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In an increasingly urban world, developing sustainable cities is crucial for global sustainability. Urban nature‐based solutions (NBS), such as green infrastructure, are often promoted for their potential to provide several urban services. These include stormwater mitigation, improving energy efficiency of buildings, and carbon emissions mitigation, but few studies have compared the multifunctionality of NBS to conventional urban solutions providing similar services. Fewer yet have acknowledged the indirect resource (specifically climate, land, energy, water [CLEW] nexus) impacts that these solutions may have. This paper analyzes these aspects, employing a simple CLEW nexus accounting framework, and attempts a consistent comparison across different resource systems. The comparison includes direct and indirect impacts of a set of stylized—and diverse—solutions, each with different primary objectives: green roofs, representing a multifunctional urban NBS; permeable pavements targeting mitigation of stormwater flows; window retrofits targeting energy efficiency; and rooftop PV installations targeting CO2 emissions mitigation. The results highlight both the direct and total (CLEW nexus) impacts of green roofs on stormwater retention, energy use, and CO2 emissions. However, also for the studied conventional solutions with primarily a single direct function, CLEW nexus impacts spread across all measured dimensions (energy, water, and CO2) to varying degrees. Although the numerical results are indicative and uncertainty needs to be further assessed, we suggest that the development of this type of multifunctional, multisystem assessment can assist urban sustainability planning, with comprehensive and consistent comparison of diverse (NBS and conventional) solutions. [ABSTRACT FROM AUTHOR]

Urban water and energy systems are crucial for sustainably meeting basic service demands in cities. This paper proposes and applies a technology-independent “reference resource-to-service system” framework for concurrent evaluation of urban water and energy system interventions and their ‘nexus’ or ‘interlinkages’. In a concrete application, data that approximate New York City conditions are used to evaluate a limited set of interventions in the residential sector, spanning from low-flow toilet shifts to extensive green roof installations. Results indicate that interventions motivated primarily by water management goals can considerably reduce energy use and contribute to mitigation of greenhouse gas emissions. Similarly, energy efficiency interventions can considerably reduce water use in addition to lowering emissions. However, interventions yielding the greatest reductions in energy use and emissions are not necessarily the most water conserving ones, and vice versa. Useful further research, expanding the present analysis should consider a broader set of resource interactions, towards a full climate, land, energy and water (CLEW) nexus approach. Overall, assessing the impacts, trade-offs and co-benefits from interventions in one urban resource system on others also holds promise as support for increased resource efficiency through integrated decision making. [ABSTRACT FROM AUTHOR]