1

MEMORANDUM 

TO: Jim Eddinger, U.S. Environmental Protection Agency, OAQPS 

FROM: Amanda Singleton, ERG 

DATE: April 2010 

SUBJECT: Methodology for Developing Model Units for Industrial, Commercial, and 

Institutional Boilers at Area Sources of Hazardous Air Pollutants 

1.0 Introduction 

This memo presents the methodology used to develop a national estimate of existing 

area source boilers potentially affected by the National Emission Standards for 

Hazardous Air Pollutants (NESHAP) for Industrial, Commercial, and Institutional 

Boilers at Area Sources of HAP. 

The national inventory of area source boilers was based on data from boiler inspector 

inventories in 13 states. These data were standardized, and model boilers were developed 

to represent the different fuel types and typical boiler size ranges reported in the boiler 

inspector inventories. 

Section 2.0 presents the results of the data collected from state boiler inspector 

datasets. Section 3.0 presents the methodology used to narrow the datasets down to area 

source boilers and standardize the records according to fuel type and unit size. Section 

4.0 documents the assumptions used to extrapolate units in the boiler inspector database 

with missing size data. Section 5.0 documents the assumptions and methodology used to 

projection the 13-state inventory to a national level. 

Appendices: 

Appendix A: ASME Conversion Table for Boiler Surface Area 

Appendix B: Distribution of Boilers by SIC Code 
2

2.0 Boiler Inspector Data Received 

 

From 2004 to 2006 boiler inspector inventories were received from thirteen 

different states. The states providing inventories included: CO, DE, HI, IN, KS, MI, NC, 

NE, NJ, NY, TX, UT and WI. Each state’s database contained a variety of different 

information and each state reported the data in a different format. The databases were 

focused on boiler safety aspects and did not contain air emission data. Many boilers at 

area sources of HAP are below air permitting thresholds and so these boiler inspector 

inventories were expected to have a better coverage of boilers at area sources. 

The boiler inspector databases include both steam boilers, heater units and other 

inspected combusted sources such as autoclaves. The data reported in each inventory did 

not distinguish between area and major sources of HAP. The data submitted from each of 

the 13 states is listed in the docket for this rulemaking. 

In addition to the lack of a common reporting format between certain state data 

had additional limitations that needed to be addressed in order to extrapolate these units 

to a national level. 

3.0 Standardizing Boiler Inspector Data 

Data from each state inventory were standardized in order to distinguish which units 

in the inventory were area sources of HAP and identify fuel and size characteristics for 

model units. 

Identifying and Eliminating Unwanted Unit Types 

 Since the inspector databases include records on other types of combustion 

equipment, each dataset was reviewed for any fields that defined the type of unit or 

primary use of the unit. For example, the NY dataset contains a column to distinguish 

between a steam unit and a heater unit while NE, NC, and WI have a ‘use’ field to 

designate what the unit is used for (e.g. process steam, hot water heat, steam heat...). 

These codes were used to narrow the content of the database down to boilers, based upon 

the limited information available. 

Identifying and Eliminating Unwanted Fuel Types 

 The datasets in some states included electric boilers and combustion equipment 

firing other fuels that are not covered by the area source boiler rule (e.g., pathological 

waste incinerators, electric fired boilers). For each dataset a LOOKUP table containing a 

unique list of fuels reported within each state was created and the fuels were classified 

according to whether or not they were of interest for the boiler database. 
3

Identifying Area and Major Source Facilities 

The boiler inspector databases do not distinguish between area and major sources. 

Table 1a shows the lower bound on unit size for various fuel types that EPA used as a 

threshold for classifying a unit as a major source. This size threshold is a rule of thumb 

estimate and some sources may apply for a limit on HAP emissions, and qualify as a 

synthetic area source, despite whether the boilers exceed the sizes listed in Table 1. We 

reviewed the total boiler size at each facility in order make a determination on the status 

of each facility. 

Table 1a Fuel and Size Criteria for Major Sources 

Boiler Fuel Boiler Size (mmBtu/hr) 

Coal Greater than 50 

Wood Greater than 250 

Liquid Greater than 1,800 

Gas Greater than 8,000 

Table 1b shows the SIC codes that are most common to major sources of HAP. Only 

some of the boiler inspector databases contained information on SIC codes. More details 

on the approaches used to identify area sources according to SIC code and size are in 

another memorandum.1 A portion of the state inspectors tracked business types using an 

internal “business code” tracking system while other states’ data did not contain any type 

of industrial classification. For these states we applied a series of key-word queries to 

identify boilers at potential major sources of HAP according to the industries identified in 

Table 1b. 

Table 1b SIC Codes for Major Sources 

SIC Code SIC Code Description 

28 Chemical Manufacturers 

21 Textiles 

26 Pulp and Paper Products 

49 Electricity Generation 

32 Steel Mills 
4

Boiler Size 

Boiler size was reported in several units of measure and they were standardized to 

units of mmBtu/hr according to the equations listed in Table 2 below. 

