Local Optima v Global Optima

City building has moved from debates about whether to act to stem the rise of carbon emissions, to how best to act.

As we laid out in our introductory post to this series, building codes and green building standards are some of the few climate action tools municipalities have at their disposal. Through our work we have observed some common shortcomings of these well-intentioned codes and policies. It is often the case that these codes and standards steer design teams to a local optima (e.g. optimizing for energy cost, on-site energy use, or high cost demand reduction strategies). However, in doing so, they do not enable the global optima. For governments who wish to take aggressive climate action the real goal is to maximize community-wide carbon reductions, with the highest certainty, at the lowest cost for citizens and consumers. Many codes and standards are falling short of optimizing for these outcomes.

It is not so much that these tools (building codes and standards) won’t result in some carbon emission reductions – it is that if we are now at the point in the conversation on how best to act, and looking at these tools through the lens of realizing the global optima (largest carbon reductions, at the highest certainty, and the lowest cost) is well deserved.

We have summarized three of the most commonly seen shortcomings below. We will expand in individual blog posts for each along with concrete examples, and possible resolutions.

Boundary Issues: Some codes and standards do not recognize off-site energy efficiency or renewable energy supply measures (e.g. use of high efficiency or renewable energy sources in district energy networks, upstream renewable fuels like renewable natural gas). If codes only recognize solutions that are constrained within a building’s footprint, they may inhibit projects from pursuing solutions that are lower cost or have deeper levels of carbon reductions because these measures are off-site, and thus would not receive recognition.

Metric Issues: Some codes and standards measure only energy use, or energy cost. They do not take into account the carbon intensity of different energy sources that heat, cool, or power a building. This would be fine if the only purpose of the code or standard were to reduce energy use, but if it is also to optimize for carbon reductions, actually controlling for carbon outcomes will bring us closer to realizing this desired outcome.

Hierarchy Of Measures: Most codes aimed at climate action that we have encountered take a prescriptive approach on carbon emission strategies. They require demand reduction first, then energy efficiency, and finally renewable energy supply. We would agree with a demand reduction and energy efficiency first approach; however, we also think there is value in testing if there are lower-cost opportunities to reduce emissions by focusing on renewable energy supply. Demand reduction and energy efficiency first and foremost – but not at all costs. Without looking at where the ‘sweet-spot’ is for a balancing between measures, we may not be optimizing for the greatest emission reductions at the lowest cost.

Policy development is tough work — we get that. The issues are complex and there is a need to balance different priorities and the input from many stakeholders, not all of whom have the same global optima as we have discussed here (greatest carbon reduction, for the highest certainty, and the lowest cost). We know our colleagues who have developed these codes and standards have given careful consideration to many factors prior to reaching the end product.

Our review of these codes and standards is not to criticize the well-meaning work of our colleagues. It is to help inform the public dialog around refining these codes and standards to realize the global optima. If the pace and magnitude of change that is required to meet climate targets is to occur, we cannot be content with just taking action, we must to aim to optimize actions.

As always we welcome thoughts and feedback. Stay tuned for blog posts to follow on the three issues raised.

Reshape Strategies