Temperature is a key environmental variable that has various impacts on the physiology and health of all animals, including humans. Mice are currently the most widely used animal model for human disease and fundamental biology. Therefore, it is important to choose a housing temperature for mice that best mimics everyday human conditions; however, which temperature to choose is not trivial. Keijer and colleagues studied the oxygen consumption of C57BL/6 mice measured across the range of temperatures from 21.4 to 30.2 °C in order to find the best housing temperature. From their results, they conclude that 25.5 °C to 27.6 °C may be optimal for solitary housed mice and discuss this in the light of suggestions and results from other groups.