Public Buildings Reform and Savings Act of 2015

Directs the General Services Administration (GSA) to establish and conduct a pilot program through 2020 to execute lease agreements using alternative procedures to reduce costs of leased space and significantly reduce or eliminate the backlog of expiring leases over the next five years. Authorizes the GSA to submit consolidated prospectuses for leases and projects to Congress for approval and to include in leases certain costs associated with agency relocation and buildout, including moving and equipment costs.

Provides for approval by congressional resolution of any costs and expenses associated with administering an acquisition by exchange involving real property or in-kind consideration, including services with a fair market value of $2.85 million or more.

Authorizes: (1) the Department of Homeland Security (DHS) to authorize contract security personnel to carry firearms, and (2) such personnel to detain individuals without a warrant. Directs DHS to establish minimum and uniform training standards for security personnel.

Directs DHS to report on: (1) the personnel needs of the Federal Protective Service (FPS), including recommendations on the numbers of FPS law enforcement officers needed to carry out the mission of FPS during the 10-year period after the enactment of this Act, and (2) the best method of funding for the FPS.

Requires the GSA to: (1) justify any need for new or replacement building space, including an explanation of why such space could not be consolidated or colocated into other owned or leased space; and (2) notify the House Committee on Transportation and Infrastructure and the Senate Committee on Environment and Public Works if the cost, scope, or size of any project changes by 5% or more.

Terminates the authority for any lease or project unless it is initiated not later than five years after congressional authorization.

Directs the GSA to sell portions of the Forrestal Complex in Washington, D.C. to generate funds necessary to construct a new Department of Energy headquarters on government-owned land in a manner consistent with the SW Ecodistrict Plan of the National Capital Planning Commission.

Directs the GSA, to the extent practicable and when cost effective, to consider the direct purchase of energy and other utilities in bulk or otherwise for leased facilities.

Exempts an individual acquisition for commercial leasing services from enhanced competition requirements for the purchase of property and services by executive agencies if such individual acquisition is made on a no cost basis and pursuant to a multiple award contract in accordance with requirements for full and open competition. Directs the Government Accountability Office to conduct biennial audits of the GSA National Broker Contract, conduct a review of the application of enhanced competition requirements, and report on such audits and reviews.