EAC - Comunicações em actas de encontros científicos internacionais
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- Air flow exchange velocity of urban canyon cavities due to thermal spatial differencesPublication . Panão, Marta Oliveira; Goncalves, Helder; Ferrão, PauloIn this paper, the air exchange velocity between the urban canyon cavity and the air layer above roof level is quantified, using a two-dimensional k-ε model, and correlated with the air cavity mean temperature, for two cases: leeward and downward wall heating. The spatial thermal differences are evaluated by assuming a wall temperature higher than the air temperature, with this difference ranging between 0 and 16 K. The undisturbed wind velocity above the roof level is varied from 1 to 6 ms-1 and the canyon aspect ratio is 1.5, which corresponds to a skimming flow regime. The model predicts two situations, which correspond to air flow regimes where one or two eddies are formed, respectively: (a) for high wind speed, the air inside the cavity is negligible affect by the buoyancy effect and the air exchange velocity linearly increases with the increase of wind velocity; (b) for low wind speed, when the buoyancy forces are stronger than the wind induced forces, the air exchange velocity is not a linear function with the wind velocity. The transition wind velocity between (a) and (b) is a function of the wall-air temperature difference. The situation of windward heated wall and two eddies air flow regime is the most favorable to extract heat from the cavity. On the contrary, the heated air is hardly extracted from the cavity when only the wind induced eddy is predicted and windward wall is heated. In this situation an increase of 10 K on the wall temperature increases by 1 K the in-cavity air temperature.
- BIPV/T versus BIPV/T-PCM: A numerical investigation of advanced system integrated into Solar XXI building façadePublication . Aelenei, Laura Elena; Pereira, R.; Goncalves, Helder
- Design issues for net zero-energy buildingsPublication . Aelenei, Laura Elena; Aelenei, Daniel; Goncalves, Helder; Lollini, Roberto; Musall, Eike; Scognamiglio, Alessandra; Cubi, Eduard; Noguchi, MassaNet Zero-Energy Buildings (NZEBs) have received increased attention in recent years as a result of constant concerns for energy supply constraints, decreasing energy resources, increasing energy costs and rising impact of greenhouse gases on world climate. Promoting whole, building strategies that employ passive measures with energy efficient systems and technologies using renewable energy, became a European political strategy since the publication of the Energy Performance of Building Directive recasr in May 2010 by the European Parliament and Council.
- Design strategies for non-residential zero-energy buildings: lessons learned from Task40/Annex 52: towards net zero-energy solar buildingsPublication . Aelenei, Daniel; Aelenei, Laura Elena; Musall, Eike; Cubi, Eduard; Ayoub, Josef; Belleri, AnnamariaNet zero-energy buildings (Net ZEBs) have been the object of various studies in recent years as various countries have set this performance as long-term goal of their energy policies. Designing successful Net ZEBs represents a challenge since the definitions are yet generic, the assessment method and monitoring approach are under development and the literature is relatively scarce about the best sets of solutions for different typologies and climates likely to deliver an actual and reliable performance in terms of energy balance (used consumed vs. generated) on a costeffective basis. The International collaborative research initiative between the Solar Heating and Cooling (SHC) and the Energy Conservation in Buildings and Community Systems (ECBCS) through Task 40/Annex 52 - Towards Net-Zero Energy Solar Buildings-, summarises most of the recent developments in this field. The authors of this article, who are participants in this task, are providing insights from on-going research work on some best practice leading projects which have been the object of an exploratory cross-case analysis in order to facilitate identification of the set of relevant design strategies. The close inspection of the strategies and indicators of the relative performance of the projects revealed interesting features about the combination of design challenges with techniques and technologies responsible for delivering the Zero Energy performance.
- Designing adaptive facades with a new holistic eco-design approachPublication . Vedula, Nitisha; Aelenei, Laura Elena; Pottgiesser, UtaABSTRACT: Implementing the Eco-designed approach in the field of adaptive façade systems, primarily aims for the future sustainable targets to develop eco-friendly and socio-responsive technologies. This will be only possible when the adaptive façade systems track design strategies endeavouring to imitate the philosophy of “the self-sufficient unit in the nature called eco-system.” With the understanding of the future sustainable targets of adaptive systems and analysing its sustainably efficient elements with the help of already existing and scattered classification schemes from the data base developed within the work of the Cost Action TU 1403 Adaptive Façade Network (AFN), this approach attempts to develop a novel matrix for re-analysing these adaptive façade projects with an eco-design approach. The aim of this approach is to examine whether these adaptive façade projects from the data base are able to seamlessly integrate themselves in this approach and to what extent. The eco-design approach on the basis of the contiguous natural environment (i.e. location and climate type), conceives the adaptive façade projects as a unit-cell in the eco-system, which should naturally attempt to be a self-sufficient unit. Understanding this approach, the various principles of the adaptive façade systems in the projects from the database are analysed. This leads to characterizing the approach in a matrix of the biotic components of eco-system (producers, consumers and decomposers) and abiotic components of ecosystem (air, soil, water, temperature, pressure, inorganic substances, etc.). These two components work collectively due to the naturally occurring energy transfer principles in amidst, known as conduction, indirect-solar, direct-solar and ventilation. The matrix also further characterizes the biotic components into active and passive systems, in order to avoid any error in analysing both, the direct and in-direct influences of the adaptive façade systems inside the project. The eco-design approach attempts to thoroughly analyse the extent of integration of this approach in the field of adaptive façade systems and to apprehend the further scope of research and development for the related industry.
