In the first-ever corporate sustainability benchmarking report from Technology Business Research, Dell scored highest, with BT and IBM coming in a distant second and third, respectively.

With its overall score of 317.9, Dell was the highest-scoring company in the computing sector, as well as the highest overall company in the ranking. British Telecom scored a 265.2 and IBM scored 258.5.

The ranking looks at a number of sustainability metrics, including overall emissions, energy efficiency and use of renewable energy, targets and achievements in emission reductions, water efficiency, recycling and other green practices.

Dell scored notably well in the rankings for renewable energy use, recycling and comprehensive corporate sustainability goals. Dell has long stated its desire to be the world's greenest IT company, and has made public goals around practices ranging from e-waste exports to energy efficient products to company-wide climate governance.

“We’ve made some great progress with regards to integrating environmental sustainability into our operations and our products, but we can – and will – do better," said Mark Newton, Dell's senior manager of environmental sustainability. "And while it’s great to be ranked No. 1, what really matters is that the entire industry is getting focused on how we can help preserve our planet.”

The top 10 companies in TBR's rankings is as follows:
1. Dell, 317.9 points
2. BT, 265.2 points
3. IBM, 358.5 points
4. HP, 255.1 points
5. Intel, 250.5 points
6. Nokia, 248.0 points
7. Sun Microsystems: 227.5 points
8. Motorola, 226.4 points
9. Qualcomm, 208.7 points
10. Cisco Systems, 203.0 points