6.23 Structures Coatings
Multiple Categories
6.23.1 Introduction
These categories account for organic gas emissions (TOG and ROG) resulting from the application of architectural coatings and associated use of additives, thinning and cleanup solvents. A full list of category numbers and their titles is included at the end of this chapter.
Architectural coatings include a variety of coatings, for example: (1) paints - flats, and non-flats, (2) clears - lacquers, varnishes, and sealers, (3) stains, (4) industrial maintenance coatings, (5) specialty coatings, etc. These coatings are used on various structures, including bridges, buildings, streets, and roofs. Emissions occur from evaporation of the organic solvents during application and air drying of the coatings. To estimate organic solvent emissions, the quantity of various types of coatings and the associated solvent content in each coating should be known. Additives are used in water-base coatings; thinning solvents are used in solvent-base coatings; cleanup solvents are used in both water-base and solvent-base coatings. There are many types of coatings and each coating formulation has its own specific amount of solvent. Each type of coating is assigned a category number.
The California Air Resources Board (CARB) conducts surveys of architectural coatings marketed in California every four or five years, with the first one in 1976, and the latest one in 2005. These surveys assist both CARB and local districts in tracking organic emissions from architectural coatings. The “2005 Architectural Coatings Survey” contains 2004 data from which this report is based upon.
6.23.2 Methodology
For certain categories in the base year inventory, emissions data are derived by CARB Inventory staff. This significant emissions dataset, sorted by county, is published every few years and is a product of the State Implementation Plan (SIP) emissions document formally known as the California Emissions Projection Analysis Model (CEPAM) inventory 256. For related sets of categories, such as airport ground support equipment (GSE), ships, structures coatings etc., where independent data collection and derivation of emissions are both cost- and time-prohibitive and likely a redundant effort, BAAQMD staff exported the emissions data directly from CEPAM into the District’s Base Year inventory package. This calculation approach and collection of categories is internally termed as “CARB Source Categories”.
The CEPAM provides historical emissions as well as forecasts emissions for major emission source classifications including – a) On-road mobile sources (from Emissions Factor (EMFAC) model), b) Off-road mobile sources (OFFROAD model), and, c) Stationary and Area-wide sources - For these major source classifications, CEPAM combines facility level /area source emissions data reported to the California Emissions Inventory Development and Reporting System (CEIDARS) for multiple years by various regional air quality agencies (including the BAAQMD).
This base year inventory uses the 2016 CEPAMv1.05 to estimate emissions from “CARB Source Categories”. This version of the CEPAM derives emissions from a 2012 base year inventory and contains backcasts and forecasts from year-2000 to year-2035. All applicable regulatory and technological controls are assumed to be built into the CEPAM dataset during CARB staff’s inventory computation work. After the emissions data are exported, the inventory for CARB Source categories is taken through a quality assurance (QA) process.
In the QA process, BAAQMD staff perform a systematic crosswalk between CEPAM’s source category classification (Emission Inventory Code - EICs) and the District’s source category classification (category identification number - cat_ids). Based on the scope of emissions covered, individual EIC or a group of EICs are mapped to a single cat_id. This process also addresses issues when cat_ids have no matching EICs or there are discontinued EICs that need to be investigated. Following this, emissions data are backcasted to year-1990, as well as forecasted to year-2040 using certain mathematical methods, as described in the Trends section. Finally, the emissions trends spanning from year 1990-2040 for each category and pollutant are evaluated, and CARB staff are consulted for explanation of any observed anomalies in trends.
6.23.3 Changes in Methodology
For base year inventories prior to 2011, thinning and cleanup solvent usage ratios were based on the assumption of one pint per gallon of solvent-based coatings. In base year 2011 these ratios were changed as follows: 0.0597 gallon of thinning solvent per gallon of solvent based coating; 0.0044 gallon additives per gallon water based coating; and, 0.0160 gallon cleanup solvent per gallon solvent and water based coatings.
