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This paper proposes a methodology for improvement of energy efficiency in buildings through the innovative simultaneous incorporation of three distinct phase change materials (here termed as hybrid PCM) in plastering mortars for façade walls. The thermal performance of a hybrid PCM mortar was experimentally evaluated by comparing the behaviour of a prototype test cell (including hybrid PCM plastering mortar) subjected to realistic daily temperature profiles, with the behaviour of a similar prototype test cell, in which no PCM was added. A numerical simulation model was employed (using ANSYS-FLUENT) to validate the capacity of simulating temperature evolution within the prototype containing hybrid PCM, as well as to understand the contribution of hybrid PCM to energy efficiency. Incorporation of hybrid PCM into plastering mortars was found to have the potential to significantly reduce heating/cooling temperature demands for maintaining the interior temperature within comfort levels when compared to normal mortars (without PCM), or even mortars comprising a single type of PCM.

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Due to communication and technology developments, residential consumers are enabled to participate in Demand Response Programs (DRPs), control their consumption and decrease their cost by using Household Energy Management (HEM) systems. On the other hand, capability of energy storage systems to improve the energy efficiency causes that employing Phase Change Materials (PCM) as thermal storage systems to be widely addressed in the building applications. In this paper, an operational model of HEM system considering the incorporation of more than one type of PCM in plastering mortars (hybrid PCM) is proposed not only to minimize the customer's cost in different DRPs but also to guaranty the habitants' satisfaction. Moreover, the proposed model ensures the technical and economic limits of batteries and electrical appliances. Different case studies indicate that implementation of hybrid PCM in the buildings can meaningfully affect the operational pattern of HEM systems in different DRPs. The results reveal that the customer's electricity cost can be reduced up to 48% by utilizing the proposed model.

a b s t r a c tGeopolymers have much higher drying shrinkage than Portland cement based composites Shrinkage performance is an important property for reinforced concrete composites just because a high shrinkage performance is associated to cracking tendency that leads to future durability problems. This paper provides results experimental and numerical investigations of fly ash based geopolymeric mortars reinforced with short hybrid polymeric fibres (SHPF). The results show that SHPF improved the flexural performance, while reducing the compressive strength and flexural stiffness of geopolymeric mortars. The addition of 0.8% SHPF increased about two times the fracture energy and about 50% the tensile strength. The adopted constitutive model well-captured the flexural performance of the tested beams.

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The use of phase change materials (PCMs) for the building sector is increasingly attracting attention from researchers and practitioners. Several research studies forwarded the possibility of incorporating microencapsulated PCM in plastering mortars for building façades, in pursuit of increased energy efficiency associated with the heat storage capacity of PCM. However, most of these studies are centred in the use of a single type of PCM, which is bound to be more adequate for a given season of the year (e.g. winter or summer) than for all the seasons. The study proposed in this work regards the evaluation of the possibility of using more than one kind of PCM, with distinct melting ranges, here termed as hybrid PCMs, in plastering mortars, to achieve adequately advantageous performance in all seasons of the year. To characterize the PCM, the specific enthalpy and phase change temperature should be adequately measured. The main purpose of this study was to show the conceptual feasibility of combining PCMs in mortars and to evaluate the behaviour of the resulting mortars with differential scanning calorimeter. The results showed that the behaviour of the mortar that contains more than one type of PCM can be predicted through the superposition of effects of the independent PCMs and no interaction occurs between them. The knowledge obtained from the experimental testing established bases for a framework of numerical simulation of real-scale applications, which can be used to ascertain the feasibility of the hybrid PCM concept for decreases in energy consumption of heating/cooling demands in the buildings.