Rain Gardens with No Scorecard

No standardized, comparable metrics exist for measuring the multi-benefit performance of nature-based solutions (NBS) in urban environments. NBS — green roofs, bioswales, urban forests, constructed wetlands — simultaneously provide stormwater management, heat reduction, biodiversity support, carbon sequestration, and social well-being benefits. But each benefit is measured by a different discipline using incommensurable units (cubic meters retained, degrees cooled, species richness, tonnes CO₂, survey scores). Cities cannot compare NBS against grey infrastructure using consistent cost-benefit frameworks because the benefits are measured on incompatible scales.

Cities are the primary arena for climate adaptation investment, with NBS increasingly recognized as cost-effective alternatives to grey infrastructure. But NBS are "largely planned, designed, and implemented without using an explicit ecosystem services approach" because no framework quantifies their full value. Investment in NBS is deterred by the inability to include co-benefits in cost-benefit analysis — a green roof that also reduces urban heat, supports pollinators, and improves mental health is evaluated only on its stormwater retention value because that's all engineers can quantify comparably. Climate adaptation funding cannot be directed to highest-performing NBS because performance is not measured comparably across projects.

Ecosystem services valuation frameworks (TEEB, CICES) provide conceptual structures but not operational measurement protocols. Monetary valuation of non-market ecosystem services (biodiversity, mental health) requires contingent valuation or hedonic pricing methods that are inherently contentious and not reproducible across studies. Engineering performance metrics (hydraulic retention, thermal reduction) are well-defined but cover only one or two benefits. Long-term NBS performance monitoring data is rare — most NBS research uses short-term studies that cannot capture multi-year performance evolution or maintenance requirements. Ecology and environmental economics have failed to converge on "what in nature should be counted for defensible value measures."

A standardized multi-criteria assessment framework that evaluates NBS across biophysical performance (water, heat, carbon, biodiversity) and social co-benefits using a common scoring system — not necessarily monetary. The model could be similar to LEED or BREEAM for buildings: a points-based rating system with category scores and an overall grade, enabling comparison across NBS types and between NBS and grey infrastructure alternatives.

A team could develop a prototype multi-benefit scorecard for a specific NBS type (e.g., bioretention cells) and apply it to existing installations in their city, quantifying how many benefits are currently measured vs. unmeasured. Alternatively, a team could instrument an existing NBS installation with low-cost sensors to monitor multiple performance dimensions simultaneously. Relevant skills: environmental engineering, urban planning, ecology, data visualization.