O estudo da ventilação natural como forma de amenização climática tem sido tema de diversos trabalhos científicos apresentados em congressos e encontros da área de conforto ambiental tanto no país como no exterior. E segundo o Método de Givoni, em 74% das horas do ano, a ventilação natural é a principal estratégia de projeto para se obter o conforto térmico dos usuários na cidade de Aracaju SE. Assim sendo, tem-se como objeto desta pesquisa a ventilação natural nas habitações, e como objetivo geral um estudo do aproveitamento do vento para promover a ventilação natural em edificações residenciais na cidade de Aracaju, a fim de proporcionar melhores condições térmicas ambientais para os usuários sem a necessidade do condicionamento artificial do ar. O produto final consiste em recomendações de projeto baseadas nas pesquisas teóricas e simulações computacionais com o ANSYS CFX Computacional Fluid Dynamics Software que serviram de base para verificar a influência da ventilação natural na edificação por meio de propostas de alterações no projeto original. / Studies of natural ventilation as a way to minimize climate influences has been theme of several scientific papers presented in congresses and meetings concerning environmental comfort, in Brazil as well as in other countries. According to Givonis method, in 74% of the year hours, natural ventilation is the main strategy to obtain thermal comfort for the inhabitants of Aracaju (Sergipe capital city). Based on that information, the object of this research is the housing natural ventilation, and its general objective is a study of wind use to promote housing natural ventilation and provide better thermal comfort conditions of its users without the need of artificial air conditioning. The final product of this research consists in design recommendations based on theoretical research and computer simulations with ANSYS CFX Computacional Fluid Dynamics Software which became the base to verify the influence of natural ventilation in a building by proposing alterations in the original project.

Together with a global concern for the reduction and conservation of energy, the oil crisis of 1973 brought about a turning point in the design of buildings. Responses in this vein were mostly concentrated on the simplistic one of sealing the building against outdoor conditions. This approach towards energy consumption, associated with the introduction of air-conditioning systems, led to different problems such as Sick Building Syndrome. Lack of user satisfaction also appeared to be a common complaint in such sealed, air-conditioned buildings, leading to a marked drop in employee efficiency and, hence, return on capital investments. In this study, Emek iShani, a sealed office building located in Ankara, whose curtain wall system was renovated in 2001, was investigated in terms of its natural ventilation potential under two sub-topics. With a survey conducted, user perception towards environmental conditions, and health problems they suffered were investigated. With a computer simulation, natural ventilation potential of the building in terms of energy consumption was examined. It was resulted from the survey that building occupants have serious health problems. They are also not satisfied with the way the ventilation system functions and most of the occupants liked to have a window opening to outside in order to adjust the inner conditions. It was resulted from the computer simulation that integration of natural ventilation did not make any significant difference in the annual energy consumption of the building. On the other hand, cooling loads of the building were eliminated in summer months. As a result, introduction of natural ventilation appeared to be an appropriate tool for more user satisfaction and energy conservation.

