1,186 research outputs found

    Cooling Infrastructure, Cooling Security, and a Warming World

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    Sustainable Urban Future in Southern Europe - What About the Heat Island Effect?

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    In general cities, and especially cities in hot zones, as the Mediterranean, suffer from raised temperatures in the city core, generally known as the heat island effect. Raised temperatures, especially in summer, may turn city centres into unwelcome hot areas, with direct effects on energy consumption for cooling buildings and morbidity and mortality risks for the population. These raised temperatures in the city centre derive from the altered thermal balances in urban spaces, mainly due to the materials and activities taking place in cities, by far different to those in rural areas. The notably raised thermal capacity of urban materials, their low albedo and their lack of porosity are of the main characteristics of urban materials, responsible for the formation of raised urban temperatures. The general lack of vegetation is a strong characteristic of the formation of the heat island effect. If building surfaces, which are greatly responsible for the formation of raised urban temperatures are covered with vegetation (roofs with grasses and walls with ivies), it is expected that urban temperatures could lower significantly. With the case study of the city of Athens, this paper explores quantitatively how raised urban temperatures could reduce in the hot and dry Mediterranean summer, when the building envelope is covered with vegetation. With the use of a prognostic, two-dimensional, micro-scale heat and mass transfer model, the effect of vegetation in urban canyons with different geometries and orientations is explored and how this could be applied at an urban scale. The effect of vegetation on the building envelope is examined on the outdoors thermal comfort and the energy consumption for cooling. Conclusions are drawn about the relationship of the effect of diverse amounts of vegetation with the urban geometry and orientation and whether such a proposal could prove beneficial for cities in the South of Europe.

    A spatial vulnerability analysis of urban populations during extreme heat events in Australian capital cities

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    Extreme heat events pose a risk to the health of all individuals, especially the elderly and the chronically ill, and are associated with an increased demand for healthcare services. In order to address this problem, policy makers need information about temperatures above which mortality and morbidity of the exposed population is likely to increase, where the vulnerable groups in the community are located, and how the risks from extreme heat events are likely to change in the future.  This study identified threshold temperatures for all Australian capital cities, developed a spatial index of population vulnerability, and used climate model output to predict changes in the number of days exceeding temperature thresholds in the future, as well as changes in risk related to changes in urban density and an ageing population.  The study has shown that daily maximum and minimum temperatures from the Bureau of Meteorology forecasts can be used to calculate temperature thresholds for heat alert days. The key risk factors related to adverse health outcomes were found to be areas with intense urban heat islands, areas with higher proportions of older people, and areas with ethnic communities.  Maps of spatial vulnerability have been developed to provide information to assist emergency managers, healthcare professionals, and ancillary services develop heatwave preparedness plans at a local scale that target vulnerable groups and address heat-related health risks. The numbers of days exceeding current heat thresholds are predicted to increase over the next 20 to 40 years in all Australian capital cities. Authors: Margaret E. Loughnan, Nigel J. Tapper, Thu Phan, Kellie Lynch, Judith A. McInne

    Heat response plans : summary of evidence and strategies for collaboration and implementation

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    Extreme heat is a major public health concern in the United States. Temperatures are increasing across the country, with more frequent and severe heat waves in many regions. This trend is projected to continue. Exposure to heat may increase the risk of illness particularly among sensitive groups such as people who do not have access to air conditioning, older adults, young children, people working outdoors, athletes, the socially isolated, people with existing chronic conditions, and some communities of color. Health departments, their partners, and other government agencies have undertaken a variety of strategies to protect the public from high temperatures. One potential strategy is a heat response plan - a coordinated plan that describes and organizes activities to prevent heat-related morbidity and mortality in a community.Health departments at all levels (state, local, Tribal, and territorial) and their partners can develop and implement a response to protect their community and vulnerable populations. There is evidence that heat response plans can protect health, but mixed evidence on the effectiveness of individual components of a heat response plan and the degree of overall health protection. This document is intended to give a summary of extreme heat, the health burden of heat exposure, the impacts of climate change, and components and effectiveness of heat response plans with a focus on relevant peer-reviewed literature and existing heat response plans. Resources and examples of successful implementation and potential collaborative efforts are included.CS311462-APublication date from document properties.HeatResponsePlans_508.pdf2020833

