The revolving door was first patented in the U.S. on 7 August 1888 by Theophilus Van Kannel of Philadelphia.  One of the purposes as listed in the original patent application was to, “…effectively prevent the entrance of wind, snow, rain, or dust.” Over time the energy efficiency of revolving doors has been studied and proven that they are an effective means of preventing drafts and increasing the heating and cooling efficiency of buildings.  In fact, in high rise buildings revolving doors are almost a necessity as a draft block is required to prevent the chimney effect from occurring whereby air is sucked in at high speed at the base and ejected through vents in the roof while trying to heat the building or reversing this effect while the building is being cooled.

Typical Revolving Door Locked Against Use

Why then do building occupants like to keep these doors locked?  So often I find buildings that have revolving doors that are kept locked and people are directed to use the hinged doors that often flank the revolving door instead.  These flanking hinged doors became a standard safety issue following the 1942 Cocoanut Grove fire in Boston where 492 people were killed.  While these flanking hinged doors provide greater safety and increased traffic flow out of the building in case of emergency, they certainly are not as energy efficient as the revolving door.  When temperatures plunge outside during winter months the propensity of building occupants to lock their revolving doors seems to even increase, which makes no sense as the flanking doors let far more cold air into and warm air out of the building than do the revolving ones.

Typical Revolving Door is Locked Sign

Architects and designers can build all kinds of energy efficiencies and features into their plans but if the building occupants chose not to use them there is nothing that they can do about it once the building is built.  I just have to wonder if the occupants don’t understand the features of they have or they just like being blasted by cold air anytime someone enters or leaves a building by the flanking doors on brutally cold winter days.