Chicago's skyline is going green, as property managers install energy efficient tools such as motion-detectors on office lights, in a project officials hope will inspire changes across the United States.

At the riverside Sheraton hotel, chief engineer Ryan Egan cannot get over what his new thermostats can do -- or the $136,000 a year in savings they are producing.

First off, they're tied into the booking management system, which means he can let the room temperature drift beyond standard comfort levels until the moment a guest checks in.

An infrared sensor means the savings don't stop there. Once the guest leaves the room, the temperature starts to drift again, giving the heating or cooling system a break until it's needed again.

The Sheraton is one of 14 major commercial buildings that signed onto the Retrofit Chicago challenge to cut energy use by 20 percent over the next five years, for savings estimated at more than $5 million a year.

If they succeed, it will be like taking 8,000 cars off the road. In addition to the greening in commercial buildings, the city plans to cut energy use by 20 percent in hundreds of municipal buildings, for an estimated monetary saving of $20 million a year and emissions savings equivalent to taking about 30,000 vehicles off the road.AFP