How do you calculate the CO2e emissions from a unit of energy used?
Energy retailers and the government produce conversion factors that describe the typical carbon impact of different energy sources. These allow us to take the energy uses (in their respective units), and calculate the approximate carbon dioxide emissions, normally measured in kilograms of carbon dioxide equivalents (kgCO2e). Defra's UK conversion factors may be found at Defra's 2018 Guidelines.
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Why are you using these units and what do they mean?
We provide three different measures of the energy used: the amount of energy, its monetary cost, and the carbon impact of the energy used.
Energy use is measured in kilowatt hours (kWh), which are the standard units of a home energy bill (1kWh is the amount of electricity used by ten 100W light bulbs in one hour).
For electricity this number represents the amount of energy that flows into a building through the meter, and excludes distribution losses. For gas it is the amount of energy that is theoretically available by burning all the gas in an imaginary ideal burner. For district heating it reflects a flow of temperature into the building over time (after the heat produced by burning the fuel has been transported to the meter, which involves other losses). So each of these numbers, while all being measured in kWh, mean very different things. This is one reason that we prefer to use 'units per hour' when combining them. In some ways it would be more correct not to combine them at all, because combining them implies that the measures are comparable. This is a global challenge though, and conventions have become established around combining kWh. So we'll have to fix that another day.
Monetary cost is calculated using the costs per 'unit' for each utility in every building. The figures used are noted below in the Notes section.
The carbon impact is measured in kg of CO2e (the e stands for equivalent) which takes other climate-affecting gasses into account in addition to carbon dioxide.
How much does this organisation pay for its energy?
Prices come from the latest energy bills for Department of Energy and Climate Change, which for Gas average out at 4.82p per unit and for district heating average out at 0.2433p per unit and for electricity average out at 0.52462p per unit. The gas volumetric measurement is converted to kWh using the meter correction factors and calorific values supplied by the utility company. These may be subject to change.
Can you show data from the transport emissions of this organisation/ building?
Data of CO2e emissions created by transport used by organisations is very interesting and powerful data to show here. We are working on ways to display and reduce the transport impacts of different organisations, and you will see some of the products of this work on these pages very soon.
What services do the electricity consumption figures relate to?
IT equipment, particularly PCs and laptops, cooling and lighting are the main users and running essential services such as ventilation, water supplies and lifts etc.