41 research outputs found

    Study of natural ventilation for a modular façade system in wind tunnel tests

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    Wind tunnel tests are a reliable tool to determine the effect of natural ventilation on buildings. This paper presents results of wind tunnel tests conducted to evaluate the influence of ventilation modules positioning on a fa√ßade system. Modules positioning was modified, resulting in different fa√ßade configurations. The tests were carried out with the use of a model, varying the position of the ventilation modules in the fa√ßade configuration. The cases tested were six ventilation modules positioned below the window-sill (ventilated window-sill), and three ventilation modules positioned above and below the fa√ßade. The fa√ßade system proposed was movable and interchangeable so that the same basic model could be used to test the possibilities for ventilation. Wind speed measurements were taken inside and outside the model for the different fa√ßades configurations to evaluate the best performance in relation to natural ventilation. Single√Ę sided and Cross ventilation were considered for wind speed measurements. Results show the use of six ventilation modules positioned below the window-sill, forming "a ventilated window-sill" is the best solution in terms of natural ventilation

    Passive façade solutions: tromble wall thermal performance and glazing daylighting performance for Guimarães - Portugal

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    Recently façade systems have integrated passive solutions to reduce the energy consumption in buildings and improve their occupants’ comfort. This paper reports the results of the thermal performance of Trombe walls and daylighting of glazing modules of a façade system in Portugal. Trombe walls are massive walls separated from the outdoors by glazing and an air space, which absorbs the solar energy and releases it selectively to the inside of the building at night. Computational simulations were carried out with the Design Builder, Ecotect and Desktop Radiance programs. The use of Trombe walls and double self-cleaning glass in the façade system led to a decrease in the heating energy needs.(undefined)The authors gratefully acknowledge the financial support provided by Erasmus Mundus ISAC - Improving Skills Across Continents for this researc

    Glazing fa√ßade modules : daylighting performance simulation for Bragan√ßa, Coimbra, √Čvora and Faro

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    The daylighting performance improvement is one better strategy to reduce the artificial lighting consumption in buildings and obviously requires solar radiation from the exterior. Daylighting comes not only from direct sunlight but also from illumination provided by the sky on overcast days. Particular attention must be given to daylighting while designing a building when the aim is to maximize visual comfort or to reduce energy consumption. Visual comfort of glazing fa√ßades is a fundamental characteristic to the global comfort. Additionally, this work reports a part of the results of an ongoing investigation about a new fa√ßade system concept: "Fa√ßade Modules for Eco-Efficient Refurbishment of Buildings", especially on the daylighting performance of double glazing modules. Ecotect 5.6 software was used to obtain the daylight factor and illuminance level for four Portugal cities and two double glazing fa√ßade modules, composed by green solar control glass and low-e glass; selfcleaning glass and float clear glass. A typical dwelling room (25m¬≤) was simulated. Daylight factor and illuminance level were obtained by means of computational simulations. These results were compared to daylighting standards and recommendations. Results showed a better daylight performance for double self-cleaning glazing for all cities. A lower performance was observed when using green solar control glass and low-e glass.Erasmus Mundus - ISAC ‚Äď Improving Skills Across Continent

