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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Long term thermal performance and application of glass fiber core vacuum insulation panels

Chan, Vivian 22 December 2020 (has links)
Glass fiber core Vacuum Insulation Panels (VIPs) have thermal performance per unit thickness of about 5-10 times higher than the traditionally used building insulation materials such as mineral wool, XPS, EPS, foam, etc. This advantage of VIP has made it very attractive new option for innovative building designs. Especially in Canada, where some of the areas have long and very cold winters. Confidence in the service life of a building material is necessary before putting a product to market. Extensive research has been conducted on the product development, quality improvement, and field application of VIPs around the world. However, there is lack of consistent and simple prediction method for the long-term thermal performance of VIPs. This paper discussed the process and performance of a field project using glass fiber VIPs to retrofit a commercial building in Yukon, Canada. The thermal performance of the VIPs used in this project was continuously monitored and critically analyzed since the start in 2011. The results have shown satisfactory thermal performance of VIPs for the past 8 years. The findings were also used to validate glass fiber core VIP accelerated aging tests conducted by the National Research Council Canada (Ottawa), and the aging rate of VIPs in a cold and dry climate was determined. The second part of this study investigated the monitored performance results from two sets of simplified accelerated laboratory aging tests, the results were analyzed with the aim to separate the impact of air diffusion from water vapour on the long-term thermal performance of glass fiber VIPs. In addition, this study also investigated the potential application of VIPs in balcony constructions to reduce heat transfer through thermal bridges. Computer modeling exercises, using a benchmarked (EN ISO 10211) three-dimensional transient and steady-state heat transfer simulation tool HEAT3, were carried out on the most optimal (thermal performance) balcony assemblies of wood framed buildings using VIP as insulation. This niche application of VIPs can significantly increase the energy efficiency of building envelopes/skins in extreme climates of Canada and elsewhere in the world. / Graduate / 2021-11-06
32

Influence of temperature and moisture content on thermal performance of green roof media

Shao, Bohan 26 October 2020 (has links)
Numerical estimates of the ability of a green roof to reduce energy consumption in buildings are plagued by a lack of accuracy in thermal properties that are input to the model. An experimental study into the thermal conductivity at different temperatures and moisture contents was performed using four different commercially available substrates for green roofs. In the unfrozen state, as moisture content increased, thermal conductivity increased linearly. In the phase transition zone between +5 ºC and -10ºC, as temperature decreased, thermal conductivity increased sharply during the transition from water to ice. When the substrate was frozen, thermal conductivity varied exponentially with substrate moisture content prior to freezing. Power functions were found between thermal conductivity and temperature (when shifted up by +10.001ºC). Two equally sized, green roof test cells were constructed and tested to compare various roof configurations including a bare roof, varying media thickness for a green roof, and vegetation. The results show that compared with the bare roof, there is a 75% reduction in the interior temperature amplitude for the green roof with 150mm thick substrate. When a sedum mat was added, there’s a 20% reduction in the amplitude of the inner temperature as compared with the cell without sedum mat. / Graduate
33

Assessing the Thermal Performance of Glazed Curtain Wall Systems : S+G Project Case Study

Emili, Antonella January 2015 (has links)
The improvement of curtain wall thermal performances and the optimisation of the issues connected with this technology can lead to a sensible reduction of the energy consumption of the building as well as to an increase level of occupant comfort and longer durability of the façade. The aim of this work is to improve the curtain wall technology especially as far as the connection between the glass and the frame is concerned, since it is the part that mainly affects the performances of the whole façade. This project focuses on the different aspects of the thermal performance of curtain wall systems in order to achieve a higher thermal performance, meeting the objectives of lowering energy demand, improving durability and enhancing indoor comfort. In order to develop new high performance curtain wall connections and to test their level of performance compared with the state of the art ones, two methods were deployed: a numerical and an experimental one. FEM analysis was performed with the software THERM (LBNL) analysing the profile of surface temperatures and the U-values of the details. In the FEM analysis, different materials and geometries were studied. The experimental characterisation of the thermal energy performance of the studied design options was performed by means of thermometric measurements in a climatic cell. The purpose of the experimental analysis was the verification of the effective improvement of the performance in the new details and the comparison with the simulation, aiming at the validation of the simulation model.
34

