985 resultados para Natural ventilation
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This research covers the topic of social housing and its relation to thermal comfort, so applied to an architectural and urban intervention in land situated in central urban area of Macaíba/RN, Brazil. Reflecting on the role of design and use of alternative building materials in the search for better performance is one of its main goals. The hypothesis is that by changing design parameters and choice of materials, it is possible to achieve better thermal performance results. Thus, we performed computer simulations of thermal performance and natural ventilation using computational fluid dynamics or CFD (Computational Fluid Dynamics). The presentation of the thermal simulation followed the methodology proposed in the dissertation Negreiros (2010), which aims to find the percentage of the amount of hours of comfort obtained throughout the year, while data analysis was made of natural ventilation from images generated by the images extracted from the CFD. From model building designed, was fitted an analytical framework that results in a comparison between three different proposals for dwellings housing model, which is evaluated the question of the thermal performance of buildings, and also deals with the spatial variables design, construction materials and costs. It is concluded that the final report confirmed the general hypotheses set at the start of the study, it was possible to quantify the results and identify the importance of design and construction materials are equivalent, and that, if combined, lead to gains in thermal performance potential.
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The present work studies the natural ventilation and its relationship with the urban standards, which establishes the form of occupation and use of the land in our cities. The method simulates the application of the urban standards of the City Master Plan over the last three years. The simulation takes place in the District of Petrópolis, in the city of Natal , Brazil and analyses the effects of the standards of natural ventilation. The formulated hypothesis states that the reductions in the urban spaces between buildings rises up the vertical profile of ventilation, reducing, therefore, the velocity of the wind at the lower levels of the buildings. To develop the study, occupation models were built, using computerized, three-dimensional models. These occupation models were analyzed using the CFD (Computational Fluid Dynamics) code. The conclusion is that the more we reduce the urban space between buildings, the more we reduce the wind speed in constructed areas, increasing, therefore, the possibility to generate heat islands
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Natural air ventilation is the most import passive strategy to provide thermal comfort in hot and humid climates and a significant low energy strategy. However, the natural ventilated building requires more attention with the architectural design than a conventional building with air conditioning systems, and the results are less reliable. Therefore, this thesis focuses on softwares and methods to predict the natural ventilation performance from the point of view of the architect, with limited resource and knowledge of fluid mechanics. A typical prefabricated building was modelled due to its simplified geometry, low cost and occurrence at the local campus. Firstly, the study emphasized the use of computational fluid dynamics (CFD) software, to simulate the air flow outside and inside the building. A series of approaches were developed to make the simulations possible, compromising the results fidelity. Secondly, the results of CFD simulations were used as the input of an energy tool, to simulate the thermal performance under different rates of air renew. Thirdly, the results of temperature were assessed in terms of thermal comfort. Complementary simulations were carried out to detail the analyses. The results show the potentialities of these tools. However the discussions concerning the simplifications of the approaches, the limitations of the tools and the level of knowledge of the average architect are the major contribution of this study
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Um dos grandes entraves para o desenvolvimento econômico mundial é a crescente demanda por energia e consequente aumento da utilização de recursos naturais para provê-la. Países em desenvolvimento, como o Brasil, apresentaram progressivo consumo de energia per capita nos últimos anos. Embora a sua maioria seja proveniente de usinas hidrelétricas (fontes não poluidoras) sua construção causa grande impacto ambiental. De todo o percentual energético gerado, as edificações são responsáveis pelo consumo de aproximadamente 40% e este percentual tende a aumentar mediante o crescimento da construção civil no país. Diante da problemática, o combate ao desperdício, a racionalização e o uso sustentável da energia consumida pelas edificações estão diretamente ligados à redução do impacto ao meio ambiente, postergando a necessidade de aumento da matriz energética nacional. Neste contexto é criado o Regulamento Técnico da Qualidade do Nível de Eficiência Energética de Edifícios Comerciais, de Serviço e Públicos (RTQ-C). Este trabalho consiste em uma aplicação crítica do RTQ-C utilizando a metodologia prescritiva, tendo como enfoque aspectos relativos a sua aplicabilidade e avaliação de conforto térmico e lumínico, tendo como premissa que o alto desempenho energético da edificação só é plenamente alcançado quando são garantidas condições satisfatórias de conforto ambiental aos usuários. Para tanto foi necessária uma etapa minuciosa de levantamento de dados e medições “in loco” de temperatura do ar, temperatura radiante, iluminância e umidade relativa em dois ambientes (laboratório de conforto e sala de aula 2) do edifício do Centro de Excelência em Eficiência Energética da Amazônia - CEAMAZON, subsidiando a utilização da metodologia proposta por Fanger (PMV e PPD), e verificação dos níveis de iluminância propostos pela NBR 5413. Como resultado a edificação apresentou bom desempenho, mas a não observância dos prérequisitos a classificou com nível “C”. A avaliação de conforto indicou que aproximadamente 23% dos usuários não estavam em conforto térmico e que a ventilação natural poderá ser utilizada como estratégia bioclimática para adequação. As medições de iluminância indicaram que apenas a sala de aula 2 possuia potencial de aproveitamento de iluminação natural no período da medição. Concluiu-se que, apesar de sua importância, o RTQ-C deve passar ainda por um processo de adaptação por parte da sociedade e dos profissionais envolvidos na certificação energética de edificações e que durante esse período modificações poderão ser incorporadas contribuindo para torná-lo um instrumento efetivamente válido para a garantia da eficiência energética das edificações do país.
