Browsing by Author "Castro, Olga"
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- Aplicação da definição nZEB da REHVA a uma renovação de um edifício de habitação Português.Publication . Monteiro, Joaquim; Castro, OlgaOs edifícios desempenham um papel-chave nas sociedades que estão a tentar atenuar os efeitos das alterações climáticas. Mais de 50% dos edifícios residenciais existentes na UE-25 foram construídos antes de 1970. Assim, estes edifícios são de significativa importância na redução de consumo de energia e emissões de CO2. Os edifícios de balanço de energia (quase) zero (nZEB) são uma solução possível para este problema. Este estudo tem por objetivo analisar a aplicação da metodologia nZEB no retrofitting de uma habitação típica Portuguesa de 1950. Foi demonstrado que a energia primária utilizada pode ser reduzida a um valor muito baixo (11,95 kWh/m2.ano) em comparação com o consumo de referência (69,15 kWh/m2.ano), através da aplicação das melhores técnicas atuais de construção, juntamente com a utilização de energia produzida localmente através de fontes renováveis. O uso de fontes de energia renovável permitiu que este edifício alcançasse um valor de RERp de 89%.
- Application of the nZEB methodology in the retrofitting of a typical Portuguese dwelling from the 60's.Publication . Monteiro, Joaquim; Castro, OlgaBuildings and the whole built environment are in a key role when societies are mitigating climate change and adapting to its consequences. More than 50% of the existing residential buildings in EU-25 were built before 1970. Thus, these buildings are of significant importance in reducing energy consumption and CO2 emissions. The existence of more nearly zero energy buildings (nZEB) is a possible solution for this problem. This study aims to analyze the application of the nZEB methodology in the retrofitting of a typical Portuguese dwelling build in 1950. It was shown that the primary energy used can be reduced to a very low value (11,95 kWhep/m2.y) in comparison with the reference consumption (69,15 kWhep/m2.y), with the application of the best construction techniques together with the use of energy from on-site renewable sources.
- Comparison of contaminant removal effectiveness and air change efficiency as indicator of air diffusion quality.Publication . Monteiro, Joaquim; Castro, OlgaThe ventilation efficiency concept is an attempt to quantify a parameter that can easily distinguish the different options for air diffusion in the building spaces. Thirteen strategies of air diffusion were measured in a test chamber through the application of the tracer gas method, with the objective to validate the calculation by Computational fluid dynamics (CFD). Were compared the Air Change Efficiency (ACE) and the Contaminant Removal Effectiveness (CRE), the two indicators most internationally accepted. The main results from this work shows that the values of the numerical simulations are in good agreement with experimental measurements and also, that the solutions to be adopted for maximizing the ventilation efficiency should be the schemes that operate with low speeds of supply air and small differences between supply air temperature and the room temperature.
- Experimental study on the impact of using a fan coil in the evaluation of contaminant removal effectiveness of common air diffusion strategiesPublication . Monteiro, Joaquim; Bathelt, Amadeusz; Castro, OlgaThe aim of this study is to investigate the differences in ventilation efficiency owing to an air supply position and air exhaust locations of an air distribution system in combination with a fan coil. Ten strategies of air diffusion strategies were performed in a test chamber applying the tracer gas techniques. All experiments were performed with a presence of the fan coil. For all the ten strategies 9 rph provided by a fan coil was investigated. Three strategies were studied with other renovations rates (6, 7 and 8 rph). For 3 strategies influence of different position of CO2 probes on the final results was checked. The main conclusions of this work are as follows: if the renovation rate is over 7 rph, the contaminants and temperature vertical distributions are destroyed due to mixing of the air; if fan coil provides renovations over 7 rph, the efficiency for every strategy approaches 1; placement of temperature and contaminant probes has an influence on the result of the experiment for particular strategies.
- Impact of design options in zero energy building conception: the case of large buildings in PortugalPublication . Lima, Pedro; Monteiro, Joaquim; Castro, OlgaThe new recast of Directive 2010/31/EU in order to implement the new concept NZEB in new buildings, is to be fully respected by all Member States, and is revealed as important measure to promote the reduction of energy consumption of buildings and encouraging the use of renewable energy. In this study, it was tested the applicability of the nearly zero energy building concept to a big size office building and its impact after a 50-years life cycle span.
- Impact of using solar heat pumps for domestic hot water in Portuguese residential buildingsPublication . Monteiro, Joaquim; Castro, OlgaIn recent years, we have seen an improvement of existing facilities in dwellings in Portugal. Within the heat pumps systems, there is a special type known as direct expansion heat pump assisted by Solar Collector (DX-SAHP). It was calculate the SPF indicator for 30 regions of Portugal. It was analyses the potential of reductions of CO2 and primary energy use for the retrofitting of DHW preparation systems. It was found that the performances of this type of equipment are benefiting from the Portuguese climate conditions, especially in the South and in the Autonomous Regions. Best SPF was obtained for Beja. It was found in all regions of the high potential for reducing CO2 emissions and verifying a potential significant reduction of primary energy consumption.
- Influência do clima e do caudal de ar variável em função da demanda para um sistema centralizado tudo-ar.Publication . Almeida, Marco; Monteiro, Joaquim; Castro, OlgaNa perspetiva da melhoria da eficiência energética e da QAI dos edifícios de serviços existentes e que são climatizados com sistemas centralizados do tipo tudo-ar, foi desenvolvida uma aplicação informática que permite simular o comportamento dinâmico de situações reais de funcionamento relativas ao tratamento de ar. Com vista à redução do consumo energético associado à utilização dos sistemas técnicos de climatização, foi desenvolvido um modelo matemático para os diversos processos físicos que ocorrem numa unidade de tratamento de ar, implementado numa aplicação informática e validado o seu funcionamento através de experiências laboratoriais desenvolvidas numa sala de testes de climatização. O presente estudo permitiu determinar a influência das variáveis, clima e caudal de ar insuflado variável em função da demanda, no consumo energético associado às condições de conforto do ambiente interior para a estação de aquecimento. Foi estimado um aumento de 65% de consumo energético para o clima mais rigoroso de Bragança, acompanhado de um menor potencial de redução de consumo energético (6% em termos médios), relativamente aos outros climas. Relativamente à utilização de estratégias de ventilação controlada pela demanda (DCV), estimaram-se que os potenciais de redução de consumo energético máximos poderão atingir valores de 40% e 39% para Faro e Porto, respetivamente, e de 30% para Bragança. A ferramenta informática desenvolvida poderá ser uma ajuda em análises económicas a efetuar, nomeadamente para renovações de edifícios de serviços existentes.
- The study of the impact of demand controlled ventilation in energy consumption of offices in Portuguese commercial buildingsPublication . Almeida, Marco; Monteiro, Joaquim; Castro, OlgaThis study presents an implementation of an application, using mathematical models, which allow to create virtual simulations to minimize energy consumption, thereby enabling an optimization of the energy efficiency of air handling equipment. The mathematical model was validated by laboratory experiments. An analysis of variation of the quantity of supply air of the system for three cities in different climatic conditions was performed. The analysis of energy consumption values for each city, show that the largest potential reduction of energy consumption can be seen to the city of Faro for the simulation of two occupants with a reduction of 39,84%.