Source energy depends on how energy is generated and transmitted. Because the energy infrastructure is different in the US and Canada, the two countries have different site/source conversion factors. For example, Canada has a higher prevalence of hydroelectric power plants, whereas the U.S. has a higher prevalence of coal power plants. Because of these types of differences the national factors for Canada are different than those of the U.S.
Full information on how we compute source EUI and the factors for each country is available on the Understanding Source and Site Energy page.
It is important to remember that the National Median values and ENERGY STAR score are based on data from each country. That is, for performance metrics, each property is compared to others in its country. Canadian properties are compared with Canadian properties and U.S. properties are compared with U.S. properties.