Numerical Analysis of Various Heat Countermeasures: Effects on Energy Consumption and Indoor Thermal Comfort in Densely Built Wooden House Area

Densely built areas with poor thermal insulation suffer from high thermal environmental risks and generally consume high energy in summer. Determining the relationship between density and energy consumption is necessary, particularly when implementing urban heat island (UHI) countermeasures. This study evaluated the effects of density and UHI countermeasures on the energy consumption and indoor thermal comfort of a detached house in a typical densely built wooden house area in Yokohama City, Japan. Three densities and six countermeasures were considered. Annual hourly simulations based on the SCIENCE-Vent thermal environment simulation model yielded the following results: in densely built wooden house areas, the energy consumption and thermal discomfort increased with density. The green roof yielded the largest energy savings in the cooling and heating seasons, demonstrating the highest annual energy savings with 5.7%. Density had little impact on rooftop countermeasures, but the effect of the high-reflectance walls increased with density, and the reduction in annual energy consumption (air conditioning and lighting) is 2.6%, 3.0%, 3.6% in 37%, 47%, and 59% density cases, respectively. The impact of thermal countermeasures on indoor thermal comfort varied according to the thermal control mechanism

Urban surface uses for climate resilient and sustainable cities: A catalogue of solutions

Abstract In the current scenario of massive urbanization and global climate change, the urban surfaces and their characteristics have a key role, as they significantly influence the quality of life in urban areas, as well as their environmental conditions. To shed light on the role of urban surfaces in fostering climate resilient and sustainable cities, this paper proposes a catalogue of solutions for the urban surface use. The catalogue presents the main surface uses suitable for the built environment, and discusses the potential conflicts and synergies among them in the view of a multiple and integrated utilization of urban surfaces. Reviewing studies published in the last 15 years, this study aims to answer three major questions: (i) which solutions do exist, (ii) where can these be applied, and (iii) which benefits do they provide. The discussion demonstrates that the use of urban surfaces might lead the development of multiple opportunities for improving the existing urban environments and supporting not only environmental, but also social and economic resilience. Finally, it emphasizes the need for specific quantitative and qualitative approaches to address the multi-disciplinary challenges posed by the design and implementation of surface uses, and the evaluation of their contribution to site-specific objectives

Temperature Reduction Technologies Meet Asphalt Pavement: Green and Sustainability

This Special Issue, "Temperature Reduction Technologies Meet Asphalt Pavement: Green and Sustainability", covers various subjects related to advanced temperature reduction technologies in bituminous materials. It can help civil engineers and material scientists better identify underlying views for sustainable pavement constructions

中国の高温多湿地域における街区の歩行者レベルでの熱的快適性に関する研究

With the rapid development of urbanization, global warming and urban heat island (UHI) effect have attracted our attention day by day. The extreme climate may lead to an increase in heat stress, causing not only financial damage but also threating to public health and safety. The pedestrian block plays an important role in humans\u27 daily life which is not only a symbol of a city but also a significant factor affecting local tourism income. Therefore, the humans\u27 requirement about the climate condition is of high importance for architects and urban planners. In this study on-site measurement and numerical simulation are conducted to evaluate humans\u27 thermal sensation in hot summer. This study investigates the thermal comfort conditions in microclimate of different blocks and put forward some suggestion for the tourists determine the best time to visit, also help managers choose their business hours.北九州市立大

Refurbishment of apartment buildings in the Mediterranean Region for natural ventilation: implications for building design

