published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

Unfavorable thermal comfort conditions are common in the non-conditioned apartment buildings typical of Dhaka (Ali, 2007; Hafiz, 2004). Causes behind such unfavorable thermal comfort conditions include (but are not limited to) Dhaka?s climate, microclimate in Dhaka's typical residential neighborhood, its socio-economic context, housing type, and its inadequate planning regulations. Dhaka's climate is hot humid but it can be tackled with well designed buildings as well as well as designed neighborhoods, both of which demands ample open space. However, due to land scarcity and high population density, building developments lack open spaces and that results in unfavorable thermal comfort conditions in apartment buildings. Dhaka?s previous zoning regulations were unable to control this dense development, and therefore, a new set of zoning regulations were enacted (2008). However, no post-evaluation study was conducted to research the effect of this new set of regulations. The intention of this research is to first evaluate the existing regulations, and second, to suggest appropriate zoning regulation schemes for Dhaka's non-conditioned apartment buildings (for a lot size of 1/3 acre), which would provide favorable thermal comfort conditions without changing its existing density. To accomplish the first goal, this research analyzed two existing zoning schemes (one based on regulations of 1996, and the other based on the regulations of 2008). To accomplish the second goal, this research analyzed two hypothetical zoning schemes. The hypothetical ones were studied because this research finds 1996 and 2008 regulations to be two extremes (in terms of allowing open space and building height), and therefore examination of in-between alternative zoning schemes seemed essential for this study. To analyze the four zoning regulation schemes' impact on thermal comfort in apartment buildings, four sets of built environment were created in EnergyPlus (Energy Simulation software) as well as in Fluent (Computational Fluid Dynamics software). Each set of built environment is a cluster of nine buildings; and each set is different from each other in terms of their building footprints and building heights. The building on the center was modeled implicitly, and remaining buildings were modeled as solid blocks (to act as neighboring buildings) for blocking sun and wind. The ES and CFD software simulated possible solar, daylight, and wind availability inside the central building, and consequently produce data on thermal comfort conditions, namely indoor temperature and air velocity. The simulation results were compared to see which zoning schemes provided the most favorable thermal comfort conditions. This research found one of the in-between schemes (60% allowable footprint, 9-story height limit) to be more appropriate in terms of thermal comfort conditions than the other three schemes; because it provides better solar protection and better natural ventilation and consequently it reduces indoor temperature and increases indoor air velocity.

