Chicago Mayor Rahm Emanuel recently announced and honored the winners of the city's second Green Office Challenge, which aims to reduce energy consumption and greenhouse gas emissions from commercial buildings.

The mayor announced the winners in collaboration with ICLEI-Local Governments for Sustainability USA. The challenge gives Chicago businesses and property managers an opportunity to receive recognition for their achievements in green energy.

“Chicago’s efforts in sustainability have created economic opportunity throughout our neighborhoods and dramatically improved the overall quality of life for residents,” said Emanuel. “The Green Office Challenge is a great example of the private sector working with government to reduce costs and create jobs while protecting the environment.”

Close to 150 property managers and tenant companies in the downtown Chicago business district participated in the challenge, working to to accomplish green energy goals throughout 2011. In total, the program achieved a reduction of 124 million kilowatt hours of electricity during the past year.

Tier 1 winners of the challenge included the Active Transportation Alliance, PepsiCo Chicago and dbHMS Engineering.

According to energy experts who recently gathered at Northwestern University, Chicago is an ideal location for wind turbines and solar energy plants.