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1. Design and Evaluation of Wearable Solar Radiation Shields for Enhanced Personal Heat Exposure Monitoring

   https://doi.org/10.3390/s25030945  

   Habeeb, Dana; Devajji, Rahul; Polak, Nick; Unabia, Greatzel; Urbina, Oscar (February 2025, Sensors)

   Extreme heat is one of the main climate-induced public health risks to communities around the world. Understanding an individual’s vulnerability to heat is challenging, as heat exposures vary significantly depending on occupation, travel behaviors, personal activities, and the surrounding urban environment. Previous validation studies have found that commonly used wearable temperature sensors are less reliable in highly urbanized areas and when worn in direct sunlight. The aim of our study is to investigate the potential to improve the reliability of wearable temperature sensors commonly used in personal heat exposure studies. To accomplish this aim, we designed and rapidly prototyped a set of solar radiations shields to decrease temperature bias when worn in direct sunlight and in areas of high impervious surfaces. In a field deployment, we tested four different form factors for solar radiation shields, which were specifically designed to house the iButton sensor and to be worn on-body. Initial results have shown that these wearable solar radiation shields can improve sensor reliability by decreasing temperature bias by 3 °F on average. These findings highlight the potential for wearable radiation shields to enhance personal heat exposure measurements in urban environments. 

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2. Quantifying the Urban Heat Island Effects and Energy Performance of Solar-Reflective Facades: A Simulation Study in a Dense Urban Context

   Chen, C.; Duan, Q.; Zhang, E.; Wang, J. (October 2023, The 18th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES))

   Many researchers have studied the roles of building envelope materials on UHI, such as roofs, and walls, but few of them have explored the impacts of the emergence of the solar-reflective coatings, films, and panels but well-visible transmittance that is increasingly applied to glazed building facades, especially in hot climates, for outdoor thermal environments. The question then arises: Despite the positive effects of these strong solar-reflective facades on building heating and cooling energy savings, do they have the same positive effects on the adjacent outdoor area, especially in a dense urban context? This research aims to quantify the potential UHI effects of the solar-reflective facades relative to the non-reflective ones in a dense urban context, along with the heating and cooling energy performance analysis. As such, a simulation method in terms of a series of tools including LBNL Radiance, EnergyPlus, and WINDOW software was adopted in this work to analyze the solar radiation interactions between the façade surface and the surrounding urban structures and potential temperature rise under solar-reflective and non-reflective facades. The result shows that the annual cooling energy savings by using the solar-reflective facades are about 33.8% relative to the typical double-pane clear glazed façade because of the substantial reduction of U-factor and solar heat gains; But, this preliminary work also unveils the potential adverse effects of using such materials at the urban scale, leading nearly 2 times greater solar irradiation and UHI effects than the ones by the solar-non-reflective building surfaces in an urban area. Future optimization studies on the trade-off between the building cooling energy savings and UHI effects by the solar-reflective façades need to be conducted. 

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3. Examining the Optimal Placement of Cooling Centers to Serve Populations at High Risk of Extreme Heat Exposure in 81 US Cities

   https://doi.org/10.1177/00333549221148174  

   Adams, Quinn H.; Chan, Elana M.G.; Spangler, Keith R.; Weinberger, Kate R.; Lane, Kevin J.; Errett, Nicole A.; Hess, Jeremy J.; Sun, Yuantong; Wellenius, Gregory A.; Nori-Sarma, Amruta (November 2023, Public Health Reports)

