Powers Scientific Rodent Incubators are capable of operating at cold temperatures for metabolism studies, while maintaining fresh air intake at room temperature. Although the temperature of the fresh air affects how low the temperature setting can be and for how long it remains at that setting without freezing the refrigeration coils, running at 6.5 C with incoming fresh air at about 20C is a common practice. We do not use defrost cycles to keep the coils frost free, because they markedly change the temperature uniformity profile over time. So, adjusting the incoming fresh air quantity and temperature play a large roll in successful operation at cold temperatures. Our fresh air intake can be positioned anywhere from completely open to completely closed, at the researcher’s discretion.