By Jared Ebersole in Video 30 Sep 2026

Why Buildings Need Revolving Doors

That awkward shuffle into the lobby serves a purpose: revolving doors control drafts, conserve heat, and help tall buildings manage powerful air pressure differences.

A revolving door asks for a small act of choreography. Pick a compartment, match its speed, shuffle forward, and emerge into the lobby. Beside it, a familiar swinging door offers a tempting shortcut. Why would a building make entering so complicated?

The answer begins with something you cannot see: the pressure difference between the street and the lobby. A building entrance has to admit people while limiting the movement of air. In a tall building during winter, those two jobs can pull against each other quite literally.

The revolving door gives people a passage through the exterior wall while keeping a barrier across that passage. Its peculiar geometry helps explain both its persistence and the drafts you feel when someone chooses the neighboring door.

The invention's documented history is more practical than the popular story about a man who hated holding doors open. On August 7, 1888, Philadelphia inventor Theophilus Van Kannel received U.S. Patent 387,571 for a “Storm-Door Structure.” His description emphasized protection from weather, quieter interiors, and a door that wind could not blow open. It does not establish an aversion to courtesy as his motivation. Van Kannel's original patent

His design had three wings radiating from a central post, enclosed by curved side walls. Flexible strips helped the moving wings fit against the enclosure. He also anticipated awkward cargo: one or more wings could fold back to create a clear opening for a long object. Even this early version acknowledged that controlling airflow had to coexist with getting things through the entrance.

The basic arrangement remains easy to understand by imagining a single compartment as it rotates. It opens toward the street, travels behind the curved enclosure, then opens toward the lobby. During normal operation, the wings interrupt a direct path between outdoors and indoors. People can keep moving without leaving a full doorway standing open.

That function made revolving doors especially useful in skyscrapers. The National Inventors Hall of Fame describes how they moderated the influx of cold air and helped with pressure differences that made conventional doors difficult to operate. Architects found another attraction in the experience: stepping from a confined compartment into an expansive lobby could make the interior feel more imposing. A piece of environmental machinery also became part of the entrance's theater. National Inventors Hall of Fame

To understand the pressure problem, picture a heated building on a cold day. Its warmer indoor air is less dense than the outdoor air. Differences between the two air columns produce what engineers call stack effect, the same principle that drives a chimney draft. Air tends to enter through lower openings and leave through higher ones.

The front entrance is one possible inlet. Cracks and other openings in the exterior also admit air; replacement air does not have to come exclusively through the doors. Inside, stairwells, elevator shafts, and service shafts provide paths between floors. Greater building height and a larger temperature difference generally increase the total stack pressure difference, although internal partitions and leakage patterns affect where that pressure acts. Wind and ventilation systems contribute their own pressures. National Research Council Canada, “Stack Effect in Buildings”

This explains why an entrance can feel windy even when the problem extends far beyond the sidewalk. A revolving door restricts one major airflow path, but it does not eliminate the building's underlying stack effect. It is a local solution within a much larger enclosure.

Nor is it a perfect seal. Air leaks around the edges, and rotating compartments carry some air between outside and inside. A 2006 MIT student study explicitly accounted for both leakage through seals and air displaced by rotation. The useful distinction is between limited exchange and the freer flow through an open swinging doorway. MIT revolving-door study

That study also helps explain why an efficient entrance can remain underused. At MIT's Building E25 in Cambridge, Massachusetts, the researchers recorded about 23 percent of passages through the revolving doors. Roughly three quarters went through the swing doors instead. This was an observation at a particular building, not evidence that 75 percent of people everywhere dislike revolving doors.

The researchers' preliminary survey captured familiar complaints: swinging doors seemed faster and easier, while revolving doors could feel cramped or require an uncomfortable pace. Those responses reveal the design challenge. A mechanism can perform well on paper and still lose users at the moment they reach for a handle.

The energy consequences became a memorable part of MIT's subsequent campaign. In September 2007, the MIT Energy Initiative reported an estimate that one person choosing a revolving door in February saved energy equivalent to running a 60-watt lightbulb for 23 minutes. It also reported that universal revolving-door use at E25, which had two revolving doors, could save about $7,500 annually in natural gas. MIT Energy Initiative

Those numbers belong to that setting and period. The bulb comparison specifies a wattage and a winter month; it is an energy equivalent, not electricity generated by pushing the door. The dollar figure is a historical estimate for changing behavior at one building, not a current guaranteed return from installing any two doors.

MIT's campaign nevertheless showed that behavior could change. The Energy Initiative reported that larger signs encouraging conservation raised revolving-door use from 23 percent to 65 percent in campus tests. The machinery was already there. Making its purpose visible helped people use it.

There is also a clear reason to preserve another way in. Under the U.S. Access Board's guidance on ADA accessibility standards, revolving doors cannot form part of an accessible route. Even automated models designed with more room do not satisfy that requirement. An accessible entrance with a revolving door must also provide a compliant manual or automated door. U.S. Access Board entrance guidance

That adjacent door serves people for whom the rotating compartment is unsuitable. Its presence belongs in the design, alongside the energy savings and pressure control. A successful entrance has to accommodate bodies and movement as carefully as air.

The next time the glass wings carry you into a lobby, notice the transition: a few steps through a confined space, then the room opens around you. Throughout that movement, the entrance has maintained a barrier against the street. It is an unusually tangible encounter with building engineering, performed at walking speed.