As the holiday season nears, so too does the cold Canadian weather. As I rush into buildings trying to escape the cold my efforts are prolonged by having to slow down and push open revolving doors. It is always around this time of year that I actually notice the presence of revolving doors. I often wonder what purpose they serve beyond delaying me from entering the warm indoors.

This delay is the beauty of revolving doors. Revolving door are never actually open because they are designed to limit the “entrance of wind, snow, rain, or dust”[1] into buildings. In fact, this attribute is what makes them important. When comparing revolving doors to a typical swinging door, students at MIT found “that the higher the number of people using revolving doors, the more effective the incremental changes”[2]. This energy savings essentially boils down to reduced air leakage. A UBC study finds that compared to a sliding or swinging door, “a revolving door can save more than eight times the amount of air leakage created by the pressure difference and door usage”[3]. With a revolving door, the air inside the building undergoes dramatically less fluctuations in temperature. Naturally, energy savings vary by outdoor temperature with cold winter months having the most energy savings. The yearly energy savings resulting from a revolving door are summarised in table 1.

Source: “Modifying habits towards sustainability: a study of revolving door usage on the MIT campus” by B.A. Cullum, O. Lee, S. Sukkasi, and D. Wesolokski, Massachusetts Institute of Technology, 2006.

As we continue our AutoCASE for buildings research we are always on the lookout for green features for buildings. Revolving doors provide energy savings benefits, and the UBC study does a good job of summarising the financial costs and benefits of revolving doors. Using the SROI framework, AutoCASE can monetize the environmental benefits outlined in the UBC and MIT studies. Using the social cost of carbon[4] AutoCASE values the avoided CO₂ from heating the building with natural gas in the 100% usage scenario at $598.31 per year. Monetizing the reduction in greenhouse gases emitted will also be possible in AutoCASE for buildings.

In addition to providing financial and social benefits, revolving doors can provide further benefits by capturing their kinetic energy and producing electricity. The UBC study estimates that electricity generating revolving doors with continuous use can power a 150W light bulb for 100 hours. Applying the revolving door usage observed in the MIT study of 23.3% for a 9 hour day, an electricity generating door can power a 150W light bulb for approximately 9 hours.

With winter upon us I still rush into buildings trying to escape the cold, but now I find myself examining the revolving doors that I meet instead of noting the small nuisance they once caused me.

[1] https://en.wikipedia.org/wiki/Revolving_door

[2] “Modifying habits towards sustainability: a study of revolving door usage on the MIT campus” by B.A. Cullum, O. Lee, S. Sukkasi, and D. Wesolokski, Massachusetts Institute of Technology, 2006.

[3]“An Investigation into Energy-Generating Revolving Doors” by Kim Limkhuntham, Qian Ma, Vincent Quach, Elvin Yutuc University of British Columbia November 30, 2010

[4] Interagency Working Group on the Social Cost of Carbon (2013). Technical Support Document: “Technical Update of the Social Cost of Carbon for Regulatory Impact Analysis – Under Executive Order 12866”.