- Eficiência energética na cidade: Estratégias para a promoção da capacidade natural de aquecimento e arrefecimento de edifíciosPublication . Panão, Marta Oliveira; Goncalves, Helder; Ferrão, P.Este estudo apresenta uma técnica para, a partir de um dado índice de construção, encontrar as formas urbanas mais favoráveis ao desempenho térmico de edifícios, com base na absorptância efectiva do edifício no Inverno e no Verão. Esse parâmetro é indicativo da exposição solar do mesmo e da capacidade natural de aquecimento de um edifício quando esse se encontra inserido numa malha urbana. A avaliação da absorptância efectiva para as duas estações do ano permitiu encontrar as formas de organização da malha que beneficiam a acessibilidade solar de Inverno, mas restrigem-na no Verão. Para o cálculo da absorptância efectiva utiliza-se o Método das Matrizes Urbanas que consiste em obter para cada geometria, uma matriz Ψ que descreve a forma como a radiação que incide em cada uma das parcelas que compõem as superfícies do bloco urbano se distribui pelas restantes superfícies. Essa matriz integra os factores de forma entre as superfícies e as respectivas propriedades de absorpção considerando, dessa forma, as reflexões múltiplas que ocorrem no interior do espaço urbano. A aplicação de uma metodologia de optimização a diversas formas urbanas, com base no conceito de algoritmo genético, permitiu concluir que, para as latitudes de 37º e 42º, as malhas urbanas mais favoráveis são os blocos de secção rectangular, com 3 a 5 pisos, dispostos segundo um eixo Este-Oeste por forma a possuirem uma maior fachada exposta a Sul. O espaçamento entre blocos é sempre maximizado na direcção Norte-Sul por forma a permitir, no Inverno, uma maior exposição solar da fachada Sul e, por outro lado, minimizando o espaçamento entre blocos na direcção Este-Oeste, prevenir os excessivos ganhos solares na estação de Verão. Para uma latitude de 37º são ainda soluções blocos de secção quadrangular com 5 a 8 pisos, que formam uma malha com ângulo de ±15º relativamente à direcção dos pontos cardeais.
- Energia solar no ambiente urbano: caso de estudo, desafios, abordagens e investigaçãoPublication . Viana, Susana; Simões, Teresa; Aelenei, Laura Elena; Justino, Paulo AlexandreRESUMO: O Município de Cascais tem vindo a empenhar-se na mitigação das alterações climáticas, na proteção do ambiente e renaturalização de florestas e espaços verdes, no aumento da recolha seletiva e melhoria de processos de tratamento de resíduos, na melhoria da mobilidade, apostando na mobilidade suave combinada com zonas intermodais de ligação a transportes públicos, como os comboios e a rede gratuita de autocarros municipais (Mobi Cascais) para residentes, trabalhadores e estudantes. Como forma de diminuir a sua pegada de carbono, o município pretende ainda apostar na geração de energia a partir de fontes renováveis, nomeadamente na integração de energia solar fotovoltaica em edifícios públicos e em edifícios geridos pela autarquia. Para atingir estes objetivos Cascais tornou-se um caso de estudo em dois projetos europeus, Re-Value e WeGenerate.
- Energy performance certificate: a valuable tool for building-to-grid interaction?Publication . Panão, Marta Oliveira; Goncalves, HelderNew challenges were opened with the recast of Energy Performance of Buildings Directive, requiring by 2020 that new buildings be “nearly Zero-Energy Buildings” (nearly ZEB). In addition to consumer buildings, Net ZEBs are also producers’ by using as much renewable energy sources as possible to compensate the building energy load. Sustainable cities require energy-efficient buildings, i.e. buildings where the use of energy is minimized without compromising the occupants comfort, namely for heating, cooling, lighting and indoor air quality. But smart cities require energy-efficient ‘interactive’ buildings, which integrate multiplecarrier energy networks and provide up-to-date valuable information for their management, where buildings are simplified to single nodes characterized by their energy load, generation, storage and conversion, applying the load-generation approach. The information currently available in the Energy Performance Certificate is not relevant for estimating the time dependent building energy load, but it can be easily improved by including a few descriptive parameters.
- Energy saving potential of a hybrid BIPV-T system integrated with heat storage materialPublication . Aelenei, Laura Elena; Pereira, R.; Goncalves, Helder; Silva, António Rocha e
- Energy simulation of a vernacular house in Santana/Madeira Island: case studyPublication . Graça, João Mariz; Andrade, Susana