There are no changes to methodology for this base year.
6.23.4 Emissions
A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.
6.23.5 Trends
(a) Historical Emissions / History
Three different methods are used for backcasting to project historical emissions prior to year-2000 going back to year-1990, which is the starting year of the current base year inventory (referred to as BY2015). Following preliminary evaluation of the data available for initial years (post-year 2000) in the CEPAM inventory, BAAQMD staff recommends a backcasting approach. The default backcasting approach is defined by a formula here –
\[ \begin{eqnarray} \text{BY2015 emissions for year X for county Y} = \text{BY2011 total emissions for year X} \\ \\ \times \dfrac{\text{BY2015 year-2000 emissions}}{\text{ BY2011 year-2000 emissions}} \\ \\ \times \dfrac{\text{county Y fraction}}{\text{ fractional total}} \end{eqnarray} \]
This calculation is referred to as the BY2011 scaling method (based on the previous base year inventory). The second calculation approach is to derive the linear regression best fit of the year 2000-2008 CARB Sources emissions data for a category, species, and county, and extrapolate that data back in time. If this backcasting results in negative emissions prior to a certain year, the lowest positive emission value is held constant from that particular year back to year-1990. The third possible calculation approach is to use a specific growth profile for the category, provided by the in-house staff expert. These custom growth profiles are often derived from surrogate data provided by another agency or resource, or available activity data that is assumed to scale with the emissions for that specific CARB Source category.
For architectural coatings, a combination of BY2011 scaling method and custom backcast was used for backcasting. Actual base year 2011 inventory data was used until 1996, this marks the first CARB survey of coatings. Linear interpolation was then used to estimate emissions from 1996 to 2000. In year 2000, CARB data is used in accordance with the BY2011 scaling method described above. This customization was implemented to represent the real survey result taken in 1996 and 2000, respectively.
(b) Future Projections / Growth
Emissions forecasting was done by holding the year-2035 emissions data constant through and up to year-2040. For CARB sources, emissions are forecasted by CARB staff by applying growth profiles to the base year-2012 inventory data (see above in ‘Methodology’ section).
(c) Controls
Rule 8-3257 was adopted by BAAQMD on March 1, 1978, and limits the volatile organic content of products sold for “application to stationary structures and their appurtenances, including houses, buildings, bridges, tanks, railings, streets and highways.” A lawsuit was filed which overturned a 1990 amendment; final elements of this lawsuit were settled in 1998. Also in 1998, an amendment incorporated provisions that would allow low solids architectural coatings to be sold and used within the BAAQMD. In November 2001, the District adopted an amendment that provided a further reduction in VOC to 19 of the architectural coatings. In July 2009, the District passed amendments to its Architectural Coating Rule that further limit the amount of VOC allowed in certain architectural coatings. The VOC limits were based on emissions standards recommended by the Final Approved Suggested Control Measure for Architectural Coatings developed by CARB in 2007. These amendments resulted in a VOC reduction of 4.02 tons/day in 2011 and 1.63 tons/day in 2012.
6.23.6 Uncertainties
For area source emission factors, the main uncertainty in the updated methodology arises from the use of emission factors for certain categories that remain constant over several decades although technological controls may have been applied at facilities. Additionally, the emission factors themselves are seldom verified and validated against measurements, in part due to the difficulty in measuring fugitive emissions from area sources.