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A presente dissertação de mestrado estuda o desempenho térmico de materiais de fachada em uma edificação verticalizada na cidade de Belém – PA, Brasil. Este trabalho tem por objetivo contribuir com estudo do desempenho térmico e eficiência de materiais utilizados na envoltória das edificações residenciais verticalizadas, entre os elementos opacos, foram selecionados dois tipos de materiais, bastante utilizados atualmente na construção civil, a pintura e revestimento cerâmico. Também estuda-se a influência da altura da edificação sobre seu desempenho térmico e eficiência energética. O estudo foi desenvolvido com o uso de modelagem em código computacional no programa EnergyPlus que permite avaliar o desempenho térmico da edificação, a influência da altura na eficiência energética da mesma. Compara-se o desempenho térmico dos dois materiais selecionados, verificou-se que o prédio com revestimento cerâmico apresentou a temperatura interna média anual de 0,42 º C acima da temperatura referente ao prédio pintado, portanto com menor desempenho térmico. A influência da altura do pavimento não produziu uma variação significativa na temperatura interna, pois com seu acréscimo, ocorreu pequena diminuição da temperatura interna, com gradiente térmico da ordem de -0,07ºC /m em decorrência da velocidade do vento que é maior quando mais alto é o pavimento. Considera-se também para este estudo a ventilação natural como estratégia passiva para a edificação em estudo, que segundo a análise da Carta Bioclimática de Givoni contribuiria positivamente para a condição de temperatura interna e umidade do ar, e consequentemente do usuário.
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This study aimed to assess measurements of temperature and relative humidity obtained with HOBO a data logger, under various conditions of exposure to solar radiation, comparing them with those obtained through the use of a temperature/relative humidity probe and a copper-constantan thermocouple psychrometer, which are considered the standards for obtaining such measurements. Data were collected over a 6-day period (from 25 March to 1 April, 2010), during which the equipment was monitored continuously and simultaneously. We employed the following combinations of equipment and conditions: a HOBO data logger in full sunlight; a HOBO data logger shielded within a white plastic cup with windows for air circulation; a HOBO data logger shielded within a gill-type shelter (multi-plate prototype plastic); a copper-constantan thermocouple psychrometer exposed to natural ventilation and protected from sunlight; and a temperature/relative humidity probe under a commercial, multi-plate radiation shield. Comparisons between the measurements obtained with the various devices were made on the basis of statistical indicators: linear regression, with coefficient of determination; index of agreement; maximum absolute error; and mean absolute error. The prototype multi-plate shelter (gill-type) used in order to protect the HOBO data logger was found to provide the best protection against the effects of solar radiation on measurements of temperature and relative humidity. The precision and accuracy of a device that measures temperature and relative humidity depend on an efficient shelter that minimizes the interference caused by solar radiation, thereby avoiding erroneous analysis of the data obtained.
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Greenhouse with natural ventilation is widely used in tropical countries, and little knowledge is available about how this type of structure affects the spatial variability of agroclimatic variables. The aim of this study was to analyse the spatial variability of relative humidity inside a greenhouse with natural ventilation. The measurement of relative humidity was done at 114 points inside the greenhouse at 9, 12 and 16 hours and on heights of 0.3, 1.2 and 2.0 m. The acquired data were processed by the geostatistical software GS+ and maps were generated and displayed for each time and height using the Surfer 10.3.705 software. The results showed that there were variations in the spatial distribution of relative humidity inside the greenhouse.
