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Projeto de sistemas eficientes para aquecimento central e água quente sanitária aplicado a um lar de idosos
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Atualmente é importante considerar projetos de climatização eficientes em edifícios (neste caso em aquecimento central e produção de água quente sanitária). A Transição Energética, tem sido um dos principais focos da União Europeia, traduzindo-se em
metas aplicadas aos Estados-Membros de forma a baixar as emissões de CO2. Segundo
a EPBD (Energy Performance of Buildings Directive), cerca de 40% do consumo de energia provém de edifícios e 75% desses edifícios têm baixa performance energética. O
objetivo principal será desenvolver edifícios mais eficientes de forma a baixar a dependência de combustíveis fosseis e consequentemente reduzir as emissões de CO2.
O objetivo do presente projeto é desenvolver um sistema de aquecimento central
e produção de água quente sanitária energeticamente eficiente ao nível dos equipamentos. A escolha de um lar de idosos foi importante, porque para além do aquecimento central, a produção de grandes volumes de água quente sanitária também é de bastante
importância.
O desenvolvimento do sistema de aquecimento central consistiu, numa primeira
fase, no cálculo das cargas térmica em aquecimento, utilizando um software de simulação
energética (Hourly Analysis Program – CARRIER/ASHRAE). A escolha do equipamento
foi feita em função dessas cargas, mas também, através de análises de eficiências e
custos energéticos, para desta forma selecionar-se o equipamento mais adequado, tanto
na fonte de calor como nos emissores térmicos.
Relativamente ao aquecimento central, a escolha da fonte de calor passou pela
bomba de calor ar-água (não foi considerado geotermia por falta de área para perfurações). Esta permite obter maiores eficiências comparativamente com caldeiras a gás natural e pellets. Esta eficiência traduz-se na fatura energética, garantindo uma redução
significativa. Para além disto, as emissões de CO2 também tem uma redução significativa
comparativamente com a caldeira a gás natural. Na caldeira de pellets não são contabilizadas as emissões de CO2, no entanto a eficiência e custo energético são superiores.
O lar contém, como emissores térmicos, radiadores, sendo a solução mais económica a substituição da fonte de calor existente por um sistema mais eficiente, mantendo
os radiadores. No entanto, observou-se que para o aquecimento central o pavimento radiante é a tecnologia com maior impacto na eficiência energética do sistema. Isto devese à operação com baixa temperatura da água, no caso 35ºC. Como não estão a ser
avaliados os custos de obra, avançou-se com a implementação de piso radiante em toda
área útil do edifício, sabendo-se que é necessária uma remodelação estruturante.
Para o cálculo de água quente sanitária, resolveu-se analisar a evolução da temperatura média da água acumulada, com o intuito de perceber qual o volume e capacidade da fonte de calor ideal para que nunca falte água quente para consumo. A utilização
de uma solução para água quente sanitária de tipologia acumulação parcial, torna-se
bastante importante para grande produção de AQS. Isto permite o desenvolvimento de
um sistema otimizado, podendo ser possível aplicar uma acumulação e potência ajustada
às necessidades do edifício. No caso da produção de AQS, a solução ao nível da fonte
de calor também passa pela bomba de calor ar-água, sendo que a escolha da mesma se
deve aos mesmos fatores que a escolha no aquecimento central.
Optou-se por fazer uma análise separada dos sistemas de aquecimento central e
produção de AQS, pois serão necessárias temperaturas diferentes da água para cada um deles. Neste sentido serão escolhidas duas fontes de calor distintas para cada uma das
aplicações.
