Urban cooling and energy-saving effects of nature-based solutions across types and scales – Nature

Report on the Efficacy of Nature-Based Solutions for Urban Sustainability and Achieving Sustainable Development Goals

1.0 Introduction: Urban Climate and Energy Challenges

The escalating global demand for urban cooling presents a significant challenge to achieving multiple Sustainable Development Goals (SDGs). This demand exacerbates the urban heat island (UHI) effect and increases building-related energy consumption, thereby impacting:

• SDG 3 (Good Health and Well-being): Increased heat stress poses risks to urban populations.
• SDG 7 (Affordable and Clean Energy): Higher cooling demands strain energy grids and increase costs.
• SDG 11 (Sustainable Cities and Communities): The UHI effect degrades urban livability and resilience.
• SDG 13 (Climate Action): Greater energy use for cooling contributes to greenhouse gas emissions.

Nature-based solutions (NBS) are increasingly integrated into urban planning as a key strategy to address these issues. However, a lack of comparative evidence on their performance across different climates and scales has hindered strategic implementation. This report summarizes a systematic meta-analysis to provide actionable, evidence-based guidance for leveraging NBS to advance the global sustainability agenda.

2.0 Methodology

A systematic meta-analysis was conducted to quantify the performance of NBS in urban environments. The scope of the analysis included:

1. A review of 373 peer-reviewed studies published between 2013 and 2025.
2. Comprehensive coverage of all 16 Köppen–Geiger climate zones to ensure global applicability.
3. Evaluation of both thermal regulation (cooling effect) and energy-saving performance.

3.0 Key Findings and Implications for Sustainable Development Goals

3.1 Overall Performance of Nature-Based Solutions

The analysis reveals that NBS provide significant global benefits that directly support key SDG targets.

• Daytime Temperature Reduction: NBS reduce temperatures by an average of 2.04 ± 0.17 °C during hot periods. This mitigation of extreme heat contributes directly to SDG 3 by reducing heat-related health risks and to SDG 11 by creating more comfortable and resilient urban environments.
• Annual Cooling Load Reduction: NBS lower annual energy demand for cooling by 1.32 ± 0.06%. This finding is critical for advancing SDG 7 by promoting energy efficiency and for SDG 13 by reducing the carbon footprint associated with urban energy consumption.

3.2 Comparative Analysis of Infrastructure Types

The type of NBS infrastructure significantly influences its effectiveness, providing clear direction for urban planning aimed at achieving SDG 11.

• Green infrastructure (e.g., parks, green roofs) consistently outperforms blue infrastructure (e.g., ponds, rivers) in both thermal regulation and energy savings across the majority of climate zones.
• This suggests that prioritizing green infrastructure investments can yield dual benefits, enhancing both urban climate resilience and energy sustainability.

3.3 Scale-Dependent Efficacy

The spatial scale of implementation is a critical determinant of NBS outcomes. Tailoring strategies by scale is essential for maximizing contributions to specific SDGs.

• Neighborhood-Scale: NBS implemented at the neighborhood level deliver the strongest cooling effects, with an average temperature reduction of -2.22 ± 0.25 °C. This approach is most effective for mitigating the UHI effect, directly supporting the creation of sustainable communities under SDG 11 and protecting public health as per SDG 3.
• Building-Scale: Strategies applied at the building level (e.g., green roofs, vertical gardens) yield the most substantial energy savings, reducing cooling loads by 8.62 ± 0.78%. This targeted approach is optimal for advancing SDG 7 by directly lowering building energy consumption.

4.0 Conclusion and Strategic Recommendations

The findings confirm that the performance of NBS is highly dependent on climate, infrastructure type, and implementation scale. These climate- and scale-dependent patterns offer actionable guidance for policymakers and urban planners to prioritize NBS investments effectively.

To maximize progress toward the Sustainable Development Goals, the following strategic actions are recommended:

1. Prioritize green infrastructure over blue infrastructure in urban planning to achieve superior outcomes in both thermal comfort and energy efficiency, aligning with SDG 7 and SDG 11.
2. Deploy neighborhood-scale NBS to combat the urban heat island effect, thereby enhancing community well-being (SDG 3) and climate resilience (SDG 13).
3. Promote building-scale NBS through policies and incentives to achieve significant reductions in energy consumption, directly contributing to targets for affordable and clean energy (SDG 7).

