Religious facilities throughout the world are unique in their operation compared to other types of commercial buildings. Due to their lower energy intensity, these buildings rarely are the recipients of traditional energy studies or assessments. This paper presents highlights from a long-term energy study of two architecturally-identical churches located in different climates. Data were collected from over 130 sensors over an 18-month time period. This paper discusses how religious facilities differ from other types of commercial buildings in regards to occupancy, lighting, HVAC usage, and comfort.