3.6. Metric Balance

3.6. Metric Balance

Ideally, we would like to see the environmental, economic and social dimensions, and benefits of new technologies balanced. However, most real-life situations would gravitate differently towards those three dimensions. Results of the metric analysis need to be presented in a way that provides a clear and informative message to stakeholders and investors. Presented below are a couple of examples from sustainability assessments performed by government organizations.

The radial diagram in Figure 3.6 was presented by the National Renewable Energy Laboratory (NREL) to describe the sustainability profiles of several energy technologies. Six selected criteria plotted in 6 different directions in the form of a propeller provide an illustration of balance or lack of balance in system analysis. Note that each of the metrics is not directly comparable to others (like we saw in the case of the energy analysis, when all impacts are normalized to the same unit and scale). In this case, the scale for each metric needs to be defined independently versus boundary conditions (minimum and maximum values) so that it covers the appropriate range of evaluation.

Figure 3.6. A visual representation of different categories of sustainability metrics.
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This diagram is basically a six-sided star with one category of sustainability metrics shown at each point. From the top right, and continuing clockwise, are the following categories:

• Climate Friendliness - GHG Emission (g-CO2 eq/kWh) - min=1000, Max=0
• Water Conservation - Annually Available Freshwater Usage (%) Min=35, Max=0
• Safety - Fatalities from Severe Incidents (fatalities/GW-year) Min=0.12, Max=0.000248
• Local Employment Impacts - Contribution to County Employment (%) - Min=0, Max=1
• Energy Affordability - LCOE (USD/kWh) - Min=0.39, Max=0
• Energy Diversity - Change in Diversity Indicator (%) - Min=-5, Max=5

Credit: National Renewable Energy Laboratory

The diagram below (Figure 3.7.) presents another example of how different categories of metrics are balanced to characterize the sustainability profile of a city. From this representation, we can immediately recognize that the most problematic areas the city may want to address first are Emission and Waste, which create a critically bad impact, and Materials and Energy flows (the lowest: red and orange scores in the pie). At the same time, Cultural Engagement and Identity is the most attractive feature of the city (the highest: bright green score). We can also conclude just from a quick glance that the ecological part of this sustainability system is most suppressed, while the cultural part is probably most developed and sound. On the political and economic fronts, some of the impacts are in the favorable range, while others are down to satisfactory. This snapshot of the disbalance provides a tool for comparison when other systems (cities) are evaluated against the same metrics.

Figure 3.7. Radial diagram showing the sustainability of metropolis of Melbourne (Australia) as developed by UN Global Compact Cities Programme.

Credit: Wikimedia Commons