Concept, design and energy simulation of a Net Zero Energy Home for the Mediterranean climate

Tese de mestrado integrado em Engenharia da Energia e do Ambiente, Universidade de Lisboa, Faculdade de Ciências, 2020Para reverter os efeitos das alterações climáticas e projetar um futuro sustentável, o setor da energia está a tomar três principais medidas: eletrificação, descarbonização e eficiência energética. Entre os três maiores consumidores de energia, logo maiores emissores de carbono, encontra-se o setor dos edifícios que, especialmente no sul da Europa, avança a passos lentos no sentido do edifício eficiente, estando em fase de desenvolvimento muito precoce da implantação do edifício de alta performance. Prevê-se que os climas temperados de latitudes médias sejam dos mais afectados pelo aquecimento global, com aumento nomeadamente da frequência, duração e intensidade das ondas de calor, pelo que perceber e instalar estratégias passivas de arrefecimento é urgente. São elas: a ventilação nocturna, a obstrução solar (sombreamento), o isolamento – desde que não exceda a capacidade do espaço de evacuar calor, acumulando-o –, trocas radiativas com o céu, convectivas, evapo-transpiração, o uso da inércia para armazenamento e modelação das condições interiores em parceria com a ventilação natural para remoção do calor, etc. Um desses climas com previsão de alargamento do verão é o clima Mediterrânico, que se traduz como um clima temparado quente – classe ‘C’ na classificação climática de Köppen-Geiger – de verão seco – subclasse ‘s’ – e quente ou ameno – subtipos ‘a’ e ‘b’, portanto Csa e Csb. Para uma recolha de 68 localidades do sul da Europa, com subtipos climáticos Csa e Csb, foi feita uma análise da temperatura ambiente e radiação global horizontal. A cidade que mais se aproximava da média da amostra em ambos os parâmetros era a de Nice, no sul de França, pelo que Nice foi escolhida como a cidade representativa da norma do clima Mediterrânico e o local de construção hipotética da casa projetada nesta dissertação. Nice apresenta clima Csa e verões quentes de Junho a Setembro. A planta da moradia foi desenhada em SketchUp considerando uma família de 4 pessoas, um só piso, e uma otimização do uso dos espaços a Sul. Assim, os quartos das crianças, a sua casa-de-banho, e o solário/marquise junto à sala foram inseridos na fachada Sul. A suite dos pais foi posicionada virada a Este com o seu WC privativo no canto nordeste da casa, protegendo a envolvente da suite a Norte. Os quartos encontram-se todos na secção Este da casa. Do outro lado, a cozinha está virada a Norte, seguida da sala de jantar+sala de estar (zona DLIV) no meio da secção com janela a Oeste, e então o solário com portas de vidro amovíveis (viradas para a sala) orientado a Sul. Uma pála horizontal exterior foi dimensionada analiticamente para que sombreasse totalmente a janela do solário e quartos das crianças (têm a mesma altura) no verão, e garantisse exposição solar total no inverno. A zona térmica da cozinha teve que ser separada da da sala pois, ao contrário da última, não tem operação AVAC; no entanto, um conceito aberto moderno era desejado, pelo que se criou uma porta interior ocupando (praticamente) toda a parede de interseção entre as zonas, e definiu-se esta porta dentro do EnergyPlus, o software de simulação energética utilizado, como estando sempre aberta. A casa tem grande área envidraçada, pé-direito de 3 m, e áreas de chão bastante razoáveis. A envolvente térmica que a compõe foi baseada na de uma casa certificada Passive House Premium localizada não muito longe de Nice (em Solliès-Pont). Os isolantes térmicos foram todos trocados por cortiça de condutividade 0.04 W/m.K, um material muito produzido no sul da Europa. A composição de cada fachada foi simplificada e os coeficientes de tranferência de calor (U-values) relaxados, excepto para o telhado plano que manteve 25 cm de isolamento. A janela escolhida foi dupla de baixa emitância térmica e preenchida com Árgon. Na construção do solo, uma simplificação foi utilizada que estabelece que as temperaturas do solo a 2 m de profundidade podem ser usadas no EnergyPlus como condição de fronteira do chão, se se projectar uma construção do pavimento com 2 m de espessura, tendo-se incluído o material ‘solo’ com a espessura em falta, 1.4 m. Já no EnergyPlus, para que a janela larga da cozinha virada a Norte ventilasse a sala, motivo pelo qual ela foi traçada, foi criado um modelo de movimentação de ar multizona, o ‘Airflow Network’ (AFN). Mas