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Abstract(s)
Na Europa, o setor dos edifícios é responsável por 40% de toda a energia primária consumida,
no entanto, possui um potencial de poupança muito significativo. A diretiva 2010/31/EU lança
o desafio dos edifícios de balanço energético quase nulo e sugere prazos de implementação
muito ambiciosos, nomeadamente para os edifícios públicos.
Este trabalho tem como objetivo principal avaliar o potencial dos materiais de mudança de fase,
enquanto solução construtiva em edifícios escolares, com vista à melhoria do desempenho
energético e do conforto dos utilizadores.
Atendendo às preocupações contemporâneas pelo aumento da eficiência energética dos
edifícios, a correta escolha de materiais e a constituição dos elementos construtivos é crucial
para alcançar bons resultados. A introdução de materiais de mudança de fase surge como um
meio de melhorar efetivamente o conforto térmico e reduzir os consumos de energia, atuando
de forma passiva.
A metodologia adotada para o trabalho incluiu, inicialmente, uma cuidada revisão bibliográfica
sobre materiais de mudança de fase com aplicação em edifícios, sobre conforto térmico e
respetivos indicadores, especialmente os relacionados com a quantificação do
sobreaquecimento, e sobre métodos de análise técnico-económica de soluções construtivas.
Depois de selecionado um conjunto de soluções construtivas com recurso a materiais de
mudança de fase com diferentes temperaturas de fusão e capacidade entálpica, foi criado um
modelo de simulação no programa DesignBuilder. O caso de estudo escolhido foi um bloco do
edifício principal da Escola Superior de Tecnologia e Gestão de Viseu. Para a validação do
modelo, foi criado um ficheiro climático real e os resultados da respetiva simulação foram
comparados com as medições da temperatura do ar ao longo de um período de três semanas. A
comparação dos dois registos, medição e simulação, conduziu a um CVRMSE de 5,57%,
validando-se, assim, o modelo de simulação.
A avaliação das soluções construtivas incluiu dois cenários de simulação:1) análise com sistema
de AVAC; 2) análise sem sistema de arrefecimento. Foram analisados os resultados em duas
salas de aula, uma no piso térreo e outra no 1º piso, com igual orientação e condições fronteira.
De cada um dos cenários, foram selecionadas para uma análise mais detalhada as cinco soluções
que apresentaram melhores resultados. O objetivo desta análise incidiu sobre o estudo do efeito
dos PCM’s quer na redução do pico de consumo e respetivo deslocamento temporal, quer na
eficiência dos ciclos de carga e descarga, quando não existe arrefecimento mecânico. A análise
económica foi realizada através da determinação do período de retorno atualizado, para três
cenários económicos distintos.
Os resultados mostraram que a seleção de uma única solução não é uma tarefa fácil. Desde
logo, observaram-se diferenças muito relevantes entre a sala do piso térreo e a do 1º piso,
implicando a escolha de soluções distintas. Adicionalmente, a performance das soluções
também varia de acordo com o critério/indicador adotado para a sua avaliação.
ABSTRACT: In Europe, the buildings sector is responsible for 40% of the primary energy demand. However, it is known that the savings potential is very significant. The directive 2010/31/EU launches a great challenge, to implement nearly zero energy buildings and suggesting very ambitious deadlines, particularly to public buildings. Given contemporary concerns about increasing energy efficiency in buildings, proper choice of materials and the constitution of building elements is crucial to achieving good results. The introduction of phase change materials emerges as a path of effectively improve thermal comfort and reduce energy consumption passively. This study aims to evaluate the potential of phase change materials, as an alternative to improve both buildings’ energy performance and users’ comfort, especially in school buildings. The methodology adopted for this work begin with a careful literature review of: phase change materials applications on buildings; thermal comfort quantification through performance indicators, especially those related to the overheating quantification; and the economic analysis methods to evaluate different constructive alternatives. After selecting a set of constructive alternatives using phase change materials, with different melting temperatures and enthalpy capacity, a simulation model was created with DesignBuilder. A block of the main building of the School of Technology & Management of Viseu was chosen as case study. To validate the model, a real weather file was created and the corresponding simulation results were compared with measurements of air temperature over a period of three weeks. The comparison of the two datasets, measurement and simulation, led to a CVRMSE of 5.57%, thus, validating the model. The evaluation of the constructive alternatives included two simulation scenarios: 1) analysis with HVAC system; 2) analysis without cooling system. Two classrooms, one on the ground floor and another on the 1st floor, with the same orientation and boundary conditions, were included in the analysis. In each scenario, the five alternatives that showed better results were selected for further analysis. The objective of this new detailed analysis was studying the effect of PCM on both the reduction of the peak demand and the corresponding time shift, and on the efficiency of the charge and discharge cycles, when no mechanical cooling was used. The economic analysis was carried out and the payback period for three different economic scenarios was computed. The results showed that the selection of a single solution is not an easy task. In fact, there were very significant differences in performance between the ground floor and the 1st floor classrooms, indicating the choice of different alternatives. Additionally, the alternatives performance of the also varied according to the criteria/indicator adopted for the evaluation.
ABSTRACT: In Europe, the buildings sector is responsible for 40% of the primary energy demand. However, it is known that the savings potential is very significant. The directive 2010/31/EU launches a great challenge, to implement nearly zero energy buildings and suggesting very ambitious deadlines, particularly to public buildings. Given contemporary concerns about increasing energy efficiency in buildings, proper choice of materials and the constitution of building elements is crucial to achieving good results. The introduction of phase change materials emerges as a path of effectively improve thermal comfort and reduce energy consumption passively. This study aims to evaluate the potential of phase change materials, as an alternative to improve both buildings’ energy performance and users’ comfort, especially in school buildings. The methodology adopted for this work begin with a careful literature review of: phase change materials applications on buildings; thermal comfort quantification through performance indicators, especially those related to the overheating quantification; and the economic analysis methods to evaluate different constructive alternatives. After selecting a set of constructive alternatives using phase change materials, with different melting temperatures and enthalpy capacity, a simulation model was created with DesignBuilder. A block of the main building of the School of Technology & Management of Viseu was chosen as case study. To validate the model, a real weather file was created and the corresponding simulation results were compared with measurements of air temperature over a period of three weeks. The comparison of the two datasets, measurement and simulation, led to a CVRMSE of 5.57%, thus, validating the model. The evaluation of the constructive alternatives included two simulation scenarios: 1) analysis with HVAC system; 2) analysis without cooling system. Two classrooms, one on the ground floor and another on the 1st floor, with the same orientation and boundary conditions, were included in the analysis. In each scenario, the five alternatives that showed better results were selected for further analysis. The objective of this new detailed analysis was studying the effect of PCM on both the reduction of the peak demand and the corresponding time shift, and on the efficiency of the charge and discharge cycles, when no mechanical cooling was used. The economic analysis was carried out and the payback period for three different economic scenarios was computed. The results showed that the selection of a single solution is not an easy task. In fact, there were very significant differences in performance between the ground floor and the 1st floor classrooms, indicating the choice of different alternatives. Additionally, the alternatives performance of the also varied according to the criteria/indicator adopted for the evaluation.
Description
Keywords
Materiais de mudança de fase Conforto Sobreaquecimento Eficiência de carga e descarga Análise económica