Urban Heat - Cooling Strategies and Clean Air

Tactical shade: how cooling Ecuadorian schools could improve student health and learning
Temperature and solar radiation in schools are relevant to children’s health and well-being. Heat exposure has a negative effect on learning, while vegetation cover appears to have a positive impact on academic outcomes. Ecuador lacks standards for temperature control, protection of students from solar radiation, or green cover on school grounds. Using satellite images, this multi-case study analyzed land surface temperature, vegetation index values, and solar radiation levels in nine schools located across Ecuador throughout 2022. Findings show heterogeneity in environmental values in schools among and within ecoregions. Only one school has an average temperature below heat stress conditions (i.e. <26 ºC). Schools on the Coast reached high mean temperatures of 37°C with maximum records of 41°C, representing very strong heat stress. Schools on the Coast have the lowest vegetation values, while schools in the Andes have the highest solar radiation levels. Increasing vegetation could help reduce temperature levels and protect students from radiation through shade. Knowledge of environmental conditions in schools should inform educational standards in Ecuador to develop focused policies addressing high temperature and radiation levels together with the vegetation indexes across ecoregions, considering the characteristics of each school.

Matea Cañizares. Columbia College, Columbia University, New York, NY, USA.

Daniel Romero-Alvarez. Emerging and Neglected Diseases, Ecoepidemiology and Biodiversity Research Group, Undergraduate Program in Biomedical Sciences, Faculty of Health Sciences, Universidad Internacional SEK, Quito, Ecuador.

Crossing Ecological Thresholds: Blue-Green Space Ecosystem Health in Delhi
This study presents a 32-year (1991–2023) assessment of blue-green space (BGS) ecosystem health in Delhi, one of the fastest-urbanising megacities in the Global South. A Vigour-Organisation-Resilience-Recoverability (VORR) framework was integrated with multi-temporal Landsat imagery, landscape metrics, and bird species diversity data to develop a composite Ecosystem Health Index (EHI) capturing structural, functional, and adaptive ecological change. Results reveal substantial deterioration: ecologically poor zones expanded by 50.8%, from 541.47 km² in 1991 to 816.36 km² in 2023; median EHI declined by 53%; and persistence surfaces contracted by 50%. Resilience weakened across all BGS categories, while the correlation structure shifted from resilience-dominated in 1991 to fragmentation-driven in 2023, making landscape configuration a primary determinant of ecosystem health. Validation with bird species richness showed strong spatial correspondence, with higher avian diversity concentrated in areas classified as ecologically resilient. District-level analysis revealed marked inequalities: Central Delhi’s “excellent” EHI coverage declined from 13.88 km² to 3.63 km², while North Delhi’s “poor” coverage more than doubled to 131.18 km². The 2023 EHI distribution indicates a significant tilt towards low values (median = 0.18), implying that Delhi's BGS may have hit an ecological inflection point where natural regeneration is inadequate for reversing deterioration. Key factors include impervious-surface expansion and landscape fragmentation. The study shows that VORR provides a replicable diagnostic framework for rapidly urbanising areas. To address this situation, reforms in governance, consolidation of fragmented institutional authority, ecological thresholds in planning, and recognition of BGS as essential urban infrastructure are necessary. Authors: P. Jha, P. K. Yadav, M. S. Joy, T. Bansal, A. N. Jha

