FPS Improvement Act of 2015

Assigns responsibility to the Federal Protective Service (FPS) for the protection of federal buildings, grounds, and property and persons on the property. Authorizes FPS to: (1) designate Department of Homeland Security employees with enhanced law enforcement powers for duty in connection with the protection of federal property and persons on the property, (2) authorize protective service officers for the protection of federal buildings and grounds, and (3) assess security charges to owners or tenants of a federal facility protected by FPS that is not in compliance with federal security standards. Requires tenants at federal facilities to maintain a Facility Security Committee.

Establishes the Interagency Security Committee to develop safety and security standards and best practices to mitigate the effects of natural and manmade hazards in federal facilities.

Requires reports on: (1) FPS personnel needs, (2) the feasibility of federalizing the protective service officer workforce, (3) a method for funding FPS, and (4) methods to detect or prevent explosives from entering federal facilities.