6.18 Asphalt Roofing

6.18.1 Emissions

Introduction

Asphalt is used to adhere, repair, and/or create a smooth finish over manufactured roofing materials (i.e. cap sheets, felt sheets and flashing squares) on commercial and industrial buildings and multiple unit dwellings. This category estimates organic emissions from roofing operations; however, it does not include the manufacture of roofing materials, nor does it cover emissions from fuel combustion.

The organic emission from asphalt roofing operations in the Bay Area was based on ARB’s methodology for emission calculations (Attachment C: Asphalt Paving and Roofing, from STI’s Area Source Emissions Updates, March 2003).

Methodology

In 2011, the Energy Information Administration (EIA) Office of Oil and Gas reported 13,703,000 barrels of asphalt were used in California for paving and roofing purposes. Of that amount, it was assumed 80% (8,471,200 barrels) of the asphalt was used for road paving and 20% (2,117,800 barrels) was used for roofing. Individual county throughputs can be apportioned from construction activity that was provided to ARB. (For the Bay Area, the fractional total to the state was approximately 0.2573.) The 2011 throughput for the BAAQMD was 544,836 bbls/yr (or 95,423 tons/yr, assuming density of asphalt at 8.34 lb/gal). Applying the AP-42 organic emission factor of 6.2 lb/ton of roofing material, the 2008 BAAQMD asphalt roofing emissions, in tons per day, is as follows:

\[ 544,836\ \tfrac{bbl}{yr} \times 42\ \tfrac{gal}{bbl} \times 8.34\ \tfrac{lb}{gal} \text{ (density factor)} \times \tfrac{1\ ton}{2000\ lb} \times \tfrac{1\ yr}{365\ days} \times 6.2 \tfrac{lb}{ton} \text{ (emission factor)} \times \tfrac{1\ ton}{2000\ lb} = 0.81 \tfrac{ton}{day} \]

Monthly Variation

According to ARB, asphalt roofing activity occurs uniformly throughout the year.

County Distribution

As mentioned previously, county throughputs can be apportioned from construction activity that was provided to ARB.

Table 6.41: County fractions.
category ALA CC MAR NAP SF SM SNC SOL SON
#1618 Asphalt Roofing 20.0% 11.0% 4.0% 2.0% 16.0% 10.0% 28.0% 3.0% 6.0%