Project Title:

Window Control Signaling Systems

Assessing the design strategies and occupant response to red/green light window control signaling systems.

Status (updated 08/01/2013): Complete

Funding sources: CBE Industry Consortium


Project Objective

Assess the effectiveness of window signaling systems in 16 buildings in North America, with analysis of the control strategies used, and occupants' responses to the signals. Because occupant response depends a great deal on context, the aim of the study is to reveal common conflicts and issues that occupants experience, leading to a set of recommendations and key considerations for designers.

Significance to Industry

Low-energy office buildings increasingly incorporate operable windows for the benefits of personal control, environmental quality, and architectural value. However, integrating operable windows with mechanical systems is an unresolved energy efficiency challenge. Signaling systems such as red/green lights and lighted signs, which inform occupants about when to open and close their windows, have become a popular, low-cost solution wherein the amenity and simplicity of manual window control is retained without foregoing building intelligence altogether. Despite their increased use, there have been no attempts to evaluate this type of “shared control” approach in operation.

Research Approach

A new module was generated for the CBE Indoor Environmental Quality (IEQ) Survey, including targeted questions about occupants’ use of windows and response to the signals. We administered the survey to over 600 occupants in 10 buildings, and collected data about a) how often occupants act on the “open” and “close” signals; b) how likely they are to open the window against the signal; and c) what the most common reasons are for disregarding the signals. We also studied key differences in how signaling systems were implemented and managed in 16 buildings, including the 10 that were surveyed, using interviews with project team members, facility managers, and on-site observations. In addition to providing a systematic comparison of the systems using survey data, we have developed a classification scheme for “green mode” control sequences that shows the diversity of strategies and design objectives that have been associated with these systems. This scheme provides a basis for potential future explorations into how energy savings can be optimized while minimizing conflicts with occupant expectations.

Publications and Reports

Ackerly, K.,and G. Brager, 2011. Occupant Response to Window Control Signaling Systems, CBE Summary Report, April. Appendix C: Mixed-mode Signal Case Study Summary.

Ackerly, K., L. Baker, and G. Brager, 2011. Window Use in Mixed-mode Buildings: A Literature Review. CBE Summary Report, April.

Ackerly, K. and G. Brager, 2012. Human Behavior Meets Building Intelligence: How Occupants Respond to “Open Window” Signals. ACEEE Summer Study on Energy Efficiency in Buildings.

Ackerly, K. and G. Brager, 2012. Window Signaling Systems: Control Strategies and Occupant Behavior. Proceedings, The changing context of comfort in an unpredictable world, Windsor, UK, April 2012.

Ackerly, K. and G. Brager, 2013. Window Signaling Systems: Control Strategies and Occupant Behavior. Building Research & Information, 41 (3): 342-360.

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Image of Kroon Hall

Kroon Hall, Yale University, was one of the 16 case study buildings.

Image of window signalling system

Window control signaling system at the Kirsch Center, at De Anza College.

Image of Operable Windows

Operable windows in Savery Hall, University of Washington.