#• \ \ d? PRO*^ 2020 National Emissions Inventory Technical Support Document: Dust - Construction - Residential ------- ------- EP A-454/R-23 -00 It March 2023 2020 National Emissions Inventory Technical Support Document: Dust - Construction - Residential U.S. Environmental Protection Agency Office of Air Quality Planning and Standards Air Quality Assessment Division Research Triangle Park, NC ------- Contents List of Tables i 20 Dust - Construction -Residential 20-1 20.1 Sector Descriptions and Overview 20-1 20.2 EPA-developed estimates 20-1 20.2.1 Activity data 20-1 20.2.2 Allocation procedure 20-6 20.2.3 Emission factors 20-6 20.2.4 Controls 20-7 20.2.5 Emissions 20-8 20.2.6 Sample calculations 20-8 20.2.7 Improvements/Changes in the 2020 NEI 20-10 20.2.8 Puerto Rico and Virgin Islands 20-11 20.2.9 References 20-11 List of Tables Table 20-1: SCCs in the Construction Dust sector 20-1 Table 20-2: Housing Start Data for 2020 20-2 Table 20-3: Breakdown of 2 to 4-unit structures 20-2 Table 20-4: Surface soil removed per unit type 20-5 Table 20-5: Emissions factors for residential construction 20-6 Table 20-6: Sample calculations for PM-10 PRI and PM25-PRI emissions from residential construction of 2-unit structures 20-9 l ------- 20 Dust - Construction -Residential 20.1 Sector Descriptions and Overview Construction dust refers to residential and non-residential construction activity, which are functions of acreage disturbed for construction. This sector will be divided below when describing the calculation of EPA's emissions. Table 20-1 lists the nonpoint SCCs associated with this sector in the 2020 NEI. The SCC level 1 and 2 descriptions is "Industrial Processes; Construction: SIC 15 -17" for all SCCs. Table 20-1: SCCs in the Construction Dust sector SCC SCC Level Three SCC Level Four TSD Section 2311010000 Residential Total 20 2311020000 Industrial/Commercial/Institutional Total 21 2311030000 Road Construction Total 22 This section covers residential construction dust. Section 21 covers dust for non-residential construction activity, and Section 22 covers dust from road construction. A list of agencies that submitted residential construction dust emissions is provided in Section 6.2.3. 20.2 EPA-developed estimates Emissions from residential construction activity are a function of the acreage disturbed and volume of soil excavated for residential construction. Residential construction activity is developed from data obtained from the U.S. Department of Commerce (DOC)'s Bureau of the Census. 20.2.1 Activity data There are two activity calculations performed for residential construction: acres of soil disturbed, and volume of soil removed for basements. Determine the Number of Housing Starts in Each County The US Census Bureau has data for New Privately Owned Housing Units Started by Purpose and Design [ref 1] which provides data on housing starts based on the groupings of 1 unit, 2-4 units, and 5 or more units. Regional-level results are also provided for quarterly totals and 1-unit structures in Table 20-2 [ref 1], In order to breakdown the 2 to 4-unit category, data from a consultation with the Census Bureau in 2002 are used; approximately 1/3 of the housing starts are for 2-unit structures, and 2/3 are for 3- and 4-unit structures. The US Census Bureau New Privately Owned Housing Units Started by Purpose and Design [ref 1] data for 2-4 units are distributed to two categories, 2 and 3-4 units, based on a ratio for 2 and 3-4 units calculated from the 2000 US Census Bureau National Housing Starts data [ref 2], for each quarter. Note that 2000 is the last full year when Census housing starts data are available separately for 2-unit and 3- 4-unit homes. Table 20-3 shows a breakdown of the 2 unit and 3-4-unit structures based on the following calculation. 20-1 ------- Where: $Q,n Un Ut Sq,2-4 $Q,n ~ ( y ) X $Q,2-4 (1) Housing starts, by quarter, Q, and number of units, n (2 units or 3-4 units), in thousand units Number of housing starts by number of units, n, from the 2000 National Housing Starts data, in thousand housing starts Total number of housing starts for both 2 units and 3-4 units from the 2000 National Housing Starts data, in thousand housing starts Number of 2-4 units by quarter, Q, from the New Privately Owned Housing Units Started by Purpose and Design data, in thousand units Table 20-2: Housing Start Data for 2020 Quarter Total Structure Region Regional Starts of Structures with 1 unit 1 unit 2 to 4 units 5 units or more NE MW S W NE MW S W Q1 328 214 3 111 29 31 186 84 12 21 127 55 Q2 299 217 3 79 22 47 157 73 13 34 120 51 Q3 387 281 3 103 32 63 203 90 19 42 154 67 Q4 363 277 3 83 29 50 191 94 17 