Table 2 Common Conversions for Unit Size 

Non-Standard Unit Unit abbreviations Multiplier for Conversion 

to mmBtu/hr 

Lbs steam per hour (#, lbs) #, lbs, lbh .001 

Heating Surface (ft2) SQ Based on ASME 

Conversion Table in 

Appendix A.2 

1000 Btus per Hour MBH, MBHI,MBtu 0.001 

Btus Btu 0.000001 

Million Btus per Hour MMBH, MMBHI, MMBtu 1 

Assumed to be Btu None listed but size is 

greater than 10,000 

0.000001 

This analysis removes area source units less than 10,000 Btus (0.01 mmBtu/hr) so 

that unrealistically small units (likely a result of data entry errors) are not projected in this 

analysis. Two state boiler inspectors indicated that their databases included a cutoff on 

the size of boilers included in their inspector datasets on the range of 30,000-40,000 

Btus/hr (0.03-0.04 mmBtu/hr). Units less than 10,000 Btus/hr were set aside and an 

average boiler size would be extrapolated to fill the reported gaps in boiler size. 

A table of boiler and heater size ranges listed by typical use is provided in Table 

3. Standardized units significantly outside of these size ranges were set aside for size 

extrapolation. 

Table 3 Typical Gas-fired Unit Sizes by End Use3 

Typical Facility Size (mmBtu/hr) 

Small commercial or residential 0.067 to 3.4 

Mid-sized commercial or small Industrial 2.5 to 10 

Large Commercial of Large Industrial 10 to 33.5 

Table 4 shows the distribution of units in the boiler inspector database based on 

state and fuel category. 
5

Table 4 Distribution of Unit Fuel Type for Each of the Thirteen States in the Boiler Inspector Dataset 

After removing major sources. 

State 

Fuel 

Category 

Number 

of Boilers State 

Fuel 

Category 

Number 

of Boilers 

CO gas 

 

24,151 NE gas - 

CO liquidD 

 

60 NE liquidD - 

CO solidB 

 

35 NE liquidR - 

CO solidC 

 

34 NE solidB - 

DE gas - NE solidC - 

DE liquidD - NJ gas 

 

20,465 

DE solidC - NJ liquidD 

 

3,515 

HI gas 

 

1,901 NJ liquidR 

 

12 

HI liquidD 

 

255 NJ solidB 

 

6 

HI solidB 

 

2 NJ solidC 

 

22 

HI solidC 

 

3 NY gas 

 

44,809 

IN gas 

 

11,966 NY liquidD 

 

27,356 

IN liquidD 

 

325 NY liquidR 

 

551 

IN liquidR 

 

1 NY solidB 

 

86 

IN solidB 

 

23 NY solidC 

 

41 

IN solidC 

 

4 TX gas 

 

46,708 

KS gas 

 

15,468 TX liquidD 

 

157 

KS liquidD 

 

34 TX SolidB 

 

20 

KS solidB 

 

5 TX solidC - 

KS solidC 

 

3 UT gas 

 

11,477 

MI gas 

 

135,250 UT liquidD 

 

63 

MI liquidD 

 

1,896 UT SolidC 

 

92 

MI liquidR 

 

6 WI gas 

 

33,878 

MI solidB 

 

178 WI liquidD 

 

2,263 

MI solidC 

 

44 WI solidB 

 

149 

NC gas 

 

14,507 WI solidC 

 

77 

NC liquidD 

 

4,452 

NC solidB 

 

165 

NC solidC 

 

44 
6

Seven size bins were created in order to aggregate units based on similar size 

characteristics. Table 5 below summarizes the distribution of unit sizes in the boiler 

inspector database. 

Table 5 Units in Boiler Inspector Database Aggregated to Seven Size Bins 

Bin 

Unit Size 

(mmBtu/hr) 

Number 

of 

Records 

No size listed or suspect size 

conversions x 

 

19,022 

1 

> 0.01 and 

<0.1 

 

18,341 

2 

≥ 0.1 and < 

0.5 

 

171,447 

3 

≥ 0.5 and < 

1.0 

 

79,854 

4 

≥ 1.0 and < 

5.0 

 

93,660 

5 

≥ 5.0 and < 

10.0 

 

12,111 

6 

≥ 10.0 and < 

100 

 

8,033 

7 

≥ 100 

91 

4.0 Filling Data Gaps in the Boiler Inspector Databases 

After the datasets were standardized to a common set of size units and fuel 

categories, there were over 40,000 boilers without a reported size. The distribution of 

units with known capacity data for each state was identified for each fuel and size group 

combination based on the seven size bins. Next, the average size of each bin for a given 

fuel and size bin was assigned to the number of extrapolated units distributed within the 

bin. It was assumed that the portion of units within each state for which the boiler size 

was unknown would have the same distribution of unit size as those units for which 

capacity was known. 

