The Standard has been awarded to LU based on actions and achievements over the last three years (from 2006 to 2009) as well LU's plans to reduce carbon emissions in the future.
Great strides have already been made.
LU's Energy Station Challenge, a staff-led scheme, came in for particular praise.
It is estimated that this initiative will have reduced CO2 emissions by 5,500 tonnes in the last three years, saving approximately £700,000.
The use of regenerative braking on new trains on the Victoria and sub-surface lines (Circle, District, Hammersmith & City and Metropolitan ) will save an estimated 17,000 tonnes of CO2 every year with a financial saving of approximately £2m.
Additionally, energy efficient lighting including Light Emitting Diode (LED) technology has been installed at several stations across the Underground network and the new Northern line service control centre boasts London's largest single membrane green roof, the first on a railway building.
John Ball, Director of Strategy and Service Development, LU, said: 'The Tube is one of the largest consumers of electricity in the country but it is also one of the most carbon efficient forms of transport.
'Achieving the Carbon Trust Standard is a testament to the work that LU staff have put in to reducing the Tube's carbon intensity.
'This is a great foundation on which to pursue further reductions in our carbon footprint while we work to upgrade the Tube and support the Mayor of London's targets to become more energy efficient, save money and reduce the capital's emissions by 60 per cent by 2025.'
LU achieved the Standard due to its improvements in carbon efficiency over the last three years with an improvement in the amount of CO2 released per passenger kilometre from 81g in 2006/7 reduced to 75g in 2008/9.
Notes to editors:
The Carbon Trust Standard