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DeterminaĆ§Ć£o experimental do fator solar do dispositivo de sombreamento Hauskool
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Os vĆ£os envidraƧados sĆ£o os elementos mais vulnerĆ”veis da envolvente de um edifĆcio, sendo responsĆ”veis pelo maior consumo de energia para aquecimento, no inverno, e arrefecimento, no verĆ£o, que representam cerca de trinta por cento da energia desperdiƧada. Ć por estes que ocorrem as maiores perdas de energia e infiltraƧƵes de ar, que muitas vezes afetam o conforto dos ocupantes, tornando o ambiente interior mais quente no verĆ£o e mais frio no inverno. O aperfeiƧoamento das suas caracterĆsticas tĆ©cnicas, como Ć© o caso do fator solar (š), o tipo de construĆ§Ć£o do edifĆcio e a caracterizaĆ§Ć£o da envolvente e dos elementos que a constituem ā vĆ£os envidraƧados e mecanismos de sombreamento ā, tornaram-se componentes obrigatĆ³rios a ter em consideraĆ§Ć£o para definir o desempenho energĆ©tico de um edifĆcio. O dispositivo de sombreamento Hauskool Ć© uma persiana constituĆda por poliĆ©ster transparente, poliĆ©ster metalizado (na parte traseira das lĆ¢minas) e polietileno branco (na parte frontal das lĆ¢minas), que se cola no lado exterior da janela. Quando ocorre incidĆŖncia da radiaĆ§Ć£o solar ocorre uma reaĆ§Ć£o de expansĆ£o que provoca o desenrolamento das lĆ¢minas, fazendo com que estas evitem a passagem de grande parte da radiaĆ§Ć£o solar incidente. Para a determinaĆ§Ć£o do fator solar do dispositivo de sombreamento Hauskool foram estudados dois casos, utilizando diferentes mĆ©todos: Testes em LaboratĆ³rio e Testes em CondiƧƵes Reais. No primeiro foram criadas condiƧƵes de regime permanente com a utilizaĆ§Ć£o de uma caixa de mediƧƵes, quatro vidros, duas lĆ¢mpadas de halogĆ©neo, um termĆ³stato/higrĆ³metro, um multĆmetro e um piranĆ³metro de termopilha. No caso Testes em CondiƧƵes Reais foi utilizada a divisĆ£o de uma habitaĆ§Ć£o para realizar as mediƧƵes, dois dataloggers e um piranĆ³metro de termopilha. A diferenƧa entre os mĆ©todos utilizados prende-se com o facto de, num caso real, ser impossĆvel nĆ£o considerar a variaĆ§Ć£o da temperatura ao longo do tempo. O facto de as dimensƵes da divisĆ£o de uma habitaĆ§Ć£o serem muito superiores quando comparado com as dimensƵes da caixa de mediƧƵes utilizada, leva a que a temperatura de equilĆbrio nĆ£o seja atingida num curto espaƧo de tempo. No caso Testes em LaboratĆ³rio foram analisados casos com e sem sombreamento, em condiƧƵes de cĆ©u limpo e de cĆ©u nublado. Para todos os casos analisados, os resultados obtidos referentes ao fator solar com aplicaĆ§Ć£o do dispositivo de sombreamento Hauskool foram inferiores, comparativamente ao estudo sem sombreamento. Para o estudo com sombreamento foram obtidos resultados referentes ao fator solar inferiores para o vidro duplo, com 0,25, face ao vidro simples, com 0,36, para condiƧƵes de cĆ©u limpo. Para condiƧƵes de cĆ©u nublado foi obtido um fator solar de 0,35 e 0,46 para o vidro duplo e simples, respetivamente. No caso Testes em CondiƧƵes Reais foram realizadas mediƧƵes nas semanas de 19 a 25 de setembro e de 29 de setembro a 3 de outubro e obtidos resultados referentes ao fator solar de 0,69 para a primeira semana, correspondente ao estudo sem sombreamento, e de 0,24 para a segunda semana, correspondente ao estudo com aplicaĆ§Ć£o do dispositivo de sombreamento Hauskool.