Inspector data reported from boilers in CO and NJ was restricted to units less than 

10 mmBtu/hr. This was not due to the actual size of boilers in the states of CO and NJ, 

but instead was a result of how the data request was interpreted. In order to correctly 

account for units larger than 10 mmBtu/hour in these states, the percentage of units from 

each of the other eleven states that belonged to Bins 6 and 7, respectively, were averaged. 

This average was applied to estimate additional larger boilers in both Colorado and New 

Jersey that were expected to be in the state but were not reported as part of the 

dataset. This extrapolation assumes that the unknown number of large units in CO and NJ 
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is expected to have the same distribution as the number of units larger than 10 mmBtu/hr 

in the other 4 states of the boiler inspector database. A consolidated standardized table of 

all thirteen states in contained in the boiler inspector inventory database 

Similar to the approach taken for filling data gaps for size, units with an unknown 

fuel type were assigned to have the same distribution of other fuel types within the state. 

It was assumed that the portion of units within each state for which the fuel was unknown 

would have the same distribution of unit size as those units for which fuel was known. 

5.0 National Estimate of Area Source Boilers 

Using the extrapolated dataset from the 13-state inspector inventory, we needed to 

estimate a total national number of boilers potentially affected by this regulation. To 

make this estimate, we projected to total heat input from small boilers in the remaining 37 

states using a ratio of state population to the total heat input from all boilers in that state. 

Table 6 Ratios of 2000 U.S. State Census Population to Total Heat Input from Boiler in State 

Area Source Heat Input (mmBtu/hr) Min Max Average 

per capita 0.0029 0.0149 0.01046 

Next, the heat input of specific fuels used in boilers were projected according to 

fuel consumption patterns in each of the other 37 states. Fuel consumption patterns are 

expected to vary according to state. This analysis assumes the distribution of fuel use in 

area source units will follow the overall fuel consumption patterns for the Residential and 

Commercial sectors of a particular state. Industrial consumption patterns were not 

considered since most of these sources are not located at industrial facilities. 

A relative statewide comparison of fuel consumption between gas, liquid, and 

solid (coal and wood) fuels was determined from the EIA state fuel consumption data. 

The boiler inspector database indicates that 2.2% of the heat input across the 6 states 

where the size of the unit is known is specified in the ‘other’ fuel category prior to any 

extrapolations. The number of units in ‘other’ fuel category in the remaining 37 states 

and the District of Columbia is expected to follow the same 2.2% distribution. The 

relative comparison of gas, liquid and solid fuels were adjusted to allow for a standard 

2.2% of the state heat input in the ‘other’ fuel category. Table 7 shows the relative 

comparisons of fuels for each of the 50 states and the District of Columbia. 
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Table 7 EIA Distribution of Heat Input for Residential and Commercial Sectors by Fuel Category4 

