Contractors will shortly begin replacing lights at the police station with more energy-efficient lighting. The project follows the recent completion of similar work at the Kennedy Middle School, according to Mayor Scott D. Galvin. The contractor for both projects is AECOM, a company that conducted energy audits of all the city’s buildings several years ago. The two projects were among those the company recommended the city undertake to save on energy costs. With AECOM’s help, the city successfully applied to NStar for cash rebates for both projects, under a program in which the utility helps cities and towns pay for energy-efficiency projects. NStar is funding $48,800 of the $69,800 cost of the police station project, and $10,800 of the $14,000 cost of the Kennedy School project. “It’s a great opportunity for us to save on our energy costs,” Galvin said. He said AECOM projects those savings will cover the city’s investment in the Kennedy School project in two years, and the police station project in just under two years.