Orientador: Lucila Chebel Labaki / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-26T07:50:03Z (GMT). No. of bitstreams: 1 Silveira_FranciscoMassucci_M.pdf: 9492485 bytes, checksum: f3520eb8830cb5c6373fb8dc37cb631c (MD5) Previous issue date: 2014 / Resumo: A obtenção de ambientes internos confortáveis termicamente é um dos aspectos fundamentais na obtenção de um edifício de qualidade. Por vezes, para se atingir este objetivo consome-se quantidades significativas de energia em sistemas de condicionamento ambiente. É preciso ressaltar que grande parte da população não possui recursos para aquisição e manutenção destes sistemas, ficando, portanto, exposta ao comportamento térmico de suas edificações. Assim, é fundamental compreender, como e sob quais circunstâncias, ocupantes de uma edificação consideram-na confortável de modo a avaliar e propor soluções que permitam a geração de conforto ao menor custo. A obtenção do conforto através do uso exclusivo da climatização artificial vem se mostrando uma prática dispendiosa, dando lugar a introdução da ventilação natural e outras práticas de resfriamento passivo. A aplicação destes instrumentos tem ganhado força recentemente, sendo referenciado em normativos internacionais que regulam sobre o tema. A partir de 2004, a norma ASHRAE 55 Environmental Conditions for Human Occupancy adotou uma abordagem de análise denominada modelo adaptativo: uma metodologia opcional, proposta para avaliação do desempenho térmico em edifícios ventilados naturalmente. O método utiliza-se da temperatura operativa - que correlaciona efeitos da temperatura de bulbo seco, temperatura radiante e velocidade do ar - como principal fator indicador de conforto. Além disso, a norma correlaciona a faixa de temperatura de conforto à ocorrência de temperaturas externas, possibilitando a comparação entre edificações situadas em climas distintos. Neste contexto, esta pesquisa destina-se à verificação do desempenho térmico de uma edificação unifamiliar através da análise do conforto térmico, levando-se em consideração aspectos de uso, ocupação e ventilação natural, utilizando-se a abordagem adaptativa proposta pela norma ASHRAE 55/2013. O método utilizado compreende a simulação computacional de uma edificação habitacional unifamiliar de 63m², por meio da utilização do software EnergyPlus. O modelo simulado não possui sistema de condicionamento ativo e a ventilação natural foi simulada pelo EnergyPlus, através do algoritmo denominado AirflowNetwork, um modelo de ventilação por rede, onde são estimados fluxos de massa através de aberturas e perda de carga térmica em decorrência de diferenças de pressão nas aberturas do edifício. A condição para abertura das janelas é dependente da temperatura externa e de uma temperatura máxima interna arbitrada, o que permite utilizar a ventilação natural como ferramenta de resfriamento passivo. O trabalho compreende a análise de diferentes variáveis de projeto, divididas em cinco grupos, a partir de um caso base inicial. Os grupos de análise definidos são: componentes de fachada; componentes de cobertura; orientação da edificação; absortância de componentes de fachada e temperatura de setpoint para ventilação. Para cada grupo foram estipulados diferentes casos, compreendendo aspectos e elementos convencionais do mercado de construção habitacional. Todos os casos foram analisados para as condições climáticas de Campinas-SP, Curitiba-PR e Natal-RN a partir de modelo adaptativo de conforto pela norma ASHRAE 55/2013, e comparados ainda a resultados obtidos através do método simplificado e simulado, presente na norma NBR15575/2013. Os resultados apontam as melhores práticas construtivas, demonstrando substancial importância do modelo adaptativo na verificação do conforto térmico em projeto para edificações destinadas à habitação de interesse social / Abstract: Achieve thermal comfortable indoor environments is a key aspect to obtaining a quality building. Sometimes, in order to achieve it, significant amount of energy in conditioning systems is consumed. It should be emphasized that a large part of the population does not have resources for acquisition and maintenance of these systems, being exposed to passive thermal behavior of their buildings. Thus, it is essential to understand how and under what circumstances, occupants of a building consider it comfortable to assess and propose solutions that generate comfort at a lower cost. Obtaining comfort through exclusive use conditioning systems has proved an expensive practice, leading to the introduction of natural ventilation and other passive cooling practices. The application of these instruments has excelled recently, being referenced in international standards. In 2004, the ASHRAE 55 Environmental Conditions for Human Occupancy adopted a method called adaptive model analysis: an optional methodology, proposed for evaluation on thermal performance in naturally ventilated buildings. The method uses the operative temperature - which correlates the effects of dry bulb temperature, mean radiant temperature and air velocity - as the main indicator of comfort. Moreover, the standard correlates the range of comfort to the occurrence of outdoor temperatures, enabling comparison between buildings located at different climates conditions. Under this context, this study aimed to verify the thermal performance of a dwelling through the analysis of thermal comfort, including aspects of use, occupancy and natural ventilation. The method comprises the computer simulation of a 63m² single-family housing construction, using the software EnergyPlus. The simulated model has no active conditioning system. Natural ventilation was simulated with EnergyPlus through the algorithm AirflowNetwork, a model of ventilation network, where mass flows through openings and loss of thermal load, due to pressure differences in building, are estimated. The condition for opening window depends on external temperature and a setpoint temperature, which supposes the use of natural ventilation only as daytime passive cooling tool. The work includes the analysis of different design variables, divided into five groups, defined from an initial base case. The analysis groups are: masonry components; roofing components; orientation; absorptance and setpoint temperature for ventilation. For each group were prescribed different situations, including aspects and elements of conventional housing construction market. All cases were analyzed for the climatic conditions of Campinas - SP, Curitiba - PR and Natal - RN for adaptive comfort model by ASHRAE 55/2013, yet compared to results obtained by the simplified method and simulated method present in NBR15575/2013. The results indicate the best construction practices, demonstrating substantial importance of adaptive model to assess thermal comfort of dwellings / Mestrado / Arquitetura, Tecnologia e Cidade / Mestre em Arquitetura, Tecnologia e Cidade

