Mortars with incorporation of phase change materials (PCM): physical and mechanical properties and durability

O despertar da consciência ambiental pela sociedade, tem levantado problemas até então ignorados tais como os consumos energéticos. Numa sociedade com um elevado ritmo de crescimento e padrões de conforto cada vez maiores, surge a necessidade de minimizar os elevados consumos energéticos, tirando partido de fontes de energia renováveis. As argamassas com incorporação de materiais de mudança de fase (PCM) possuem a capacidade de regular a temperatura no interior dos edifícios, contribuindo desta forma para o aumento do nível de conforto térmico e diminuição do recurso a equipamentos de climatização, apenas com recurso à energia solar. Contudo, a incorporação de materiais de mudança de fase em argamassas modifica algumas das suas principais características. Portanto, o principal objetivo deste estudo consistiu na caracterização física e mecânica de argamassas aditivadas com PCM, assim como na avaliação da sua durabilidade. Para tal foram desenvolvidas 12 composições distintas, à base de diferentes ligantes e dopadas com 40% de PCM. Tendo sido possível observar que a incorporação de PCM provoca diferenças significativas em propriedades tais como a trabalhabilidade, resistência à compressão, resistência à flexão, aderência, absorção de água por capilaridade, absorção de água por imersão e resistência a ações de gelo-degelo. Contudo, foi possível concluir que a incorporação de PCM nas argamassas pode ser realizada com sucesso. Sendo que, as alterações verificadas nas argamassas podem ser contornadas através da incorporação de uma maior dosagem de ligante, superplastificante e até mesmo a inclusão de fibras. Apesar dos resultados desta investigação serem promissores é importante referir que outras investigações devem ser realizadas com o intuito de observar a influência do PCM em argamassas constituídas por outros materiais.The awakening of environmental awareness by society has raised issues previously ignored such as energy consumption. In a society with a high growth rate and increased standards of comfort arises the need to minimize the currently high energy consumption by taking advantage of renewable energy sources. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing to the thermal comfort and reduction of the use of heating and cooling equipment, using only the energy supplied by the sun. However, the incorporation of phase change materials in mortars modifies its characteristics. The main purpose of this study was the physical and mechanical characterization, as well the evaluation of the durability. Twelve compositions were developed, based in different binders and doped with 40% of PCM. It was possible to observe that the incorporation of PCM in mortars caused significant differences in properties, such as workability, compression strength, flexural strength, adhesion, water absorption by capillarity, water absorption by immersion and degradation after freeze-thaw cycles. However, it was concluded that the incorporation of PCM in mortars can be performed successfully. Being that the changes in mortars can be solved by incorporating a higher content of binder, superplasticizer and the inclusion of fibers. Although the results of this investigation are promising it is important to note that further investigations should be performed aiming to observe the influence of PCM in mortars composed by other materials.Fundação para a Ciência e Tecnologia pelo financiamento deste trabalho de investigação desenvolvido no âmbito do projeto “ Contribuição de Argamassas Térmicas Ativas para a Eficiência Energética dos Edifícios” (PTDC/ECM/102154/2008) e à atribuição da bolsa individual de doutoramento com referência SFRH/BD/95611/2013

Design of Predictive Control Strategies for Active BITIES Systems Using Frequency Domain Models

Active building-integrated thermal energy storage (BITES) systems, such as ventilated concrete slabs, are able to effectively store and release abundant of thermal energy to assist space conditioning. Since active BITES systems are strongly thermal-coupled to the rest of the room, the desires for comfortable room temperature and utilization of renewable thermal energy, together with BITES' large thermal inertia place challenges in the operation of active BITES systems. With desired room temperature profiles and corresponding thermal loads, frequency domain models can readily provide predictive operation information for the active BITES systems. This paper will demonstrate the concept, methodology, and techniques in using frequency domain models to conduct predictive operations of active BITES systems. Using frequency domain models in optimizing the design of active BITES systems will also be discussed

An information driven hybrid evolutionary algorithm for optimal design of a Net Zero Energy House

Building Performance Simulation (BPS) is a powerful tool to estimate and reduce building energy consumption at the design stage. However, the true potential of BPS remains unrealized if trial and error simulation methods are practiced to identify combinations of parameters to reduce energy use of design alternatives. Optimization algorithms coupled with BPS is a process-orientated tool which identifies optimal building configurations using conflicting performance indicators. However, the application of optimization approaches to building design is not common practice due to time and computation requirements. This paper proposes a hybrid evolutionary algorithm which uses information gained during previous simulations to expedite and improve algorithm convergence using targeted deterministic searches. This technique is applied to a net-zero energy home case study to optimize trade-offs in passive solar gains and active solar generation using a cost constraint

From the Sum of Near-Zero Energy Buildings to the Whole of a Near-Zero Energy Housing Settlement: The Role of Communal Spaces in Performance-Driven Design

Almost a century ago Modernism challenged the structure of the city and reshaped its physical space in order to, amongst other things, accommodate new transportation infrastructure and road networks proclaiming the,nowadays much-debated ‘scientificated’ pursuit of efficiency for the city. This transformation has had a great impact on the way humans still design, move in, occupy and experience the city. Today major cities in Europe, such as Paris and London, are considering banning vehicles from their historic centers. In parallel, significant effort is currently underway internationally by designers, architects, and engineers to integrate innovative technologies and sophisticated solutions for energy production, management, and storage, as well as for efficient energy consumption, into the architecture of buildings. In general, this effort seeks for new technologies and design methods (e.g., DesignBuilder with EnergyPlus simulation engine; Rhicoceros3D with Grasshopper plugin and Ecotect, Radiance and EnergyPlus tools) that would enable a holistic approach to the spatial design of Near-Zero Energy buildings, so that their ecological benefits are an added value to the architectural design and a building’s visual, and material, impact on its surrounding space. The paper inquires how the integration of such technological infrastructure and performance-orientated interfaces changes yet again the structure and form of cities, and to what extent it safeguards social rights and enables equal access to common resources. Drawing from preliminary results and initial considerations of ongoing research that involve the construction of four innovative NZE settlements across Europe, in the context of the EU-funded ZERO-PLUS project, this paper discusses the integration of novel infrastructure in communal spaces of these settlements. In doing so, it contributes to the debate about smart communities and their role in the sustainable management of housing developments and settlements that are designed and developed with the concept of smart territories