How To Hack Big Energy Savings With a Simple Sign and a Revolving Door
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 stories, is clad in a beautiful aluminum facade, and has LEED Gold certification. Yet, the air that escapes its frequently-opened swinging doors seems to defeat the building's energy efficiency. So I set out to understand the problem and design a solution.
Invented in 1888, the first 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. 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. Revolving doors can prevent a building from losing up to 18 percent of its heat.
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 to 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.