Orientador: Lucila Chebel Labaki / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-19T06:39:40Z (GMT). No. of bitstreams: 1 Camargo_RenataMartinhode_M.pdf: 4984279 bytes, checksum: 362dc581c34f0a018e1778f146c62eab (MD5) Previous issue date: 2011 / Resumo: A ventilação natural em regiões tropicais é uma eficiente estratégia de projeto para a obtenção de conforto térmico e para a redução do consumo de energia. O aproveitamento dos recursos naturais e das condicionantes do clima melhora a integração do edifício com o entorno e a obtenção do conforto através de sistemas passivos de condicionamento. Os efeitos do vento em um edifício são analisados através da dinâmica dos fluidos computacional (CFD, Computational Fluid Dynamics) ou de estudos em túnel de vento. É importante quantificar variáveis como: velocidade, pressão, temperatura e coeficiente de pressão. Os Hospitais da Rede Sarah Kubistchek, projetados por João Filgueiras Lima, Lelé, são considerados bons exemplos de arquitetura bioclimática, devido as suas soluções passivas de conforto, como a utilização dos sheds, que promovem a iluminação e a ventilação natural. Esses hospitais foram construídos em várias capitais brasileiras, com diferentes climas. Este trabalho tem como objetivo avaliar a eficiência da ventilação natural dos Hospitais Sarah localizados nas cidades de Brasília e Belém. Essas cidades foram escolhidas devido às características climáticas bastante diferenciadas - clima quente seco e quente úmido. Os sheds no hospital de Belém funcionam como extratores de vento, ao passo que no hospital de Brasília Lago Norte foram projetados como captadores de vento. A análise é feita através de ensaios em túnel de vento de camada limite atmosférica. Os testes incluem medições de velocidade do ar e pressão em vários pontos dentro e fora dos edifícios. O hospital de Belém é analisado em sua implantação real e na situação em que o vento predominante incide perpendicularmente à fachada. Os resultados mostram que, tanto o conjunto de aberturas e o sistema de sheds do hospital de Belém, quanto a sua implantação, proporcionaram maior velocidade do ar nos ambientes internos do que o hospital Brasília Lago Norte. Os resultados dos coeficientes de pressão permitiram confirmar que, para os dois hospitais analisados, o projeto de ventilação natural aproveita as áreas de maior pressão para posicionamento das aberturas de entrada e saída de ar / Abstract: Natural ventilation in tropical regions is an efficient design strategy for achieving thermal comfort and reducing energy consumption. The utilization of natural resources and climate conditions improves integration of the building with its surroundings and allows comfort conditions through passive systems of conditioning. The effects of wind on a building are analyzed using computational fluid dynamics (CFD, Computational Fluid Dynamics) or wind tunnel studies. It is important to quantify variables such as speed, pressure, temperature and pressure coefficient. The Sarah Kubitschek Network hospital, designed by João Filgueiras Lima, Lelé, are considered good examples of bioclimatic architecture, due to the passive solutions for comfort, such as the use of sheds, which provide natural lighting and ventilation. These hospitals were built in several Brazilian cities with different climates. This study aims to evaluate the efficiency of natural ventilation of Sarah hospitals located in the cities of Brasília and Belém. These cities were chosen because of the different climate characteristics of the two cities - mild dry and hot humid. The sheds in the hospital of Belem act as wind extractors, while those in in Brasilia Lago Norte hospital was designed as a means of wind catchers. The analysis is done through testing in atmospheric boundary layer wind tunnel. The tests include measurements of air velocity and pressure at several points inside and outside of buildings. The Belém hospital is analyzed in its actual implantation and in the situation where the prevailing incident wind is perpendicular to the facade. The results show that both the number of openings and the shed system in the hospital in Belém, as well as its implantation, provided a higher air speed in indoor environments than the hospital Brasília Lago Norte. The results for the pressure coefficients allow to confirm that for both hospitals studied, the design of natural ventilation takes advantage of the higher pressure areas for positioning of the income and exit of air / Mestrado / Arquitetura e Construção / Mestre em Engenharia Civil

No abstract available. / Dissertation (MArch (Prof))--University of Pretoria, 2005. / Architecture / unrestricted

