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

Abstract

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, 1X—see Definitions, the Toyota Prius, the Honda Insight, a 3X Hybrid, and a Fuel Cell Hybrid) with a varying auxiliary load. For a conventional 1X vehicle, using the AC increases fuel consumption by 35% (or drops fuel economy by 26%). For the Honda Insight, using the AC increases fuel consumption 46%. For a 3X Hybrid, using the AC increases fuel consumption 128%. 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 AC Load is an