Operational Carbon in Whole Life Carbon Assessments

United Kingdom ·

Reducing operational energy and embodied carbon are key to the reduction of the environmental impact of the built environment. As industry becomes more familiar with embodied and whole life carbon assessments, operational energy is more regularly converted to operational carbon within a whole life carbon approach.
This analysis is increasingly used for scrutinising and evaluating design options, as well as quantifying the total impact of buildings.


This LETI Opinion Piece proposes a methodology for the conversion of operational energy into operational carbon, for the purpose of making design decisions. This methodology has been developed by a LETI workstream and aims to provide a basis for further analysis and discussion, through which this conclusion can be further refined.

Operational and embodied carbon emissions are interrelated, as well as varying in both numerical value and certainty over time. Central to these complexities are uncertainties around the decarbonisation of the UK electricity grid, alongside the interdependence of the amount of energy used by buildings and the ability of the UK grid to decarbonise.

The methodology proposed in this LETI Opinion Piece to convert operational energy operational carbon is a ‘split carbon factor’ method. In this method, a decarbonised carbon factor is applied to the electricity consumption that is below a LETI Energy Use Intensity (EUI) target, and a non decarbonised carbon factor is applied to electricity above a LETI EUI target.

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