Search Results (438)

High-solar-reflectivity cladding materials are widely promoted to reduce cooling demand and mitigate urban heat island effects. However, in cold and mixed climates, their overall energy and carbon performance remains uncertain due to potential winter heating penalties and embodied carbon trade-offs. This study presents a comparative evaluation of energy use, annual operational carbon emissions, and material-level embodied carbon for high-reflectivity cladding applied to commercial buildings across representative Canadian climate zones. Dynamic simulations were conducted in EnergyPlus using a standardized warehouse archetype in Montreal, Toronto, and Vancouver, representing cold continental, mixed continental, and marine climates. Roof and wall solar reflectivity (albedo) was varied from 0.2 (baseline) to 0.8 (high reflectivity), while other envelope properties remained constant. Increasing reflectivity reduced annual cooling demand by approximately 15% in Montreal and Toronto and 20% in Vancouver, with the largest reductions during peak summer periods. However, reduced winter solar heat gains produced heating penalties, increasing total annual energy use by 1% in Montreal, 0.5% in Toronto, and less than 0.5% in Vancouver. Operational greenhouse gas emissions were calculated by converting simulated annual electricity and natural gas use into CO₂-equivalent emissions using provincial grid emission factors and combustion factors consistent with Environment and Climate Change Canada reporting. The results demonstrate the strong influence of regional energy supply on operational carbon outcomes. A cradle-to-gate (A1–A3) life cycle assessment quantified embodied carbon of representative cladding materials using Environmental Product Declarations and North American databases. Embodied carbon varied considerably: product-specific steel cladding manufactured in low-carbon electricity regions showed global warming potential as low as 1.76 kg CO₂e/kg, compared with industry averages exceeding 2.4 kg CO₂e/kg. Rather than performing a complete whole-life carbon assessment, this study comparatively evaluates annual operational carbon emissions and material-level embodied carbon to improve understanding of the energy and carbon implications of high-solar-reflectivity cladding materials in representative Canadian climates. The results demonstrate that climate conditions, envelope thermal performance, regional energy supply, and manufacturing pathways influence the environmental performance of cool envelope strategies. Full article

As rapid population aging coincides with intensifying urban heat island (UHI) effects, ensuring the outdoor thermal comfort of the elderly in hot–humid regions has become a critical challenge. This study investigates the influence of residential spatial morphology and wind environment on elderly thermal comfort in Fuzhou, China, by integrating PHOENICS and RayMan numerical simulations with a multivariate statistical framework. The Physiological Equivalent Temperature (PET) was calculated across three metabolic intensities (sedentary, walking, and exercising), while the LMG algorithm was used in R to identify the driving mechanisms. Residential layouts are stratified into High-Performance (Group A) and High-Risk (Group B) categories based on their thermal risk. In Group A, the microclimate is convective-dominant wind speed and air changes per hour are the primary determinants of thermal comfort. Conversely, Group B exhibits a radiation-dominant mechanism, with the sky view factor acting as the primary driver of heat stress in confined environments. Furthermore, metabolic intensity emerges as a decisive factor, as physical exercise frequently pushes PET beyond the 37.1 °C threshold even in high-performance layouts. Accordingly, this study proposes differentiated strategies: prioritizing ventilation-led optimization for Group A and radiation-shielding interventions for Group B, while advocating for supplementary active cooling in high-intensity activity zones to safeguard the geriatric population during peak summer heat. Full article

Climate change and rapid urbanisation increasingly threaten urban water security and grey infrastructure, calling for adaptive stormwater strategies to mitigate hydroclimatic extremes. This study evaluates the hydrologic performance of decentralised infiltration ponds functioning as natural/small water retention measures in the regional recharge zone of the Nyírség region, Debrecen, Hungary. Using a sensor-calibrated Hydrus-1D model, we simulated a no-intervention baseline against three pond sizes across historical and mid-century regional climate model projections. While the baseline scenario yielded negligible deep percolation across all scenarios, the smallest infiltration pond resulted in increased vertical moisture flux. The infiltration pond simulation improved ET/PET ratios and increased root zone saturation, improving urban vegetation health and evaporative cooling. All the pond designs attenuated and stored runoff without overspilling. Emission pathway sensitivity showed different responses driven by regional climate scenarios; temperature-driven evaporative offsets dominated under moderate warming, whereas extreme precipitation intensity increased infiltration gains under higher emissions. These findings support infiltration ponds as resilient, dual-purpose measures for mitigating regional water table decline while providing local flood protection under changing climate futures. Full article