The present work consists of two parts: experimental study of natural ventilation in a model room and the flow associated with a source-sink pair. The first part describes the natural ventilation of a model room of size 300mmx 300mm x 300mm with water as the fluid medium. It is insulated by air gaps on the four sides and at the top. A constant heat flux of 3148W/m2 has been maintained on the bottom surface of the room. This ‘room’ is surrounded by a large exterior tank containing water. The changes in temperature of the bottom, the interior and the exterior have been measured using T-type thermocouples. There are three openings each on two opposing sides of the model room. For any experiment, only one opening on each side is kept open. Fluid enters or leaves these openings and the flow is driven entirely by buoyancy forces. Three configurations have been studied: (1) The bottom opening at the inlet side and the top opening at the outlet side are open, (2) the bottom opening at the inlet side and the middle opening at the outlet side are open, and (3) the middle opening at the inlet side and the top opening at the outlet side are open. Shadowgraph technique is used for visualization. The buoyancy causes flow to enter through the bottom opening and leave through the top opening. At the openings, buoyant jets are observed and which have higher or lower relative densities. The buoyant jet at the inlet interacts with the plumes on the heated bottom plate. From these visualizations, it appears that free convection at bottom plate will be affected by the buoyant jets at the openings and the degree to which it is affected depends on the position and size of openings and distance between inlet and outlet. The flow rate due to the natural ventilation depends on the bottom surface heat flux and the height difference between the openings. The temperatures of the floor, the interior and the exterior are calculated using a simple mathematical model (Hunt and Linden [1999]). The mathematical model assumes well mixed conditions within the room and accounts for losses at the openings. The values of temperatures obtained in the experiments are reasonably well predicted by the mathematical model. The second part of the work is concerned with the interaction of a source -sink pair. The source consists of fluid issuing out of a nozzle in the form of a jet and the sink is a pipe that is kept some distance from the source pipe. Such source -sink pairs are observed in many situations including data centers, and collection of fresh water from a large reservoir that has also a discharge of pollutants. The main parameters of the problem are source and sink flow rates, the axial and lateral separations of the source and sink, and the angle between the axes of source and sink. Of concern is the percentage of source fluid that enters the sink as a function of these parameters. The experiments have been carried in a large glass water tank. The source nozzle diameter is 6mm and the sink pipe diameter is either 10mm or 20mm. The horizontal and vertical separations and angles between these source and sink pipes are adjustable. The Reynolds numbers of the source jet is about 3200. Experiments were done with the sink flow rate equal to, lower or higher than the source flow rate. The flow was visualized using KMnO4 dye and planar Laser Induced Fluorescence (LIF). The velocity fields for some cases were obtained using Particle Image Velocitymetry (PIV). To obtain the efficiency (that is percentage of source fluid entering the sink pipe), titration method is used. A small amount of hydrochloric acid (HCL) is added in the jet fluid through the overhead tank and the fluid collected at the sink is titrated with the Sodium hydroxide (NaOH) as base and Phenolphthalein as the pH indicator. The main characteristics of the jet, without a sink, were measured using PIV. The velocity profiles, jet widths and volume flow rates at various axial locations were obtained and compared with results reported in the literature for similar Reynolds number jets. For 100%, 70%, 50% and 25% efficiencies or removals and for zero lateral separations, the sink flow rate is about 1.5 times the flow rate predicted on the basis of jet properties at that point in the absence of a sink. The sink flow rate to obtain a certain efficiency increase dramatically with lateral separation; for example, when the lateral separation is about one half jet width, the required sink flow rate to obtain a certain efficiency increases by about five times. The sink diameter and the angle between source and the sink axes don’t influence efficiencies as much as the lateral separation. Data from our all experiments have been consolidated in the form of correlations that can be used for design of appropriate sinks for removal of heat and pollutants.

No description available.

This thesis considers the composition of the daily heat load in six Swedish district heating systems supplying heat for space heating and hot water supply. The analysis was performed by bringing together a heat load model and series of daily heat load observations covering periods ranging from five to eleven years. The influences of transient heat transmission, solar gain, and wind infiltration are found to be significant but small. It is shown that a natural self control of water radiators affects the magnitude of these influences when the control systems are incomplete. The annual fraction of each heat load component, the composition of the heat load duration graph, and the long term changes in heat consumption are presented. Furthermore, the heat load composition estimated facilitates future heat load simulations in order to quantify the outcome of various energy conservation measures with respect to reductions in design heat load and annual heat demand.

