Boston-based Berkeley Investments Inc. plans to construct 100 apartments at the Millbrook Cold Storage building in Somerville.

Berkeley Investments plans to renovate the recently acquired building at 9 Medford St. to create 100 loft-style rental apartments along with a fitness center and arts-related amenities. The existing seven-story building offers roughly 106,000 square feet of space that was used for cold storage since its construction in 1916.

"We are excited about the interplay between the exposed concrete and attractive contemporary finishes set against the backdrop of large windows offering expansive views," Joel Bargmann, principal at Bargmann Hendrie + Archetype Inc., the project architect, said in a statement.

The project will consist of a mix of studio, one-bedroom and two-bedroom units. Of the 100 units, 15 will be set aside as affordable and five of those will be artist live/work units. The project will be a green building with high-efficiency building systems and various other sustainability features. Berkeley Investments will be seeking a LEED Gold certification.

Construction is targeted to start in the spring and be completed by summer 2015.