BT will rely on wind farms to produce a quarter of its UK power by 2016, as part of a major drive to cut CO2 emissions.
The telecoms giant will build the largest wind-power project outside of the energy sector as part of a push to slash its 1996 global CO2 emission levels by 80 percent by 2016.
Its Climate Stabilisation Intensity (CSI) target is one of the most aggressive yet set by a corporation.
BT has already cut emissions in the UK by 58 percent between 1996 and 2008 but does not, at present, monitor its global emissions.
Dr Chris Tuppen, BT's director of sustainable development, said in a statement: "The Climate Stabilisation Intensity target creates a relationship between BT's CO2 emissions and its financial performance, so that they become interdependent."
"It is a powerful tool for embedding sustainability into organisations worldwide, and critical in effecting change," said Tuppen.
BT's 2008 Sustainability report revealed that, during the last financial year, the company saved £365.3m as a result of its environmental-management programme.
A second renewable energy project will be undertaken at BT's office complex in Southern California, where it has begun building a solar-powered system.
By March 2009, the company will have upgraded 90 datacentres worldwide, about 25 of which are in the UK, cutting power consumption by 60 percent, using fresh-air cooling and AC-DC power conversion.
BT has already delivered energy savings of 8.4GWH across its UK datacentres over the past year.
During the next year, BT will also conduct a trial of electric vehicles in two of its lines of business and will also pilot the use of bio-diesel.
The company aims to cut the amount of UK waste sent to landfill by six percent. Over the past year, BT has increased the amount of waste it recycles by four percent.
BT will also ensure that a third of its product- or service-replacement contractors are able to demonstrate increased efficiency or reduced environmental impact.
The Sustainability report shows that BT has failed on some measures, such as an aborted trial to use hybrid vehicles, and the roadmap for the global rollout of its environmental-management systems, which has been delayed until September this year.