Roofing systems strongly influence the energy performance and environmental footprint of buildings, particularly in hot–arid climates such as Saudi Arabia, where cooling dominates electricity demand; however, the comparative lifecycle environmental performance of alternative roofing strategies remains underexplored in this specific climatic and market context. This study therefore aims to evaluate and compare the environmental performance of four sustainable roofing strategies against a conventional flat roof (FR) baseline in order to provide evidence-based guidance for climate-specific roofing selection in Saudi Arabia. This study conducts a comparative cradle-to-grave lifecycle assessment (LCA) of four sustainable roofing strategies considering the hot–arid climate of Saudi Arabia. Green roof (GR), cool roof (CR), solar photovoltaic roof (SPV), and roof canopy (RC) were assessed using the ReCiPe 2016 method in the SimaPro software. The environmental impacts of these strategies were assessed across product, construction, use, and end-of-life stages relative to conventional flat roofs (FRs). The results indicate that the production stage consistently contributes the highest environmental impacts, with increases ranging from 30 to 3000% for GR, CR, and RC and exceeding 10,000% for SPV. On the other hand, the use stage offers the greatest reductions ranging from 10 to 200%, particularly for SPV and CR, due to operational energy savings and electricity generation. Overall, CR demonstrates the most balanced environmental performance, combining high impact reductions with minimal trade-offs, while SPV provides significant climate and fossil resource benefits but increases mineral resource use. These findings highlight the importance of climate-specific and resource-conscious selection of roofing strategies in Saudi Arabia and provide a transferable comparative LCA framework that can inform sustainable roofing decisions in other hot–arid and hot–humid regions, in support of the Kingdom’s Vision 2030 objectives for sustainable urban development. Full article

This study quantifies five decades (1975–2025) of residential architectural transformation in Delhi (Tier-I) and Patna (Tier-II), India, among middle-income-group households, and evaluates its implications for passive design loss and mechanical cooling dependence. A stratified survey of 1080 middle-income-group (MIG-I and MIG-II) households across six construction decades documents the systematic elimination of passive features: courtyard presence collapsed from 54.44% (Cohort A, 1975–1985) to 1.39% (Cohort C, 2015–2025); load-bearing masonry declined from 47.78% to 7.78%; and houses lacking passive cooling features quadrupled from 10.83% to 40.83%. Correspondingly, households with three or more air conditioning (AC) units rose from 12.78% (Cohort A) to 33.06% (Cohort C). However, 30–35% of households across all cohorts stated that the ‘indoor temperature remains comfortable without AC’, challenging deterministic AC-dependence assumptions. Regional divergence in drivers is evident: globalization dominates in Delhi (59.24%), while lack of traditional awareness dominates in Patna (39.29%), suggesting hierarchical diffusion and indicating a need for differentiated policy responses. Architectural homogenization shows a consistent association with higher AC ownership and electricity consumption, raising concerns about energy insecurity and climate vulnerability. Hybrid design, integrating traditional passive strategies with contemporary spatial needs, offers a pathway toward climate-resilient urban futures. Full article

Urbanisation and climate change have intensified the Urban Heat Island (UHI) effect in European cities, increasing thermal stress and health risks, especially for vulnerable people. Nature-based Solutions (NbS), such as green infrastructures (GI), offer effective mitigation strategies. A notable example is the Horizon 2020 URBAN GreenUP project in Valladolid, Spain, where a green shade shelter infrastructure was installed and monitored between 2019 and 2022 to evaluate its cooling performance and its effects on temperature-based urban heat indicators through the use of Key Performance Indicators (KPIs). Local thermal conditions were monitored across two adjacent narrow streets—one with the green shade shelter and one as a control. The installation of the green shade shelter in Valladolid produced measurable thermal benefits. During summer peaks, it reduced ambient temperatures by approximately 0.9 °C, with daily maximum temperatures decreasing by 1.0–3.0 °C. In winter, daily minimum temperatures dropped by around 1.0 °C, while autumn saw an increase of 0.7 °C. Summer minimum temperatures varied, ranging from a 0.2 °C decrease in early summer to a 0.7 °C increase in late summer, with a 0.3 °C rise during peak summer in mid-July. The intervention also reduced the frequency and delayed the onset of days exceeding 35 °C and nights above 20 °C, although the delay in peak tropical nights was limited to seven days. These findings indicate that green shade shelters can contribute to improving street-level thermal conditions and reducing temperature-based heat exposure indicators in dense urban environments. Full article

