Appendix A - Carbon Footprint Methodology
Measurement is a vital part of managing greenhouse gas emissions, enabling us to understand how much is released and from which activities The Scottish Government completed 7 years of its operational Carbon Footprint (2007/08, 2008/09, 2009/10, 2010/11, 2011/12, 2012/13 and 2014/15). The carbon footprint is produced in-house with the contribution of data from a variety of sources. The footprint covers the following greenhouse gases:
- Carbon dioxide (CO 2) - the dominant greenhouse gas, emitted directly from burning of fuel for heating and transport and indirectly from electricity use in our assets and buildings and business travel;
- Methane (CH 4) - produced in small quantities from direct burning of fuels and generation of electricity and also from the disposal of wastes to landfill and treatment of waste water;
- Nitrous Oxide (N 2O) - produced in small quantities from direct burning of fuels and generation of electricity and also from the disposal of wastes to landfill and treatment of waste water.
Greenhouse gases are converted to a common 'currency' of carbon dioxide equivalents. Both methane and nitrous oxide have a higher global warming impact per molecule than CO 2 (for example 1 tonne of methane is equivalent to 21 tonnes of CO 2) and therefore converting these gases into CO 2 equivalents allows for simple comparison between emission sources.
As with all carbon footprints there are uncertainties within the overall footprint. The main sources of certainty and uncertainty include:
Measurement accuracy of consumption/production:
- High - Utilities that are metered half-hourly, including electricity, gas and many water supplies. Accuracy can be assessed by requesting information about the meter class from the supplier.
- Medium - Fuel consumption of vehicles is measured directly, through invoices via fuel cards for vehicles. This requires suitable operating procedures to make sure all fuel is paid for and recorded using those methods. Waste is segregated off-site and tonnage information for individual uplifts across several different waste streams and disposal routes is now provided by the waste management facilities. Accuracy can be assessed by conducting waste journey audits to reveal the measurements behind waste composition. Energy consumption that is not measured through half-hourly metering is based on less regular meter inspection. Accuracy can be assessed by checking consumption trends against previous periods.
- Low - Unmetered data is usually less accurate and third party emissions depend on the ability of internal systems to accurately record when an activity is occurring. Business travel relies on travel agents reporting mileages, or internal estimates based on cost, and accuracy can be assessed by auditing journey information and the internal calculation procedures. Sites with unmetered water consumption may be either estimated or omitted owing to their small contribution. Waste streams that are outside the main waste management contract often require broad assumptions of the weight of individual items, although the counting of those items is likely to be highly accurate.
- Data conversions - Some data will be ready to use, e.g. kWh of electricity from half-hourly meters, and therefore no uncertainty will occur at this stage. For other data such as waste where the number of items requires conversion to a tonnage, or cost to an equivalent mileage, uncertainty can occur.
- Emissions factors - These are usually beyond the control of an organisation because emission factors are calculated for the UK as a whole by DECC/Defra. For direct emissions, such as burning natural gas, these factors are highly accurate. For indirect emissions, e.g. waste, water, grid electricity, and vehicles, there is likely to be some uncertainty in the emission factor because processes and activities are measured across the UK and averaged.
It not possible to eliminate uncertainty completely within the reported carbon footprint and it is good practice to report a quantitative or qualitative assessment of the uncertainty with the footprint.
It is also good practice therefore to undertake a regular programme of data improvement to reduce uncertainty and improve both quality and accuracy. This programme should be pre-determined and evaluated post-implementation.
Energy ICT - Under the SG Facilities Management contract, the SG's maintenance contractor operates an Energy Bureau utilising the Energy ICT (Remote Monitoring & Targeting) system to provide energy management and bill validation services. This ensures that energy performance is closely managed and utility accounts are checked against meter readings, prior to accounts being settled with utility supply companies. SG sites and utilities meters are loaded onto Energy ICT and data is populated directly from the supply companies. The SG's maintenance contractor provides performance reports and comparisons of this utility data on a monthly basis which is presented to FS managers.
Billing - The bill validation process for gas, electricity and water supplies are undertaken by the SG's maintenance contractor's energy bureau team. Oil bill validation is undertaken by the energy manager assigned to the SG contract. The bills are received at the energy bureau from the various suppliers as either e-bills, access to bills on suppliers web sites or scanned copies of bills via the SG accounts team. The invoice and consumption data is recorded on Energy ICT which also holds the tariffs for each supply and automatic updates of half hourly data (HHD) from smart meters. The bill validation process recreates the bill within Energy ICT, applying the bill consumptions to the known tariffs to create a dummy bill; this bill is then compared to the actual charges to ensure the monetary values match.
The HHD is then used to ensure the consumption level indicated on the bill matches that seen through the HHD. If both these checks correspond, then the invoice is approved for payment and the energy bureau issues a report to SG accounts indicating the invoice is approved for payment. If bill discrepancies are found, figures are challenged with the supplier. Consequently, the Energy Manager and Bureau Team are informed of any metering or tariff changes. For sites where there is no HHD, the invoice is checked against the applicable tariff and then a comparison against previous consumption is made to ensure there are no consumption exceptions.
Vehicle Fleet - Scottish Government vehicles are managed by the Motor Services team and are purchased in accordance with the sustainable procurement policy. Vehicle mileage and fuel purchased for each journey are manually logged by staff. Invoices are supplied to the SG by fuel companies through the associated fuel card for each vehicle.
Each vehicle log sheet is collated by Motor Services and details are recorded in a fleet management database. The vehicle information is used to assess the need for vehicle replenishment and to monitor fleet performance. Headline information on the fleet is currently forwarded to members of the Carbon Management Team for reporting purposes.
Data Management Systems
The Scottish Government collects a wide range of consumption information which is used for annual carbon reporting purposes.
- The monitoring and targeting system, Energy ICT, captures around 80% of utility data (electricity, gas and water) which is also made available to the public automatically through the GOLSPIE portal.
- A bespoke internal database is in operation and currently
includes management information on:
- our buildings (location and occupancy);
- our organisation (as a financial hierarchy);
- utilities (electricity, gas, oil and water);
- waste (arisings and disposal routes); and
- business travel (contracted and non-contracted).
There is a problem
Thanks for your feedback