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Crambe (Crambe abyssinica Hochst) seeds have high oil contents and its growth in Brazil aims to produce bio diesel. The crambe seeds production and commercialization began a few years ago. Research in technology production is essential and it is also important to use high quality seeds regardless of the technological level employed in the crop production. One of the factors that affect seed quality there is the drying process. Seed drying performed properly can reduce seed moisture content for storage without decrease in its qualitative characteristics. The aim of this study was to evaluate the immediate effect of natural and artificial drying methods (using heated and unheated air) on crambe seeds quality. The seeds were produced at Fazenda Lageado, Faculdade de Ciências Agronômicas, UNESP, Botucatu/SP, on April 2009. Seeds were submitted to the following drying methods: a) seed drying in the shade with natural ventilation; b) artificial drying method using heated air; c) artificial drying method using unheated air; d) drying on ceramic patio; e) drying on the mother plant. The seeds were evaluated immediately after drying. The following tests were performed: seed moisture content; standard germination; first count of germination; seedling emergence; emergence speed index and electrical conductivity. The experimental design was randomized blocks and the data obtained was subjected to analysis of variance, worth means being compared by Tukey test at 5% probability. There was no significant difference among drying treatments in relation to: germination rate, first count of germination, electrical conductivity, seedling emergence and emergence speed index. The highest percentage of abnormal seedlings was obtained on treatment with heated air drying. The drying on the mother plant method showed the lower percentage of dead seeds. The drying methods studied did not cause an immediate effect on crambe seeds quality, which showed high percentage of dormant seeds post-harvest.
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Estratégias passivas de projeto reduzem significativamente o uso de ar condicionado e melhoram o conforto térmico dos usuários. Isto pode ser ilustrado através dos hospitais da Rede Sarah Kubitschek projetados pelo arquiteto João Filgueiras Lima, Lelé, cujas soluções além de propiciarem ambientes mais agradáveis e salubres, evitam o uso de sistemas mecânicos de resfriamento, reduzindo o consumo de energia elétrica. Deste modo, o presente artigo tem como objetivo avaliar o conforto térmico dos hospitais Sarah de Salvador e do Rio de Janeiro, através de medições in loco da temperatura do ar, umidade relativa do ar e velocidade do ar. A análise dos resultados foi baseada em leituras de projeto, na norma ASHRAE Standard 55/2004 e em parâmetros adquiridos na literatura especializada. Os resultados demonstram a preocupação de Lelé na incorporação de aspectos bioclimáticos nos projetos. No Sarah - Salvador, alguns ambientes permaneceram fora da zona de conforto no período do meio dia, devido ao ganho de calor pela cobertura. No entanto, o uso da ventilação natural auxilia no efeito de resfriamento, melhorando o conforto térmico nos espaços internos. Já no Sarah - Rio, todos os ambientes permanecem dentro da zona de conforto proposta pela ASHRAE 55.
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The general aim of this work is to contribute to the energy performance assessment of ventilated façades by the simultaneous use of experimental data and numerical simulations. A significant amount of experimental work was done on different types of ventilated façades with natural ventilation. The measurements were taken on a test building. The external walls of this tower are rainscreen ventilated façades. Ventilation grills are located at the top and at the bottom of the tower. In this work the modelling of the test building using a dynamic thermal simulation program (ESP-r) is presented and the main results discussed. In order to investigate the best summer thermal performance of rainscreen ventilated skin façade a study for different setups of rainscreen walls was made. In particular, influences of ventilation grills, air cavity thickness, skin colour, skin material, orientation of façade were investigated. It is shown that some types of rainscreen ventilated façade typologies are capable of lowering the cooling energy demand of a few percent points.
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Esta tesis se enmarca dentro de una línea de investigación iniciada en el 2004 focalizada en el estudio de soluciones constructivas energéticamente eficientes para la crianza del vino. El objetivo principal es promover el ahorro energético y la sostenibilidad en el diseño de la sala de crianza de las bodegas. Para ello, se profundiza en el estudio de las bodegas subterráneas, ejemplo de eco-construcción, ya que por lo general proporcionan condiciones adecuadas para la crianza sin gasto energético en climatización. En concreto, se abordan aspectos clave para la caracterización y comprensión del funcionamiento de estas construcciones, que en muchas ocasiones condicionan el éxito o el fracaso de las mismas. Así, se analiza el complejo comportamiento de la ventilación natural a lo largo del año, determinando los factores que la condicionan, desvelando el papel que desempeña tanto el túnel de acceso como las chimeneas de ventilación en su funcionamiento. Además, se desarrollan y validan modelos de simulación mediante CFD, que permiten evaluar y predecir con detalle el comportamiento termofluidodinámico de las construcciones subterráneas. Por otra parte, se cuantifica la uniformidad y estabilidad de la sala de crianza a lo largo del año, información que permite fijar recomendaciones y pautas concretas de diseño de los planes de monitorización. Finalmente, se determinan las diferencias de comportamiento higrotérmico existentes entre un amplio abanico de bodegas subterráneas para vino tinto, bodegas representativas de otras soluciones constructivas alternativas de vino tinto, así como bodegas para cavas y vinos generosos, enmarcando el comportamiento de estas bodegas en un contexto global. Además, se desarrollan metodologías adaptadas a las características particulares de estas construcciones, en concreto un sistema de monitorización basado en termografía