Power Station Thermal Efficiency Performance Method Evaluation

Heerlall, Heeran 16 February 2022 (has links)
Due to global warming, there is an escalated need to move towards cleaner energy solutions. Almost 85% of South Africa's electric energy is provided via Eskom's conventional coal-fired power plants. Globally, coal-fired power plants have a significant share in the power generation energy mix and this will be the case over the next 20 years. A study, aligned with the aspiration of improving the thermal efficiency of the coal-fired power plants, was initiated, with a focus on the accuracy of energy accounting. The goal is that: if we can accurately quantify efficiency losses, the effort can be prioritized to resolve the inefficiencies. Eskom's thermal accounting tool, the STEP model, was reviewed against relevant industry standards (BS 2885, BS EN 12952-15, IEC 60953-0/Ed1) to evaluate the model uncertainty for losses computed via standard correlations. Relatively large deviations were noted for the boiler radiation, turbine deterioration and make-up water losses. A specific review of OEM (Original Equipment Manufacturer) heat rate correction curves was carried out for the determination of turbine plant losses, where these curves were suspected to have high uncertainty, especially when extrapolated to points of significant deviation from design values. For an evaluated case study, the final feed water correction curves were adjusted based on an analysis done with the use of power plant thermodynamic modelling tools namely: EtaPro Virtual Plant® and Steam Pro®. A Python® based computer model was developed to separately propagate systematic (instrument) and combined uncertainties (including temporal) through the STEP model using a numerical technique called sequential perturbation. The study revealed that the uncertainties associated with thermal efficiency, heat rate and individual thermal losses are very specific to the state of operations, as demonstrated by individual unit performance and the power plant's specific design baseline performance curves. Whilst the uncertainties cannot be generalized, a methodology has been developed to evaluate any case. A 3600 MWe wet-cooled power plant (6 x 600 MWe units) situated in Mpumalanga was selected to study the impact of uncertainties on the STEP model outputs. The results from the case study yielded that the thermal efficiency computed by the “direct method”, had an instrument uncertainty of 0.756% absolute (abs) versus the indirect method of 0.201% abs when computed at the station level for a 95% confidence interval. For an individual unit, the indirect efficiency uncertainty was as high as 0.581% abs. A study was conducted to find an optimal resolution (segment size) for the thermal performance metrics to be computed, by discretizing the monthly data into smaller segment sizes and studying the movement of the mean STEP model outputs and the temporal uncertainty. It was found that the 3-hour segment size is optimal as it gives the maximum movement of the mean of performance metrics without resulting in large temporal uncertainties. When considering the combined uncertainty (temporal and instrument uncertainty) at a data resolution of 1 minute and segment size of 3 hours, the “direct method”, had a combined thermal efficiency uncertainty of 0.768% abs versus the indirect method of 0.218% abs when computed at the station level for a 95% confidence interval. This would mean that the temporal uncertainty contribution to the combined uncertainty is 2.915% for the “direct method” and 14.919% for the “indirect method” of the above-stated uncertainties. The term “STEP Factor” can be used synonymously with effectiveness (percentage of the actual efficiency relative to the target efficiency). For the case evaluated, the mean “indirect method” STEP Factor at the station level moved from 86.698% (using monthly aggregated process data) to 86.135% (when discretized to 3-hour segments) which is roughly a 0.189% abs change in the station's thermal efficiency. This would appear fairly small on the station's overall efficiency but had a significant impact on the evaluation of the STEP Factor losses and the cost impact by the change in the plant efficiency, e.g. the final feed water STEP Factor loss at a unit level moved from 2.6% abs to 3.5% abs which is significant for diagnostic and business case motivations. Later the discrepancy between the direct STEP Factor and indirect STEP Factor were investigated as the uncertainty bands did not overlap as expected. The re-evaluation of the baseline component performance data resulted in the final feed water and the condenser back-pressure heat rate correction curves being adjusted. The exercise revealed that there could be potentially be significant baseline performance data uncertainty. The corrected indirect STEP Factor instrument uncertainty was now found to be 0.468% abs which translates to 0.164% abs overall efficiency. The combined uncertainty was corrected to 0.485% abs at a 3-hour segment size which translates to 0.171% abs overall efficiency. It has been deduced that the figures stated above are case-specific. However, the models have been developed to analyse any coal-fired power plant at various operating conditions. Furthermore, the uncertainty propagation module can be used to propagate uncertainty through any other discontinuous function or computer model. Various recommendations have been made to improve: the model uncertainty of STEP, data acquisition, systematic uncertainty, temporal uncertainty and baseline data uncertainty.
35

Measuring and modeling the effects of temperature on the amphibian chytrid fungus and assessing amphibian skin bacterial communities