The post-apartheid repetition and insertion of an unchanged standard clinic design across South Africa, has resulted in a number of urban and design problems stemming from the architecture of the clinics and their inability to adapt. Designed before the resurgence of the Tuberculosis epidemic, the facilities were not designed for optimal ventilation or air-borne infection prevention . The current healthcare facilities cannot support the ever-increasing urban population, and as a result, patients are forced to wait for long hours before being attended to, in poorly ventilated, unstimulating spaces. Emanating from an understanding of the relationship between architecture, health and the transmission of disease, the dissertation endeavours to create a new healthcare facility that remedies these problems through design. The dissertation identifies Alaska, an informal settlement, as an appropriate site in need of and with a population size to support a new public healthcare facility. Recognising the risks of blind top-down provision of buildings into informal settlements, the dissertation explores the power of a collaborative approach towards design. The design process engages the community in a series of participatory exercises in order to discover and enable grass-roots knowledge and innovation, and to instill a sense of ownership and responsibility for the intervention, after construction is complete. The dissertation studies the traditional healthcare practitioners within the settlement, for spatial clues and an alternate approach to the provision and architecture of healthcare. The Salutogenic (the healthy pole of the health- disease continuum) approach of the traditional healers is merged with the pathogenic design sensibilities of typical western facilities, in order to create a facility which not only focuses on curing disease, but also on instilling preventative habits within the community. The intervention intention to be reflective of and responsive to the dynamic context of Alaska, is realised through the spatial and design intelligences of a top-down provider enabling the innovation and local knowledge of bottom-up approaches through a collaborative design process. The intetnion is expressed through the inclusion and manipulation of local building materials and techniques. / Dissertation (MArch(Prof))--University of Pretoria, 2014. / Architecture / MArch(Prof) / Unrestricted

Energy demands are projected to continue increasing over the next decade, which is prompting a change towards higher efficiencies and better utilization of the current energy supply. Thermal waste energy, a prominent inefficiency during any process, can be converted to electrical energy or re-purposed for low-grade energy needs, such as hot water and space heating/cooling. Naturally ventilated chimneys, driven by buoyancy differences between the exhaust gases and the surrounding air, prove to be a source of waste heat. The challenge of waste heat recovery from naturally ventilated exhaust networks is the reduction in buoyancy effects and increase in flow restrictions within the network. This research study will focus on understanding the effects of waste heat recovery and the associated exhaust control devices on the performance of a naturally ventilated exhaust network and the accompanying appliance(s). To investigate the effects, a nodal network methodology using mass and energy conservation principles was adapted for exhaust networks to develop a one-dimensional computational model. In contrast to previous exhaust flow design methodologies, this method solves for the thermal input of the appliance and the associated flow rates, temperature, and pressures via the appliance set point temperature and exterior conditions, such as outside temperature and pressure. Using empirical correlations for heat transfer and pressure loss coefficients of appliance and exhaust components, the computational model was validated through experimental testing of an exhaust network used in the development of a waste heat recovery system called TEG POWER (Thermal Electrical Generator Pizza Oven Waste Energy Recovery). The experimental facility was constructed to investigate the exhaust network with and without the TEG POWER system, along with exhaust control devices. These devices included an exhaust throttling valve and a draft hood to induce dilution air into the chimney. To investigate the individual effects of the devices, experimental testing was conducted at an oven temperature of 300°F (148.9°C), 500°F (260°C), and 600°F (315.6°C) with varying degrees of throttling and/or dilution air. The mass flow measurements were calculated using an energy balance technique validated against a two-way energy balance and well-established heat transfer and pressure loss correlations of the heat exchanger. The experimental mass flow, temperature, and draft pressure results were compared against the respective computational predictions and found to be within a ±10% agreement. The application of the exhaust control techniques with and without waste heat recovery is highly dependent on the objective(s), such as reducing natural gas consumption, and the constraint(s), such as a minimum chimney temperature, placed on the exhaust network design. Using the computational model, a design methodology was proposed to meet the objective(s) within the constraints of the exhaust network. To test the design methodology, a case study was performed with the objective to minimize oven natural gas consumption with a TEG POWER system in relation to a baseline appliance solely fitted with a draft hood. Within the constraints, the methodology was able to identify the appropriate degree of throttling and dilution air intake to minimize natural gas consumption. With the inclusion of the TEG POWER system, the case study showed a potential reduction in natural gas consumption by up to 18% (1.7 L/min) and 13% (3 L/min) at 300 and 600°F oven operating temperatures, respectively. The implementation of the control technique allowed the oven to minimize the intake of dilution air by up to 70% and maintain operational stability during exterior fluctuations in temperature and pressure. The implementation of the waste heat recovery device captured up to 1.0 and 2.7 kW, or a natural gas equivalent of 1.9 and 5 L/min, at 300 and 600°F oven operating temperatures respectively. Implemented into the 8,000 pizza restaurants across Canada, the TEG POWER system would reduce total natural gas consumption by up to 65.5 million cubic meters, which is enough to heat 24,000 Canadian homes, and reduce CO2 output by 112,000 metric tonnes. / Thesis / Master of Applied Science (MASc)

