When it comes to changing the ways energy is produced and used, MIT has long been at the forefront of research. Now, in addition, students, faculty and staff are working hard to put improvements in energy efficiency into practice on campus.

From the article on Sustainability @ MIT

Why should I use the revolving door?

You’ve probably seen the signs around campus saying "Help MIT save energy. Please use the revolving door." But does it really make any difference? Absolutely. Our estimates show that if everyone used the revolving doors at E25 alone, MIT would save almost $7500 in natural gas amounting to nearly 15 tons of CO2. And that’s just from two of the 29 revolving doors on campus!

On average 8x as much air is exchanged when a swing door is opened as opposed to a revolving door. That's 8x as much new air that needs to be heated or cooled and that's why using the revolving door is a great way to reduce energy requirements on campus.

How does using the revolving door save energy?

The air that is inside a building has been "conditioned" to make it comfortable for the occupants. We call the equipment that does this “air conditioners” in the summer, but the air heating equipment in use during the winter and ventilation "make-up air" consumed year round is also conditioned air. Energy is required to condition air -- to make hot, moist air cold and dry in the summer and to make cold, dry air warm in the winter. Thus, whenever air is exchanged between inside and outside, air conditioning equipment has to work harder, using more energy.

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