In office buildings located on hot humid climate areas, the architectonical typology could improve the regional winds entrance and minimize the energy consumption. The increase of ventilation inside the rooms depends on the architectonical typology adopted and the specifications related on the room s openings. The room s openings allow or make difficult to distribute the air flow inside the places, either being responsible by the rain protection, noises and excessive solar radiation. Thus, the opening s design must be considered, otherwise it will endanger the comfort condition inside an ascertain place. The opening typology influences the ventilation of the rooms offering more or less resistance to the air s flow. The Building Regulation of Maceio of 1985 determines the minimum openings area based on the floor s area, as 1/6 for light and 1/12 for ventilation. In this paper the position, orientation or main kinds of ventilation are not mentioned. These items have a straight influence on the air flow determination inside the rooms, as well the users thermal comfort. The aim of this study is to investigate three different kinds of openings in office buildings in Maceio city (sash, top hung and vertical pivot window) with area based on the Building Regulation. Computational simulations where realized with PHOENICS 3.6 software on a typical office building. The opening design is an important aspect in buildings where passive cooling is a bioclimatic strategy. Building Regulation needs to consider this aspect. For the same opening area specified for the Building Regulation the airflow and air velocity inside the office building will be different depends on the opening design. In this case, some coefficients need to be investigating for different opening design. The Building Regulation needs to apply large openings to improve air flow inside the buildings. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Em edificações de escritório localizadas em regiões quentes e úmidas, as tipologias arquitetônicas poderiam favorecer o aproveitamento dos ventos regionais, minimizando assim os gastos com energia para climatização dos mesmos. O incremento da ventilação no interior dos ambientes dependerá, entre outros fatores, da tipologia arquitetônica adotada e das especificações relacionadas às aberturas do ambiente. Tais itens estão intrinsecamente relacionados às escolhas realizadas pelo profissional que desenvolve o projeto que, por sua vez, se aplicar os princípios bioclimáticos pode aumentar consideravelmente, a construção de edifícios energicamente eficientes. Nesse sentido, pesquisas têm sido desenvolvidas para incorporar o conhecimento existente sobre as estratégias de condicionamento ambiental recomendadas para cada tipo de clima, transformando-as em especificações para normas e Códigos de Obras. Entretanto, os aspectos relacionados à ventilação, apresentam requerimentos referentes às áreas das aberturas, independentemente das diversas tipologias de aberturas existentes e da localização das mesmas. Esse trabalho investiga o impacto decorrente da utilização do tipo de 3 tipos diferentes de esquadrias (correr, maxim-ar e pivô vertical), na distribuição do fluxo de ar, considerando a área de abertura especificada pelo Código de Obras de Maceió/AL. A metodologia constitui-se em uma análise comparativa dos três tipos de esquadrias, utilizando o software PHOENICS 3.6, de uma edificação considerada típica. A esquadria de pivô vertical demonstrou um melhor desempenho quanto à distribuição do fluxo do ar e velocidade do vento no interior dos ambientes. O tipo de correr proporciona um insuflamento de ar concentrado na área das aberturas e ocorre a formação de zonas de vórtices no ambiente. A esquadria maxim-ar, além de não proporcionar um insuflamento de ar uniforme no ambiente, mostrou-se como obstáculo à entrada dos ventos devido ao seu formato. Para a mesma especificação de área de abertura do Código de Obras, a distribuição do fluxo de ar e a velocidade do vento serão influenciadas pela tipologia de esquadria adotada pelo projetista. As especificações poderiam adotar coeficientes de correção para diferentes tipologias de esquadria a rever a área de abertura para a ventilação.

