September 2013: The London Datastore has recently posted detailed greenhouse gas emission data for London across a wide range of economic sectors. The spreadsheet for the 2011 update to the London Energy and Greenhouse Gas Inventory (LEGGI) provides estimates of energy consumption and CO2 emissions from Homes, Workplaces and Transport within the Greater London area and is produced by the GLA on an annual basis to measure progress against the Mayor’s Climate Change Mitigation and Energy Strategy.
The Department of Energy and Climate Change (DECC) also provide London emissions data (though not to the level of detail as that set out in the LEGGI) in a series of sub-regional statistics which can be downloaded here.