39 153 69 Table 20-3: Breakdown of 2 to 4-unit structures Quarter 2 to 4 units 2 units 3-4 units Q1 3.0 1.11 1.89 Q2 3.0 1.11 1.89 Q3 3.0 1.11 1.89 Q4 3.0 1.11 1.89 Ratios of the number of 2, 3-4, and 5 or more-unit structures are then used to estimate the number of structures of each type in each region. The ratios are calculated by dividing the housing starts by quarter for each unit type by the total housing starts for buildings with 2 or more units. ^Q,n , rQ,n ~ T (2) ^Q.t Where: rem = Ratio of structures with number of units, n, to total number of units by quarter, Q Sa„ = Housing starts, by quarter, Q, and number of units, n, from distributed calculation in Step 1 for the 2-unit or 3-4 unit categories or directly from the New Privately Owned Housing Units Started by Purpose and Design data for the 5 units or more category, in thousand housing starts 20-2 ------- Sat = Housing starts, by quarter, Q, for total number of buildings with 2 or more units, t (excludes 1-unit category), in thousand housing starts The ratio is then used to distribute the New Privately Owned Housing Units Started by Purpose and Design regional data for all unit types to the 2, 3-4, or 5 or more-unit categories within each Census region - Northeast, Midwest, South, and West. Q,n,rgn ^~Q,n (fi^t,rgn RS±,rgn) (3) Where: AQ,n,rgn = Number of housing units started in quarter Q, by number of units, n, and region of the country, rgn, in thousand units rQ/n = Ratio of structures with number of units, n, to total number of units by quarter, Q RSt,rgn = Total regional starts from the New Privately Owned Housing Units Started by Purpose and Design data, in thousand housing starts RSijgn = Regional starts of structures with 1 unit from the New Privately Owned Housing Units Started by Purpose and Design data, in thousand housing starts Data from the Census report New Privately Owned Housing Units Authorized Unadjusted Units [ref 3] is used to calculate a conversion factor to determine the ratio of structures to units in the 5 or more-unit category. The conversion factor is calculated by dividing the total number of units in structures with 5 or more units by region [ref 2] by the total number of buildings with 5 or more units by region [ref 3], = r1 hi ^5,rgn Where: CF5,rgn = Ratio of 5 units or more to the number of buildings with 5 units or more by region, rgn Usjgn = Total number of 5 or more units by region, rgn Bsjgn = Total number of buildings with 5 or more units by region, rgn Structures started by category are then calculated at a regional level by summing the number of housing unit starts across all four quarters and dividing by the number of units in each building type. For the 3-4- unit type, the number of units per building is 3.5. The value is multiplied by 1,000 because the Census data are in units of thousand building starts. For buildings with 1, 2, or 3-4 units: -.Q4 .n.rgn) x 1,000 ^ Bn,rqn a n Where: Bn,rgn = Number of building starts by the unit number category, n, and by region, rgn AQ,n,rgn = Number of housing units started in quarter 0, by number of units, n, and region of the country, rgn, in thousand units 20-3 ------- n = Number of units per building For buildings with 5 or more units: B, (O iQi^Q.n.rgn) x 1,000 CFs (6) n,rgn Where: Bn,rgn = Number of building starts by the unit number category, n, and by region, rgn AQ,n,rgn = Number of housing units started in quarter Q, by number of units, n, and region of the country, rgn, in thousand units CFs = Ratio of 5 units or more to the number of buildings with 5 units or more Annual county-level building permit data were obtained from the US Census Bureau [ref 4], The County Level Residential Building Permit dataset has data to allocate regional housing starts to the county level. This results in county-level housing starts by number of units. The number of building permits for each unit number category by region is calculated by summing the county-level Census data to the Census region level. BPn,rgn = Number of building permits by the unit number category, n, and by region, rgn BP„/C = Number of building permits by the unit number category, n, and by county, c The ratio of the number of building permits by county to the total number of building permits by region in which the county is located, for each unit number category, is then calculated. Rbp,c = Ratio of building permits, BP, to total regional building permits in county c BP„/C = Number of building permits by the unit number category, n, and by county, c BPn,rgn = Number of building permits by the unit number category, n, and by region, rgn The final number of building starts for each unit type category is then