Fugitive Emissions from Motor Vehicle Air Conditioning
Most on-road vehicles have air conditioning systems, which may use refrigerants that contain or consist of GHG gas compounds listed in Appendix E of the LGOP.
HFCs-predominately, HFC-134a-are the primary refrigerants used for motor vehicle air conditioners and are themselves GHGs. Leaks from HFC-based air conditioning systems (which are common) are considered Scope 1 fugitive emissions.
Read the LGOP's recommended and alternate approaches for calculating Scope 1 fugitive emissions from mobile sources.
Recommended Approach: Mass Balance Method
- Confirm what refrigerants and HFCs are being used in local government vehicles.
- Using Table 7.1, determine:
a. Base inventory for each HFC in use at each facility - Determine the quantity of the HFC in storage at the beginning of the year (A) and the quantity in storage at the end of the year (B).
b. Changes to the base inventory for each HFC – Include any purchases/acquisitions of each HFC, sales/disbursements of each HFC, and any changes in capacity of A/C equipment.
- Purchases/acquisitions is the sum of all the HFC acquired during the year either in storage containers or in equipment (C).
- Sales/disbursements is the sum of all the HFC sold or otherwise disbursed during the year either in storage containers or in equipment (D).
- Net change to the total equipment volume, also known as the capacity/full charge of equipment, for a given HFC during the year (E) must be assessed.
- Calculate annual emissions of each type of HFC using Equation 7.10.d. Use Equation 7.11 and the appropriate GWP (global warming potential) factors from LGOP Appendix E to convert each HFC to units of CO2e.
- Use Equation 7.12 to sum the totals of each type of HFC, in units of CO2e, to determine total HFC emissions at each facility.
Alternate Approach: Estimation based on fleet inventory and refrigerants used
- Determine the types and quantities of HFC used. Determine: the number of vehicles with A/C equipment, the types of refrigerant used, and the refrigerant charge capacity of each piece of equipment, using Table 7.2.
- For each type of refrigerant, estimate annual emissions using Equation 7.13. Default emissions for estimation purposes are provided in Table 7.2
- Convert to units of CO2e and determine total HFC emissions using Equation 7.11 and the appropriate GWP factors from Appendix E.
- Use Equation 7.12 to sum the totals of each type of HFC, in units of CO2e, to determine total HFC emissions at each facility.
Estimate annual emissions of each type of HFC using Equation 6.33. Default emission factors are provided in Table 6.3. Note: Default emission factors are currently not available for fire suppression equipment.
