Center for the Built Environment

Designs for low-energy buildings increasingly incorporate operable windows for the benefits of personal control, environmental quality, and architectural value. In practice, however,there are unresolved debates about whether operable windows can be integrated with mechanical systems to optimize both comfort and energy efficiency. Signals that inform occupants about when to open and close their windows (usually red/green lights) have become a popular solution. These systems essentially propose a compromise between manual and automatic control philosophies, asserting that information from the building can influence behavior while retaining the fundamental benefit of personal control. Results from interviews, site visits and surveys of 16 U.S. case studiesshow mixed results. Signals play a role in window use behavior for only a minority of occupants under normative management/education practices. However, greater participation is possible given efforts to communicate the tangible benefits of the devices. Office type (shared or private), visibility of the signals from workstations, reliability of the signal modes, and a range of personal circumstances (noise, wind, window hardware) also influence participation.If conceived as reinforcement to an internal policy rather than as an element of the building controls, this technology holds promise for a wide range of building and user types, and the programming can be flexible and adaptable as circumstances change in our rapidly changing built environment.