State Pct Coal Pct NG Pct Dist. Pct Residual 

Pct 

Wood/Biomass 

Alabama 0.4% 86.9% 5.7% 0.0% 7.0% 

Alaska 11.9% 53.0% 32.7% 0.0% 2.4% 

Arizona 0.0% 83.2% 5.5% 0.0% 11.4% 

Arkansas 0.0% 92.2% 4.6% 0.0% 3.2% 

California 0.0% 93.1% 2.2% 0.0% 4.7% 

Colorado 3.2% 90.9% 1.9% 0.0% 4.0% 

Connecticut 0.1% 44.7% 50.9% 0.5% 3.8% 

Delaware 0.0% 59.9% 29.6% 5.4% 5.1% 

Dist. of Col. 2.2% 82.8% 12.0% 0.0% 3.0% 

Florida 1.7% 72.2% 19.2% 0.1% 6.8% 

Georgia 0.2% 88.3% 4.9% 0.0% 6.6% 

Hawaii 0.0% 75.0% 25.0% 0.0% 0.0% 

Idaho 0.7% 82.9% 10.7% 0.0% 5.7% 

Illinois 0.8% 95.6% 1.9% 0.1% 1.7% 

Indiana 2.2% 87.7% 5.2% 0.0% 4.9% 

Iowa 5.4% 86.8% 4.1% 0.0% 3.6% 

Kansas 0.0% 92.1% 4.2% 0.0% 3.6% 

Kentucky 4.9% 82.4% 7.9% 0.0% 4.8% 

Louisiana 0.0% 93.7% 1.9% 0.0% 4.5% 

Maine 0.2% 6.3% 82.4% 1.8% 9.4% 

Maryland 1.0% 72.0% 21.6% 0.1% 5.4% 

Massachusetts 0.1% 50.5% 44.3% 0.9% 4.2% 

Michigan 0.0% 93.9% 4.3% 0.0% 1.8% 

Minnesota 0.0% 88.1% 7.9% 0.6% 3.4% 

Mississippi 0.0% 89.4% 3.4% 0.5% 6.7% 

Missouri 2.2% 87.7% 5.5% 0.1% 4.4% 

Montana 0.0% 89.7% 5.5% 0.0% 4.7% 

Nebraska 0.1% 93.8% 2.4% 0.1% 3.6% 

Nevada 0.0% 89.4% 5.2% 0.0% 5.4% 

New Hampshire 0.2% 27.3% 66.4% 0.9% 5.3% 

New Jersey 0.0% 80.8% 16.8% 0.5% 1.8% 

New Mexico 0.2% 91.5% 3.1% 0.0% 5.3% 

New York 0.2% 62.8% 26.1% 3.8% 7.1% 

North Carolina 2.3% 64.6% 23.5% 0.5% 9.0% 

North Dakota 6.5% 74.1% 15.0% 0.7% 3.8% 

Ohio 1.0% 92.0% 5.0% 0.0% 2.0% 

Oklahoma 0.0% 94.1% 3.4% 0.0% 2.6% 

Oregon 0.0% 75.8% 14.6% 0.3% 9.3% 

Pennsylvania 3.5% 66.7% 26.4% 0.5% 2.9% 

Rhode Island 0.0% 51.8% 40.0% 4.4% 3.8% 

South Carolina 0.0% 75.0% 10.3% 1.0% 13.6% 

South Dakota 0.4% 81.8% 13.4% 0.0% 4.5% 

Tennessee 2.5% 86.3% 4.4% 0.0% 6.9% 

Texas 0.1% 92.5% 4.9% 0.0% 2.5% 

Utah 1.2% 90.7% 4.6% 0.1% 3.4% 
9

Vermont 0.0% 20.2% 71.5% 2.3% 6.1% 

Virginia 1.6% 65.0% 22.8% 0.9% 9.7% 

Washington 0.3% 81.6% 10.0% 0.0% 8.0% 

West Virginia 1.6% 86.8% 7.2% 0.0% 4.4% 

Wisconsin 2.1% 83.5% 11.4% 0.5% 2.4% 

Wyoming 10.0% 77.5% 8.9% 0.0% 3.6% 

 

The minimum, maximum, and average heat input for each fuel category was 

calculated by the following equation: 

Heat Input (HI)a,b = (Total HI in Statea) x (% HI From Fuelb) (Eqn. 1)

Where: 

a = State or District of Colombia{AK, AZ,...,WY} 

b = Fuel Category{solid, gas, liquid, other} 

The distribution of heat inputs within each fuel category is shown in Table 8. 
10

Table 8 Distribution of Model Boilers According to Fuel Type and Size from the 13-State Boiler 

Inspector Database 

Fuel 

Category SizeBin 

Avg. Boiler 

Size 

(mmBtu/hr) 

Percent 

of Fuel 

Category 

gas 1 0.067291 0.2% 

gas 2 0.307398 7.5% 

gas 3 0.721795 9.9% 

gas 4 2.099534 33.0% 

gas 5 6.887038 12.9% 

gas 6 24.14245 33.4% 

gas 7 137.3751 3.1% 

liquidD 1 0.057543 0.1% 

liquidD 2 0.314211 3.7% 

liquidD 3 0.735697 3.4% 

liquidD 4 2.467187 18.2% 

liquidD 5 6.760865 10.4% 

liquidD 6 25.31204 56.5% 

liquidD 7 173.4401 7.7% 

liquidR 1 0.037193 0.0% 

liquidR 2 0.291135 0.2% 

liquidR 3 0.73576 0.5% 

liquidR 4 2.68188 39.2% 

liquidR 5 5.94997 41.7% 

liquidR 6 17.56013 13.4% 

liquidR 7 126 4.9% 

solidB 1 0.05099 0.0% 

solidB 2 0.293961 0.4% 

solidB 3 0.765927 0.9% 

solidB 4 2.717461 5.6% 

solidB 5 7.445966 8.5% 

solidB 6 21.03538 77.0% 

solidB 7 131 7.6% 

solidC 1 0.01526 0.0% 

solidC 2 0.256002 1.1% 

solidC 3 0.779042 1.8% 

solidC 4 2.350075 14.3% 

solidC 5 6.596056 6.6% 

solidC 6 23.49254 76.3% 
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The distribution of heat inputs to the different size bins within a given fuel 

category in the remaining 37 states and the District of Columbia are assumed to have the 

same size distribution pattern as those in the boiler inspector database. Based on the 

distribution of heat inputs in each size bin, the number of units in each size bin was 

calculated by the following equation: 

b c

a b c

a,b,c Avg.Unit Size in Fuel and SizeBin

Heat Input in State ,Fuel ,SizeBin NumberofUnits 

 

 Where: 

a = State or District of Colombia {AK, AZ,...,WY} 

b = Fuel Category {solid, gas, liquid, other} 

c = Size Bin {1, 2,..., 7} 

Table 9 shows the results of the calculation above; summed over each fuel 

category. This table represents the national minimum, maximum and average number of 

units projected within each fuel category.

