Fuel Used for Vehicle Air Conditioning: A State-by-State Thermal Comfort-Based Approach

How much fuel does vehicle air conditioning actually use? This study attempts to answer that question to determine the national and state-by-state fuel use impact seen by using air conditioning in light duty gasoline vehicles. The study used data from US cities, representative of averages over the past 30 years, whose temperature, incident radiation, and humidity varied through time of day and day of year. National surveys estimated when people drive their vehicles during the day and throughout the year. A simple thermal comfort model based on Fanger's heat balance equations determined the percentage of time that a driver would use the air conditioning based on the premise that if a person were dissatisfied with the thermal environment, they would turn on the air conditioning. Vehicle simulations for typical US cars and trucks determined the fuel economy reduction seen with AC use. Combining these statistics and models with vehicle and truck registrations and vehicle miles traveled resulted in a state-by-state estimate of fuel used for air conditioning in vehicles. The study showed that the US uses 7.1 billion gallons (27 billion liters) of gasoline every year for air conditioning vehicles, equivalent to 6% of domestic petroleum consumption, or 10% of US imported crude oil.