    Estudo da eficiência energética de fachadas fotovoltaicas em Portugal

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    A redu√ß√£o dos n√≠veis de CO2 emitidos para a atmosfera, resultantes do consumo energ√©tico, vem constituindo ao longo dos √ļltimos anos uma preocupa√ß√£o global. Neste sentido, a Uni√£o Europ√©ia vem desenvolvendo um conjunto de documentos que visam a regulamenta√ß√£o da redu√ß√£o do consumo de energia e das emiss√Ķes de gases com efeito estufa, e aumento da quota de energias renov√°veis at√© 2020. O uso de sistemas fotovoltaicos em fachadas se insere nesse contexto de aumento da quota de energias renov√°veis. Os ganhos que a fachada fotovoltaica apresenta s√£o referentes √† efici√™ncia energ√©tica e ao desempenho ambiental dos edif√≠cios. Diante desses aspectos foi executado um estudo para Portugal (Porto, Lisboa e Faro) sobre uso de pain√©is fotovoltaicos em fachadas por meio de simula√ß√£o computacional no qual foram analisadas as caracter√≠sticas dos pain√©is mais eficientes. Para alcan√ßar tais resultados, a metodologia incluiu simula√ß√Ķes computacionais realizadas com o software SolTerm 5.0. Com base nos resultados, observou-se que existe um potencial para o uso de pain√©is fotovoltaicos em Portugal, principalmente para latitudes pr√≥ximas √† Faro. Al√©m disso, observou-se que o tipo de tecnologia com maior rendimento s√£o os pain√©is de sil√≠cio policristalino na posi√ß√£o inclinada, sendo que o tipo de painel fotovoltaico mais eficiente foi o Kyocera KC167G-2, seguido do painel BP 3160. Atrav√©s da compara√ß√£o dos resultados de simula√ß√£o computacional com outros estudos, verificou-se que a ferramenta computacional utilizada se apresenta vi√°vel para a an√°lise da efici√™ncia energ√©tica deste tipo de sistema.¬†The reduction in CO2 emitted in the atmosphere resulting from energy consumption has constituted a global concern over the past years. Thus, the EU has developed a set of proposals in order to reduce the energy consumption and emissions of greenhouse gases, encouraging the use of renewable energy until 2020. On this topic, the photovoltaic facade is known to be a solution that allows both energy efficiency and environmental performance of buildings. In this respect, a study of facade systems that incorporate photovoltaic panels, considering computational simulations for Portugal, is presented in this work. The main objective of the present research is to analyze the characteristics and parameters that define of more efficient systems based on computer simulations. On this purpose, the version 5.0 of SolTerm computer program was used. The results show that there is a high potential on the use of the proposed technology in Portugal, especially in Faro region, because of its latitude. Besides, inclined polycrystalline silicon solar panels achieved the best results. Considering the energy efficiency and environmental performance, the most efficient panel was the Kyocera KC167G-2, followed by BP 3160. It should be noted that the comparison of results obtained by numerical simulation and the ones presented in literature show that the use of computer programs is viable to the analysis of energy efficiency of the photovoltaic systems in fa√ßades.Os autores agradecem ao Programa Erasmus Mundus ISAC - Improving Skills Across Continents pelo apoio financeiro a esta pesquisa.info:eu-repo/semantics/publishedVersio

    Eficiência energética de fachadas fotovoltaicas destinadas às diferentes latitudes de Portugal

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    A redu√ß√£o dos n√≠veis de CO2 emitidos para a atmosfera, resultantes do consumo energ√©tico, vem constituindo ao longo dos √ļltimos anos uma preocupa√ß√£o global. Neste sentido, a Uni√£o Europ√©ia vem desenvolvendo um conjunto de documentos que visam a regulamenta√ß√£o da redu√ß√£o do consumo de energia e das emiss√Ķes de gases com efeito estufa, e aumento da quota de energias renov√°veis at√© 2020. O uso de sistemas fotovoltaicos em fachadas se insere nesse contexto de aumento da quota de energias renov√°veis. Os ganhos que a fachada fotovoltaica apresenta s√£o referentes √† efici√™ncia energ√©tica e ao desempenho ambiental dos edif√≠cios. Diante desses aspectos foi executado um estudo para Portugal sobre uso de pain√©is fotovoltaicos em fachadas por meio de simula√ß√£o computacional no qual foram analisadas as caracter√≠sticas dos pain√©is mais eficientes. Para alcan√ßar tais resultados, a metodologia incluiu simula√ß√Ķes computacionais realizadas com o software SolTerm 5.0. Com base nos resultados, observou-se que existe um potencial para o uso de pain√©is fotovoltaicos em Portugal, principalmente para latitudes pr√≥ximas √† √Čvora. Al√©m disso, observou-se que o tipo de tecnologia com maior rendimento s√£o os pain√©is de sil√≠cio policristalino na posi√ß√£o inclinada, sendo que o tipo de painel fotovoltaico mais eficiente foi o Kyocera KC167G-2, seguido do painel BP 3160. Atrav√©s da compara√ß√£o dos resultados de simula√ß√£o computacional com outros estudos, verificou-se que a ferramenta computacional utilizada se apresenta vi√°vel para a an√°lise da efici√™ncia energ√©tica deste tipo de sistema.The reduction in CO2 emitted in the atmosphere resulting from energy consumption has constituted a global concern over the past years. Thus, the EU has developed a set of proposals in order to reduce the energy consumption and emissions of greenhouse gases, encouraging the use of renewable energy until 2020. On this topic, the photovoltaic facade is known to be a solution that allows both energy efficiency and environmental performance of buildings. In this respect, a study of facade systems that incorporate photovoltaic panels, considering computational simulations for Portugal, is presented in this work. The main objective of the present research is to analyze the characteristics and parameters that define of more efficient systems based on computer simulations. On this purpose, the version 5.0 of SolTerm computer program was used. The results show that there is a high potential on the use of the proposed technology in Portugal, especially in √Čvora region, because of its latitude. Besides, inclined polycrystalline silicon solar panels achieved the best results. Considering the energy efficiency and environmental performance, the most efficient panel was the Kyocera KC167G-2, followed by BP 3160. It should be noted that the comparison of results obtained by numerical simulation and the ones presented in literature show that the use of computer programs is viable to the analysis of energy efficiency of the photovoltaic systems in fa√ßades