   Objective:Although extreme heat can impact the health of anyone, certain groups are disproportionately affected. In urban settings, cooling centers are intended to reduce heat exposure by providing air-conditioned spaces to the public. We examined the characteristics of populations living near cooling centers and how well they serve areas with high social vulnerability. Methods:We identified 1402 cooling centers in 81 US cities from publicly available sources and analyzed markers of urban heat and social vulnerability in relation to their locations. Within each city, we developed cooling center access areas, defined as the geographic area within a 0.5-mile walk from a center, and compared sociodemographic characteristics of populations living within versus outside the access areas. We analyzed results by city and geographic region to evaluate climate-relevant regional differences. Results:Access to cooling centers differed among cities, ranging from 0.01% (Atlanta, Georgia) to 63.2% (Washington, DC) of the population living within an access area. On average, cooling centers were in areas that had higher levels of social vulnerability, as measured by the number of people living in urban heat islands, annual household income below poverty, racial and ethnic minority status, low educational attainment, and high unemployment rate. However, access areas were less inclusive of adult populations aged ≥65 years than among populations aged <65 years. Conclusion:Given the large percentage of individuals without access to cooling centers and the anticipated increase in frequency and severity of extreme heat events, the current distribution of centers in the urban areas that we examined may be insufficient to protect individuals from the adverse health effects of extreme heat, particularly in the absence of additional measures to reduce risk. 

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4. Greater aridity increases the magnitude of urban nighttime vegetation-derived air cooling

   https://doi.org/10.1088/1748-9326/abdf8a  

   Ibsen, Peter C.; Borowy, Dorothy; Dell, Tyler; Greydanus, Hattie; Gupta, Neha; Hondula, David M.; Meixner, Thomas; Santelmann, Mary V.; Shiflett, Sheri A.; Sukop, Michael C.; et al (February 2021, Environmental Research Letters)

   Abstract High nighttime urban air temperatures increase health risks and economic vulnerability of people globally. While recent studies have highlighted nighttime heat mitigation effects of urban vegetation, the magnitude and variability of vegetation-derived urban nighttime cooling differs greatly among cities. We hypothesize that urban vegetation-derived nighttime air cooling is driven by vegetation density whose effect is regulated by aridity through increasing transpiration. We test this hypothesis by deploying microclimate sensors across eight United States cities and investigating relationships of nighttime air temperature and urban vegetation throughout a summer season. Urban vegetation decreased nighttime air temperature in all cities. Vegetation cooling magnitudes increased as a function of aridity, resulting in the lowest cooling magnitude of 1.4 °C in the most humid city, Miami, FL, and 5.6 °C in the most arid city, Las Vegas, NV. Consistent with the differences among cities, the cooling effect increased during heat waves in all cities. For cities that experience a summer monsoon, Phoenix and Tucson, AZ, the cooling magnitude was larger during the more arid pre-monsoon season than during the more humid monsoon period. Our results place the large differences among previous measurements of vegetation nighttime urban cooling into a coherent physiological framework dependent on plant transpiration. This work informs urban heat risk planning by providing a framework for using urban vegetation as an environmental justice tool and can help identify where and when urban vegetation has the largest effect on mitigating nighttime temperatures. 

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5. Metalized polyamide heterostructure as a moisture-responsive actuator for multimodal adaptive personal heat management

   https://doi.org/10.1126/sciadv.abj7906  

   Li, Xiuqiang; Ma, Boran; Dai, Jingyuan; Sui, Chenxi; Pande, Divya; Smith, David R.; Brinson, L. Catherine; Hsu, Po-Chun (December 2021, Science Advances)

   Personal thermal management textile/wearable is an effective strategy to expand the indoor temperature setpoint range to reduce a building’s energy consumption. Usually, textiles/wearables that were engineered for controlling conduction, convection, radiation, or sweat evaporation have been developed separately. Here, we demonstrate a multimodal adaptive wearable with moisture-responsive flaps composed of a nylon/metal heterostructure, which can simultaneously regulate convection, sweat evaporation, and mid-infrared emission to accomplish large and rapid heat transfer tuning in response to human perspiration vapor. We show that the metal layer not only plays a crucial role in low-emissivity radiative heating but also enhances the bimorph actuation performance. The multimodal adaptive mechanism expands the thermal comfort zone by 30.7 and 20.7% more than traditional static textiles and single-modal adaptive wearables without any electricity and energy input, making it a promising design paradigm for personal heat management. 

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