By adopting these evidence-based approaches, cities can strategically implement NBS to strengthen urban energy resilience and accelerate the achievement of a sustainable, climate-resilient future.

Analysis of Sustainable Development Goals (SDGs) in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

The article on nature-based solutions (NBS) for urban cooling and energy savings connects to several Sustainable Development Goals (SDGs). The primary SDGs addressed are:

• SDG 7: Affordable and Clean Energy: The article directly addresses this goal by quantifying how NBS can “reduce energy use associated with buildings” and lower “annual cooling loads.” This focuses on improving energy efficiency, a key component of sustainable energy.
• SDG 11: Sustainable Cities and Communities: This is a central theme, as the research provides “actionable guidance for prioritizing NBS” within “urban planning.” It aims to mitigate the “urban heat island effect,” making cities more resilient, sustainable, and safer from climate-related hazards like extreme heat.
• SDG 13: Climate Action: The article’s entire premise is based on climate action. By studying strategies that “mitigate the urban heat island effect” and reduce energy consumption, it directly contributes to climate change adaptation (strengthening resilience to heat) and mitigation (reducing energy-related emissions).

2. What specific targets under those SDGs can be identified based on the article’s content?

Based on the article’s focus, the following specific SDG targets can be identified:

1. SDG 7: Affordable and Clean Energy

   • Target 7.3: By 2030, double the global rate of improvement in energy efficiency. The article supports this target by demonstrating that NBS can lead to significant “energy savings,” specifically by lowering “annual cooling loads by 1.32 ± 0.06% globally” and achieving optimal savings of “8.62 ± 0.78%” with building-scale strategies.

2. SDG 11: Sustainable Cities and Communities

   • Target 11.3: By 2030, enhance inclusive and sustainable urbanization and capacity for participatory, integrated and sustainable human settlement planning and management. The article directly informs this target by providing “comparative evidence” and “actionable guidance” for integrating NBS into urban planning to manage urban growth sustainably.
   • Target 11.b: By 2020, substantially increase the number of cities and human settlements adopting and implementing integrated policies and plans towards inclusion, resource efficiency, mitigation and adaptation to climate change, resilience to disasters. The research provides the scientific basis for policies and plans focused on climate adaptation and resource (energy) efficiency through NBS, aiming to “strengthen urban energy resilience.”

3. SDG 13: Climate Action

   • Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries. The article addresses this by evaluating NBS as a tool to mitigate the “urban heat island effect,” which is a significant climate-related hazard. The findings on temperature reduction directly relate to strengthening urban resilience against extreme heat events.
   • Target 13.2: Integrate climate change measures into national policies, strategies and planning. The meta-analysis provides robust, evidence-based findings that can be used by policymakers to integrate NBS—a key climate change adaptation measure—into urban planning and development strategies.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

Yes, the article provides specific, quantifiable indicators that can be used to measure progress towards the identified targets.

1. Indicators for SDG 7 (Energy Efficiency)

   • Percentage reduction in annual cooling loads: The article states that NBS lower “annual cooling loads by 1.32 ± 0.06% globally.”
   • Energy savings from building-scale strategies: A more specific indicator is the “optimal energy savings (8.62 ± 0.78%)” achieved through building-scale NBS.

2. Indicators for SDG 11 & SDG 13 (Urban Resilience and Climate Adaptation)

   • Reduction in daytime ambient temperature: The article provides a clear metric, stating that NBS “reduce daytime temperatures by 2.04 ± 0.17 °C during hot periods.”
   • Cooling effect at the neighborhood scale: Progress can also be measured by the temperature reduction achieved by specific scales of intervention, such as the “strongest cooling effects (−2.22 ± 0.25 °C)” delivered by neighborhood-scale NBS.
   • (Implied) Extent of NBS integration in urban planning: While not a direct metric from the results, the article’s purpose is to guide planning. Therefore, an implied indicator for targets 11.3 and 13.2 would be the percentage of urban areas or new developments that incorporate evidence-based NBS strategies.

4. Summary Table of SDGs, Targets, and Indicators

Source: nature.com