    Análise do conforto térmico na obra de João Filgueiras Lima, Lelé: Hospitais Sarah de Salvador e do Rio de Janeiro

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    Estrat√©gias passivas de projeto reduzem significativamente o uso de ar condicionado e melhoram o conforto t√©rmico dos usu√°rios. Isto pode ser ilustrado atrav√©s dos hospitais da Rede Sarah Kubitschek projetados pelo arquiteto Jo√£o Filgueiras Lima, Lel√©, cujas solu√ß√Ķes al√©m de propiciarem ambientes mais agrad√°veis e salubres, evitam o uso de sistemas mec√Ęnicos de resfriamento, reduzindo o consumo de energia el√©trica. Deste modo, o presente artigo tem como objetivo avaliar o conforto t√©rmico dos hospitais Sarah de Salvador e do Rio de Janeiro, atrav√©s de medi√ß√Ķes in loco da temperatura do ar, umidade relativa do ar e velocidade do ar. A an√°lise dos resultados foi baseada em leituras de projeto, na norma ASHRAE Standard 55/2004 e em par√Ęmetros adquiridos na literatura especializada. Os resultados demonstram a preocupa√ß√£o de Lel√© na incorpora√ß√£o de aspectos bioclim√°ticos nos projetos. No Sarah - Salvador, alguns ambientes permaneceram fora da zona de conforto no per√≠odo do meio dia, devido ao ganho de calor pela cobertura. No entanto, o uso da ventila√ß√£o natural auxilia no efeito de resfriamento, melhorando o conforto t√©rmico nos espa√ßos internos. J√° no Sarah - Rio, todos os ambientes permanecem dentro da zona de conforto proposta pela ASHRAE 55.Design passive strategies reduces the use of air conditioning significantly and improve users' thermal comfort. This be illustrated through the Sarah network of hospitals designed by the architect Jo√£o Filgueiras Lima, L√©l√©, whose solutions providing more pleasant environments and avoid the use of cooling mechanical systems. This paper aims to evaluate the thermal comfort of Sarah hospitals located in Salvador and Rio de Janeiro cities, through measurements on site of air temperature, air relative humidity and wind velocity. The results analyses are based on projects lectures, ASHRAE Standard 55/2004 and parameters acquired in the specialized literature. The results demonstrate the Lel√©'s concern in incorporating the bioclimatic aspects in his projects. The measurements show that the midday period some Salvador hospital environments remain outside of the comfort zone due to heat gain from coverage. However, the use of natural ventilation, allows a cooling effect during this period, improving the thermal conditions in internal spaces. In the case of Rio de Janeiro hospital, all environments are inside the comfort zone proposal by ASHRAE Standard 55.√Ä Funda√ß√£o de Amparo √† Pesquisa do Estado de S√£o Paulo (FAPESP) pelo financiamento da presente pesquisa e a toda a equipe dos hospitais Sarah de Salvador e Rio de Janeiro, que permitiram a realiza√ß√£o das medi√ß√Ķes in loco

    Specification of glazings for façades based on spectrophotometric characterization of transmittance