Currently, it is important to consider efficient air conditioning projects in buildings (in this case in central heating and domestic hot water production). The Energy Transition has been one of the main focuses of the European Union, translating into targets applied to Member States in order to reduce CO2 emissions. According to the EPBD (Energy Performance of Buildings Directive), around 40% of energy consumption comes from buildings and 75% of these buildings have low energy performance. The main objective will be to develop more efficient buildings in order to reduce dependence on fossil fuels and consequently reduce CO2 emissions. The objective of this project is to develop an energy-efficient central heating and domestic hot water production system in terms of equipment. The choice of a nursing home was important, because in addition to central heating, the production of large volumes of domestic hot water is also very important. The development of the central heating system consisted, in the first phase, of calculating the thermal loads in heating, using energy simulation software (Hourly Analysis Program – CARRIER/ASHRAE). The choice of equipment was made based on these loads, but also through analysis of efficiencies and energy costs, in order to select the most suitable equipment, both in terms of heat source and thermal emitters. Regarding central heating, the choice of heat source was the air-water heat pump (geothermal was not considered due to lack of area for drilling). This allows, through aerothermal, to obtain greater efficiencies compared to natural gas and pellet boilers. This efficiency translates into the energy bill, guaranteeing a significant reduction. In addition, CO2 emissions also have a significant reduction compared to the natural gas boiler (pellets do not take into account CO2 emissions, however the efficiency and energy cost are higher). The home contains, as thermal emitters, radiators, the most economical solution being to replace the existing heat source with a more efficient system, while maintaining the radiators. However, it was observed that for central heating, underfloor heating is the technology with the greatest impact on the energy efficiency of the system. This is due to operation at low water temperature, in this case 35ºC. As construction costs are not being evaluated, progress was made with the implementation of underfloor heating throughout the building's entire usable area, knowing that structural remodeling is necessary. To calculate sanitary hot water, it was decided to analyze the evolution of the average temperature of the accumulated water, in order to understand the volume and capacity of the ideal heat source so that there is never a lack of hot water for consumption. The use of a solution for domestic hot water with a partial storage type becomes quite important for large DHW production. It allows the development of an optimized system, making it possible to apply accumulation and power adjusted to the needs of the building. In the case of DHW production, the solution in terms of heat source also involves the airwater heat pump, and the choice of this is due to the same factors as the choice in central heating. It was decided to carry out a separate analysis of the central heating and DHW production systems, as different water temperatures will be required for each of them. In this sense, two different heat sources will be chosen for each of the applications.
Currently, it is important to consider efficient air conditioning projects in buildings (in this case in central heating and domestic hot water production). The Energy Transition has been one of the main focuses of the European Union, translating into targets applied to Member States in order to reduce CO2 emissions. According to the EPBD (Energy Performance of Buildings Directive), around 40% of energy consumption comes from buildings and 75% of these buildings have low energy performance. The main objective will be to develop more efficient buildings in order to reduce dependence on fossil fuels and consequently reduce CO2 emissions. The objective of this project is to develop an energy-efficient central heating and domestic hot water production system in terms of equipment. The choice of a nursing home was important, because in addition to central heating, the production of large volumes of domestic hot water is also very important. The development of the central heating system consisted, in the first phase, of calculating the thermal loads in heating, using energy simulation software (Hourly Analysis Program – CARRIER/ASHRAE). The choice of equipment was made based on these loads, but also through analysis of efficiencies and energy costs, in order to select the most suitable equipment, both in terms of heat source and thermal emitters. Regarding central heating, the choice of heat source was the air-water heat pump (geothermal was not considered due to lack of area for drilling). This allows, through aerothermal, to obtain greater efficiencies compared to natural gas and pellet boilers. This efficiency translates into the energy bill, guaranteeing a significant reduction. In addition, CO2 emissions also have a significant reduction compared to the natural gas boiler (pellets do not take into account CO2 emissions, however the efficiency and energy cost are higher). The home contains, as thermal emitters, radiators, the most economical solution being to replace the existing heat source with a more efficient system, while maintaining the radiators. However, it was observed that for central heating, underfloor heating is the technology with the greatest impact on the energy efficiency of the system. This is due to operation at low water temperature, in this case 35ºC. As construction costs are not being evaluated, progress was made with the implementation of underfloor heating throughout the building's entire usable area, knowing that structural remodeling is necessary. To calculate sanitary hot water, it was decided to analyze the evolution of the average temperature of the accumulated water, in order to understand the volume and capacity of the ideal heat source so that there is never a lack of hot water for consumption. The use of a solution for domestic hot water with a partial storage type becomes quite important for large DHW production. It allows the development of an optimized system, making it possible to apply accumulation and power adjusted to the needs of the building. In the case of DHW production, the solution in terms of heat source also involves the airwater heat pump, and the choice of this is due to the same factors as the choice in central heating. It was decided to carry out a separate analysis of the central heating and DHW production systems, as different water temperatures will be required for each of them. In this sense, two different heat sources will be chosen for each of the applications.
Descrição
Palavras-chave
Aquecimento central Água Quente Sanitária Eficiência energética Bomba de Calor Pavimento radiante Central heating Domestic Hot Water Energy efficiency Heat Pump Underfloor heating