Gajewski, Zachary John 17 August 2021 (has links)
Emerging infectious diseases are a threat to wildlife populations and conservation efforts. One example of this is the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis and has been linked to amphibian populations declines worldwide. There have been numerous attempts to mitigate the effects of Bd on amphibians, all with mixed results. Two factors that have previously been found to correlate with Bd infection intensity and prevalence are the amphibian skin bacterial communities and environmental temperatures. Some naturally occurring bacteria on the skin of amphibians and warmer temperatures can limit Bd infection. For my dissertation research, I aimed to 1) assess the amphibian skin bacterial communities across species, developmental stage, infection status, and different local environments, and 2) understand and predict the effect of a natural, varying temperature regime on the growth of Bd from constant temperature data. In Chapter 1, I reviewed the amphibian chytrid fungus and the effects of varying temperature on organisms' performance or trait rates. In Chapter 2, I sampled bacterial communities on ranid tadpoles and three ranid frog species at Mianus River Gorge Preserve in Bedford, New York, USA. I found that tadpoles had significantly different bacterial alpha diversity measurements than adult frogs, with higher Faith's phylogenetic diversity, Shannon diversity, and amplicon sequence variant (ASV) richness. Bacterial communities between the three different adult frogs species were not different. Additionally, infected frogs did not have significantly different bacterial communities than uninfected frogs. In Chapter 3, I predicted Bd growth in three varying temperature environments with Bayesian hierarchical models assuming different thermal performance curves. My predictions overestimated the growth of Bd in varying temperature environments, and the choice of thermal performance curve used in the models strongly impacted the predictions by altering the implied relationship between Bd's growth rate and temperature. In Chapter 4, I aimed to improve modeling methods for predicting in vitro Bd growth in varying temperature environments by adding additional features to the model based on observed biological phenomena, specifically a temperature-dependent delay period for Bd development. However, the model parameters were unidentifiable with this added complexity when only optical density data are available to quantify growth, highlighting the need to match the appropriate data to the complexity of the model. In Chapter 5, I created a mechanistic model that was parameterized by a combination of optical density, MTT assays (a metabolic assay), and zoospore count data to learn more about Bd growth dynamics. I also examined how many days of zoospore count data are needed to fit the mechanistic model. By combining these three data sources, I increased the ability to estimate most model parameters. My dissertation added to both the amphibian skin bacterial community literature, supporting differences between tadpoles and adult frog bacterial communities, and added new data from a previously unsurveyed area. Attempts are being made to use bacterial communities to limit diseases in many wildlife populations, through a probiotic. To use skin bacterial communities, factors that shape these communities need to be understood to ensure the successful application of a probiotic. My dissertation also added to the thermal ecology literature, showing that current methods and my optical density Bayesian hierarchical model do not accurately predict performance in varying temperature environments. As temperatures are changing around the world and temperature variability is expected to increase in many places, predicting how organisms will perform in new thermal environments is becoming increasingly important. / Doctor of Philosophy / Infectious diseases around the world have led to wildlife population declines. Chytridiomycosis is a disease in amphibians caused by the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd). Bd infects the skin of amphibians and can cause death. The composition of amphibian skin bacterial communities, bacteria that live on the skin of amphibians, can limit the growth of Bd on amphibians and reduce disease. Due to some species of bacteria inhibiting Bd growth, attempts have been made to try to use bacteria to limit disease in amphibians. But, we still do not know to what extent some host and environmental factors influence host bacterial communities, and how this might influence disease in amphibians. Warmer environmental temperatures have also been associated with reduced chytridiomycosis in amphibians. However, the effect of temperature is often studied at constant temperatures instead of natural, varying temperatures. The impact of varying temperature on Bd growth dynamics is still not fully understood. My dissertation research examined 1) differences in amphibian bacterial communities in different species and at different developmental stages (tadpoles vs. frogs), and 2) whether I can accurately predict Bd growth in varying temperature environments. First, I examined skin bacterial communities of three frog species at Mianus River Gorge, in Bedford, NY. I found that tadpoles had more diverse bacterial communities than adult frogs and that adults from the three species had similar bacterial communities, and that Bd infection status did not correlate with skin bacterial community composition. Second, I examined how temperature impacts the growth of Bd and whether we can predict how Bd grows in natural, fluctuating temperature conditions. Specifically, I used data from lab experiments in which I grew Bd at constant temperatures to fit a model and then predict how Bd grew in temperatures that fluctuate over the day as they would in nature. I found that current methods that use constant temperature data to predict how Bd grows in natural temperature scenarios are not accurate. Third, I attempted to improve modeling methods to predict Bd growth in natural temperature scenarios by specifying that Bd development is dependent on temperature. I found that the increasing model complexity without the correct type or amount of data leads to not being able to fit the model. Lastly, I combined three different types of Bd growth data to fit a new model that describes Bd growth. Fitting this new model with three data sources, I learned more about Bd growth and was more certain about the values of the parameters in the model. Additionally, this model has parameters and model components directly related to Bd growth, unlike in the previous Chapters' models. Using this model will allow us to examine how temperature influences specific Bd growth stages in future studies. My dissertation examined host and environmental factors that influence skin bacterial communities. Determine how these factors shape and change host bacterial communities will allow scientists to successfully use bacteria to reduce disease in amphibians and other wildlife. Additionally, I examined methods in the literature and built my own model to predict Bd growth in varying temperature environments. I found that taking constant temperature data from the lab to predict Bd growth in more natural varying temperature environments is not accurate and future studies need to improve these methods. Developing these methods is becoming more important as temperatures change around the world and organisms are exposed to new temperatures. Improving these methods would allow more accurate predictions about organisms' performance in new environmental conditions.
36

