This page provides guidance on the UK benefits prices for the reporting phase of an i-Tree Eco survey.
Full guidance on project set up, fieldwork and reporting is available in the i-Tree Eco v6 manual, available as free download from the resources section of the i-Tree website.
Details of UK training for i-Tree Eco are available from the Aboricultural Association.
This project is ongoing.
Reporting your i-Tree Eco survey should include the following stages:
- Ensure all data is entered into the i-Tree Eco programme. If this was done manually, having used paper field-survey sheets, perform a Quality Control exercise by re-opening 10% of the plots within the i-Tree Eco programme and checking that the information has been entered correctly.
- Follow the i-Tree Eco manual instructions to generate your urban forest structure results.
- Follow the i-Tree Eco manual instructions to generate your ecosystem service provision results. Ecosystem services are reported as both quantities of provision (for example, tonnes of carbon stored, tonnes of particulate air pollution removed, volume of stormwater intercepted) and as an economic value (in US $ or GB £). Default values for UK Benefit prices are built into i-Tree Eco V6, where possible. Where these are not reported or where you intend to use a more up to date or locally specific value, a Benefit price can be entered and the report re-run. Guidelines on Benefit prices are given below.
- Collate outputs as an interim report with headline figures for discussion with project partners.
- Produce a final report.
UK Benefit prices and data sources
Pollution removal value
- Calculated based on the UK social damage costs (UKSDC) published by the Department for Environment, Food and Rural Affairs (DEFRA) in Guidance on Assessing the Impact of Air Quality. These figures were last updated in July 2020 and are periodically revised.
- UK pollution values are source and location specific. For example the UKSDC of pollution in Central London is greater than that for a town in the north east of England. Select the appropriate damage costs for the location of your project.
- The default values for the UK within i-Tree Eco v6 are as follows:
- £957 per metric ton CO (carbon monoxide)
- £3613 per metric ton O3 (ozone)
- £539 per metric ton NOx (oxides of nitrogen)
- £196 per metric ton SO2 (sulphur dioxide)
- £125,472 per metric ton PM2.5 (particulate matter less than 10 microns and greater than 2.5 microns)
- The 2020 UKSDC values are as follows:
- Between £3,166 and £52,587 per metric ton NOx (oxides of nitrogen from road transport)
- £13,026 per metric ton SO₂ (sulphur dioxide)
- £89,456 (domestic sources); £71,445 (industrial sources) per metric ton PM2.5 (particulate matter less than 2.5 microns. Government guidance also includes values for other sources.)
- UKSDCs are not currently available for carbon monoxide (CO) or ozone (O₃). Therefore, US externality cost prices (USEC) for pollutants are reported in i-Tree Eco.
- The latest version of i-Tree Eco (v6) calculates removal of only PM2.5. Previous versions calculated removal of both PM2.5 and PM10.
Carbon storage and carbon sequestration values
Stormwater alleviation value
- Calculated based upon the amount of water held in the tree canopy and re-evaporated after the rainfall event (avoided runoff) and not entering the water treatment system.
- The default value in i-Tree Eco v6 2020 is £1.516 per m3.
- The cost of treating surface water runoff avoided is not reported directly by water treatment companies in the UK. Typically, FR led projects have inferred a value as the standard volumetric rate per cubic metre charge (i.e. the cost of removing, treating and disposing of used water including a charge for surface water and highway drainage) minus the standard volumetric rate–surface water rebated per cubic metre charge (i.e. the cost of removing, treating and disposing of used water).
- For example, using Welsh Water’s 2015/16 prices, this calculates as £1.6763 – £1.3238 = £0.35 per m3 (i.e. the cost of managing surface water, or the surface water rebate charge).
- However, this cost is a conservative estimate of the total ‘avoided charges’ across the full survey area as it does not account for infrastructural, operational and treatment charges linked to surface water management by local authorities, internal drainage boards and government. Therefore, the Bridgend County Borough Council and Tawe Catchment i-Tree Eco studies used the ‘Standard volumetric rate – Surface water rebated per cubic metre value’ of £1.3238 as a representative value of the avoided cost of treating surface water runoff across the whole survey area. These are charges common to water utility companies, published annually.
- Use values from the water utility company operating within your study area for reporting your i-Tree Eco project.
- Other projects, for example the London Victoria BID and Sidmouth, have used the Energy and CO2 emissions savings from reduced volume of stormwater entering combined sewers and water company information on site area charges for surface water drainage. These figures are not available from a single source nationally. They need to be calculated depending on the water utility company operating within the area of the project.
Building energy saving value
- Calculated based on average unit costs for electricity and gas in the UK published by BEIS in Annual domestic energy bills. These figures were last updated in June 2020 and updated annually.
- The default values in i-Tree Eco v6 are set at £152.0 per MWh for electricity and £14.24 per MBTu for gas.
- The UK values for 2020 are £166.17 per MWh for electricity and £11.11 per MBTu (£37.89 per MWh) for gas.
- This is termed ‘structural value’ in the US and within i-Tree Eco, however this term has a different meaning to economists in the UK and so ‘replacement cost’ is used.
- This is the cost of the trees based on the physical resource itself (e.g. the cost of having to replace a tree with a similar tree)
- The value is determined within i-Tree Eco according to the CTLA (Council of Tree and Landscape Appraisers) method and the value is reported in UK £.