Measure Progress Not Just Carbon

I have been thinking for a little while about the suitability or otherwise of the metrics we use to measure sustainability. Given peoples’ reactions at a few meetings recently, including the Edge Debate on the Politics of Carbon Measurement and a conversation with the UK Consul for Climate Change in Chongqing, I think that the time has come to look seriously at this issue.

Presently we attempt to measure the impacts of what we build, but we rarely measure the beneficial outcomes. Therefore we risk focussing attention on all that is bad and forgetting the good. Taken to extremes we could end up going backwards socially and economically in order to address the political imperative to deliver zero (or at least very low) carbon buildings. For example, many sub-saharan africans live in housing that would easily satisfy the Zero Carbon Hub’s definition. However if we were to adopt housing of this standard in the UK it would not be considered social progress. This rather exaggerated example highlights the need to find some form of metric that acknowledges the benefits of expending some carbon in certain circumstances in order to deliver social and economic progress.


I was involved a few years ago in a new headquarters building for CAFOD in Lambeth. The building followed closely on the heels of two other charity headquarters, Heelis, the National Trust HQ and the Woodland Trust HQ, and it received comparatively little attention. Perhaps this was because the CAFOD building was mechanically ventilated and cooled, whereas the others were natural ventilation exemplars. CAFOD had to be mechanically cooled as the tight urban site available required a very high occupancy density to accommodate the entire organisation, whereas the other buildings were on suburban or extra-urban sites with plenty of space for low occupancy density and natural ventilation. On the face of it this means that the CAFOD building was both more expensive and had higher carbon emissions. However these standard metrics of cost and carbon per square metre of space do not account for how the buildings can subsequently be used. I decided to look again at the buildings in terms of the occupancy. Occupancy rates are after all what office tenants will be most interested in. The results completely reversed the ranking of the three buildings as shown below.

CAFOD Comparison Graphs

Whilst the metric of carbon per desk or carbon per worker is certainly much more useful than carbon per square metre in linking impact to business targets, an even better metric would link carbon to a measure of business success, such as productive hours or added value. Thus at a stroke we would be able to distinguish between well designed environmental buildings that reduce carbon and promote productivity and those that pay scant attention to the design and bolt on EcoBling to achieve the carbon reduction.

Take hospitals as another example. Lots of good work has been done in the past on identifying the quality design factors that influence patient outcomes, by providing a better working environment or recovery environment. The NHS metric for energy efficiency is presently kWh/m3 per year. Using such measures as targets can create perverse incentives. A hospital could economise on carbon by reducing ventilation rates, but this would increase recovery times and cross infection rates. A better metric for the NHS would surely be kWh per bed, to account for spatial efficiency, but in order to measure the real success of hospitals we should link energy efficiency to patient outcomes. Perhaps a metric of kWh per patient discharged. The shorter the stay in hospital the better the outcome for both the patient and the NHS and the less energy expended in achieving the outcome.

Designing these new metrics will be complicated to get right. As soon as any measure is adopted as a target it creates an incentive and we must ensure that the perverse incentives in the system are as few and as little impact as possible. However any work in this area has got to be better than simply sticking with metrics that incentivise unrealistic outcomes for the businesses that have to occupy the buildings. If those of us who work in sustainability want to see positive outcomes from our efforts then we must find means to set the importance of carbon reduction within social and economic context that will deliver better business outcomes too.

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