Windows are the most vulnerable elements of a building, being responsible for the higher energy consumption for heating, in winter, and cooling, in summer, accounting for about 30 percent of the wasted energy. Through them occur higher energy losses and air infiltrations, which often affects occupant comfort, making the environment warmer in the summer and colder in the winter. The improvement of its technical characteristics, such as solar factor (š), the type of construction of the building and the characterization of the surrounding and the elements that constitute it ā windows and shading mechanisms ā, becomes the required components to take into account to define the energy performance of a building. The Hauskool shading device is a blind formed by transparent polyester, metallized polyester (on the back of the blades) and white polyethylene (on the front of the blades), which sticks to the outside of the window. When there is an incidence of solar radiation, there is an expansion reaction that causes the unwinding of the blades, causing them to avoid the passage of much of the incident solar radiation. In order to determinate the solar factor of the Hauskool shading device, two cases were studied: Laboratory Tests and Tests in Real Conditions. In the first one, permanent conditions were created using a measurement box, four glasses, two halogen lamps, a thermostat/hygrometer, a multimeter and a thermopile pyranometer. For Tests in Real Conditions was used the division of a house to perform the measurements, two dataloggers and a thermopile pyranometer. The difference between the used methods relates to the fact that, in a real case, it is impossible not to consider the temperature variation over time. The fact that the dimensions of the room of a dwelling are much higher when compared to the dimensions of the measurement box used, leads to the equilibrium temperature not being reached in a short time. In the Laboratory Tests, cases with and without shading, in conditions of clear and cloudy sky were analyzed. For all the analyzed cases, the results obtained regarding the solar factor with application of the Hauskool shading device were lower, compared to the study without shading. For the study with shading, were obtained lower results for the solar factor for double glass, with 0.25, compared to single glass, with 0.36, for clear sky conditions. For cloudy conditions, was obtained a solar factor of 0.35 and 0.46 for double and single glass, respectively. In the Tests in Real Conditions, measurements were taken in the weeks of September 19 to 25 and September 29 to October 3 and were obtained results referring to the solar factor of 0.69 for the first week, corresponding to the study without shading, and 0.24 for the second week, corresponding to the study with application of the Hauskool shading device.
Windows are the most vulnerable elements of a building, being responsible for the higher energy consumption for heating, in winter, and cooling, in summer, accounting for about 30 percent of the wasted energy. Through them occur higher energy losses and air infiltrations, which often affects occupant comfort, making the environment warmer in the summer and colder in the winter. The improvement of its technical characteristics, such as solar factor (š), the type of construction of the building and the characterization of the surrounding and the elements that constitute it ā windows and shading mechanisms ā, becomes the required components to take into account to define the energy performance of a building. The Hauskool shading device is a blind formed by transparent polyester, metallized polyester (on the back of the blades) and white polyethylene (on the front of the blades), which sticks to the outside of the window. When there is an incidence of solar radiation, there is an expansion reaction that causes the unwinding of the blades, causing them to avoid the passage of much of the incident solar radiation. In order to determinate the solar factor of the Hauskool shading device, two cases were studied: Laboratory Tests and Tests in Real Conditions. In the first one, permanent conditions were created using a measurement box, four glasses, two halogen lamps, a thermostat/hygrometer, a multimeter and a thermopile pyranometer. For Tests in Real Conditions was used the division of a house to perform the measurements, two dataloggers and a thermopile pyranometer. The difference between the used methods relates to the fact that, in a real case, it is impossible not to consider the temperature variation over time. The fact that the dimensions of the room of a dwelling are much higher when compared to the dimensions of the measurement box used, leads to the equilibrium temperature not being reached in a short time. In the Laboratory Tests, cases with and without shading, in conditions of clear and cloudy sky were analyzed. For all the analyzed cases, the results obtained regarding the solar factor with application of the Hauskool shading device were lower, compared to the study without shading. For the study with shading, were obtained lower results for the solar factor for double glass, with 0.25, compared to single glass, with 0.36, for clear sky conditions. For cloudy conditions, was obtained a solar factor of 0.35 and 0.46 for double and single glass, respectively. In the Tests in Real Conditions, measurements were taken in the weeks of September 19 to 25 and September 29 to October 3 and were obtained results referring to the solar factor of 0.69 for the first week, corresponding to the study without shading, and 0.24 for the second week, corresponding to the study with application of the Hauskool shading device.
DescriĆ§Ć£o
Tese de mestrado integrado, Engenharia da Energia e do Ambiente, Universidade de Lisboa, Faculdade de CiĆŖncias, 2019
Palavras-chave
Hauskool Fator solar Coeficiente de transmissĆ£o tĆ©rmica RadiaĆ§Ć£o solar incidente Teses de mestrado - 2019