tanto os controlos de abertura de janelas para ventilação natural do AFN, como de operação dos dispositivos de sombreamento amovíveis – estores exteriores e persianas interiores – foram personalizados com detalhe usando o ‘Energy Management System’ (EMS). Programando dentro do EnergyPlus, escrevendo códigos curtos e simples, as condições de controlo limitadas do software são ignoradas e sobrepostas. Assim, um modo de condicionamento híbrido de AVAC e ventilação natural foi criado, que tendo ambas as opções disponíveis ao mesmo tempo, garante que não há simultaneidade de operação entre elas, bem como um programa de controlo dos sombreamento amovível das janelas exteriores, que permite que haja um segundo dispositivo na mesma janela; tal foi feito impondo uma mudança da construção da janela para uma que inclui o estor na posição exterior, quando as suas condições de operação são satisfeitas. O estor funciona como isolamento amovível, prevenindo arrefecimento excessivo e sobraquecimento quando a casa está desocupada. As persianas interiores também são controladas no mesmo program de EMS para bloquearem a radiação directa quando: a família está em casa, a sala está perto do sobreaquecimento e a radiação incidente tem uma intensidade superior a 150 W/m2. Todos estes controlos resultaram em cargas térmicas anuais de 3.62 kWh/m2.a e 2.90 kWh/m2.a por Área Tratada (TFA, soma das áreas de todas as zonas condicionadas) para aquecimento e arrefecimento, respectivamente, portanto muito abaixo do requisito do standard Passive House de 15 kWh/m2.a para cada carga. Uma bomba de calor teórica de eficiência global de 20% foi usada como equipamento AVAC, e uma série de sete módulos fotovoltaicos foi suficiente para suprir o consumo anual total de electricidade da casa de 1.99 MWh. As horas de operação das janelas, estores e persianas foram constatadas como elevadas, evidenciando a eficiência da aplicação destas estratégias passivas – excepto para as persianas, como se previa, visto que estas bloqueiam radiação excessiva quando a casa está ocupada, e à semana a família só chega às 18:30, quando a radiação já não é elevada; estas persianas são úteis ao fim-de-semana. No entanto, verificou-se um consumo de arrefecimento elevado na sala, e taxas de desconforto por sobreaquecimento quando a casa está ocupada acima do desejado. O modo passivo revelou menor desconforto térmico, o que valida que o problema terá estado na operação do AVAC. O horário de operação intermitente deve ser demasiado reduzido, a meia hora que antecede a chegada da família a casa e em que o sistema liga será insuficiente para colmatar sobreaquecimentos. De qualquer forma, um edifício de baixíssimo consumo foi alcançado.A single-family single-floor detached NZEH was designed for the city of Nice, France, of Mediterranean climate. A horizontal overhang was projected analytically to completely shade the South glazing on summer and assure total exposure on winter. The thermal envelope was based on a nearby certified Passive House Premium, with some relaxation of the heat transfer coefficient, except for the roof (25 cm of cork insulation). An intermittent operation was used for the HVAC. A modern open concept of kitchen-dining-living room was applied, with separation of the untreated kitchen from the dining-living room (DLIV) by an always open door that covers the whole joint wall. A sunroom faces South, DLIV is in the middle (West glazing), the kitchen on the North with a wide window specifically to provide north winds for night flushing of DLIV. Thus, a multizone Airflow Network was created on EnergyPlus (E+). Both venting and movable shading devices’ operation controls were customised using EMS. By writing simple codes inside E+, its limited control conditions were overridden, enabling a hybrid conditioning mode with HVAC and natural ventilation available at the same time but never overlapping, and a second shading device on windows, the external shutter, through a full window construction change. The shutters act as movable insulation, preventing overcooling and overheating when the house is unoccupied. The internal blinds, that block beam radiation when the occupants are home, were also optimised with EMS. All these controls resulted in thermal loads below 4 kWh/m2.y per Treated Floor Area for both cooling and heating, well below the Passive House 15 kWh/m2.y threshold for each. A theoretical heat pump was used, and a string of 7 PV modules was sufficient to supply the 1.99 MWh annual total electric consumption