NUMERICAL AND EXPERIMENTAL ANALYSIS OF HEAT PIPES WITH APPLICATION IN CONCENTRATED SOLAR POWER SYSTEMS

Mahdavi, Mahboobe January 2016 (has links)
Thermal energy storage systems as an integral part of concentrated solar power plants improve the performance of the system by mitigating the mismatch between the energy supply and the energy demand. Using a phase change material (PCM) to store energy increases the energy density, hence, reduces the size and cost of the system. However, the performance is limited by the low thermal conductivity of the PCM, which decreases the heat transfer rate between the heat source and PCM, which therefore prolongs the melting, or solidification process, and results in overheating the interface wall. To address this issue, heat pipes are embedded in the PCM to enhance the heat transfer from the receiver to the PCM, and from the PCM to the heat sink during charging and discharging processes, respectively. In the current study, the thermal-fluid phenomenon inside a heat pipe was investigated. The heat pipe network is specifically configured to be implemented in a thermal energy storage unit for a concentrated solar power system. The configuration allows for simultaneous power generation and energy storage for later use. The network is composed of a main heat pipe and an array of secondary heat pipes. The primary heat pipe has a disk-shaped evaporator and a disk-shaped condenser, which are connected via an adiabatic section. The secondary heat pipes are attached to the condenser of the primary heat pipe and they are surrounded by PCM. The other side of the condenser is connected to a heat engine and serves as its heat acceptor. The applied thermal energy to the disk-shaped evaporator changes the phase of working fluid in the wick structure from liquid to vapor. The vapor pressure drives it through the adiabatic section to the condenser where the vapor condenses and releases its heat to a heat engine. It should be noted that the condensed working fluid is returned to the evaporator by the capillary forces of the wick. The extra heat is then delivered to the phase change material through the secondary heat pipes. During the discharging process, secondary heat pipes serve as evaporators and transfer the stored energy to the heat engine. Due to the different geometry of the heat pipe network, a new numerical procedure was developed. The model is axisymmetric and accounts for the compressible vapor flow in the vapor chamber as well as heat conduction in the wall and wick regions. Because of the large expansion ratio from the adiabatic section to the primary condenser, the vapor flow leaving the adiabatic pipe section of the primary heat pipe to the disk-shaped condenser behaves similarly to a confined jet impingement. Therefore, the condensation is not uniform over the main condenser. The feature that makes the numerical procedure distinguished from other available techniques is its ability to simulate non-uniform condensation of the working fluid in the condenser section. The vapor jet impingement on the condenser surface along with condensation is modeled by attaching a porous layer adjacent to the condenser wall. This porous layer acts as a wall, lets the vapor flow to impinge on it, and spread out radially while it allows mass transfer through it. The heat rejection via the vapor condensation is estimated from the mass flux by energy balance at the vapor-liquid interface. This method of simulating heat pipe is proposed and developed in the current work for the first time. Laboratory cylindrical and complex heat pipes and an experimental test rig were designed and fabricated. The measured data from cylindrical heat pipe were used to evaluate the accuracy of the numerical results. The effects of the operating conditions of the heat pipe, heat input, and portion of heat transferred to the phase change material, main condenser geometry, primary heat pipe adiabatic radius and its location as well as secondary heat pipe configurations have been investigated on heat pipe performance. The results showed that in the case with a tubular adiabatic section in the center, the complex interaction of convective and viscous forces in the main condenser chamber, caused several recirculation zones to form in this region, which made the performance of the heat pipe convoluted. The recirculation zone shapes and locations affected by the geometrical features and the heat input, play an important role in the condenser temperature distributions. The temperature distributions of the primary condenser and secondary heat pipe highly depend on the secondary heat pipe configurations and main condenser spacing, especially for the cases with higher heat inputs and higher percentages of heat transfer to the PCM via secondary heat pipes. It was found that changing the entrance shape of the primary condenser and the secondary heat pipes as well as the location and quantity of the secondary heat pipes does not diminish the recirculation zone effects. It was also concluded that changing the location of the adiabatic section reduces the jetting effect of the vapor flow and curtails the recirculation zones, leading to higher average temperature in the main condenser and secondary heat pipes. The experimental results of the conventional heat pipe are presented, however the data for the heat pipe network is not included in this dissertation. The results obtained from the experimental analyses revealed that for the transient operation, as the heat input to the system increases and the conditions at the condenser remains constant, the heat pipe operating temperature increases until it reaches another steady state condition. In addition, the effects of the working fluid and the inclination angle were studied on the performance of a heat pipe. The results showed that in gravity-assisted orientations, the inclination angle has negligible effect on the performance of the heat pipe. However, for gravity-opposed orientations, as the inclination angle increases, the temperature difference between the evaporator and condensation increases which results in higher thermal resistance. It was also found that if the heat pipe is under-filled with the working fluid, the capillary limit of the heat pipe decreases dramatically. However, overfilling of the heat pipe with working fluid degrades the heat pipe performance due to interfering with the evaporation-condensation mechanism. / Mechanical Engineering
37