O padrão de adensamento urbano impacta no conforto do pedestre no que diz respeito, sobretudo, à possibilidade de alterar as condições de vento ao nível do solo gerando zonas de desconforto. As cidades convivem com constantes mudanças em sua configuração tanto pelo adensamento quanto pela verticalização de suas estruturas, esta condição modifica a ventilação natural urbana, alterando as condições de vento no entorno de edifícios, o que afeta o escoamento de ar ao nível do solo, atingindo o conforto do pedestre. Então, o objetivo desta pesquisa é analisar o conforto do pedestre em relação ao vento em analogia a padrões de adensamento urbanos, considerando ensaios experimentais em túnel de vento a partir da aplicação em área urbana da cidade de João Pessoa-PB. A área investigada é parte dos bairros Altiplano Cabo Branco e Cabo Branco, localidade que, nos últimos anos, tem passado por grandes mudanças em sua configuração, respaldadas por alterações do instrumento urbanístico. Motivando o estudo de padrão de ocupação e seu reflexo no conforto do pedestre frente ao vento, pelo meio da avaliação de duas configurações de vizinhança ensaiadas em túnel de vento. As proposições referem-se a padrão de adensamento antigo, anterior ao ano de 2005 e adensamento recente, referente a situação atual, ano de 2012, as duas situações propostas reproduzem circunstâncias reais Os experimentos foram realizados com modelos, M1 e M2, em escala reduzida, referente a 1/400; no Túnel de Vento Prof. Joaquim Blessmann da Universidade Federal do Rio Grande do Sul, mesa M-II; pela simulação de vento do tipo turbulento, compatível com as condições do local estudado. Consideraram-se as configurações de ensaio utilizadas nesse túnel de vento para simular perfis de velocidade média, que correspondem às categorias de terreno definidos na NBR 6.123/1988, vento mar, categoria I, e vento terra, entre a categoria III e IV. Iniciou-se com os ensaios de escoamento de camada limite, que envolve a aquisição de dados de velocidades instantâneas do vento, obtidos com anemômetros de fio quente, a partir de malha de medição definida, sendo, sete linhas, oito posições e dez alturas, para dois rumos de vento, sendo 900 e 1500, definindo o comportamento do vento para a área E, prosseguiram-se com os ensaios de conforto do pedestre, através de medições de velocidades ao nível do solo para trinta e seis posições, pontos distribuídos por passeios e calçadas, por meio de sondas de pedestres, sondas tipo Irwin, realizando tomadas para vinte e quatro ângulos de incidência de vento, marcados a cada 150. Para aferir as condições de vento para o pedestre, utilizaram-se critérios de conforto baseados na Escala Beaufort, que relacionam a atividade, o local e o nível de conforto relativo, pondera ainda acerca de critérios de aceitação para períodos de retorno, um ano, um mês e uma semana. Os resultados obtidos para as configurações de vizinhança referentes ao escoamento para a área e ao conforto do pedestre, foram confrontados, atentando-se que o adensamento urbano modifica consideravelmente o campo de vento de áreas urbanas, atingindo o conforto do pedestre, impossibilitando-o, para algumas posições estudadas, de realizar atividades corriqueiras com conforto. Então, assentam-se fundamentos que orientam a ocupação do solo com vistas à garantia de realização pelo pedestre, com nível de conforto relativo “aceitável”, das atividades inerentes aos usos propostos para o ambiente urbano, colaborando com o planejamento, o controle e a intervenção em áreas urbanizadas, favorecendo, também, o crescimento saudável das cidades. / The pattern of urban densification impacts on pedestrian comfort, specially, in relation with the possibility of changing the wind conditions at ground level, generating discomfort zones. Cities live with constant changes in its configuration due to the densification and to the verticalization of its structures. This condition modifies the urban natural ventilation, changing, the wind conditions in the building surroundings, which affects the air outflow at ground level, impacting on pedestrian comfort. The objective of this work is to analyze the relation between the pedestrian comfort and the wind, similarly to the patterns of urban densification, considering experimental tests in wind tunnel, since application in the urban area of João Pessoa-PB city. The investigated area is part of the neighborhoods of Altiplano Cabo Branco and Cabo Branco, João Pessoa-PB, region that, in the last years, has been passing through considerable changings in its configuration, supported by alterations in the urban instrument. Motivating the study of the occupation patterns and its reflection in the pedestrian comfort facing the wind through the analysis of two neighborhood configurations, simulated in the wind tunnel, through experiments. The propositions refer to an old densification before the year of 2005 and to a recent densification, referring to a current situation, both proposed situations reproduce real circumstances The experiments were realized with models, M1 and M2, in reduced scale, regarding 1/400; in the Túnel de Vento Prof. Joaquim Blessmann from Universidade Federal do Rio Grande do Sul, table M-II; by the simulation of the turbulent wind, compatible with the conditions of the studied place. The configurations of