6.23.7 List of Categories
| Category No. | Category Title |
|---|---|
| 1010 | Solvent Base - Flats |
| 1011 | Solvent Base - Non-Flats- High Gloss |
| 1012 | Solvent Base - Non-Flats - Low & Medium Gloss |
| 1014 | Solvent Base - Non-Flats - Quick Dry Enamels |
| 1015 | Solvent Base - Clear Wood Finishes - Varnish, Clear & Semi-Transparent |
| 1016 | Solvent Base - Clear Wood Finishes - Lacquers |
| 1019 | Solvent Base - Stains, Clear & Semi-Transparent |
| 1020 | Solvent Base - Stains, Opaque |
| 1021 | Solvent Base - Wood Preservatives |
| 1022 | Solvent Base - Primers, Sealers, & Undercoats |
| 1023 | Solvent Base - Quick Dry Primers, Sealers, & Undercoats |
| 1026 | Solvent Base - Industrial Maintenance Coatings |
| 1027 | Solvent Base - Traffic Marking |
| 1028 | Solvent Base - Waterproofing Sealers |
| 1030 | Solvent Base - Concrete Curing Compounds |
| 1031 | Solvent Base - Roof Coatings |
| 1032 | Solvent Base - Dry Fog Coatings |
| 1035 | Solvent Base - Metallic Pigmented Coatings |
| 1039 | Solvent Base - Form Release Compounds |
| 1275 | Solvent Base - Bituminous Roof |
| 1277 | Solvent Base - Floor |
| 1629 | Solvent Base - Bituminous Roof Primer |
| 1630 | Solvent Base - Faux Finishing |
| 1631 | Solvent Base - Rust Preventative |
| 1632 | Solvent Base - Specialty Primer, Sealer, & Undercoat |
| 1633 | Solvent Base - Waterproofing Concrete/Masonry Sealers |
| 1042 | Solvent Base - Other Coatings |
| 1043 | Water Base - Flats |
| 1044 | Water Base - Non-Flats, High Gloss |
| 1045 | Water Base - Non-Flats, Low & Medium Gloss |
| 1048 | Water Base - Clear Wood Finishes, Varnish, Clear & Semi-Transparent |
| 1049 | Water Base - Clear Wood Finishes, Lacquers |
| 1052 | Water Base - Stains, Clear & Semi-Transparent |
| 1053 | Water Base - Stains, Opaque |
| 1054 | Water Base - Wood Preservatives |
| 1055 | Water Base - Primers, Sealers, & Undercoats |
| 1056 | Water Base - Quick Dry Primers, Sealers, & Undercoats |
| 1059 | Water Base - Industrial Maintenance Coatings |
| 1060 | Water Base - Traffic Marking |
| 1061 | Water Base - Waterproofing Sealers |
| 1063 | Water Base - Concrete Curing Compounds |
| 1064 | Water Base - Roof Coatings |
| 1065 | Water Base - Dry Fog Coatings |
| 1068 | Water Base - Metallic Pigmented Coatings |
| 1072 | Water Base - Form Release Compounds |
| 1279 | Water Base - Bituminous Roof |
| 1281 | Water Base - Floor |
| 1635 | Water Base - Bituminous Roof Primer |
| 1636 | Water Base - Faux Finishing |
| 1637 | Water Base - Rust Preventative |
| 1638 | Water Base - Specialty Primer, Sealer, & Undercoat |
| 1639 | Water Base - Waterproofing Concrete/Masonry Sealers |
| 1075 | Water Base - Other Coatings |
| 1888 | Other - Thinning (for Solvent Base Coatings) |
| 1889 | Other - Additives (for Water Base Coatings) |
| 1890 | Other - Cleanup Solvents (for Solvent & Water Base Coatings) |
| 2350 | Other - Sanding Sealers, Solvent Base |
| 2351 | Other - High Temp Coatings, Solvent Base |
| 2352 | Other - Sanding Sealers, Water Base |
6.23.8 Contact
Author: Ariana Husain
Reviewer: Michael Nguyen
Last Update: November 06, 2023
6.23.9 References & Footnotes
CARB. Criteria Pollutant Emission Inventory Information (CEPAM) . [accessed 2023 Mar 13]. https://ww2.arb.ca.gov/criteria-pollutant-emission-inventory-data↩︎
BAAQMD. 2009. Regulation 8, Rule 3 - Architectural Coatings, https://www.baaqmd.gov/rules-and-compliance/rules/reg-8-rule-3-architectural-coatings↩︎