Steve & Deona Thomas of 5T management in one of their buildings at 6859 S Ada, showing the new heating system and the insulated pipes.Tuesday, April 3, 2012. | Brian Jackson~Sun-Times

Steve & Deona Thomas of 5T management in one of their buildings at 6859 S Ada, showing the new heating system and the insulated pipes.Tuesday, April 3, 2012. | Brian Jackson~Sun-Times

Jayne Choi, energy analyst for CNT Energy, tests the combustion efficiency of a steam boiler in a century-old building on the Northwest Side. (Photo by Carl Hertz/CNT)

Mark Dunn, construction manager for the Energy Savers program, tests that water heaters are properly operating in a building in South Chicago. | CNT Energy photo

Jayne Choi, energy analyst for CNT Energy, tests the combustion efficiency of a steam boiler in a century-old building on the Northwest Side. (Photo by Carl Hertz/CNT)

Henock Kidanu, energy analyst for Energy Savers, checks that the domestic hot water heaters in a building in Logan Square are safely venting exhaust gases. | CNT Energy photo