Office landlord Boston Properties Inc. agreed to buy specific-source renewable energy equal to the expected electricity needs of its portfolio of 33 buildings and garages, spanning 15 million square feet in Massachusetts.

Under the agreement with power marketer Calpine Energy Solutions LLC and Taylor Consulting & Contracting, Boston Properties will obtain 650,000 megawatt-hours of environmental attributes over three years. The move is intended to decrease the developer's carbon footprint by upward of 55,000 metric tons of carbon dioxide equivalent annually and reduce the carbon intensity of its Massachusetts operations by approximately 78% compared to a 2008 base year.

The landlord bought the environmental attributes associated with energy from Capricorn Ridge II Wind Farm in Sterling, Texas, for the projected power consumption at its properties in Boston, Cambridge, Waltham, Lexington, Weston and Needham.

Boston Properties plans to surpass its 2025 greenhouse gas emissions intensity reduction target in 2019.