With the emergence of climate change, the increasing figure of energy consumption for cooling in buildings expresses an urgent need for energy conscious design of new and existing buildings, and there is a significant opportunity for implementation of natural ventilation strategies. The high-energy consumption of the Greek domestic sector, the number of existing multi-storey apartment buildings, the small rate of building retrofitting in Greece and the warm, dry climate of Greece, indicate the potential to achieve significant energy reductions for cooling via natural ventilation. The aim of this research was to evaluate the energy saving potential of natural ventilation solutions for domestic buildings in the Mediterranean climate to deliver summer comfort, and to propose a low-energy refurbishment design guide. The natural ventilation efficiency of an urban multi-storey apartment building in Athens and the potential implementation of advanced natural ventilation strategies, were evaluated using modelling tools. This would provide the knowledge for future energy refurbishments. The building was a representative example of over 4 million buildings in Greece. Several ventilation strategies were implemented in a single apartment (51.4m2) and evaluated in order to enhance the existing single-sided ventilation strategy of the building, including: daytime and nighttime ventilation; cross ventilation strategies; use of a wind-catcher; lightweight dynamic façade with shading system; new internal openings; and passive downdraught evaporative cooling strategies. The ventilation performance of the strategies was investigated over the full cooling period using DTM simulations. Controlled natural ventilation strategies, in response to internal and external air properties, delivered: occupants comfort; ventilation rates increase; and reductions in air temperatures and in CO2 levels. Natural day and night ventilation contributed to significant temperature reductions (up to 7oC) relative to the base-case ventilation strategy. The proposed strategies marginally reduced the hours during the cooling period for which the CO2 levels exceeded the upper acceptable limit for comfort. The strategies also achieved air change rates above the minimum acceptable values for comfort were provided; and therefore occupants comfort was achieved. De-coupled internal-external steady state CFD airflow simulations were performed to predict wind pressures across the building openings, and to predict detailed ventilation rates for a number of climate scenarios. Using CFD it was possible to overcome the limitation of DTM and predict average pressures at the location of the openings, considering the location of the building within its surroundings (both external and internal flow simulations were performed), leading to accurate results. It was predicted that the ventilation performance of the wind catcher was significant relative to the simple single or cross-ventilation strategies. The downdraft evaporative cooling performed best at low ventilation rates providing up to 4oC further temperature reductions. Indoor comfort was provided during windless hours for specific strategies (buoyancy driven); this is significant considering that low wind speeds (below 1m/s) were predicted for 14% of the cooling period. The performance of the strategies varies considerably with regard to both wind speed and direction; these should be considered when retrofitting natural ventilation strategies in existing buildings. The proposed strategies delivered natural cooling and adequate ventilation rates, relative the base-case strategy. The combined wind catcher and dynamic façade strategy performed the best; this combined strategy would be recommended for the Mediterranean sub-climate, and for buildings comparable to the type studied. This should be combined with evaporative cooling strategies particularly during windless hours, and mechanical cooling only when these strategies do not provide sufficient performance. For both the CFD and DTM results, empirical relationships were established with statistical methods between indoor air properties and climate characteristics, which can be used to predict behaviours under conditions that have not been examined using simulations. This assists extrapolation of patterns in ventilation performance, to facilitate design guidance of the natural ventilation strategies for implementation in similar buildings. The established performance of the natural ventilation strategies in the case study building assisted the development of a prototype scenario for similar building designs with comparable climatic context. A low-energy refurbishment design guide for natural ventilation was proposed that provides guidelines and design recommendations. Retrofitting such natural ventilation strategies in existing apartment buildings in similar climates presents a significant opportunity to achieve significant energy consumption reductions

A bottom-up interdisciplinary research approach for thermal sensitive urban design in an era of climate change - the case of Lisbon

Tese de Doutoramento em Urbanismo, com a especialização em Urbanismo apresentada na Faculdade de Arquitetura da Universidade de Lisboa para obtenção do grau de Doutor.Na cidade contemporânea, factores como as elevadas temperaturas e a intensidade dos efeitos da ilha de calor em meio urbano, têm vindo a revelar proeminente desconforto térmico e importantes preocupações com a saúde durante os períodos anuais de maior estímulo térmico. Para além destes riscos já existentes e inerentes ao clima urbano, as projecções das alterações climáticas apontam para uma exacerbação destes factores de risco ao longo do Séc. XXI. Muito embora as avaliações e outputs top-down tenham revelado informação de carácter imperativo relativamente a tais fenómenos, a emergência da agenda de adaptação às alterações climáticas veio também incentivar a comunidade científica internacional a maturar e a desenvolver abordagens bottom-up mais incisivas, com vista a fazer frente aos factores de risco locais. Assim sendo, a perspectiva de "localidade" tem vindo a ganhar um novo significado para disciplinas como o urbanismo e o design urbano, quando confrontados com aspectos como a segurança, o conforto térmico humano e a prosperidade do meio urbano contemporâneo. Todavia e, atendendo ao seu carácter emergente, as abordagens bottom-up ainda se encontram numa fase inicial e, consequentemente, relativamente limitadas, tendo em conta a distância existente entre a teoria e a aplicação prática. Como resposta, esta tese efectua uma abordagem bottom-up e uma reflexão acerca do modo como a união entre a climatologia urbana e o design do espaço público urbano, enquanto campos distintos, pode ser fortalecida. Tal fortalecimento visa investigar de forma directa sobre a possibilidade de "localmente", o conforto térmico humano em meio urbano exterior, ser melhorado através de práticas interdisciplinares apoiadas no conhecimento científico. Tendo em consideração o caso de Lisboa, esta investigação analisa a forma como esta abordagem pode suplantar questões como a incerteza climática/aplicacional e, consequentemente: (i) traduzir-se em linhas de orientação para o urbanismo e para o design urbano local, que poderão ser aplicadas/implementadas em múltiplas circunstâncias e contextos urbanos; visando ainda, (ii) auxiliar especialistas "não-climatólogos" a realizar levantamentos bioclimáticos (baseados em dados locais e/ou na informação obtida a partir da estação meteorológica) com o intuito de determinar/atenuar os factores de risco de stress associados ao calor e ao frio num determinado contexto exterior. Consequentemente e, focado numa abordagem bottom-up que para além disso considera outputs relevantes a partir de avaliações top-down, o design do espaço público é retratado como sendo uma ferramenta indispensável, com vista a assegurar "localmente" um meio urbano activo, confortável e seguro, tanto no presente, quanto num futuro que se afigura incerto.ABSTRACT: Within the existing city, factors such as elevated urban temperatures and intensities of urban heat island effects are already revealing prominent thermal discomfort and health concerns during annual periods of more accentuated climatic stimuli. In addition to these exiting risks upon the urban microclimate, climate change projections indicate further exacerbations of such risks factors throughout the course of the twenty-first century. Although top-down assessments and disseminations have revealed imperative information with regards to such phenomena, the emergence of the climate change adaptation agenda has also arguably propelled the scientific international community to further mature bottom-up approaches to address local risk factors. As such, the perspective of ‘locality’ has been one which has gained new meaning for disciplines such as urban planning and design when considering the climatic safety, human thermal comfort, and prosperity of the contemporary public realm. Nevertheless, and resultant of its emerging nature, bottom-up approaches are still somewhat limited in terms of its existing breadth between theory and application and practice. As a response, this thesis undertakes a bottom-up approach and discusses how the union between the individual fields of urban climatology and public space design can be fortified. Such a fortification is directly aimed at investigating how local outdoor human thermal comfort can be improved through an interdisciplinary practice which is backed by scientific know-how and practice. Considering the case of Lisbon, this research deliberates upon how such an approach can overcome issues of climatic and applicative uncertainty, and can: (i) be translated into local design and planning guidelines which can be applied within numerous different urban circumstances; and (ii) aid non-climatological experts to undertake bioclimatic surveys (based both upon site and/or meteorological station data) to determine, and attenuate, local heat and cold stress risk factors within a particular outdoor context. Accordingly, and centred upon a bottom-up approach, which moreover considers important disseminations from top-down assessments, public space design is portrayed as an imperative tool to locally ensure an active, comfortable and safe public realm, both presently, and in an uncertain future.N/