Human Dimensions Of Building Performance: Sensing, Modeling, And Predicting Indoor Environmental Quality

The indoor environment critically affects occupant health and comfort, especially since humans spend most of the day indoors. Meanwhile, occupant activities, preferences, and behaviors may contribute to a significant amount of building energy consumption. The focus of environmental buildings shifted from automated systems to a paradigm of collective environmental design since the second half of the 20th century, emphasizing human dimensions in building performance, which allows occupants to participate as active/passive actuators and sensors. Concurrently, increased environmental awareness further spurred the green building movement intending to encourage more high-performance buildings. The question remains as to whether high-performance buildings are also healthy buildings. This dissertation aims to cast new light on how environmental design and building systems work for people as well as how building sensors and human senses work together to inform the organization and optimization of various performance targets such as sustainability, public health, and resiliency. Special attention is given to the non-visual environment attempting to facilitate human-in-the-loop of the building design and operation processes. In order to achieve this goal, environmental monitoring, data analysis, and human subject recruitments are developed to characterize the human dimension of building performance

Re-addressing the Window: Environmental Performance of Adaptive Fenestrations for Indian Climate

The primary function of building fenestrations known to humankind is to provide daylight, fresh air and view. However, with the emergence of mechanical systems, the purpose of space heating and cooling, ventilation and lighting are widely fulfilled artificially. The comprehensive focus of this research is to investigate the role and evolution of windows to date, the factors that have influenced them, its effect on human psychology and their contribution in creating better living spaces. The Indian government’s scheme of constructing 20 million homes by 2022 and about 15% rise in the use of air conditioning per year in the urban and rural parts of India can be directly associated with the persistent shortage in electricity supply which has led to power cuts of about 16 hours per day in mostly the rural areas of the country and especially during the summer months (National Building Organization, 2016), (The Hindu, 2013; Wolfram, 2012). Hence, it is of specific importance to undertake this research to understand how windows have evolved and what their role in the future might be, especially in relation to design and the attainment of comfort. This research will contribute by portraying ‘window’ as an adaptive tool since they have the potential to create diversity, flexibility and social interaction on along with providing thermal and visual comfort for its users. This will be achieved by examining and readdressing passive design elements prevalent in the traditional Indian buildings, by documenting the current trend in window design and user preference, and by testing the documented windows through computational analysis to understand their impact on the thermal comfort in a modern residential unit setting. The final outcomes of this study that were achieved through fieldwork and performance analysis strongly demonstrated the significance of windows in improving the indoor thermal comfort. Moreover, the simulations ascertained that the contribution of windows was more substantial when they were a part of a holistic design intervene on that took into consideration on window design, building materials, building form and orientation, building techniques, climactic conditions, surrounding context and application of appropriate environmental controls

Addressing variability as an expansion of naturalistic lighting theory for user wellbeing

This study is an exploration into the relationship between lighting and office occupant productivity and wellbeing, attempting to better understand how enhanced naturalistic lighting and lighting control might enable an environment that affects occupants positively. To explore the possibilities of this concept, a morphological research approach has been implemented to ultimately integrate the following three major lighting developments; human affinity to nature; accommodation of physiological, functional, and psychological aspects; and acknowledgement of the inherent need for variability and evolution. This study consisted mainly of two segments. First, through the review of literature, three key lighting-oriented developments have been identified; human affinity to nature; accommodation of physiological, functional, and psychological aspects; and acknowledgement of the inherent need for variability and evolution. No lighting solution that integrates all these factors has yet been found. Second, the study introduces the concept of enhanced naturalistic lighting and its control schematic, holistically combining all three of these key developments. Future exploration of interior design implications related to enhanced naturalistic lighting and associated control systems will be discussed to clarify how such lighting systems could impact the wellbeing of the users

