The Circular Economy Outcome Metric

The Circular Economy Outcome Metric, or ‘CE Outcome Metric’ (£/m2) is intended for use in client briefs. It is LETI’s proposed method to quantify a property development’s circular economy outcomes, expressed as the value of the environmental burden a project places on the planet (also known as Environmental Externalities). The metric is calculated by multiplying the Material Intensity (kg/m2) by a material ‘Circularity Factor’ (£/kg), aggregated for each building element (material or component) on the project.

The Circularity Factor combines the impacts from each of the categories in a building element’s EPD using weights that convert each impact to a cost of restitution of that impact. The proposed set of weights are the impact-to-€ conversion values currently provided in the Dutch Environmental Performance of Buildings (MPG) framework. Existing CE metrics, most of which we define as ‘CE Process Metrics’, should continue to inform the design process that drives a project’s ultimate CE outcome.

Whole life and upfront impacts
There are two versions of the CE Outcome Metric. The ‘CE Outcome Metric (Whole Life)’ covers all RICS LCA stages (A1-D) and should be used for briefing and reporting only, as the estimated impact of later LCA stages is more subjective. The ‘CE Outcome Metric (Upfront)’ covering only Stages A1- A5 is to be used for targets, limits, and performance measurement, in addition to briefing and reporting.