Table 9 Summation of Heat Inputs and Number of Units for Each Fuel Category 

Fuel 

Min Heat Input 

(mmBtu/hr) 

Max Heat Input 

(mmBtu/hr) 

Avg Heat Input 

(mmBtu/hr) Min Units Max Units Avg Units 

gas 

 

1,484,214 

 

4,105,623 

 

2,632,383 

 

925,221 

 

2,504,762 

 

1,617,067 

liquidD 

 

276,952 

 

667,548 

 

448,032 

 

102,146 

 

247,631 

 

165,866 

liquidR 

 

5,939 

 

13,036 

 

9,047 

 

1,330 

 

3,166 

 

2,137 

solidB 

 

28,593 

 

198,497 

 

103,011 

 

3,307 

 

20,761 

 

10,958 

solidC 

 

6,659 

 

39,772 

 

21,163 

 

1,418 

 

6,652 

 

3,710 

6.0 Assigning SIC Codes to the National Boiler Inventory 

Using the business categories, SIC codes, and keyword analysis conducted on the 

13-state boiler inspector inventory, large and small boilers were distributed to various 

industries in order to help identify sectors likely affected by this rulemaking. A summary 

of the distribution of boilers by SIC code is provided in Appendix B. These SIC 

distributions were applied to the national inventory in order to assess national economic 

impacts of the rule on different affected sectors. 
12

7.0 References 

1. Burlew, C., ERG. Identification of Area Sources in the Industrial, Commercial, and 

Institutional Boilers and Process Heaters Databases. October 2002. 

2. Wisconsin Administrative Code. WI Code 41 Appendix H, Table Hg 400.1, 

containing excerpts from ASME Sections I, IV, and VIII. Table HG-400.1 Register, 

February, 20000, No. 530. 

3. Alliant Energy. Energy Expertise: Energy Efficiency HVAC-Boilers. Accessed 

online: 

http://www.alliantenergy.com/stellent/groups/public/documents/pub/bus_exp_eff_01

2392.hcsp

4. U.S. Department of Energy. Energy Information Administration. 2003 State Fuel 

Consumption Data by Sector, Accessed online at: 

http://www.eia.doe.gov/emeu/states/sep_sum/html/sum_btu_res.html and 

http://www.eia.doe.gov/emeu/states/sep_sum/html/sum_btu_com.html
Appendix A: ASME Conversion Table for Sizes Reported as Heating Surface (ft2)

Boiler Type

Boiler Categorized 

As Firing Method

Multiplier for 

mmBtu/hr

CI ? AUTO

CI ? BURN

CI ? HAND

CAST IRON ? AUTO

CAST IRON ? BURNER

CPFT FT ATMO

CPFT FT AUTO

CPFT FT BURN 0.008

FT FT AUTO 0.008

FT FT BURN 0.005

FT FT HAND 0.005

FTFB FT AUTO 0.008

FTFB FT BURN

FTHR FT AUTO

FTSM FT AUTO 0.005

FTVT FT AUTO

WT WT AUTO 0.01

WT WT BURN 0.006

WT WT HAND

WT WT STOK

FIRE TUBE FT AB

FIRE TUBE FT AUGER

FIRE TUBE FT AUTO 0.008

FIRE TUBE FT BLOWER

FIRE TUBE FT CONVEYOR

FIRE TUBE FT GAS

FIRE TUBE FT HAND 0.005

FIRE TUBE FT HAND FIRED

FIRE TUBE FT HOPPER

FIRE TUBE FT MAN

FIRE TUBE FT MANAUL

FIRE TUBE FT MANUAL 0.005

FIRE TUBE FT MANUEL

FIRE TUBE FT MECH

FIRE TUBE FT NAT GAS

FIRE TUBE FT STOKER 0.007

H RET TUBE AUTO

HOT OIL ? AUTO 0.008

HOT OIL ? STOKER

MINIATURE ? AUTO

MINIATURE ? ELEC

V TUBELESS ? AUTO 0.008

V TUBELESS ? ELEC

V TUBELESS ? FISSION

V TUBELESS ? HAND

V TUBELESS ? NAT GAS

WATER TUBE WT AB

WATER TUBE WT AUTO 0.01

WATER TUBE WT ELEC

WATER TUBE WT GAS 0.01

WATER TUBE WT MANUEL

WATER TUBE WT NAT GAS

WATER TUBE WT PULVERIZER

WATER TUBE WT STOKER 0.008

WT COILED WT AUTO 0.01

WT COILED WT NAT GAS 0.01

Notes:

FT = firetube

WT = watertube

CI = cast iron

If no multiplier is available, the heating surface was not converted to mmBtu/hr.
SIC Code 

Description SIC Code

Distillate 

Liquids

Residual 

Liquids

Wood/ 

Biomass Coal All Fuels

pct_Distillate 

Liquids

pct_Residual 

Liquids

pct_Wood/ 

Biomass pct_Coal pc

82 Educational Services 393 4 1 1 9044 41.2% 17.4% 7.7% 33.3% 65 Real Estate 35 3525 3.7% 0.0% 0.0% 0.0% 80 Health Services 186 2724 19.5% 0.0% 0.0% 0.0% 86 Membership Organizations 37 1 2193 3.9% 0.0% 7.7% 0.0% 70 Hotels And Other Lodging Places 56 1 1700 5.9% 0.0% 7.7% 0.0% 91 to 98 Government-Owned Buildings (State, Local, and Federal) 62 1540 6.5% 0.0% 0.0% 0.0% 72 Personal Services, Membership-Basis Organization Hotels 26 825 2.7% 0.0% 0.0% 0.0% 75 Auto Repair, Services, And Parking 13 12 684 1.4% 52.2% 0.0% 0.0% 79 Amusement & Recreation Services, Video Tape Rental 14 532 1.5% 0.0% 0.0% 0.0% 20 Food And Kindred Products 57 2 523 6.0% 0.0% 0.0% 66.7% 58 Eating And Drinking Places 11 460 1.2% 0.0% 0.0% 0.0% 53 General Merchandise Stores 6 302 0.6% 0.0% 0.0% 0.0% 60 Depository Institutions 4 264 0.4% 0.0% 0.0% 0.0% Unknown Unknown 7 158 0.7% 0.0% 0.0% 0.0% 87 Engineering & Management Services 7 2 97 0.7% 8.7% 0.0% 0.0% 48 Communication 9 91 0.9% 0.0% 0.0% 0.0% 55 Automotive Dealers & Service Stations 7 5 91 0.7% 21.7% 0.0% 0.0% 83 Social Services 78 0.0% 0.0% 0.0% 0.0% 59 Miscellaneous Retail 1 59 0.0% 0.0% 7.7% 0.0% 84 Museums, Botanical, Zoological Gardens 2 51 0.2% 0.0% 0.0% 0.0% 51 Wholesale Trade--Nondurable Goods 3 36 0.3% 0.0% 0.0% 0.0% 64 Insurance Agents, Brokers, & Service 35 0.0% 0.0% 0.0% 0.0% 47 Transportation Services 30 0.0% 0.0% 0.0% 0.0% 24 Lumber And Wood Products 1 9 27 0.1% 0.0% 69.2% 0.0% 54 Food Stores 26 0.0% 0.0% 0.0% 0.0% 02 Agricultural Production--Livestock 3 24 0.3% 0.0% 0.0% 0.0% 42 Trucking And Warehousing 1 24 0.1% 0.0% 0.0% 0.0% 73 Business Services 2 21 0.2% 0.0% 0.0% 0.0% 50 Wholesale Trade--Durable Goods 2 19 0.2% 0.0% 0.0% 0.0% 40 Railroad Transportation 4 18 0.4% 0.0% 0.0% 0.0% 52 Building Materials & Garden Supplies 12 0.0% 0.0% 0.0% 0.0% 45 Transportation By Air, Water Transportation Services 11 0.0% 0.0% 0.0% 0.0% 43 U.S. Postal Service 9 0.0% 0.0% 0.0% 0.0% 56 Apparel And Accessory Stores 9 0.0% 0.0% 0.0% 0.0% 57 Furniture And Homefurnishings Stores 9 0.0% 0.0% 0.0% 0.0% 17 Special Trade Contractors 3 8 0.3% 0.0% 0.0% 0.0% 14 Nonmetallic Minerals, Except Fuels 1 3 0.1% 0.0% 0.0% 0.0% 23 Apparel And Other Textile Products 1 3 0.1% 0.0% 0.0% 0.0% 81 Legal Services 3 0.0% 0.0% 0.0% 0.0% 01 Agricultural Production - Crops 2 0.0% 0.0% 0.0% 0.0% 41 Local And Interurban Passenger Transit 2 0.0% 0.0% 0.0% 0.0% 76 Miscellaneous Repair Services, Automotive Services, except Repair 2 0.0% 0.0% 0.0% 0.0% 07 Agricultural Services 1 0.0% 0.0% 0.0% 0.0% 09 Fishing, Hunting, And Trapping 1 0.0% 0.0% 0.0% 0.0% 16 Heavy Construction, Ex. Building 1 0.0% 0.0% 0.0% 0.0% 26 Paper And Allied Products 1 0.0% 0.0% 0.0% 0.0% 44 Water Transportation 1 0.0% 0.0% 0.0% 0.0% 