The Effects of Indoor Temperature and CO2 levels as an Indicator for Ventilation Rates on Cognitive Performance of Adult Female Students in Saudi Arabia

Educational buildings are complex spaces to design, as they need to perform well in all aspects of environmental conditions. Research has clearly established that problems with indoor environmental quality in classrooms, including, but not limited to, thermal and air quality, can directly influence students’ outcomes and learning. There is a growing body of evidence that improved environmental conditions in classrooms increases productivity and improves the performance of mental tasks, such as improved concentration and recall. It is of particular importance to investigate the effects in educational buildings relying on mechanical for ventilation and cooling in the hot desert climates like Saudi Arabia where great reliance on air conditioners occurs, especially after energy has become cheap and affordable. An experimental approach was adopted in this study via an intervention study in a selected female university building to investigate the effects of classrooms’ temperature and CO2 levels on a set of vigilance and memory tasks exemplifying the basic yet most critically important functions involved in the process of learning. The experiments were performed using a blind cross-over design with repeated-measures. Data analysis was performed using a multi-variable multilevel statistical analysis approach. The study is based on two classrooms’ physical environmental measurements data collected from 499 adult female participants. After considering the possible confounders of the study, the main findings highlight the potential benefits of effectively managing indoor temperature and CO2 levels in the air-conditioned university/college buildings in Saudi Arabia for improved educational environments in which students are expected to learn and produce. The research concludes that temperature affects the accuracy of tasks differently according to the type of task while performance in all tasks improved significantly when CO2 levels decreased from 1800 ppm to 600 ppm and also from the currently recommended levels by ASHRAE of 1000 ppm to 600 ppm

Different Strategies of Housing Design

As one of the largest consumers of energy, the housing sector and its unconscious occupants' activities negatively affect the environment. Architects and engineers have a major role in resolving the associated problems while maintaining comfort for occupants. Also very important are environmental education and awareness of appropriate environmental development in designing activity and selecting building materials and products. There are different architectural strategies that are aimed to achieve a low-energy built environment. Determining the needed strategy according to function, economy, and occupant comfort and affordability is the crucial step. This book helps the reader to achieve a sustainable development without destruction of the resources while maintaining a growing universal awareness of protecting the living and non-living environment

Thermal delight in architecture

Thesis. 1978. M.Arch.--Massachusetts Institute of Technology. Dept. of Architecture.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCHBibliography: leaves 104-108.by Lisa Heschong.M.Arch

Profitable thermal renovation of hotels to combat climate change and depletion of fossil fuels: the case of Cyprus

Hotel buildings were identified as significant energy consumers. Within the theoretical framework of the thesis it was argued that climate change and increasing energy prices due to depletion of fossil fuels would cause pressure on hotel operations in Cyprus by increasing their cooling loads and operational costs. The analysis was techno-socio-economic and the core aim was to evaluate the costeffectiveness of selected energy saving strategies. These were in the form of building envelope upgrades, changes in indoor environmental criteria and introduction of renewable energy technology via solar air-conditioning to be implemented as part of the hotels’ periodic scheduled building and systems upgrades with the aim of lowering their space conditioning energy costs and improving their profitability and competitiveness. The applied methodology consisted of auditing of a case study hotel, energy consumption data collection both from a sample of hotels and industry-wide and a hotel guest survey. Thermal simulation of hotels in present and future climates was used to identify technically viable renovation strategies. Strategies found cost-effective were further checked for sensitivity to energy prices, hotel occupancy and climate. The major findings of the thesis predict over 20% savings in space conditioning energy costs due to strategic building envelope upgrades, over 50% savings if in addition adjustments in thermal comfort criteria are included and over 80% savings if solar AC is added into the above. It was further found that with a minimal increase in room rates hotels could implement thermal renovation while maintaining or even increasing room income. A unique cost-efficiency indicator that measures profitability of the proposed energy saving strategies in terms of hotels’ room income generation potential was developed in this thesis. Finally, if the suggested renovations were implemented on a mass scale, one quarter of Cyprus’ national energy saving and renewable energy targets could be met

Proceedings experiencing light 2009 : international conference on the effects of light on welbeing

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Proceedings experiencing light 2009 : international conference on the effects of light on welbeing

no abstrac