It slips into buildings, slaps us in the face, and sends shivers down our spines: we have all felt the chill of cold air that rushes through an open door. I doubt that I am the only person annoyed by uncomfortable drafts, which is why I am often surprised when so many of us use swinging doors instead of revolving doors. I recently noticed this at Columbia University's new "Northwest Corner" building, which rises 14-story, is clad in a beautiful aluminum facade, and has LEED Gold certification. Yet, the air that escapes its frequently-opened swinging doors seemed to defeat the building's energy efficiency. So I set out to understand the problem and design a solution.

First invented in 1888, the revolving door was designed to prevent wind, snow, rain, dust, or noise from entering buildings. In comparison, swinging doors exchange eight times more air. Revolving doors also allow people to enter and exit buildings at the same time without running into each other. In fact, a standard "4-wing" door can move 4,800 people into and out of a building every hour.

We usually see revolving doors in large buildings—the same buildings that account for 18.6 percent of America's total energy costs. In fact, revolving doors can prevent a building from losing from losing up to 18 percent of its heat. According to a 2006 study by MIT urban planning students, if everyone used revolving doors in a building, those buildings could save thousands of dollars a year, enough energy to heat 5 homes, and would avoid 14.6 tons of carbon emissions. These numbers are impressive, but multiply them by the total number of buildings that have revolving doors and the total impact would be massive. So how can we get more people use them? To answer this question, I headed to a neighborhood in New York City where it would be easy to see how people choose between swinging and revolving doors: mid-town Manhattan.

I watched people entering and exiting 42 buildings and counted approximately 28 percent of them using revolving doors. I noticed three reasons why people used swinging doors: people followed the person in front of them through open swinging doors, door attendants opened them as people approached buildings, and because no signs instructed people to use the revolving doors (or the signs were small). While swinging doors are essential for many people who are disabled, or to carry large equipment into the building, our country could decrease the $68 billion we spend on heating and cooling every year if the rest of us used revolving doors.

In the 2006 study, the MIT students learned that some people think revolving doors are difficult to push, while others said they fear getting stuck or injured. While revolving doors need to be easy for everyone to use, most of the people I saw in midtown seemed to use swinging doors out of habit, without thinking twice about which door to use. After all, we spend nearly half of our time in the same locations every day, where we quickly form habits. The MIT students recommended several ways to motivate people to use revolving doors, including better signs. I wondered if better signs could disrupt people's habit of using the swinging doors at Columbia. So I went back to Columbia to test the impact of different signs.

There are no signs on the doors at Columbia, and only 29 percent of people chose the revolving doors. So I taped crude, 8.5" x 11" signs to the swinging door with a simple message: "Please Use Revolving Doors." The sign increased the number of people who used the revolving door to 58 percent, making it clear to me that a simple sign could prompt people to change their behavior. The second sign I made was smaller but had an arrow pointing to the revolving door. The average number of people who used the revolving doors only increased to 53 percent. This proves the importance of the sign's size: signs will be more effective if people can read them at a distance and have time to understand them so they can act on them. My third sign spanned two feet long, was seven inches tall (allowing for larger letters), and it not only pointed in the direction of the revolving doors but also adopted the dark blue color of Columbia University to give it more authority. This larger sign caused 70 percent of people to use the revolving doors. It seems clear that even more people would use revolving doors if even larger signs were used on the swinging doors (or covered the whole door), but I resisted this temptation to test or install larger signs since I carried out these experiments discreetly. However, I shared my research and findings with officials at Columbia.

Download Signs

The best way to plug the draft your lobby is by installing revolving doors, which pay for themselves in just a few years. And the best way to make sure people use your revolving doors is with effective signs. If you need new or updated signs, download these sign templates to use at your building. You can customize the templates with your color scheme, logo, address, and contact information. If you need a printer, check Inker Linker for one in your area. Then add the directional arrows to your swinging doors, the circular facts to your revolving doors, and use the 8.5" x 14" poster near the entryway. Cold-blooded people like me will thank you.



  • "Power MIT, Help MIT Save Energy and Keep Clean Air" ‹link›
  • "The Revolving Door since 1881," by Alan Bearmore (2000)
  • "2400 persons each-way per hour is an average speed; but it can vary considerably. For example, office workers who use a revolving door everyday going into work will usually go faster than shoppers or hotel guests. There are also regional differences. Pedestrian traffic in the North and East is generally faster than it is in the West and South." Source: International Revolving Doors ‹link
  • 18.6% equals the commercial buildings share of U.S. primary energy consumption ‹link›
  • Modifying Habits Towards Sustainability: A Study Of Revolving Door Usage On The Mit Campus; Cullum, B.A.; Lee, Olivia; Suddasi, Sittha; Wesolowski, Dan; May 25, 2006 ‹link
  • Practically Green ‹link
  • “Come Walk The Talk – Our Own Energy Challenge and Community Opportunity" (January 12, 2009) ‹link›
  • Also, National Fire Protection Association 101 Life Safety Code regulations require that swinging doors be located within 10-feet of revolving doors. ‹link
  • $68 billion (this number equals 36.7% of 184 billion, or the percent of total U.S. energy that heating and cooling make up). ‹link› If we cut the energy use of U.S. buildings by 20%, we could save approximately $80 billion annually on energy bills, reduce greenhouse gas emissions, and create jobs. ‹link
  • $400 billion (this number equals the total power of homes and commercial buildings) ‹link
  • Automaticity in Situ: The Nature of Habit in Daily Life, David T. Neal and Wendy Wood ‹link