Grand Total 953 23 13 3 25279

Number of Boilers > Than 10 mmBtu/hr Percentage in SIC Code

Appendix B-1: Small (<10 mmBtu/hr) Boiler Distribution by Two-Digit SIC Code
SIC Code 

Description SIC Code

Distillate 

Liquids

Residual 

Liquids

Wood/ 

Biomass Coal All Fuels

pct_Distillate 

Liquids

pct_Residual 

Liquids

pct_Wood/ 

Biomass pct_Coal pct_All Fuels

Unknown Uknown 6 24 3.6% 0.0% 0.0% 0.0% 2.9%

02

Agricultural Production--Livestock 3 17 1.8% 0.0% 0.0% 0.0% 2.0%

17 Special Trade Contractors 2 3 1.2% 0.0% 0.0% 0.0% 0.4%

20 Food And Kindred Products 28 3 163 16.6% 0.0% 14.3% 0.0% 19.4%

24

Lumber And Wood Products 14 16 0.0% 0.0% 66.7% 0.0% 1.9%

45

Transportation By Air, Water Transportation Services 1 5 0.6% 0.0% 0.0% 0.0% 0.6%

48 Communication 2 0.0% 0.0% 0.0% 0.0% 0.2%

50

Wholesale Trade--Durable Goods 1 1 6 0.6% 0.0% 4.8% 0.0% 0.7%

51

Wholesale Trade--Nondurable Goods 4 3 1 13 2.4% 100.0% 4.8% 0.0% 1.5%

53

General Merchandise Stores 3 15 1.8% 0.0% 0.0% 0.0% 1.8%

57

Furniture And Homefurnishings Stores 1 0.0% 0.0% 0.0% 0.0% 0.1%

59 Miscellaneous Retail 1 0.0% 0.0% 0.0% 0.0% 0.1%60 Depository Institutions 4 0.0% 0.0% 0.0% 0.0% 0.5%64

Insurance Agents, Brokers, & Service 1 4 0.6% 0.0% 0.0% 0.0% 0.5%

65 Real Estate 1 1 23 0.6% 0.0% 0.0% 25.0% 2.7%

70

Hotels And Other Lodging Places 3 7 1.8% 0.0% 0.0% 0.0% 0.8%

72

Personal Services, Membership-Basis Organization Hotels 5 16 3.0% 0.0% 0.0% 0.0% 1.9%

73 Business Services 3 0.0% 0.0% 0.0% 0.0% 0.4%75

Auto Repair, Services, And Parking 2 0.0% 0.0% 0.0% 0.0% 0.2%

79

Amusement & Recreation Services, Video Tape Rental 2 0.0% 0.0% 0.0% 0.0% 0.2%

80 Health Services 68 1 205 40.2% 0.0% 0.0% 25.0% 24.3%

82 Educational Services 25 1 222 14.8% 0.0% 0.0% 25.0% 26.4%

86 Membership Organizations 1 11 0.6% 0.0% 0.0% 0.0% 1.3%

87

Engineering & Management Services 1 0.0% 0.0% 0.0% 0.0% 0.1%

91 to 98 Government-Owned Building 17 2 1 76 10.1% 0.0% 9.5% 25.0% 9.0%

Grand Total 169 3 21 4 842

Number of Boilers > Than 10 mmBtu/hr Percentage in SIC Code

Appendix B-2: Large (≥10 mmBtu/hr) Boiler Distribution by Two-Digit SIC C
SIC Keywords Other Cr

20

(Like '*food*' Or Like '*brew*' Or Like '*bake*' Or Like '*baki*' Or Like '*beverage*' Or Like '*feed*' Or Like '*meat*' Or Like '*beef*' Or Like '*poultry*' Or Like '*soy*' Or 

Like '*fleisch*' Or Like '*malt*' Or Like '*bottl*' Or Like '*sugar*' Or Like '*coca*' Or Like '*frito*' Or Like '*cracker*' Or Like '*dair*' Or Like '*milk*' Or Like '*cheese*' Or Like '*distill*' Or Like '*mill *' Or Like '*soup*' Or Like '*corn *' Or Like '*potato*' Or Like '*heinz*' Or Like '*agri*' Or Like '*ingredients*' Or Like '*citrus*' Or Like '*BUSCH*' Or Like '*grain*' Or Like '*brand*' Or Like '*nutrition*' Or Like '*Archer Daniel*' Or Like '*cand*' Or Like '*packing*' Or Like '*kraft*') And Not Like '*legion*' And Not Like '*grocer*' And Not Like '*condo*'

