One of our students found this astonishing fact:
A study analyzed ten identical homes located on the same street and found that the total energy use varied by a factor of three (Parker, Mills, & Rainer, 2012).
Source: Parker, Danny, et al. "Accuracy of the home energy saver energy calculation methodology." Proceedings of the 2012 ACEEE Summer Study on Energy Efficiency in Buildings (2012). Link to pdf