A Variation of Positioning Phase Change Materials (PCMs) Within Building Enclosures and Their Utilization Toward Thermal Performance

Abuzaid, Abdullah Ibrahim 26 April 2018 (has links)
Recently, buildings have been receiving more serious attention to help reduce global energy consumption. At the same time, thermal comfort has become an increasing concern for building occupants. Phase Change Materials (PCMs), which are capable of storing and releasing significant amounts of energy by melting and solidifying at a given temperature, are perceived as a promising opportunity for improving the thermal performance of buildings. This is because they use their thermophysical properties and latent heat while transforming state (or phase) as a feature for thermal energy storage systems to reduce overall energy demand, specifically during peaks hours, as well as to improve thermal comfort in buildings. This research aims to provide an overview of opportunities and challenges for the utilization of PCMs in the Architecture, Engineering, and Construction (AEC) sector, a broader understanding of specifically promising technologies, and a clarification of the effectiveness of different applications in building enclosures design especially in exterior walls. The research discusses how PCMs can be incorporated within building enclosures effectively to enhance building performance and improve thermal comfort while reducing heating and cooling energy consumption in buildings. The major objectives of the research include studying the properties of PCMs and their potential impact on building construction, clarifying PCMs selection criteria for building application, identifying the effectiveness of utilizing PCMs on saving energy, and evaluating the contribution of utilizing PCMs in building enclosures to thermal comfort. The research uses an exploratory quantitative approach that contains three main stages: 1) a systematic literature review, 2) laboratory experiments, and 3) validation to meet the goal of the research. Finally, by extrapolating results, the research ends with a practical assessment of application opportunities and how to effectively utilize PCMs in exterior walls of buildings. / PHD / With the growing concern of energy savings and selecting the most efficient way to provide thermal comfort for buildings’ users, buildings need to be constructed with an effective utilization method of materials and systems. Phase Change Materials (PCMs) have the ability to moderate temperatures within a specific range. They can be applied to reduce the energy used in buildings and improve thermal comfort. This is because they absorb heat when materials melt and release it when materials solidify. This research studies the properties of PCMs and their potential impact on building construction and clarifies PCM selection criteria for building applications. Also, the research illustrates the impacts of utilizing PCMs in different positions within an external wall on energy savings and thermal comfort. The research uses an exploratory quantitative approach that contains three main stages: 1) a systematic literature review, 2) laboratory experiments, and 3) validation to meet the goal of the research. Finally, the research ends with a practical assessment of application opportunities and how to effectively utilize PCMs in exterior walls of buildings.
38

Conforto térmico no Colégio de Aplicação Pedagógica da Universidade Estadual de Maringá: proposta para melhoria do desempenho térmico de um antigo CAIC / Thermal Comfort in the Pedagogical College of the State University of Maringá: proposal for improving the thermal performance of an old CAIC