calculated at the county-level by multiplying the number of structures started at the regional level and the building permit ratio. (7) Where: (8) Where: (9) Where: Number of building starts by the unit number category, n, and by county, c Number of building starts by the unit number category, n, and by region, rgn 20-4 ------- Rbp,c = Ratio of building permits, BP, to total regional building permits in county c Determine Amount of Soil Removed for Basements To calculate basement soil removal, the Characteristics of New Single-Family Houses Completed, Foundation table [ref 5] is used to estimate the percentage of 1-unit structures that have a basement at the regional level. The data indicate whether the structure has a full/partial basement, slab or other type, or crawl space. However, only structures with full/partial basements are used in this calculation. BMrm = rgn BMtrgn (10) Where: BMrgn = BMfprgn = BMt,rgn = Fraction of basements for buildings in the region Number of full or partial basements, fp, by region, rgn Total number of houses regardless of basement type (full/partial, slab/other, crawl space by region, rgn To estimate the number of building starts with and without basements in each county, the county level estimate of the number of 1-unit starts (from equation 9) is multiplied by the percent of 1-unit houses in the region that have a basement. BC,BM Bn.C ^ BMrgyi Bc,tibm Bn.c X (1 BMrgn) (11) (11a) Where: Bc,bm Bc,nBM Bn,c BMran Number of building starts by county, c, with a basement, BM Number of building starts by county, c, without a basement, BM Number of building starts by the unit number category, n, and by county, c Fraction of basements for buildings in the region Basement volume is calculated by assuming a house with a 2000 square foot footprint has a basement dug to a depth of 8 feet (making 16,000 ft3 per basement). An additional 10% is added for peripheral dirt bringing the total to 17,600 ft3 (651.85 yd3) per basement. Determine Amount of Soil Disturbed by Unit Type The number of acres of soil disturbed by the construction of residential buildings is calculated for apartment buildings, buildings with 2 units, and buildings with 1 unit. Table 20-4 below shows the assumptions used for the surface area disturbed for each unit type. Buildings with unit types of 3-4 and 5 or more are grouped together as apartments in this step. Table 20-4: Surface soil removed per unit type Structure Type Acres disturbed 1-Unit 1/4 acre per structure 2-Unit 1/3 acre per structure Apartment 1/2 acre per structure 20-5 ------- For apartment buildings (sum of 3-4 and 5 or more units) and buildings with 2 units: ^n,c Bn.c ^ (12) Where: Sn,c = Surface soil disturbed by building construction by county, c, and unit type category, n, in acres B„/C = Number of building starts by the unit type category, n, and by county, c a„ = Acres of surface soil disturbed by each unit type category, n. See Table 20-4Table 20-4 for values for each type. For buildings with 1 unit, with or without a basement: Sn,c Bc,BM ^ (13) Where: S„/C = Surface soil disturbed by building construction by county, c, and unit type category, n, in acres Bc,bm = Number of buildings by county, c, with or without a basement, BM a„ = Acres of surface soil disturbed by each unit type category, n. See Table 20-4 for values for each type. 20.2.2 Allocation procedure Annual county building permit data were obtained from the US Census Bureau [ref 4], The County Level Residential Building Permit dataset is used to allocate regional housing starts to the county level. 20.2.3 Emission factors Initial PM10 emissions from construction of single family, 2-unit, and apartments structures, provided in Table 20-5, are calculated using the emissions factors [ref 5], These emissions factors describe average "unit operations," such as "loading and unloading of earth and aggregate materials, land clearing and general vehicle traffic" [ref 6], They therefore take into account the entire duration of construction, and not simply the duration of active excavation. The duration of construction activity for houses is assumed to be 6 months and the duration of construction for apartments is assumed to be 12 months. Table 20-5: Emissions factors for residential construction Type of Structure Emissions Factor Duration of Construction Apartments 0.11 tons PMlO/acre-month 12 months 2-Unit Structures 0.032 tons PMlO/acre-month 6 months 1-unit Structures with Basements 0.011 tons PMlO/acre-month 6 months 0.059 tons PM10/1000 cubic yards 1-Unit Structures w/o Basements 0.032 tons PMlO/acre-month 6 months To account for the soil moisture level, the PM10 emissions are weighted