As building codes become more stringent and there is a market push for higher energy performance through superior envelopes, HVAC equipment, lighting, and controls, the relative energy-related impact of occupants and their presence, habits, and actions increases. Occupants make equipment purchasing decisions; generate heat, moisture, and contaminants; adjust operable windows, window blinds, thermostats, electric lighting; and, use appliances. Their behaviors may result in a difference in energy use by a factor of two or more. 1 Even in buildings with a high degree of automation, occupants may use buildings in ways never conceived of by the designer, or complain to the operator at the possible cost of a permanent and energy-intensive override on building controls.(2)