21 Like '*textile*'24

Like '*lumber*' Or Like '*flooring*' Or Like '* wood *' Or Like '*plywood*' Or Like '*hardwood*' Or Like '*mould*' Or Like '*willamette*' Or Like '*timber *' Or Like '*forest product*' Or Like '*paperboard*' Or Like '*sawmill*' Or Like '*veneer*' Or Like '*forest prod*' Or Like '*cascade*' Or Like '*weyerhae*' Or Like '*cabinet*'

26 Like '*paper*' Or Like '*pulp*' Or Like '*mill*' SIC IS NOT 

28 Like '*chemical*' Or Like '*rubber*' Or Like '*phamaceut*'32 Like '*steel *' Or Like '*Nucor*' Or Like '*IPSCO*'49 Like '*electric*' Or Like '*cogen*' Or Like '*power*'51 (Like '*oil*' Or Like '*petroleum*' Or Like '*terminal*' Or Like '*fuel*' Or Like '*commodit*' Or Like '*pipe*' Or Like '*distribut*') And Not Like '*school*'

58 Like '*diner*' Or Like '* bar *' Or Like '*cafe*' Or Like '*grill*' Or Like '*tavern*' Or Like '*deli*' Or Like '*steakhouse*' Or Like '*restaurant*'

60 (Like '*bank*' Or Like '* asset *' Or Like '*credit*' Or Like '*solomon smith*') And Not Like '*apts*' And Not Like '*apartment*'65

(Like '*apt*' Or Like '*apartm*' Or Like '*hous*' Or Like '*mgmt*' Or Like '*management*' Or Like '*realty*' Or Like '*theater*' Or Like '*pier*' Or Like '*center*' Or Like 

'*dock*' Or Like '*home*' Or Like '*garden*' Or Like '*courts*' Or Like '*park*' Or Like '*condo*' Or Like '*propert*' Or Like '*bldg*' Or Like '*building*' Or Like '*tower*') And Not Like '* inn *' And Not Like "*' college '*" And Not Like '*courthouse*' And Not Like '*court house*'

70 Like '*hotel*' Or Like '*motel*' Or Like '*resort*' Or Like '*casino*' Or Like '* inn *' Or Like '*red roof*'72

(Like '*funeral*' Or Like '*cremator*' Or Like '*laundr*' Or Like '*dry clean*' Or Like '*cleaner*' Or Like '*linen*' Or Like '*uniform*' Or Like '*garmet*' Or Like '*barber*' Or Like '*salon*' Or Like '*manicure*' Or Like '*cosmetology*' Or Like '*beauty*') And Not Like '*college*'

80

(Like '*hosp*' Or Like '*psych*' Or Like '*mental*' Or Like '*rehab*' Or Like '*clinic*' Or Like '*surgery*' Or Like '*hygeine*' Or Like '*health*' Or Like '*medical*') And Not Like '*animal*'

82

Like '*librar*' Or Like '*seminar*' Or Like '*academ*' Or Like '*school*' Or Like '*educat*' Or Like '*circulat*' Or Like '*univ*' Or Like '*suny*' Or Like '*vocation*' Or Like '*H S*' Or Like '*board of educ*' Or Like '*bd of ed*' Or Like '* elem*'

86

Like '*YMCA*' Or Like '*church*' Or Like '*temple*' Or Like '*mosque*' Or Like '*convent*' Or Like '*sister*' Or Like '*relig*' Or Like '*shrine*' Or Like '*jew*' Or Like '*methodist*' Or Like '*baptist*' Or Like '*luther*'

97

(Like '*military*' Or Like '*marine corp*' Or Like '*army*' Or Like '*AFB*' Or Like '*usaf *' Or Like '*navy*' Or Like '*naval*' Or Like '*armory*' Or Like '*defense*' Or Like '*air force*' Or Like '* guard *' Or Like '*ammunition*') And Not Like '*salvation*' And Not Like '*volunteer*' And Not Like '*bank*'

87

(Like '*engineer*' Or Like '*research*' Or Like '*technolog*' Or Like '* lab*') And Not Like '*school*' And Not Like '*college*' And Not Like '*univ*' And Not Like '*apts*' 

And Not Like '*animal*'

92

(Like '*prison*' Or Like '*correction*' Or Like '*justice*' Or Like '*juvenile*' Or Like '*youth center*' Or Like '*penitentiar*' Or Like '*jail*' Or Like '*sheriff*' Or Like '*public safety*' Or Like '*police*' Or Like '*fire*' Or Like '*rescue squad*' Or Like '*ambula*') And Not Like '*college*' And Not Like '*not apts*' And Not Like '*apartment*' And Not Like '*restaurant*' And Not Like '*golf*'

Appendix B-3: Keywords for SIC Assignments at Inventories without Industrial Classifications