using the 30-year average precipitation-evaporation (PE) values from Thornthwaite's PE Index. Average precipitation evaporation 20-6 ------- values for each state are estimated based on PE values for specific climatic divisions within a state. The average PE value for the test sites from which the PM10 emissions factor was developed is 24 [ref 6], Equation 14 is used to adjust the county-level emissions factor based on this PE value. To account for the silt content, the PM10-PRI emissions are weighted using average silt content for each county. EPA used the National Cooperative Soil Survey Microsoft Access Soil Characterization Database to develop county-level, average silt content values for surface soil [ref 7], The U.S. Department of Agriculture and the National Cooperative Soil Survey define silt content of surface soil as the percentage of particles (mass basis) of diameter smaller than 50 micrometers (nm) found in the surface soil [ref 8], Note that this definition is different than the U.S. Environmental Protection Agency's definition [ref 9] that includes all particles (mass basis) of diameter smaller than 75 micrometers. This database contains the most commonly requested data from the National Cooperative Soil Survey Laboratories including data from the Kellogg Soil Survey Laboratory and cooperating universities. The average silt content for the test sites from which the PM10 emissions factor was developed is 9% [ref 6], Equation 7 is used to adjust the county-level emissions factor based on this silt content value. 24 s AFpmw=JeX9% (14) Where: AFpmio = PM10-PRI adjustment factor PE = precipitation-evaporation value for each State s = % dry silt content, by county, in soil for area being inventoried This adjustment factor is used to adjust the PM10-PRI emissions factor for each unit type category - apartment, 2-unit, 1-unitwith basement, and 1-unit without basement. EFp,n,c AFpMio ^ X EForig (15) Where: EFPt„tc = Adjusted county-level, c, PM10-PRI emissions factor, p, for each unit type category, n, in tons/acre AFpmio = PM10-PRI adjustment factor D„ = Duration of construction by unit type category, n, in months. See Table 20-6 for duration values. EForig = Original unadjusted PM10 emissions factor, in tons/acre. See for original emissions factors The resulting emission factors therefore vary by county and the composite minimum, median, and maximum emission factors for these sources are provided in the "Wagon Wheel Emission Factor Compendium" on the 2020 NEI Supporting Data and Summaries site. 20.2.4 Controls There are no controls assumed for this category. 20-7 ------- 20.2.5 Emissions The PM10-PRI emissions are calculated by taking the sum of the surface soil disturbed by county and unit type category and multiplying it by the corresponding adjusted PM10-PRI emissions factor. Once PM10-PRI adjustments have been made, PM25-PRI emissions are estimated by applying a particle size multiplier of 0.10 to PM10-PRI emissions [ref 8], Primary PM emissions are equal to filterable emissions since there are no condensible emissions from residential construction. The PM10-PRI emissions are calculated at the county-level by multiplying the surface soil disturbed from construction for each unit type by the corresponding emissions factor for that unit type, and then summed across unit types. -PM 10, JV \c ^n, c x EFpMio,n,c (1) n=1 Where: Epmio,c = Total PM10-PRI emissions in county c, in tons S„/C = Surface soil disturbed by building construction by county, c, and unit type category, n EFPt„tc = Adjusted county-level, c, PMio emissions factor, p, for each unit type category, n, in tons/acre The PM25-PRI emissions are calculated based on the assumption that they are 10% of the PM10-PRI emissions. EpM2.5,c = EpM10,c X 0.1 (2) Where: Epm2.5,c = Total county-level, c, PM25-PRI emissions Epmio,c = Total county-level, c, PM10-PRI emissions 0.1 = Particle size multiplier 20.2.6 Sample calculations Table 20-6 shows sample calculations for PM10-PRI and PM25-PRI emissions from residential construction for a 2-unit structure in Suffolk County, Massachusetts. The first 3 equations use the first quarter (Ql) of 2020 for 2-unit structures as an example. However, these calculations would need to be repeated to calculate values for all 4 quarters for all 3-unit sizes. Note that structures with 5 or more units and structures with 1 unit with or without a basement have additional steps not shown in the sample calculations here. 20-8 ------- Table 20-6: Sample calculations for PM-10 PRI and PM25-PRI emissions from residential construction of 2-unit structures Eq. # Equation Values Result 1 5 3Q,n ~ \U J (?,2—4 /14 two unit housing