Managing Air for Green Inner Cities

点击翻译按钮获取中文摘要

The challenge articulated in this proposal is: how to develop cities with no air pollution and no heat-island effect by 2050?It is difficult to predict with precision the future of cities, but there will be significant adaptations and changes by 2050, due to advances in technology, changing populations, social expectations and climate change. A roadmap is needed to ensure that decisions taken as the city evolves lead towards a sustainable future. Approximately half of the energy use, carbon dioxide emissions and exposure to air pollution in cities is due to either buildings or transportation, and this total energy use is increasing. Air pollution is projected to be the leading global cause of mortality by 2050. Therefore the question posed here in terms of air quality and temperature rise is important in its own right. However, these quantities together also provide, perhaps uniquely, specific measurable physical properties that cover an entire city and provide a metric for assessing the sustainability of system-wide decisions. Traditional approaches to urban environmental control rely on energy-consuming and carbon/toxics-producing heating, ventilation and air conditioning (HVAC) systems. These traditional approaches produce an unsustainable cycle of increasing energy use with associated emissions of carbon dioxide and pollutants leading to rising temperatures implying, in turn, greater use of HVAC. Breaking this vicious cycle requires a completely different engineered solution, one that couples with natural systems and does not depend solely on mechanical systems. This project will develop a facility consisting of an integrated suite of models and an associated management and decision support system that together allow the city design and its operation to manage the air so that it becomes its own HVAC system, with clean, cool air providing low-energy solutions for health and comfort. This will be achieved by using natural ventilation in buildings to reduce demand for energy and ensuring air pollutants are diluted below levels that cause adverse health effects, coupled with increased albedo to reduce the heat island effect plus green (parks) and blue (water) spaces to provide both cooling and filtration of pollutants. We have brought together a trans-disciplinary research team to construct this facility. It will be comprised of three components: (i) a fully resolved air quality model that interacts with sensor data and provides detailed calculations of the air flow, pollutant and temperature distributions in complex city geometries and is fully coupled to naturally ventilated buildings, and green and blue spaces; (ii) reduced order models that allow rapid calculations for real time analysis and emergency response; and (iii) a cost-benefit model to assess the economic, social and environmental viability of options and decision. The scientific air quality component is a fully-resolved computational model that couples external and internal flows in naturally ventilated buildings at the building, block and borough scales. It will be supported and validated by field measurements at selected sites and by wind tunnel and salt-bath laboratory studies. The reduced order models will be developed from the computational model and from laboratory process studies, and will be capable of producing gross features such as mean pollutant concentrations and temperatures. They will be used to provide capabilities for scoping studies, and real-time and emergency response. The cost-benefit model will provide the link between the scientific and engineering models and implementation advice. It will include modules for the built environment, public spaces and transportation, and provide estimates of the life-cycle costs and benefits of the various scenarios at the individual building, city block and borough scales. Eventually, it is envisaged that this will also include social and health effects.