The General Services Administration, the federal government’s landlord, began soliciting bids this week for energy retrofits for 30 buildings across the country.

The “Deep Retrofit Challenge”is a step in the government’s push to save money on its real estate costs by making federal property more energy efficient— an expensive up-front investment the Obama demonstration hopes will save money in the long run.

Last December, President Obama directed federal agencies to enter into $2 billion in energy retrofit contracts over the next two years. They are performance based, which allows the government to measure results better and assess the contractor’s performance over the course of the project.

GSA has designated 30 properties across the country, a total of 117 million square feet, for retrofits. In the Washington area, they include the Silver Spring Metro Center on East-West Highway, Columbia Plaza on E. St Northwest and the New Carrollton Federal Building on Ellin Rd. in New Carrollton. The changes could range from better insulation to new windows and air-conditioning systems.

The Department of Energy, which is under contract with a group of energy service companies, is consulting with those firms on designs. . The companies will do energy audits of the buildings to identify where improvements are needed. The contractors must guarantee that the work will lower utility bills and generate enough other cost savings to pay for the project over the term of the contract, which may go as long as 25 years.