Green-Blue Infrastructure Loss, Urban Heat, and Resilient City Pathways in Ethiopia
Rapid urbanization in African cities is degrading green-blue infrastructure (GBI)—forests, farmlands, and water bodies—undermining water, biodiversity, and thermal regulation. Yet empirical evidence for climate-resilient planning in this region remains scarce. This study quantifies the nexus between GBI dynamics, urban heat island (UHI) intensification, regional heat island (RHI) formation, and ecosystem service value (ESV) changes across four major Ethiopian cities (Addis Ababa, Adama, Bahir Dar, Hawassa) over 1990–2020. Using a hybrid geospatial approach, we classified LULC and retrieved LST from Landsat via the Mono-window algorithm. Spatial regression and modified ESV models assessed the spatial dependence of UHI, RHI, and ESV on urbanization-driven LULC transitions. Built-up areas expanded—by 17,341 ha (32.2%) in Addis Ababa, 2,151 ha (19.6%) in Adama, 2,715 ha (12.2%) in Bahir Dar, and 2,600 ha (15.7%) in Hawassa—while forests and water bodies declined. High-LST zones (>2°C above mean) correlated with sprawl (p<0.05). Isolated UHIs merged into RHIs by 2020, signaling escalating climate loss and damage. Water, evapotranspiration, and vegetation health were dominant UHI moderators (p<0.01). LST sensitivity to forests increased by ~1°C, indicating declining cooling efficiency. Total ESV rose nominally (e.g., +24.8% for Addis Ababa), yet masked severe trade-offs: regulating/biodiversity services declined while provisioning increased. ESV elasticity to LULC was 8.9%, underscoring vulnerability. Results confirm thermal and biodiversity flows are shaped by GBI conversion and RHI dynamics, providing actionable pathways for water-sensitive design, forest conservation, and adaptive infrastructure to avert irreversible climate loss.

Clean Air, Warm Homes: What Beijing's Coal-to-Gas Transition Proved — and What It Only Modeled
A USD 250 million corporate loan connected 214,000 households across 468 villages to natural gas, displaced 642,000 tons of coal a year, and finished 18 months early. The independent evaluation rated it highly successful. It also found that the air-quality outcome the project existed to deliver rested on modeled estimates rather than measurement, and that its durability depends on municipal subsidies no appraisal priced.

This submission draws on the published Project Learning Review of the Beijing Air Quality Improvement and Coal Replacement Project, approved in December 2017 and evaluated after closure in 2025. It was the financier's first corporate loan and first nonsovereign operation in China, and the first such operation its independent evaluation function has reviewed.

Delivery was strong on every dimension the financier controlled: 98.7 percent of planned household coverage, 4,883 km of village distribution pipeline, construction complete in December 2019 against a June 2021 target, no cost overrun, USD 252.8 million of client capital mobilized alongside, and early prepayment in 2023. Estimated annual reductions, net of gas combustion, were 588,000 tons of CO₂, 3,653 tons of PM2.5, 1,469 tons of SO₂, and 4,388 tons of NOₓ.

The evaluation's value lies in what those figures cannot show. Environmental and health outcomes were modeled, not measured, and the results framework lacked the specificity to test them. Universal adoption depended on connection subsidies and tariff support, without which low-income households can revert to coal. And the 2017–18 gas shortage, which left more than 426,000 households across northern China short of heat, showed that downstream conversion fails when upstream supply is not planned alongside it.

Context-specific life cycle emissions pathways for EU buildings and construction
Authors: Nicolas Alaux(1), Nicolas Bechstedt(1), Xiaoyang Zhong (2,3), Alessio Mastrucci(2), Delphine Ramon(4), Dominik Steinberger-Maierhofer(1), Karen Allacker(4), Alexander Passer(1), and Martin Röck(4,5).

Affiliations: (1)Graz University of Technology (Austria); (2)International Institute for Applied Systems Analysis (IIASA, Austria); (3)Tsinghua Shenzhen International Graduate School (China); (4)KU Leuven (Belgium); (5)RISE Institute for Regenerative Spatial Systems Science (Austria).

The European Union aims to reduce greenhouse gas emissions by 55% by 2030 and achieve climate neutrality by 2050. This study develops a comprehensive whole-life carbon assessment of the EU-27 building stock using the PULSE-EU model and evaluates 4,096 life-cycle greenhouse gas emission scenarios. The analysis integrates operational and embodied emissions while accounting for national implementation capacities. Results show that achieving EU climate targets would require avoiding 8.53 billion tonnes CO2e between 2020 and 2050. Current policy approaches relying predominantly on operational efficiency improvements and cleaner material production would exceed realistic national implementation capacities by 2.72 billion tonnes CO2e. A broader strategy mix combining operational improvements with circularity measures, reduced per-capita space demand, and increased use of bio-based materials could deliver an additional 2.19 billion tonnes CO2e of reductions within realistic capacity constraints. The study identifies context-specific mitigation priorities for each EU Member State and demonstrates that differentiated pathways are necessary to achieve climate targets efficiently and feasibly. The findings provide an evidence base for designing building-sector climate policies that address both operational and embodied emissions while reflecting national circumstances.