Natural ventilation is an effective method to save energy required to condition buildings and to improve indoor air quality. Computational fluid dynamics (CFD) was used to model single-sided buoyancy-driven natural ventilation in a single room with a heater and door. The velocity and temperature profiles at the doorway agreed fairly well with published literature that includes Mahajan's experimental [2] and Schaelin et al's numerical studies [1]. The 2D and 3D models predicted the neutral level with a difference of 5.6 % and 0.08 % compared to the experimental results, respectively. Using solutions at the doorway, heat transfer rates were calculated. More realistic situations were studied considering conduction, various ambient conditions, wind speeds, and additional heat sources and furniture in the room. The heat loss through the wall was modeled and the airflow and temperature within the room showed no significant changes despite modeling conduction through the walls. Various ambient temperatures and wind speeds were tested, and the neutral level height and total heat transfer rate through the doorway increased with decreasing ambient temperatures. However, the neutral level did not significantly change as wind speeds varied. Total heat transfer rate at the doorway became positive, that is heat transferred into the room, with wind speed. Lastly, the effect of additional heat sources (mini-refrigerator, monitor and computer) and furniture (bookshelf, desk, chair and box) on airflow and heat transfer in the room was analyzed by comparing with a simple case of a room with a heater. Large velocities and high temperatures were predicted in the vicinity of the heat sources. However, the spatially averaged velocity and temperature did not change significantly despite additional heat sources. The room with furniture was modeled at lower ambient temperature, where the spatially averaged velocities were larger and temperatures were lower than the simple case. The room heated up and reached its thermal comfort level, but the velocities exceeded the maximum acceptable level set by ASHRAE guidelines [8]. Wind was considered simultaneously with the lower temperature, and the room was cooled faster with wind. However, the room was never able to achieve the comfortable level both in velocity and temperature. / Master of Science

Designing buildings to use energy more efficiently can lead to lower energy costs, while maintaining comfort for occupants. Computational fluid dynamics (CFD) can be utilized to visualize and simulate expected flows in buildings and structures. CFD gives architects and designers the ability to calculate the velocity, pressure, and heat transfer within a building. Previous research has not modeled natural ventilation situations that challenge common design rules of thumb used for cross-ventilation and single-sided ventilation. The current study uses a commercial code (FLUENT) to simulate cross-ventilation in simple structures and analyzes the flow patterns and heat transfer in the rooms. In the Casa Giuliana apartment and the Affleck house, this study simulates passive cooling in spaces well-designed for natural ventilation. Heat loads, human models, and electronics are included in the apartment to expand on prior research into natural ventilation in a full-scale building. Two different cases were simulated. The first had a volume flow rate similar to the ambient conditions, while the second had a much lower flow rate that had an ACH of 5, near the minimum recommended value Passive cooling in the Affleck house is simulated and has an unorthodox ventilation method; a window in the floor that opens to an exterior basement is opened along with windows and doors of the main floor to create a pressure difference. In the Affleck house, two different combinations of window and door openings are simulated to model different scenarios. Temperature contours, flow patterns, and the air changes per hour (ACH) are explored to analyze the ventilation of these structures. / Master of Science

This study sought to demonstrate the potential applications of the solar chimney for the naturally ventilating a building. Computational fluid dynamics (CFD) was used to model various room configurations to assess ventilation strategies. A parametric study of the solar chimney system was executed, and three-dimensional simulations were compared and validated with experiments. A new definition for the hydraulic diameter that incorporated the chimney geometry was developed to predict the flow regime in the solar chimney system. To mitigate the cost and effort to use experiments to analyze building energy, a mathematical approach was considered. A relationship between small- and full-scale models was investigated using non-dimensional analysis. Multiple parameters were involved in the mathematical model to predict the air velocity, where the predictions were in good agreement with experimental data as well as the numerical simulations from the present study. The second part of the study considered building design optimization to improve ventilation using air changes per hour (ACH) as a metric, and air circulation patterns within the building. An upper vent was introduced near the ceiling of the chimney system, which induced better air circulation by removing the warm air in the building. The study pursued to model a realistic scenario for the solar chimney system, where it investigated the effect of the vent sizes, insulation, and a reasonable solar chimney size. It was shown that it is critical to insulate the backside of the absorber and that the ratio of the conditioned area to chimney volume should be at least 10. Lastly, the application of the solar chimney system for basement ventilation was discussed. Appropriate vent locations in the basement were determined, where the best ventilation was achieved when the duct inlet was located near the ceiling and the exhaust vent was located near the floor of the chimney. Sufficient ventilation was also achieved even for scenarios of a congested building when modeling the presence of multiple people. / Ph. D.