Goulart, Mariana Fortes 07 April 2014 (has links)
O Colégio de Aplicação Pedagógica da Universidade Estadual de Maringá (CAP/UEM) fazia parte de um projeto de âmbito nacional criado na década de 1990, os Centros de Atenção Integral à Criança e ao Adolescente - CAIC´s. O projeto inicial é de autoria do arquiteto João Filgueiras Lima, Lelé, reconhecido pela preocupação com o conforto ambiental dos usuários em suas obras. Em geral, sabe-se que os alunos têm uma melhor qualidade no aprendizado quando os espaços estão bem ventilados, iluminados e silenciosos. Sendo assim, este trabalho tem como objetivo avaliar o conforto térmico no edifício do CAP/UEM verificando o desempenho das estratégias passivas para proporcionar conforto térmico, a sensação térmica dos usuários e aferindo o desempenho de uma estratégia, sugerida pelo arquiteto Lelé em entrevista a autora, para melhoria do comportamento térmico da cobertura. A metodologia proposta consiste, inicialmente, em um levantamento de dados que se destaca pela entrevista com o arquiteto. Após, foi feita uma análise projetual para a identificação e caracterização das soluções passivas de conforto e a verificação do funcionamento destas no âmbito de projeto. Para verificar a eficiência destas estratégias foi aplicado o método dos Votos Médios Preditos (PMV), que envolve medições das variáveis ambientais concomitantemente com aplicação de questionários aos alunos no período de verão. Além disso, ainda foi avaliado o desempenho térmico da cobertura, através de medições de temperaturas superficiais internas e externas comparadas entre três salas de aula: uma inalterada, outra lavada e a terceira, lavada e pintada de branco, sugestão do arquiteto Lelé para melhorar o desempenho térmico do edifício. Os resultados indicaram que a cobertura do prédio ocasiona grande ganho térmico e insatisfação dos usuários praticamente o tempo todo, prejudicando as condições de conforto no interior do edifício. Esse alto grau de desconforto pode ser explicado pela falta de manutenção e a pouca inércia térmica do sistema, principalmente da cobertura. A pintura do telhado de branco se mostrou eficiente para diminuir o calor que entra pela cobertura, ressaltando a importância da temperatura radiante para promoção das condições de conforto térmico nas salas de aula. / The Pedagogical College of the State University of Maringá (CAP/UEM) was part of a nationwide project created in the 1990s, the Centres for the Integral Care to Children and Adolescents - CAIC\'s. The initial design was concived by the architect João Filgueiras Lima (a.k.a. Lelé), acknowledged for his concern for the environmental comfort of users in his work. In general, it is known that the students have a better quality of learning when the spaces are well chilled, lighted and quiet. Therefore, this study aims to evaluate the thermal comfort in the building of the CAP/UEM checking the performance of passive strategies of thermal comfort, thermal sensation of users and verifying the performance of a strategy, suggested by the architect Lelé in an interview for the author, to improve the thermal performance of the roof. The proposed methodology consists, initially, in a collection of the datas that stands out from the interview with the architect. Afterwards, it was made an analysis projectual in order to identify passive solutions to obtain thermal comfort, at the same time, to verify the work system of this project. To check the efficiency of these strategies it was apllied the Predicted Mean Vote Method (PMV), that envolve measurements of environmental variables concurrently with questionnaires applied to students during the summer time. Futher there, it was analized the thermal performance of the roof, throught out indoor and outdoor superficial temperature measurements, compared between three classrooms: one untouchable, another washed and the third one washed and white painted, suggested by the architect Lelé to improve thermal comfort of the building. The results indicate that the roof of the building causes huge thermal gain and unsatisfaction of the users all the time, damaging the comfort conditions within the building. This high level of uncomfortable can be explained by the lack of maintenance and the low thermal inertia of the system, especially the roof. The white paint of the roof has shown efficient to reduce the heating coming throughout the roof, highlighting the importance of radiant temperature for promotion of thermal comfort conditions in classrooms.
39

Resiliência das edificações às mudanças climáticas na região metropolitana de São Paulo. Estudo de caso: desempenho térmico de edifícios residenciais para idosos / Resilience of buildings to climate change in the metropolitan region of São Paulo. Case study: thermal performance of residential buildings for seniors