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    The correct specification of glazings for fa√ßades can reduce the energy consumption in buildings. The heat exchange occurs through transparent surfaces and radiation reaches the building as light and heat. Therefore, glazings significantly contribute to the heat transfer between outdoor and indoor spaces and act directly on daylighting and thermal comfort. This paper reports on the spectrophotometric characterization of glazings transmittance for the study of components of a modular fa√ßade system and its suitability for the climate of Portugal (temperate climate). The study focused on results of spectrophotometric measurements of optical properties, specifically the transmittance of some types of glazings (solar control, self-cleaning, low-e, float, and extra-clear) and two types of double glazings. The results show the percentage of transmission to ultraviolet, visible, and near-infrared regions and its importance, which enabled the analysis of the glazing efficiency regarding daylighting and the correlation to thermal performance. Subsidies and indications for the specification and adequate uses of transparent surfaces have been presented and complemented the datasheets available from the manufactures.This research was funded by Erasmus Mundus External Cooperation Window‚ÄďISAC: Improving Skills Across Continents (Framework Partnership Agreement 2008-1021/001 FRAMEECW L16 Coimbra, Specific Grant Agreement 2008-3628/001-001-MUN-ECW)

    Estudo da ventila√ß√£o natural em t√ļnel de vento para um sistema de fachadas modular

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    Os ensaios em t√ļnel de vento s√£o uma ferramenta confi√°vel para determinar o efeito da ventila√ß√£o natural em edif√≠cios. Por meio do presente estudo s√£o analisadas as condi√ß√Ķes de ventila√ß√£o de um modelo, de acordo com o posicionamento de m√≥dulos de ventila√ß√£o num sistema de fachadas. Os ensaios foram realizados em t√ļnel de vento, variando a posi√ß√£o dos m√≥dulos de ventila√ß√£o na configura√ß√£o fachada. Os casos apresentados ser√£o dois, um deles com seis m√≥dulos de ventila√ß√£o posicionados no peitoril da janela (peitoril ventilado) e outro com tr√™s m√≥dulos de ventila√ß√£o posicionados acima e abaixo na fachada. Trata-se de um sistema de fachadas m√≥vel e intercambi√°vel, de forma que o mesmo modelo b√°sico fosse utilizado para testar as diferentes possibilidades de ventila√ß√£o. Medi√ß√Ķes da velocidade do ar foram obtidas para o interior e exterior do modelo para as diferentes configura√ß√Ķes de fachadas, de modo a avaliar o melhor desempenho em rela√ß√£o √† ventila√ß√£o natural. Casos com e sem ventila√ß√£o cruzada foram considerados para medi√ß√£o da velocidade do ar. Os resultados indicaram que o uso de m√≥dulos de ventila√ß√£o posicionados abaixo do peitoril da janela, formando um peitoril ventilado foi a melhor solu√ß√£o em termos de ventila√ß√£o natural.¬†Wind tunnel tests are a reliable tool to determine the effect of natural ventilation on buildings. This paper discusses the ventilation conditions of a model, according to the ventilation modules positioning in a fa√ßade system. The tests were carried out in a wind tunnel, varying the position of the ventilation modules in the fa√ßade configuration. The cases presented were two, one with six ventilation modules positioned below the window-sill (ventilated window-sill), and another with three ventilation modules positioned above and below the fa√ßade. The fa√ßade system proposed was movable and interchangeable so that the same basic model could be used to test the possibilities for ventilation. Air speed measurements were taken inside and outside the model for the different fa√ßades configurations to evaluate the best performance in relation to natural ventilation. Single-sided and Cross ventilation were considered for air speed measurements. Results show the use of six ventilation modules positioned below the window-sill, forming a ‚Äúventilated window-sill‚ÄĚ was the best solution in terms of natural ventilation.Os autores agradecem o apoio financeiro concedido pelo programa Erasmus Mundus ISAC ‚Äď Improving Skills Across Continents a presente pesquisa.info:eu-repo/semantics/publishedVersio

    Absort√Ęncias e emit√Ęncias efetivas de superf√≠cies: um m√©todo para estim√°-las, um modelo experimental e exemplos de suas import√Ęncias

