Comparative performance of six carbon footprint models for use in Ireland

Carbon footprint models are increasingly being used to manage personal and household carbon dioxide emissions. Six models were compared for their suitability for use in Ireland using typical data for a household of three people. The annual household energy and transportation emissions ranged from 10,540 to 17,361 kg CO2 yr− 1 (mean 12,886; sd 2135) rising to a total footprint of 12,053 to 27, 218 kg CO2 yr− 1 (mean 18,117; sd 5106) when aviation emissions were included. This represents a potential range for individual CO2 emissions of between 4018 and 9073 kg CO2/person/annum, a variation of over 5 tonnes/person. The information provided by these models proved to be inconsistent and often contradictory. The high variability between models was due to a number of anomalies. When these were corrected mean household energy and transportation emissions fell to 12,130 kg CO2 yr− 1 (sd 805), with a total household footprint of 16,552 kg CO2 yr− 1 (sd 1101). Models vary in their complexity in terms of what is included in the overall estimation of emissions making a full analysis of the primary carbon footprint very difficult. When compared to current Irish conversion factors the corrected models either underestimated or overestimated CO2 emissions by approximately 10%. Current carbon footprint models excluded emissions from CH4 and N2O underestimating CO2 emissions for the household by 1.8%.