Alves, Carolina Abrahão 20 January 2015 (has links)
O objeto desta pesquisa é o desempenho térmico de edifícios residenciais na cidade de São Paulo, tendo em vista as mudanças climáticas previstas e a maior vulnerabilidade da população idosa. O objetivo é a avaliação de desempenho térmico e de conforto ambiental de edifícios residenciais no cenário RCP 8.5 do Quinto Relatório do IPCC - IPCC AR5 e durante a onda de calor ocorrida em janeiro e fevereiro de 2014. Este trabalho se utiliza de estudos de casos reais e de simulações computacionais. O método é indutivo, por meio de levantamentos de campo, e dedutivo, por meio de comparações entre os resultados das medições e das simulações computacionais; o trabalho apresenta, ao final, estudos preditivos do comportamento térmico e do conforto ambiental dos usuários nos edifícios estudados. Para tanto, foram levantadas e monitoradas seis residências de idosos voluntários, além de uma residência de controle, e foram realizadas simulações com o modelo EDSL/Bentley TAS (Thermal Analysis Software). Para a simulação computacional foram utilizados dados climáticos simulados e medidos. Os dados climáticos simulados foram tratados a partir de dados cedidos pelo Instituto de Astronomia, Geofísica e Ciências Atmosféricas/IAG-USP representando os períodos presente (1975 a 2005), futuro próximo (2015 a 2044), futuro intermediário (2045 a 2074) e futuro distante (2076 a 2096). Os dados medidos foram os registrados pela estação meteorológica do IAG-USP, localizada na zona sul de São Paulo, para três períodos distintos: o ano de 2013, quando foram monitoradas as residências, o ano de 1972, selecionado como representativo do período de construção das residências estudadas, e também o ano de 2014, para fins de estudo dos efeitos da onda de calor ocorrida em janeiro e fevereiro desse mesmo ano. Os resultados foram analisados comparativamente entre os diferentes cenários climáticos e também entre as unidades habitacionais estudadas, adotando-se os índices de conforto adaptativo De Dear et al. (1997) / ASHRAE 55 (2013) e Humphreys et al. (2010), considerados os mais adequados para a avaliação térmica da operação em modo passivo no clima local, dentre os índices já existentes. As análises revelaram que, com a progressão dos cenários climáticos futuros, há tendência de alteração na condição de conforto dos usuários com aumento da sensação de calor e redução da sensação de frio, expressos aqui em número de horas e de graus-hora de desconforto. Além disso, sob a ocorrência de ondas de calor, o aumento abrupto e persistente da temperatura do ar tende a tornar as condições de desconforto térmico ainda mais acentuadas. Dentre todos os cenários estudados, e aplicando-se os dois modelos de conforto, foi encontrado um valor médio de aumento da condição de calor de 271%, variando de 83% a 694%, e uma redução média da condição de frio de 51%, variando de 24% a 70%. Os resultados mostram que a conjugação desses dois fenômenos, mudança climática e onda de calor, pode provocar um efeito potencializador para o desconforto térmico por calor, tornando as condições inóspitas para o conforto humano, além de implicar em maior consumo de energia para climatização artificial. / The subject of this research is the residential buildings performance in the city of São Paulo, taking into account the climate changes predicted for the next decades and the greater vulnerability of the elderly related to the environmental conditions. The aim is the evaluation of thermal performance and comfort in residential buildings under the RCP 8.5 scenario from the IPCC Fifth Assessment Report - IPCC AR5, as well as under the heat wave occurred in January and February 2014. This work is based on real case studies and computer simulations. The method is inductive, by field surveys, and deductive, though the comparison between measurements and computer simulation; finally, predictive studies of thermal performance and comfort are presented. For this purpose, six elderly dwellings, besides a control one, were surveyed and monitored, and computer simulations were carried out using EDLS/Bentley TAS (Thermal Analysis Software). For the computer simulations, simulated and measured climate data were employed. The simulated data were treated starting from data provided by the Institute of Astronomy, Geophysics and Atmospheric Sciences/IAG-USP representing the periods present (1975 to2005), near future (2015 to 2044), intermediate future (2045 to 2074 and far future (2076 to 2096). Measured data were recorded by the IAG-USP meteorological station, located in southern São Paulo, for three different periods: 2013, when the residences were monitored; 1972, selected as representative of the buildings\' construction period, and also 2014, to study the January and February heat wave effects. Results were analyzed comparing comfort conditions in the different climate scenarios and also among the case studies, following the adaptive comfort indices De Dear et al. (1997) / ASHRAE 55 (2013) and Humphreys et al. (2010), which were considered the two most appropriate ones, among the existing indexes, for the passive mode operation in the local climate. Analysis revealed a tendency of change in comfort conditions throughout the progression of future climate scenarios, showing an increase in heat sensation and a decrease in cold sensation, which were expressed in number of hours and degree-hours of discomfort. Furthermore, in the occurrence of heat waves, the unexpected and persistent increase in air temperature tends to make thermal discomfort even more pronounced. Among all the studied scenarios, and applying both comfort models, in average, discomfort by heat increased 271%, ranging from 83% to 694%, and discomfort by cold decreased 51%, ranging from 24% to 70%. The results show that the combination of both phenomena, climate change and heat wave, may lead to a potential effect of heat discomfort, making thermal conditions inhospitable for human comfort, besides implying a higher energy consumption for air conditioning.
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Avaliação comparativa do desempenho térmico de painéis de Light Steel Frame pré-fabricados para uso em construções modulares. / Comparative assessment of the thermal performance of pre-fabricated light steel frame panels for use in modular constructions.