assay used in this wind tunnel to simulate average velocity profiles were considered, which correspond to the ground defined in NBR 6.123/1988, sea wind, category I, and land wind, between the category III and IV. Beginning with experiments of the boundary layer’s outflow that are related to the acquisition of the wind’s instantaneous velocities’ data obtained with hot wire anemometers, from the defined measurements mesh, being seven lines, eight positions and ten heights, to two wind courses, being 900 and 1500, defining the behavior of the wind to the area. And, continued with the assays of pedestrian comfort, through measurements of the velocities at ground level for thirty six positions, points distributed for sidewalks, through pedestrian sensors, sensors of the Irwin type, realizing measurements for twenty four incidence angles, marked every 150 In order to verify the wind conditions for the pedestrians, comfort criterions based in the Escala Beaufort were utilized, which make a relation of the activity, the place and the relative comfort level, it still ponders about the acceptance criterions for return periods, one year, one month and one week. The results obtained for the configurations of the neighborhoods referents to the area’s outflow and to the pedestrian comfort were confronted, paying special attention to the fact that the urban densification modifies substantially the wind field of the urban areas, affecting the pedestrian comfort, impossibilitating it, for some studied positions, for realizing everyday activities with comfort. Then, fundamentals that guide the pattern of ground occupation were consolidated, aiming the guaranty of realization by pedestrian, with an “acceptable” relative comfort level, for the activities inherent to the uses proposed to the urban ambient, collaborating with the planning, the control and the intervention in urbanized areas, still assisting the healthy growth of the cities.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Natural ventilation is recognized by the scientific community as an important strategy for the promotion of thermal comfort. It s application in real situations, however, is extremely low, which is believed to be due to the lack of specific information as well as the lack of reliability in the success of these strategies. The present study aimed to propose, measure and evaluate natural ventilation strategy. It was defined the ventilation through the chimney effect for multiple floors educational buildings, disregarding the wind incidence, in the city of Santa Maria, RS, Bioclimatic Zone 2. Eight sizes of frames combinations have been proposed to be analyzed. Simulations with all openings combinations were made through DesignBuilder software. Based on the simulations results, it was calculated the maximum possible wind speeds through the strategy. Obtained such values, it was possible to analyze the thermal comfort gains with the different combinations of frames. It sets up, as the most suitable design and better performance, the use of all the frames in the same size, this being equivalent to 5,71% of the floor area. Analyzing through adaptive comfort, such configuration has resulted in reduction of degree-hour of discomfort in 27,9%, 33,3%, 38,8% and 42.7% for one floor, two floors, three floors and four floors building, respectively, comparing to the building without the use of the strategy. Since the results for the analyzed situation, compared to the recommended values by normatives for thermal confort condition, the strategy is evaluate as good potential and easily aplication in real situations. / A ventilação natural é reconhecida pela comunidade científica como uma importante estratégia para a promoção do conforto térmico. Sua aplicação em situações reais, no entanto, ainda é extremamente baixa, o que se acredita ser devido à falta de informação específica bem como à falta de credibilidade no sucesso de tais estratégias. Assim, o presente trabalho objetivou propor, dimensionar e avaliar estratégia de ventilação natural. Definiu-se a ventilação através do efeito chaminé para edificações de ensino de múltiplos pavimentos, desconsiderando-se a incidência de vento, para a cidade de Santa Maria, RS, Zona Bioclimática 2. Foram propostas 8 combinações de tamanhos de esquadrias a serem analisadas. Através do software DesignBuilder foram realizadas simulações com todas as combinações de aberturas pré-determinadas. Frente aos resultados das simulações foram calculadas as máximas velocidades de vento possíveis através da estratégia. Obtidos tais valores analisaram-se os ganhos obtidos em conforto térmico frente às diferentes combinações de esquadrias. Definiu-se, enquanto dimensionamento mais adequado e de melhor desempenho, o uso de todas as esquadrias de mesmo tamanho, sendo este equivalente a 5,71% da área de piso. Analisando-se via conforto adaptativo, tal configuração resultou em redução dos graus-hora de desconforto em 27,9%, 33,3%, 38,8% e 42,7% para as situações térrea, 2 pavimentos, 3 pavimentos e 4 pavimentos, respectivamente, comparando-se à edificação sem o uso da estratégia. Visto os resultados obtidos para a situação analisada, frente aos valores recomendados por normativas para condição de conforto térmico, avaliase a estratégia como de bom potencial e fácil aplicabilidade em situações reais.

