Detailed emissions breakdown

Emission source       tonnes of CO2
  2010 2009 2008 2007 2006
Scope 1 – Stationary combustion          
Gas combustion 7,193 4,889 4,537 6,178 N/A
Heating oil combustion 2,182 1,393 1,400 1,547 N/A
Total scope 1 emissions 9,375 6,282 5,938 7,725 2,479
Scope 2 – purchased electricity          
Total purchased electricity (gross) 156,749 160,414 135,658 121,648 141,875
Less purchases of:          
Renewable electricity1 (25,011) (23,542) (20,024) (5,038)
Scope 2 emissions (net) 131,738 136,872 115,634 116,611 141,875
Combined scope 1 and 2 emissions (net) 141,113 143,154 121,572 124,335 144,354
Scope 3 – other indirect emissions          
Air travel 85,848 76,073 89,500 92,269 81,733
Other indirect emissions2 34,044 32,884 31,661 32,491 33,913
Total scope 3 emissions 119,892 108,957 121,161 124,760 115,646
Total CO2 emissions (net) 261,004 252,111 242,733 249,095 260,000

Carbon intensity

Emission scope   tonnes of CO2 per person
  2010 2009 2008 2007 2006
Scope 1 0.09 0.06 0.06 0.09 0.03
Scope 2 (net) 1.27 1.39 1.21 1.29 1.79
Scope 3 1.15 1.10 1.27 1.38 1.46
Total (net) 2.51 2.55 2.54 2.76 3.28
Percentage change from base year (net) -23% -22% -22% -16%

Office energy use

    megawatt hours
  2010 2009 2008 2007 2006
Total office energy use 350,724 340,647 284,930 272,545 297,406
1
When calculating our carbon footprint we rate renewable electricity as zero emissions.
2
We add an additional 15% to our carbon footprint to account for unmeasured impacts, such as couriers and taxis.