infrarroja para llevar a cabo inspecciones puntuales para el control ambiental de grandes naves de crianza. Es de esperar que los estudios técnicos y las herramientas desarrolladas ayuden a mejorar el diseño de nuevas bodegas, y a la mejora de las condiciones higrotérmicas de las ya existentes, colaborando a que España siga situada en la vanguardia de la producción de vino de calidad. ABSTRACT This thesis is part of the research started in 2004 and focusing on the study of the energy efficiency in wine aging constructive solutions. The main objective is to promote energy conservation and sustainability in the design of wine aging rooms. To do so, this study focuses on the analysis of the underground cellars, example of eco-construction, since they usually provide adequate conditions for wine aging without using air-conditioning systems. In particular, key aspects for characterizing and understanding these constructions, which often determine the success or failure of them. Thus, the complex behavior of natural ventilation throughout the year is discussed, determining the influencing factors and revealing the role of both the access tunnel and the ventilation chimney. In addition, numerical models are developed and validated using CFD simulation, allowing an in-depth assessment and prediction of the thermofluidynamic behavior in underground constructions. Moreover, uniformity and stability of the aging room throughout the year is quantified, allowing for precise information useful to set recommendations and design guidelines for defining monitoring plans. Finally, hygrothermal behavior differences between a wide range of underground cellars for red wine, red wine wineries with alternative construction solutions and wineries for generous wines and cava wines, In addition, new methodologies adapted towards the particular characteristics of these constructions, a monitoring system based on infrared thermography to perform periodic inspections for environmental controls of the aging rooms, are developed. It is expected that the technical studies and tools developed here will help to improve the design of new wineries, and also the hygrothermal conditions of the existing ones, headed for keeping Spain in the forefront of the countries producing high quality wine.
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Hurricane is one of the most destructive and costly natural hazard to the built environment and its impact on low-rise buildings, particularity, is beyond acceptable. The major objective of this research was to perform a parametric evaluation of internal pressure (IP) for wind-resistant design of low-rise buildings and wind-driven natural ventilation applications. For this purpose, a multi-scale experimental, i.e. full-scale at Wall of Wind (WoW) and small-scale at Boundary Layer Wind Tunnel (BLWT), and a Computational Fluid Dynamics (CFD) approach was adopted. This provided new capability to assess wind pressures realistically on internal volumes ranging from small spaces formed between roof tiles and its deck to attic to room partitions. Effects of sudden breaching, existing dominant openings on building envelopes as well as compartmentalization of building interior on the IP were systematically investigated. Results of this research indicated: (i) for sudden breaching of dominant openings, the transient overshooting response was lower than the subsequent steady state peak IP and internal volume correction for low-wind-speed testing facilities was necessary. For example a building without volume correction experienced a response four times faster and exhibited 30–40% lower mean and peak IP; (ii) for existing openings, vent openings uniformly distributed along the roof alleviated, whereas one sided openings aggravated the IP; (iii) larger dominant openings exhibited a higher IP on the building envelope, and an off-center opening on the wall exhibited (30–40%) higher IP than center located openings; (iv) compartmentalization amplified the intensity of IP and; (v) significant underneath pressure was measured for field tiles, warranting its consideration during net pressure evaluations. The study aimed at wind driven natural ventilation indicated: (i) the IP due to cross ventilation was 1.5 to 2.5 times higher for Ainlet/Aoutlet>1 compared to cases where Ainlet/Aoutlet<1, this in effect reduced the mixing of air inside the building and hence the ventilation effectiveness; (ii) the presence of multi-room partitioning increased the pressure differential and consequently the air exchange rate. Overall good agreement was found between the observed large-scale, small-scale and CFD based IP responses. Comparisons with ASCE 7-10 consistently demonstrated that the code underestimated peak positive and suction IP.
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This work analyses a study on natural ventilation and its relation to the urban legislation versus the building types in an urban fraction of coastal area of Praia do Meio in the city of Natal/RN, approaching the type or types of land use most appropriate to this limited urban fraction. The objective of this study is to analyse the effects of the present legislation as well as the types of buildings in this area on the natural ventilation. This urban fraction was selected because it is one of the sites from where the wind flows into the city of Natal. This research is based on the hypothesis stating that the reduction on the porosity of the urban soil (decrease in the set back/boundary clearance), and an increase in the form (height of the buildings) rise the level of the ventilation gradient, consequently causing a reduction on the wind speed at the lowest part of the buildings. Three-dimensional computational models were used to produce the modes of occupation allowed in the urban fraction within the area under study. A Computational Fluid Dynamics (CFD) software was also used to analyse the modes of land occupation. Following simulation, a statistical assessment was carried out for validation of the hypothesis. It was concluded that the reduction in the soil porosity as a consequence of the rates that defined the minimum boundary clearance between the building and the boundary of the plot (and consequently the set back), as well as the increase in the building form (height of the buildings) caused a reduction in the wind speed, thus creating heat islands