada study 

(administered by the Puget Sound Clean Air Agency – PSCAA), which measured dioxin and 

furan (TEQ values) emissions, as well as, the key pollutants listed above on one additional 

firelog (a west coast manufactured Duraflame product) did directly measure emissions from 

cordwood for comparison and in that case the cordwood burn rate was 3.3kg/hr (dry reporting 

basis). 

It is my understanding that there is concern about cordwood burn rates for fireplaces used for 

aesthetic purposes being less than for fireplaces used for heating and, that because of this, 

difference the comparisons between air emissions from cordwood and wax fiber firelogs are not 

applicable to the aesthetic use of fireplaces in the Sacramento area. This is not the case for 

several reasons: (1) The distinction between the aesthetic and heating use has been traditionally 

based on the number of fires per year rather than the intensity of the fires. The distinction 

between aesthetic use and heating use is a “gray” area as both the enjoyment and the utility of a 

fireplace share a common commodity – heat. Generally, if a home occupant reports using a 

fireplace less than several times a year it is considered aesthetic use. (2) There is only a small 

range of burn rates that are reasonable for a given fireplace size regardless of whether its use is 
described as for heating or aesthetics and the burn rate is also largely independent of the climate 

where the fireplace is located. For a standard 36-inch fireplace, the burn rate range would be 

about 3.0 to 5.0 kg/hr (dry reporting basis). The 36-inch size is the most common size in the 

Sacramento area. Below about 3.0 kg/hr the fire does not burn well and can go out. Above 

about 5.0 kg/hr the fire is too hot for most rooms and also can become a fire hazard. It should be 

remembered that a fireplace is a room heater, not a centralized heating system, its heating use is 

almost always classified as “secondary” not “primary” and its heat output doesn’t, and can’t, 

tract heating demand well. It should also be remembered that while true wood heaters 

(freestanding stoves and fireplace inserts) have air controls that regulate fires, fireplaces have no 

such controls – fire burn rates are primarily a function of how much wood is put into the unit, 

which has practical limits. (3) According to a survey conducted by the University of California, 

Berkeley in 2002, for the Sacramento Valley, 56% of the respondents that use fireplaces reported 

using them for aesthetics and 44% using them for heat. Even if there is a slightly lower burn rate 

on average for fireplaces used for aesthetics, the impact is diluted by the high fraction of 

fireplaces that are used for heating. 

Over the last two decades, there have been numerous studies conducted by various laboratories 

funded by both the private and public sector that show wax/fiber firelogs offer an air emission 

reduction as compared to cordwood use in fireplaces. Emission comparisons for fireplaces 

should be on a mass pollutant per unit time, not mass of pollutant per mass of fuel burned. 

Wax/fiber fielogs have a heat content of about 15,700 Btu/dry pound of fuel as compared to 

wood, which averages about 8900 Btu/ dry pound of fuel. In addition wax/fiber firelogs average 

2.2% moisture (dry basis) as compare to typical well-seasoned cordwood, which averages 24.1% 

moisture (dry basis). Less energy is required to evaporate the water from firelogs as an equal 

mass of cordwood. Due to the higher heat content and lower moisture content, a lower mass of 

firelogs is needed for the same heat output. Further, one-at-a-time usage instructions are 

included with most firelogs and the use of multiple 5 lb or 6 lb firelogs produces an obviously 

unsafe fire, which would be found to be unacceptable by most consumers. Reflective of the 

higher heat content, lower water content, and one-at-a-time use, the average firelog burn rate in 

fireplaces is 0.74 dry kg/hr – significantly less than cordwood. 

The results of the second Environment Canada (PSCAA) study, which consisted of a western 

Duraflame firelog burned in a typical 36-inch fireplace and of cordwood burned at a rate of 3.3 

kg/hr, provide a snapshot of the level of emission reduction achievable for firelog use in lieu of 

cordwood in the Sacramento area. The PM 2.5 emissions at a level reflective of aesthetic 

fireplace use are 6.79 g/hr for a wax/fiber firelog and 26.7 g/hr for cordwood, respectively. In 

addition the emission rates for all other air pollutants measured, importantly including dioxin 

TEQ values, were less for the normal use of a firelog than for the use of cordwood. 

I hope this information answers your questions. If you have any other questions please do not 

hesitate to contact me. 

Sincerely, 

James E. Houck, Ph.D.