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Air Pollution

Volume 458: debated on Monday 26 March 2007

To ask the hon. Member for North Devon, representing the House of Commons Commission what the annual absolute carbon emissions of the parliamentary estate were in each of the last five years. (120553)

The annual absolute carbon emissions of the House of Commons estate in each of the last three years from gas and electricity are in the following table.

Absolute carbon emissions in tonnes
















Gas consumption reduced in 2004-05 and then increased in 2005-06; due to fluctuations in heating energy consumption caused by variations in outside temperatures measured in degree days. The following table shows the degree days for the Thames Valley region which includes London. From these figures a higher emission would have been expected in 2005-06. That it was not so is due to the installation of more efficient Palace boilers in 2004.

Degree Days








The steady increase in carbon emissions from electricity was due to an increase in electricity consumption in the Palace and 7 Millbank. This was due mainly to the installation and usage of more air conditioning units.

The figures have been calculated from gas and electricity invoices and not meter readings taken by estate staff, but estimated invoices were amended using actual meter readings where possible. Natural gas invoices list several multiplying factors used to calculate each month's consumption and the existing monitoring and targeting system used on the parliamentary estate, based on staff meter readings, is not as sophisticated and therefore not as accurate.

The figures for the years 2001-02 and 2002-03 have not been calculated since the energy invoices for those two years are not readily available.

To ask the hon. Member for North Devon, representing the House of Commons Commission what estimate the House authorities have made of the volume of (a) carbon dioxide, (b) methane, (c) perfluorocarbons, (d) nitrous oxide and (e) carbon equivalent released by the incineration of waste from the House of Commons estate when calculating the estate's carbon footprint.

Nick Harvey [pursuant to the reply, 21 March 2007, Official Report, c. 907W]: I regret that my previous answer was not published in full. The complete answer is set out as follows:

Only residual waste after recycling has taken place is sent for incineration with energy recovery. In 2006 residual waste collected from the parliamentary estate amounted to 1,299 tonnes. This material was combusted at an energy recovery facility regulated by the Environment Agency, generating 725,000 kilowatt hours of electricity. The recovered energy is classed as renewable energy by the UK Government, in line with directive 2001/77/EC on the promotion of electricity produced from renewable energy sources in the internal electricity market.

Recovering energy from waste is acknowledged in the Stern Review as an effective weapon in combating climate change, displacing carbon dioxide emissions from fossil fuel power generation sources.

The carbon footprint associated with the combustion of this waste is made up of a number of components:

(1) Direct emissions of greenhouse gases (GHG), expressed as carbon equivalents

(2) "Avoided" emissions of GHG (that is, emissions displaced from an equivalent amount of fossil fuel power generating capacity)

(3) GHG emissions (additional or saved) from waste transportation

(4) Net GHG emissions, taking account of direct, avoided and transport-related emissions.

Direct emissions of GHG

GHG emissions from waste combustion are calculated in two steps. First, an estimate is made of the percentage of fossil and non-fossil carbon in the waste. Second, the emissions from the combustion of the fossil carbon within the waste are calculated. Emissions of non-fossil carbon do not contribute to global warming and are therefore not taken into account.

Methane is not produced in combustion plants. The remaining greenhouse gases are released in trace quantities relative to emissions of carbon dioxide. Because their concentrations in the emission gases vary according to the composition of the waste, the total GHG effect expressed in tonnes of carbon dioxide equivalents (Teq) is estimated using emission factors developed by Defra, based on measured emissions averaged across UK energy recovery facilities.

Direct GHG emissions following the combustion of residual waste from parliamentary estates amounts to 415 Teq, of which 295 Teq is carbon dioxide.

“Avoided” emissions of GHG

Combustion of parliamentary estates waste in an energy recovery facility also results in avoided carbon dioxide emissions. The electricity produced by the facility displaces electricity that would otherwise be provided by an electricity utility power plant. Because most utility power plants burn fossil fuels and thus emit carbon dioxide, the electricity produced by waste combustion reduces utility carbon dioxide emissions. These avoided GHG emissions must be subtracted from the GHG emissions associated with combustion of the waste.

The convention is to assume that the electricity displaced arises from so-called “marginal” power generators, which in the UK is assumed to be gas-fired power stations. As with direct GHG emissions, emission factors are used to estimate the tonnes of carbon dioxide equivalents avoided when waste is combusted.

GHG emissions avoided following the combustion of residual waste from parliamentary estates amounts to 435 Teq, of which 405 Teq is carbon dioxide.

GHG emissions from waste transportation

A saving in GHG emissions is realized when residual waste from the parliamentary estates is combusted, since the energy recovery facility is just 12 miles from the House. Previously the waste was being transported to landfill further away from the estate.

The GHG emission factor developed by Defra for waste transportation varies between 0.37 and 0.49 kg carbon dioxide equivalents per tonne of waste transported, depending on distance travelled. For transportation of 1,299 tonnes of parliamentary estates waste, this amounts to a GHG emission of between 0.48-0.65 Teq. Since this is less than 1 per cent. of the emissions of direct or avoided emissions, the GHG saving in transporting the waste a shorter distance will be omitted when presenting net emissions.

Net GHG emissions

The carbon footprint associated with the combustion of waste from the parliamentary estates is obtained by subtracting avoided emissions from direct emissions.

This equates to a net GHG saving of 20 Teq. Therefore 20 Teq should be subtracted when determining the total carbon footprint of parliamentary estates. (120729)