Energy Cost Metric

Achieving emission targets by 2050

If national and international CO2 emission targets are to be met, it is clear that the energy demands of buildings need to be reduced due to their large contribution to global emissions. However, because of capital cost considerations, low-energy buildings will remain the exception rather than the rule for new building. Further, evidence from practice shows that despite best intentions of government schemes and building assessment tools to drive a reduction in energy, award-winning projects do not necessarily perform better in terms of overall life cycle energy consumption.

About the metric

The Energy Committee for the ‘Move West’ project in Cambridge University Engineering Department, led by the late Regius Professor David MacKay, devised the Energy Cost Metric (ECM) which seeks to bridge the gap between cost and energy considerations in a transparent and effective manner. The ECM relates the total lifetime energy of the building to its capital cost, factored by the current or anticipated cost of energy. It is agnostic to the scale and detail of considered design options.

The ECM was put into immediate application for the first building in the West Cambridge Development: to guide design decisions from initial stage to construction. Max Fordham, Grimshaw Architects, Smith and Wallwork Engineers, AECOM, and SDC have been applying the metric to provide quantitative measures for making key design decisions that will affect the overall cost and energy consumption of the project. To prevent the design process driving unwanted outcomes that may be lower in overall energy at the expense of occupant comfort, explicit design imperatives are set.

Next steps

ECM provides a novel and meaningful approach for designers to achieve very-low energy designs at early stages of the design project. Still in its infancy, we invite academic and industry partners to join our efforts in developing the metric further and creating a canon of use cases to establish its impact on sustainability.