Made available in DSpace on 2014-12-17T13:57:18Z (GMT). No. of bitstreams: 1 FernandoJMC_ate_referencias.pdf: 2000893 bytes, checksum: 7383eee0619fc2770d78eab5d841f5cd (MD5) Previous issue date: 2001-04-18 / 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 Petr?polis, 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 / O objetivo deste trabalho ? o estudo da ventila??o natural e a sua rela??o com as normas edil?cias. O trabalho simula a aplica??o das prescri??es urban?sticas dos ?ltimos tr?s Planos Diretores de Natal em um trecho do tecido urbano do bairro de Petr?polis, analisando os efeitos sobre a ventila??o natural. A pesquisa parte da hip?tese de que a redu??o dos recuos e a conseq?ente diminui??o da porosidade na massa edificada, eleva o n?vel do gradiente de ventila??o, reduzindo a velocidade dos ventos nos n?veis mais baixos das edifica??es. Para o desenvolvimento do estudo, s?o produzidos modelos de ocupa??o com recursos de modelagens computadorizadas em tr?s dimens?es, as quais s?o posteriormente submetidas ? an?lise em programa de Mec?nica dos Fluidos Computadorizada. Conclui-se que a redu??o sucessiva nos ?ndices que definem os afastamentos m?nimos entre os edif?cios, produz a redu??o da velocidade dos ventos em ?reas adensadas, aumentando a possibilidade de forma??o de ilhas de calor

Made available in DSpace on 2014-12-17T13:57:19Z (GMT). No. of bitstreams: 1 SilenoCT.pdf: 2677839 bytes, checksum: ab606ee9a9e47606999ca5cf548141a6 (MD5) Previous issue date: 2006-12-08 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / 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 / A ventila??o natural se constitui no principal recurso passivo para obten??o do conforto t?rmico em climas quentes e ?midos, al?m de promover a redu??o do consumo energ?tico com condicionamento artificial. Entretanto, existem restri??es ao seu uso por parte dos arquitetos por n?o haver garantias de que ela possa resolver os problemas de conforto t?rmico, quando comparada aos sistemas artificiais. Nesse sentido, decidiu-se investigar formas de prever o comportamento da ventila??o natural atrav?s de ferramentas de simula??o computacional, visando auxiliar a decis?o arquitet?nica. O objeto de estudo ? o edif?cio pr?fabricado tipo galp?o devido ?s suas caracter?sticas geom?tricas e ? freq??ncia de uso na regi?o, especificamente no campus universit?rio central da UFRN. Foi utilizado um programa de din?mica de fluidos (Computational Fluid Dynamics - CFD) e um de simula??o do comportamento t?rmico e energ?tico de edifica??es (energy tool - ET). A pesquisa priorizou a discuss?o dos procedimentos necess?rios para viabilizar as an?lises da ventila??o em galp?es. Durante seu desenvolvimento, ? mostrado como o m?todo teve que ser adequado ? complexidade de sucessivas abordagens, resultando em simplifica??es e incertezas de resultados. Para exemplificar a abordagem s?o apresentados alguns resultados de simula??es. Ao final, as limita??es e potencialidades do m?todo s?o discutidas com base nas caracter?sticas dos c?digos de simula??es utilizados, das condi??es de simula??o e da representatividade dos modelos