A Study of the Effect of Weather Data and Other Assumptions on MAC LCCP

Average temperatures on Earth have been on the rise due to excessive emission of man-made carbon dioxide (CO₂). These emissions include contributions from automobiles and their air-conditioners, or mobile air-conditioners (MACs). The Improved Mobile Air Conditioner Greenhouse Gas Life Cycle Climate Performance (IMAC-GHG-LCCP) tool is used to analyze the life cycle climate performance (LCCP) of a MAC system and calculates the resultant total lifetime CO₂-equivalent (CO₂e) emissions for the vehicle. The IMAC-GHG-LCCP tool is an adaptation and improvement of the automotive LCCP standard, GREEN-MAC-LCCP (Global Refrigerants Energy & Environmental-MAC-LCCP) with a focus on simplicity and ease-of-use. The user has the option to choose which refrigerants to analyze, driving parameters/drive cycle, cities for comparison, and power consumption of the MAC system. The tool uses the latest weather data for the emissions calculations. The method used to bin temperature data has an impact on the CO₂ emissions calculated by the tool. Previous versions used average temperatures for each hour of each month to develop temperature bin percentages. The newest version of the tool bins the weather data according to the frequency each city experiences each 10-degree temperature bin. The change in weather data binning methodology has shown a change in reported CO₂e emissions. An updated analysis of the impact of internal heat exchangers has been included, showing the impact of updated weather data binning on the results. Additionally, a sensitivity analysis was conducted using the tool, showing that the vehicle lifetime, driving time, and driving distance have the largest impact on MAC LCCP.