【研究分野別】シーズ集 [英語版]

[英語版

Aerosols and Electrical Discharge: 1. Examination of Potential Climate Impact of Mercury Control in Electrostatic Precipitators (ESPs); 2. Instantaneous Bioaerosol Inactivation by Non-Thermal Plasma

One common technology for airstream aerosol (or particulate matter) control is through electrical discharge. Electrical discharge within a neutral gas under atmospheric conditions has two major essential applications related to either its physical or chemical properties. Devices such as electrostatic precipitators (ESPs) are widely applied to reduce stationary PM emission utilizing physical properties of electrical discharge. Separately, the chemical properties of the high voltage discharge can be utilized in several chemical processes, including bioaerosol disinfection. This dissertation had two research focuses related to either the physical or chemical properties of electrical discharge on aerosol control. The first study focus is on potential impact of mercury emission control by powdered activated carbon (PAC) injection to climate change due to low removal efficiency of PAC in ESPs. The injection into the flue gas of PAC is the most mature technology for controlling mercury emissions from coal combustion. However, carbonaceous particles are known to have poor capture in ESPs. Thus, the advent of mercury emissions standards for power plants has the potential for increased emissions of PAC, whose climate change impact is unclear. The study conducted the first comparative measurements of optical scattering and absorption of aerosols comprised of varying mixtures of coal combustion fly ash and PAC. A partially fluidized bed (FB) containing fly ash-PAC admixtures with varying PAC concentrations elutriates aerosol agglomerates. A photo-acoustic extinctiometer (PAX) extractively samples from the FB flow, providing measurements of optical absorption and scattering coefficients of fly ash (FA) alone and FA-PAC admixtures. The results indicate that the increase of carbonaceous particles in the FB emissions can cause a significant linear increase of their mass absorption cross sections. Thus, widespread adoption of activated carbon injection in conjunction with ESPs has the potential to constitute a new source of light absorbing (and climate warming) particle emissions. The second research focus is on packed-bed non-thermal plasma (NTP) discharges and its in-flight inactivation of bacteriophage MS2 and Porcine Reproductive and Respiratory Syndrome virus (PRRSv). To reduce threats of airborne infectious disease outbreaks, there exists a need for control measures that provide effective protection while imposing minimal pressure differential, where NTP can be a solution. In the first part of this study, a low-cost consumer-grade ultrasonic humidifier is proved to consistently suspend dry MS2 aerosols into a constant air flow, and the ultrasonic atomization rate can be monitored in real-time by laser-photodiode light attenuation measurements. In the second part, suspended viral aerosols in a controlled airstream were subjected to NTP exposure within a packed-bed dielectric barrier discharge reactor. Results of plaque assays for MS2 and TCID50 (50% Tissue culture infective dose) for PRRSv showed increasing inactivation of aerosolized viruses (42% to >99%) with increasing applied voltage. No evidence showed that the lipid layer of enveloped PRRSv offered any protection against inactivation, and the virus were inactivated comparably to MS2 by the reactor. Increasing the air flow rate did not significantly impact virus inactivation effectiveness. Activated carbon based ozone filters greatly reduced residual ozone, in some cases down to background levels, while adding less than 20 Pa pressure differential to the 45 Pa differential pressure across the packed bed. The study shows promising results that the prototype packed bed NTP reactor has the potential to reduce airborne infectious disease transmission into indoor environment without significant ozone emission and pressure drop.PHDEnvironmental EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/146103/1/xiatian_1.pd