starts in 2002\ V 38 total housing starts in 2002 J X 2 two to four unit housing starts in Q1 2020 0.74 thousand housing starts for 2-unit structures in Q1 2020, nationally 2 Sq,11 0.74 two unit housing starts 0.01 ratio of buildings with 2 units to all 2 or more-unit housing starts for Q1 2020, nationally 1Q,n o ^Q.t 72 two or more unit housing starts 3 Q,n,rgn ^~Q,n X (fi^t -RSj 0.01 x (23 total Q1 housing starts in Northeast — 9 one unit housing starts in Northeast) 0.14 thousand housing starts for 2-unit structures for Q1 2020 in the Northeast 4 Us.rgn CFk = „ #5,r N/A Equation is for 5 or more-unit buildings; example is for 2- unit buildings 5 Bn,rgn .n.rgn) x 1<000 n 0.772 two unit structures x 1,000 2 units per building 386 2-unit structures constructed in the Northeast 6 Bn,rgn (EqiAq n.rgn) x 1<000 CF5 N/A Equation is for 5 or more-unit buildings; example is for 2- unit buildings 7 RP =\ Ftp ±J1n,rgn / ±J1n,c Northeast two unit building permits 1,545 2-unit structure building permits in the Northeast 8 BP U 1 yt C R — 49 county building permits 0.03172 ratio of county-level building permits to regional-level building permits hBP,c Bp n,rgn 1,545 Northeast building permits 20-9 ------- Eq. # Equation Values Result 9 Bn,c Bn,rgn ^ RBP,c 386 X 0.03172 12.25 total 2- unit structure building starts 10 BMrm = B"'rn" rgn BMtrgn N/A Equation is for 1-unit buildings; example is for 2- unit buildings 11 ^c,BM Bn.c ^ BMrgn N/A Equation is for 1-unit buildings; example is for 2- unit buildings 12 n,c Bn.c ^ 12.25 two unit structures x 0.33 acres per structure 4.08 acres surface soil disturbed by 2- unit structures 13 Sn,c ^c,BM ^ N/A Equation is for 1-unit buildings; example is for 2- unit buildings 14 24 s AFpMi°=PEXWo 24 119.7 PE value for the state 27.07% silt content x 9% 0.603 PM10-PRI adjustment factor for 2-unit structures 15 EFp n,c AFpMio X ^m,n x FF A orifl 0.603 x 6 months x 0.032 tons per acre 0.1158 tons/acre PM10- PRI emissions factor for 2-unit structures 16 EpM10,c ^ EFp:n:c 4.08 acres x 0.1158 tons per acre 0.47 tons PM10- PRI emissions for 2-unit structures 17 EpM2.5,c = EpM10,c X 0.1 0.47 tons x 0.1 0.047 tons PM25-PRI emissions for 2- unit structures 20.2.7 Improvements/Changes in the 2020 NEI Except for activity data updates, there are no significant changes from the methodology used in the 2020 NEI. 20-10 ------- 20.2.8 Puerto Rico and Virgin Islands Since insufficient data exist to calculate emissions for the counties in Puerto Rico and the US Virgin Islands, emissions are based on two proxy counties in Florida: 12011, Broward County for Puerto Rico and 12087, Monroe County for the US Virgin Islands. The total emissions in tons for these two Florida counties are divided by their respective populations creating a tons per capita emissions factor. For each Puerto Rico and US Virgin Island County, the tons per capita emissions factor is multiplied by the county population (from the same year as the inventory's activity data) which served as the activity data. In these cases, the throughput (activity data) unit and the emissions denominator unit are "EACH". 20.2.9 References 1. U.S. Census Bureau. New Privately Owned Housing Units Started by Purpose and Design in 2020. accessed December 2021. 2. U.S. Census Bureau. 2001. Housing Starts. Table 1. New Privately-Owned Housing Units Started. 3. U.S. Census Bureau. New Privately-Owned Housing Units Authorized - Unadjusted Units for Regions. Divisions, and States. Annual 2020. 4. U.S. Census Bureau, Annual Housing Units Authorized by Building Permits. ASCII files by State. MSA. County or Place. co2020a. 5. U.S. Census Bureau, Characteristics of New Housing. Characteristics of New Single-Family Houses Completed, Annual 2020, Foundation Table. 6. Midwest Research Institute. 1996. Improvement of Specific Emission Factors (BACM Project No. 1). Prepared for South Coast Air Quality Management District. 7. U.S. Department of Agriculture, National Cooperative Soil Survey, NCSS Microsoft Access Soil Characterization Database. 8. Cowherd, C. J. Donaldson, R. Hegarty, and D. Ono. 2006. Proposed Revisions to Fine Fraction Ratios Used for AP-42 Fugitive Dust Emission Factors. 15th International Emission Inventory Conference, New Orleans, LA. 9. Midwest Research Institute. 1999. Estimating Particulate Matter Emissions from Construction Operations. Prepared for Emission Factor and Inventory Group, Office of Air Quality Planning and Standards US EPA. 20-11 ------- United States Office of Air Quality Planning and Standards Publication No. EPA-454/R-23-001t Environmental Protection Air Quality Assessment Division March 2023 Agency Research Triangle Park, NC ------- |