The method includes operating an HVAC unit for a test period in an automatic temperature control mode and measuring power consumed at one or more testing heat loads at one or more rotational speeds. The method further includes determining an association between the measured power consumed at the one or more testing heat loads and one or more tested bus engine speeds and calculating power consumed at the one or more testing heat loads at a plurality of profiled bus engine speeds based on the association, wherein the plurality of profiled bus engine speeds is derived from a bus road profile of known bus engine speeds at known time durations, with the known time durations summing to a time period. The method also includes calculating energy consumed at the one or more testing heat loads over the time period.