    An Aggregate Model of the Flexible Energy Demand of Thermostatically Controlled Loads with Explicit Outdoor Temperature Dependency

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    In this paper we describe an aggregate model of Thermostatically Controlled Loads (TCLs) for Demand Response (DR) scheduling that, through a new approximation, makes explicit the dependency between the feasible control region and the time series of outdoor temperatures. In turn, the model can easily account for non-constant, stochastic temperatures during the control period, expressing the feasible load control through a set of linear equations and constraints with stochastic parameters. To highlight this feature we present a stochastic optimization formulation for the management of the DR-TCL and compare it with its deterministic counterpart, and with various equivalent models aimed at reducing the complexity of the constraints in the market optimization

    Assessing urban heat island mitigation capacities of green infrastructure to address heat vulnerability inequities in San Francisco, California

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    With extreme heat events projected to become more frequent and longer-lasting, heat vulnerable communities affected by urban heat islands face disproportionate heat impacts. While cities have adopted heat adaptation efforts, there needs to be a focus on vulnerable communities to ensure an equitable distribution of adaptation efforts. Green infrastructure has been a long-standing heat adaptation method with benefits including reduced temperatures, reduced energy consumption, and reduced air pollution. This research analyzed the heat mitigation capacity of four green infrastructure types and identified heat vulnerable communities to address whether current green infrastructure in San Francisco is equitably distributed. Dense tree cover and increased tree abundance had positive impacts on the mitigation ability of each green infrastructure type. San Francisco census tracts with 4.1% poverty had the highest amount of tree abundance and were situated in the coolest parts of the city, while census tracts with 71% poverty were lacking green infrastructure and experienced hotter temperatures. In order for San Francisco to ensure green infrastructure is equitably distributed, I recommend that the scoring process for heat vulnerabilities be modified to consider smaller communities, green infrastructure heat mitigation goals be set for individual districts, and resources for community-led street tree implementation be directed toward vulnerable communities, and green roof retrofitting subsidies or grants offered to existing building. Extreme heat events will continue to affect vulnerable communities if cities are not well prepared, and a just distribution of the resources already being implemented needs to be a priority

    Risk factors and costs influencing hospitalizations due to heat-related illnesses: patterns of hospitalization

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    The objective of this dissertation was to identify individual and environmental risk factors, investigate outcomes and hospital resource use, including costs, and document the pattern of heat-related illness hospitalizations in the United States. The main data source for the study population was the 2001-2010 Nationwide Inpatient Sample (NIS). The study population for heat-related illnesses (HRIs) consists of patients in the NIS with at least one diagnosis of a heat-related illness (ICD-9 codes 992.0 - 992.9) from 2001 to 2010. Outcome analysis included a study population of patients who had primary or secondary diagnoses of diabetes, cardiovascular diseases, respiratory illnesses, nephritic illnesses and acute renal failure along with a diagnosis of a heat-related illness. Outcomes for costs were calculated and adjusted using the medical consumer price index for 2013. Data on air conditioner use and total cost of electricity use from air conditioning was derived from the Residential Energy Consumption Survey. This study identified a number of previously unknown risk factors for heat morbidity HRI, including age greater than 40, males and hospitalization in rural areas and small urban clusters. Additionally, stratified analyses of outcomes further identified specific risk factors among vulnerable populations. Elevated risk of negative health outcomes and increased hospital resource use was seen in patients diagnosed with common comorbidities, in particular those of a lower socioeconomic status, minority and most age groups with diagnoses of cardiac and respiratory diseases with a HRI. Analyses of costs showed substantial costs associated with hospitalizations due to heat-related illnesses with the average mean cost approximately $52.7 million while the total aggregate cost for the time period at just over half a billion dollars. Projected estimates for the average yearly cost of these hospitalizations in the future climate with estimates around half a billion US dollars by the late-21st century. In conclusion, the study revealed a number of risk factors and negative health outcomes associated with hospitalizations of heat-related illnesses. These findings provide additional scientific evidence that heat-related illnesses will continue to rise and will continue to be a public health burden as climate changes increase in frequency and intensity of extreme weather events
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