Urban areas face increasing challenges related to heat stress and urban heat islands, necessitating effective strategies for microclimate regulation and thermal comfort enhancement. This study investigates the cooling effect of three tree species, Ficus retusa, Ficus benjamina and Fraxinus spp. (Ash trees), on urban microclimates and thermal comfort in downtown Annaba, Algeria, during the summer. The methodology comprises two complementary methods. First, field measurements of air temperature (Ta), relative humidity (RH), and wind speed (Ws) were recorded hourly from 9 a.m. to 9 p.m. Second, collected data was inputted into the ENVI-met microclimate model to simulate various urban canopy scenarios. Microclimate variations, including air temperature (Ta), mean radiant temperature (T_mrt), relative humidity, wind speed, and the Physiological Equivalent Temperature (PET) index, were computed over a 13 h period, from 9 a.m. to 9 p.m., to examine the cooling effect of each species and their impact on outdoor thermal comfort. The results demonstrate the notable cooling effect of Ficus species and Fraxinus spp. with Ficus species generally exhibiting larger reductions in air temperature (0.9 °C to 2 °C) and PET index (7.3 °C to 7.7 °C), and higher increases in relative humidity (5.6% to 6.8%) compared to Ash trees. Full article

This study aims to evaluate the comprehensive potential of cooling strategies in an old urban block in Xi’an, China, where the outdoor environment requires significant improvement. The Luomashi block is chosen as a case study. The strategies include cool pavement (CP) and facade (CF), green facade (GF) and roof (GR), tree-planting (TP), water fountain (WF) and mist (MR), and their combinations. The results show that most of the individual strategies can reduce the canyon air temperature and the physiological equivalent temperature (PET) at the pedestrian height of 1.5 m throughout the day. The combination of CP, CF, CR, TP, WF, and MR (CC1) can reduce the daily N–S and E–W canyon air temperatures by 1.4 °C and 1.0 °C, respectively. For the combination of CP, GF, GR, TP, WF, and MR (CC2), the reductions are 1.4 °C and 1.1 °C. Meanwhile, these two combination scenarios can reduce the daily mean PET by 2.71 °C and 2.87 °C, and reduce the daily cooling energy demand by 8.4% and 8.9%. The exploratory findings reveal the site-specific cooling potential of these particular mitigation configurations within the historical fabric of the Luomashi block, highlighting that the performance is highly dependent on the chosen baseline parameters and local morphological constraints. Full article

Many airports now consider implementing urban-cooling measures as proven strategies to reduce energy use and improve environmental conditions. Studies have also shown that reflective surfaces on roofs and grounds can have beneficial effects on thermal environment and airport workers’ productivity. To date, no studies have been undertaken to specifically assess whether any effects on aircraft performance would also result from implementing these measures. In this exploratory study, high-resolution micrometeorological modeling and remote-sensing analysis were undertaken to quantify the potential reductions in fuel use and, thus, emissions from aircraft taxiing on cooler surfaces. The results suggest small but non-zero benefits in terms of emissions and takeoff-roll distances. Using the Dallas–Ft. Worth International Airport (DFW) as a case study and Boeing 737 aircraft type as an example, it is found that if taxiways and shoulders albedo is increased to 0.35, an average of 2.3 kg CO₂ can be saved per single taxi-out or taxi-in operation around midday and about 1.5 kg CO₂ earlier in the morning or later in the evening. It is also found that even though runways albedo remains unchanged, cooler air advected over runways from modified taxiways can reduce the takeoff-roll distance by an average of 3% around midday that tapers off to an average of 1% early in the morning or late evening. Indeed, these are small effects per single taxi-in or taxi-out operation but when scaled by some 2000 arrivals and departures per day at DFW, saving 4000–5000 kg CO₂ per day, and if further scaled by the number of eligible airports, the impacts become significant. Furthermore, the effects reported here are from taxiway and shoulder modifications alone; if combined with the effects from cool roofs and other cool ground surfaces at terminals, tarmacs, ramps, and parking areas, the benefits will add up significantly. Limitations in this study, that would be addressed in future work, include simplifying assumptions regarding aircraft-engine performance, specifications, and aircraft types mix and operations. Full article

