Revolving Green

By Dan Estabrook - September 12, 2008 Here's something I would never have thought about: on average, 8x as much air is exchanged when a swing door is opened as opposed to a revolving door.  Who cares?  That's 8x as much new air that needs to be heated or cooled - and much more energy and money expended.

One of my colleagues here at Tonic, Ben, shared a report with me from MIT that analyzed energy costs on its campus.  In fact, the savings are so great, MIT has posted signs all around its campus that say "Help MIT save energy.  Please use the revolving door."  MIT's estimates show that if everyone used the revolving doors at one of its many campus buildings, the university would save $7,500 in natural gas amounting to nearly 15 tons of carbon emissions.  And that's just from 2 of the 29 revolving doors on the campus.

How much energy does a revolving door really save?  Check it out...

Revolving-door usage 50% 75% 100% Saving of annual energy consumption 14.5% 38.7% 74.0% # of houses the saved energy can heat in one year 1.0 2.7 5.1 # of years the saved energy can light a 100W bulb 5.8 15.3 29.0 Tons of CO2 prevented 3.0 7.7 14.6

The study even compares the waste of a swing door with other activities.  Opening a swing door is the equivalent of:

1.3 hours of light from a desk lamp 4.3 hours of light from a compact fluorescent bulb Driving a car 306 feet Half a mile jog

Who knew?  I guess it's time to put a revolving door in my loft.  I'm not sure if that came out the right way?!