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    Imperfei√ß√Ķes, sali√™ncias e reentr√Ęncias existentes nas superf√≠cies t√≠picas das edifica√ß√Ķes constituem obst√°culos que podem alterar significativamente o comportamento delas em rela√ß√£o aos fluxos por radia√ß√£o. Al√©m de ampliar a √°rea efetiva de troca de calor, criam sombras e reflex√Ķes, que n√£o ocorreriam em. Assim, os procedimentos de c√°lculo, ao inv√©s de considerar as superf√≠cies perfeitamente lisas e planas, deveriam aplicar corre√ß√Ķes nas propriedades radiativas das superf√≠cies. Denominam-se efetivas as absort√Ęncias e emit√Ęncias que resultam dessas corre√ß√Ķes. O presente artigo apresenta um m√©todo simples desenvolvido para avaliar essas influ√™ncias e exemplifica a import√Ęncia das corre√ß√Ķes acima mencionadas, apresentando resultados de simula√ß√Ķes elaboradas no programa EnergyPlus para uma edifica√ß√£o de geometria simples, submetida ao longo de 1 ano ao clima da cidade de Bras√≠lia. Adotando-se absort√Ęncias e emit√Ęncias efetivas, os resultados das simula√ß√Ķes revelam diferen√ßas de at√© 2,8 ¬ļC nas temperaturas internas do ar em rela√ß√£o √†s obtidas desprezando-se as influ√™ncias que as ondula√ß√Ķes das telhas exercem sobre os fluxos radiantes. Considerando o uso de condicionadores de ar, essa diferen√ßa pode representar uma varia√ß√£o de cerca de 30% nas estimativas de consumo de energia

    Absort√Ęncia solar e desempenho t√©rmico de tintas frias para uso no envelope construtivo

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    Materials with low absorptance and high emittance are known as cool materials. When used on the building envelope these materials decrease building surface temperatures, reducing energy demand in conditioned buildings and making more comfortable non conditioned buildings. In this work, cool and standard paints for exterior walls and roofs were comparatively evaluated through their absorptance and emittance properties, as well as the thermal performance evaluation with surface temperature measurements. Cool paints were selected from available products in the Brazilian and international market, as well as standard paints with the same color, totaling 15 samples. Results indicated that cool paints with low near-infrared absorption, but with the same color of standard ones have lower solar absorptance. Surface temperature measurements for samples exposed to the sun confirmed that coatings solar absorptance directly affects the thermal performance of painted surfaces, which corroborates that as lower is the surface solar absorptance, lower is the building envelope temperature. It was observed that the potential to use cool paints on buildings results from the decrease in the near-infrared solar absorptance, with the possibility to use paints with darker colors, but with better thermal performance when compared with standard paints with the same color.Materiais que apresentam baixas absort√Ęncias e altas emissividades s√£o conhecidos como materiais refletivos ou frios. Esses materiais, quando usados como revestimento no envelope construtivo permitem a redu√ß√£o de temperaturas superficiais nos edif√≠cios, minimizando a necessidade de energia para refrigera√ß√£o em edifica√ß√Ķes artificialmente condicionadas e tornando mais confort√°veis edifica√ß√Ķes n√£o condicionadas. Neste trabalho, tintas frias e convencionais para pintura externa de paredes e coberturas s√£o avaliadas comparativamente atrav√©s da caracteriza√ß√£o de suas absort√Ęncias e emissividades, assim como o desempenho t√©rmico das mesmas a partir de medi√ß√Ķes de temperaturas superficiais. Foram selecionadas tintas frias para pintura de paredes e coberturas a partir de produtos dispon√≠veis no mercado nacional e internacional, assim como tintas convencionais de cores correspondentes, totalizando 15 amostras. Os resultados indicaram que tintas frias com baixa absor√ß√£o no infravermelho-pr√≥ximo, por√©m de cor e tonalidade iguais √ɬ†s tintas convencionais, resultam em tintas com menores absort√Ęncias solares. As temperaturas superficiais das amostras expostas ao sol evidenciaram que a absort√Ęncia solar das tintas afeta diretamente o desempenho t√©rmico das superf√≠cies pintadas, comprovando que quanto mais baixa √© a absort√Ęncia solar da superf√≠cie, menor a temperatura do envelope construtivo. Observou-se que o grande potencial de uso das tintas frias em edifica√ß√Ķes √© resultado da diminui√ß√£o da absort√Ęncia solar na regi√£o do infravermelho, com a possibilidade de se utilizar cores de tonalidade mais escura, por√©m com melhor desempenho t√©rmico quando comparadas com tintas convencionais de cor e tonalidade semelhante
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