Environmental injustices in the United States are rooted in structural racism, particularly policies of racial segregation and disinvestment such as redlining that have produced enduring inequalities in the built environment and population health. This concept paper examines extreme heat as a racialized environmental exposure in Buffalo, New York—a post-industrial Great Lakes city increasingly framed as a “climate haven”. While such designations suggest relative protection from climate risk, they obscure the socio-spatial inequalities that shape uneven vulnerability on the ground. Drawing on a structural racism framework and insights from urban political economy, this study argues that extreme heat vulnerability in Buffalo is not incidental but produced through historically embedded patterns of disinvestment in housing, infrastructure, and environmental resources. Neighborhoods such as the East Side, Black Rock, and the West Side exhibit heightened exposure due to concentrations of thermally inefficient housing, limited tree canopy and green space, and unequal access to cooling resources. These conditions reflect the material legacy of segregation and uneven urban development, which continue to structure differential capacity to adapt to rising temperatures. Although extreme heat is widely recognized as a major public health threat, it remains underexamined in mid-sized northern and Rust Belt cities, where risk is often perceived as episodic rather than structurally produced. This paper addresses this gap by advancing a conceptual critique of the “climate haven” narrative, demonstrating that relative geographic advantage does not equate to equitable resilience. By theorizing extreme heat as a mechanism through which structural racism is reproduced, this study highlights the need for place-based, justice-oriented climate adaptation strategies that confront the historical and institutional drivers of vulnerability in Great Lakes cities. Full article

Rapid urban expansion and agricultural development have substantially altered land use/land cover (LULC), surface thermal regimes, and ecosystem conditions in semi-arid cities. This study investigates the spatiotemporal dynamics of LULC and evaluates their associations with land surface temperature (LST), vegetation health, soil moisture, and drought conditions in Ghazni City, Afghanistan, between 2013 and 2023 using a Google Earth Engine (GEE)-based framework. Landsat 8 OLI/TIRS imagery was classified using a Random Forest (RF) algorithm, while the Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), Vegetation Condition Index (VCI), Temperature Condition Index (TCI), Vegetation Health Index (VHI), and LST were derived to evaluate environmental responses. To provide a comprehensive evaluation of urban–climate interactions, monthly Landsat-derived LST time series were analyzed and compared to MODIS and ERA5 datasets through a multi-source consistency assessment framework. The RF classification achieved overall accuracies of 95.56% (2013) and 97.77% (2023), with Kappa coefficients of 0.89 and 0.94, respectively. Results revealed a substantial expansion of built-up areas (5.4%) and vegetation/agricultural land (7.2%), accompanied by a decline in bare land. Urban and barren surfaces consistently exhibited higher LST values, whereas vegetated areas demonstrated a pronounced cooling effect. NDVI and SAVI analyses indicated improving vegetation conditions and soil moisture status over the study period. LST exhibited strong seasonal variability, with summer maxima reaching 49.74 °C and winter minima declining to −8.39 °C. Comparisons among the Landsat, MODIS, and ERA5 datasets demonstrated strong agreement, with a high correlation between Landsat- and MODIS-derived LST (R = 0.84), supporting the reliability of the Landsat-derived LST estimates. Generally, the findings demonstrate the critical role of vegetation in moderating surface temperatures and enhancing urban climate resilience, providing scientific evidence for sustainable land use planning and climate adaptation strategies in semi-arid cities. Full article

The intensification of heat waves and the increase in average temperatures, particularly evident in the Mediterranean context, underline the urgency of strengthening sustainable spatial planning, introducing concrete tools to understand and manage how urban form, land-use and local microclimate interact with each other. In this direction, the paper proposes an integrated methodological path to map territorial exposure to surface heat stress in densely urbanised contexts, applying it to the case study of the Caserta conurbation. The approach uses several levels of analysis: (i) the estimation of the Normalised Difference Vegetation Index (NDVI) and the calculation of Land Surface Temperature (LST) from the Landsat series (1987–2022), using radiance/reflectance measurements and deriving LST from the Top-of-Atmosphere Brightness Temperature (BT) and from the Land Surface Emissivity (LSE); (ii) the consistency check of satellite-derived surface temperature using meteorological station data from the archive of the Multi-Risk Functional Center of the Civil Protection of the Campania Region, fed by the measurements of the sensors installed in the area by the Campania Regional Environmental Protection Agency (ARPAC); (iii) the evaluation of the intensity of the Surface Urban Heat Island (SUHI) as the difference between LST values extracted from paired urban and non-urbanised reference areas; (iv) the verification of the relationship between NDVI and LST by linear regression, with NDVI as the explanatory variable and LST as the dependent variable, showing a statistically consistent inverse relationship. The results support a multi-scalar reading of the intervention priorities, highlighting that the potential relevance of nature-based solutions (NBS) and cooling strategies varies according to local urban morphology, geographical configuration, and degree of soil sealing, requiring context-specific planning evaluations. Full article

