Why is the tool needed?
Embodied carbon can account for up to 50-70% of the emissions of a building over its life cycle and is growing in importance due to improvements in operational energy efficiency and decarbonisation of the grid.
What is embodied carbon?
Embodied carbon is the total greenhouse gas emissions (often simplified to ‘carbon’) generated to produce any material or product. In this case the focus is on the embodied carbon related to buildings or home. It does not include operational carbon – emissions that arise from the energy used to operate the house (e.g. for heating).
The focus for this tool is largely on ‘upfront carbon‘ (A1-A5, see adjacent diagram), the embodied carbon which relates to emissions from the material production, transport and construction phases before the building has been completed. These emissions have already been released into the atmosphere before the building is occupied and make up the majority of carbon impacts.
Who is the tool for?
The tool is intended for use by development professionals and their consultants, with particular focus on supporting housing associations and local authorities, to assess opportunities to reduce embodied carbon without the need for detailed modelling and calculation.
The Welsh Development Quality Requirements (2021) encourages social housing providers to “assess and reduce upfront and embodied carbon”, and local authorites in England are adopting embodied carbon policies such as B&NES (Policy SCR8) and Bristol City Council (Policy NZC3).
When should the tool be used?
The tool has been developed for use at the early stages of new housing development (planning, design brief).
“The earlier you consider embodied carbon, the greater your ability to reduce it.“
What the tool is
- A simple web-based tool for use at the very early stages of housing development. No downloads, logins or plugins required.
- Highlights carbon impacts, high carbon ‘hotspots’ and lower carbon alternatives.
- Little embodied carbon knowledge or experience of using life cycle analysis (LCA) tools required.
- Provides short guidance notes on embodied carbon and also flags up wider considerations such as circular economy and biodiversity impacts.
- Results displayed with a simple Low-Medium-High rating with an estimated upfront carbon figure (kg CO2e/m²) and percentage decrease against higher carbon options.
What the tool isn’t
- A complex tool requiring lots of numerical input from the user such as bills of quantities, dimensions and carbon data.
- A tool for use at detailed design stages of housing development.
- Aimed at LCA experts and housing designers with lots of expertise.
- A tool with a lengthy accompanying guidance document or manual as a separate PDF.
- A full building life cycle analysis tool.
This tool was conceived and delivered by Woodknowledge Wales, the Alliance for Sustainable Building Products and the Good Homes Alliance as part of the Welsh Government Funded Home-Grown Homes project.
Tool version 1.0 – Published May 2025