Bernardo, Márcio 11 April 2017 (has links)
As evoluções tecnológicas juntamente com o surgimento de novas necessidades dos usuários resultaram em diversos novos tipos de métodos construtivos. O conceito de industrialização das edificações vem evoluindo com velocidade, e estes novos sistemas construtivos surgiram como alternativa aos sistemas tradicionais buscando entre outros, melhor desempenho térmico, energético, lumínico, acústico e de sustentabilidade. Diante desta crescente demanda por inovação, a ABNT (Associação Brasileira de Normas Técnicas) passou a estudar um conjunto de normas para estabelecer critérios de desempenho ao validar os novos sistemas construtivos de edificações habitacionais. Isto se concretizou com a publicação da Norma de Desempenho (ABNT NBR 15575/2013), que estipula parâmetros para desempenho dessas construções e métodos detalhados de acordo com o desempenho desejado. Simultaneamente, as simulações computacionais evoluíram, permitindo menor custo de experimentação, são capazes de antecipar resultados antes somente possíveis após testes físicos com protótipos e também a encontrar alternativas de soluções também quanto à eficiência energética e ao conforto dos usuários. Entre alguns programas existentes para simulação de desempenho térmico, está o EnergyPlus, o qual foi utilizado para este estudo, tendo como principal objetivo avaliar o desempenho térmico de painéis de light steel frame pré-fabricados utilizados na fachada e nas vedações internas de um sistema construtivo modular composto por estrutura metálica, e piso e a laje de concreto. Para o desenvolvimento do estudo, foi utilizado como modelo base uma residência térrea, configurada por ambientes independentes, que virão a compor uma residência inteira onde serão inseridos os painéis de light steel frame pré-fabricados. As 16 tipologias de painéis foram estudadas em três diferentes cidades do Brasil, sendo elas situadas nas regiões Nordeste, Sudeste e Sul e em dias típicos de verão e inverno, utilizando os recursos de simulação computacional (EnergyPlus) possibilitando a análise comparativa de desempenho térmico de cada tipologia ao serem submetidos a diferentes temperaturas e regime de insolação. A maioria das tipologias de painéis apresentam resultados favoráveis apenas para a cidade de Fortaleza, e desfavoráveis para as cidades de São Paulo e Curitiba, onde somente a última tipologia de painel atendeu os requisitos mínimos de desempenho para todas as cidades. Este estudo não contempla dados experimentais ou ensaios físicos. / Technological developments coupled with the emergence of new user needs resulted in several types of new construction methods. The concept of building industrialization has been evolving with speed, and these new construction systems have emerged as an alternative to traditional systems. These alternative systems seek better thermal performance, energy efficiency, light performance, acoustic and sustainability, among other things. Faced with this growing demand for innovation, ABNT (Brazilian Technical Standards Association) went on to study a set of rules to establish performance criteria to validate the new construction systems of residential buildings. These criteria were established with the publication of Performance Standard (NBR 15575/2013), which provides detailed parameters for performance of these buildings and provides methods according to the desired performance. At the same time, computer simulations have evolved, allowing lower cost of experimentation. These simulations are able to anticipate results which were previously only possible after physical tests of prototypes and also are able to find alternative solutions for energy efficiency and comfort of users. Among some existing programs for simulating thermal performance is the EnergyPlus, which was used for this study, with the primary objective of evaluating the thermal performance of prefabricated light steel frame panels. These panels were used in the facade and the internal seals of a building system composed of modular steel structure and floor and the concrete slab. To develop the study, a one-story residence was used as a base model, set by independent environments, composed entirely of the prefabricated light steel frame panels. The 16 panel types were studied in three different cities in Brazil, located in the Northeast, Southeast and South, and on a typical day of summer and winter. Using the computer simulation resources (EnergyPlus) enabled comparative analysis of thermal performance of each type when subjected to different temperatures and insolation regime. Most panel types have favorable results only in the city of Fortaleza, and unfavorable in the cities of São Paulo and Curitiba, whereas only the last panel type met the minimum performance requirements for all cities. This study does not include experimental data or physical tests.

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