This study applies the Heat Resilience Framework (HRF) as a methodological approach to assess and compare heat resilience across Mumbai, Thane, and Nagpur. The HRF integrates multiple dimensions, namely Physical, Social, Economic, Institutional, and Environmental, to systematically evaluate vulnerabilities and adaptive capacities at the city level. Using the Analytical Hierarchy Process (AHP), indicators within each dimension were weighted and normalized to derive a comprehensive resilience ranking, allowing for a nuanced understanding of intra-city disparities and evidence-based policy interventions. The analysis reveals that Mumbai demonstrates the highest overall heat resilience, supported by strong physical, social, and institutional capacities, although economic resilience remains comparatively weaker. Thane exhibits relatively strong physical resilience but faces challenges in Institutional and Natural dimensions, contributing to a lower overall resilience score. Nagpur demonstrates the strongest economic resilience among the three cities but continues to face challenges in social resilience and adaptive capacity in the Natural dimension. These findings highlight the need for targeted interventions, including infrastructure improvements, financial inclusivity, strengthened institutional preparedness, and community-based resilience strategies, to address city-specific vulnerabilities. The study underscores the importance of adaptive measures such as green infrastructure, cool pavements, cooling shelters, and parametric insurance to enhance urban resilience. By leveraging the HRF, this study contributes to climate-responsive urban planning by offering a structured framework for policymakers to develop targeted, data-driven heat-mitigation strategies. Full article

Green façade applications are among the visible strategies to mitigate Canopy Urban Heat Islands (CUHIs) and improve thermal comfort, particularly in hot arid climates. However, their combined effectiveness at the urban scale, particularly with respect to urban canyon geometry, remains underexplored. This study evaluates the cooling efficiency of green façades and their relationship with height-to-width (H/W) ratios in the hot arid climate of Tehran, Iran. Urban canyons with varying geometries and façade conditions are simulated using ENVI-met 5.1 to assess impacts on air temperature and the Universal Thermal Climate Index (UTCI). Results indicate that urban canyon geometry, particularly higher H/W ratios, plays a dominant role in reducing CUHI intensity and improving outdoor thermal comfort, especially during summer, when deeper canyons show lower air temperature and UTCI values. The addition of green façades further enhances this cooling effect, most significantly in deeper canyon configurations. In contrast, winter conditions show minimal sensitivity to both geometry and façade greening, with only minor variations observed. Overall, the study highlights the importance of integrating urban form and vegetation strategies, demonstrating that the effectiveness of green façades is strongly influenced by canyon geometry and seasonal conditions, providing insights for climate-responsive, geometry-sensitive urban design. Full article

Rising global temperatures and more frequent heat waves pose a growing threat to public health, particularly among older adults. Age-related declines in thermoregulatory capacity such as reduced sweating, impaired vasodilation, and diminished hypothalamic responsiveness make it more difficult to cope with elevated nighttime temperatures. These thermal challenges disrupt sleep by prolonging sleep onset, fragmenting slow-wave and REM sleep, and suppressing melatonin secretion. Importantly, sex-related differences in thermoregulatory aging—particularly menopause-associated vasomotor instability in women and testosterone-related autonomic changes in men—further modulate individual vulnerability to heat-induced sleep disruption. Beyond sleep, heat-induced stress affects metabolic, cardiovascular, and immune systems, promoting insulin resistance, endothelial dysfunction, sympathetic overactivation, and chronic inflammation. Socioeconomic disparities, urban heat island exposure, and differential access to cooling infrastructure function as critical environmental modifiers that amplify biological vulnerability, particularly in disadvantaged older populations. This narrative review aims to synthesize current knowledge on the specific thermoregulatory mechanisms of sleep disruption induced by heat stress in older adults. Understanding these interactions is crucial for developing effective interventions, including environmental cooling, circadian-aligned behaviors, and targeted public health strategies, to mitigate the compounded risks of heat exposure and preserve healthy sleep in aging populations. However, many proposed mechanistic pathways are primarily derived from animal models, and controlled human studies specifically targeting heat-exposed older adults remain scarce. Full article