The State Energy Office will provide technical assistance to the Department of Transportation for a recently announced energy efficiency program at state airports that is expected to save $518 million in energy costs over 20 years, the state announced Wednesday.

Improvements to be made at the state’s 12 airports include the replacement of transformers, light fixtures and chilled water and air conditioning systems, according to a news release from the state Department of Business, Economic Development and Tourism. The upgrades include the addition of solar photovoltaic panels, installation of smart controls, and deferred maintenance.

The state is paying for the program using a financing mechanism approved by the Legislature known as energy savings performance contracting.

In a energy savings performance contract a private energy service company identifies and evaluates energy-saving opportunities and then recommends a package of improvements to be paid for through savings. The company guarantees that savings meet or exceed annual payments to cover all project costs. If savings don’t materialize contractor pays the difference.