Methodology to Quantify the Petroleum Equivalent Fuel Economy Impact of BEV Thermal System Energy Consumption

This paper will present research and 1D modeling results to support a proposed methodology to determine a fleet ambient weighted average Petroleum Equivalent Fuel Economy (PEFE) for the energy consumed by the thermal system of a BEV, including a proposal of how factor in the thermal system PEFE result into an OEM’s overall CAFE determination on an incentivized (not punitive) basis, within the existing regulatory framework. The topic is particularly important because EPA and NHTSA final rules issued in early 2024 eliminated A/C Efficiency Credits for BEVs that are currently in place for all classes of light duty vehicles. However, without some sort of regulatory incentivization, market forces will dictate thermal comfort system solutions that consume more energy – and with that more negative secondary effects such as higher greenhouse gas emissions and vehicle mass - than would otherwise be the case. Eliminating incentivization for BEVs is particularly concerning because the thermal comfort system of a BEV is the second-largest energy consuming system on the vehicle, and proportionally higher energy consumer of energy than on an ICE vehicle, since ICE vehicles can use waste heat for cabin heating. Furthermore, with the combined thermal requirements of cooling for fast charging while keeping the vehicle cabin comfortable for the occupants, the maximum refrigeration capacity of future BEVs, and the energy consumed when running at maximum capacity, will be significantly higher than that of today’s BEVs – up to and beyond 15 kW refrigeration capacity, vs. 7-8 kW today. It seems unreasonable that OEMs should focus considerable time and expense to minimize the energy consumed by the propulsion system of a BEV, while often only giving energy consumption of the second-largest consumer on the vehicle what only amounts to a passing grade to the end user, absent of some regulatory incentivization.