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Envelope systems are the main contributors to the energy consumption associated to cooling or heating buildings. There have been significant research efforts to improve the performance of building envelope systems by integrating passive cooling strategies to reduce cooling loads and maintain acceptable indoor thermal comfort. The ventilated wall cavity system is one of these passive-cooling strategies that have received considerable attention recently due to the significant benefits of reducing thermal loads of buildings. In particular, evaporative cooling inside ventilated wall cavities is an attractive passive cooling technique especially in hot and dry climates. This paper presents the initial findings of a current research study focusing on improving the ventilated wall cavity with spray evaporative cooling system that produce fine water droplets. Specifically, this paper describes a numerical modeling approach to evaluate the performance of the proposed passive cooling system to cool buildings in hot and dry climates. The simulation results suggest that a significant reduction in cooling loads can be achieved since the wall cavity can absorb heat from the indoor and outdoor while inducing acceptable supply air temperature capable of maintaining indoor thermal comfort within buildings. [ABSTRACT FROM AUTHOR]

This paper provides a comparative study of the energy efficiency of a conventional ventilating and air conditioning (VAC) system with three configurations. This system was used to cool an experimental room in an office building in more control scenarios realised by adopting different cooled water temperatures and chiller cooling systems. In this purpose, an air–water mist cooled system for an air-cooled chiller is proposed. Depending on the components, the analysed VAC system has the following configurations: (1) air handling unit (AHU) and fan-coil units (FCUs); (2) air handling unit (AHU); and (3) heat recovery unit (HRU) and fan-coil units (FCUs). The electricity consumption weight of the equipment of each VAC system, the total energy consumption and the influence of control parameters on this consumption are analysed. The results of the experiments indicate that the optimal efficiency VAC system in office buildings includes an AHU and FCUs with an air–water mist cooled chiller and a cooled water temperature of 8 °C. For this system, a mathematical model is developed to minimise the electricity consumption by optimal control, where the consumption depends only on non-controlled parameters (solar radiation intensity and outdoor air temperature). This model is verified with actual measurements to confirm its accuracy, and a good agreement between the prediction and measurement is achieved. Additionally, the assessment of thermal comfort in the experimental office is performed based on the PMV-PPD model using the ASHRAE Thermal Comfort programme. The obtained results demonstrate that the AHU&FCUs system assures an increase in thermal comfort. Finally, a TRNSYS simulation model of energy consumption and PMV-PPD indices for the AHU&FCUs system is developed and experimentally validated. [ABSTRACT FROM AUTHOR]

Abstract: This paper aims to explore how and where phase change materials (PCMs) are used in passive latent heat thermal energy storage (LHTES) systems, and to present an overview of how these construction solutions are related to building''s energy performance. A survey on research trends are firstly presented followed by the discussion of some physical and theoretical considerations about the building and the potential of integrating PCMs in construction elements. The different types of PCMs and main criteria that govern their selection are reviewed, as well as the main methods to measure PCMs’ thermal properties, and the techniques to incorporate PCMs into building elements. The numerical modeling of heat transfer with phase-change and heat transfer enhanced techniques are discussed, followed by a review of several passive LHTES systems with PCMs. Studies on dynamic simulation of energy in buildings (DSEB) incorporating PCMs are reviewed, mainly those supported by EnergyPlus, ESP-r and TRNSYS software tools. Lifecycle assessments, both environmental and economic are discussed. This review shows that passive construction solutions with PCMs provide the potential for reducing energy consumption for heating and cooling due to the load reduction/shifting, and for increasing indoor thermal comfort due to the reduced indoor temperature fluctuations. [Copyright &y& Elsevier]

Abstract: This paper investigates design features that can potentially reduce the energy consumed in attaining appropriate thermal comfort levels in typical residential buildings. A numerical model coupled with a PID controller is developed to predict the indoor air temperature that is adjusted via mechanical ventilation. The model is used to simulate and evaluate various scenarios of building wall layouts and materials. From the various simulation runs, the wall configurations and materials were refined to combinations that rendered the mechanical ventilation a feasible option for attainment of comfort for the largest number of hours per year. The runs were conducted for a typical residential apartment located in the city of Beirut, Lebanon, which is characterized by mild coastal climatic conditions. Different wall configurations were assumed for each of the living zone and the bedroom zone of the apartment. The simulation results suggest an optimal wall configuration comprised of a 5cm layer of insulating strawboard sandwiched between a 2cm×10cm wall made of masonry units consisting of Hempcrete (mixture of Portland cement, aggregates, and industrial hemp fibers) for the living zone, whereas the wall for the bedroom zone consists of a 10cm of Hempcrete. [Copyright &y& Elsevier]

Abstract: The paper presents a study on the behaviour of solar walls in a residential building under a Mediterranean climate, in terms of energy performances and thermal comfort all year round. The aims of this study are: the investigation of Trombe wall''s thermal behaviour; the evaluation of solar wall''s influence on heating and cooling energy needs and indoor thermal comfort; the analysis and optimization of solar wall''s behaviour in an accommodation varying the envelope insulation level. In order to do that, various activities were carried out: a series of monitoring campaigns in different seasons; dynamic simulations with software EnergyPlus; calibration of the model with experimental data; parametric analyses on the interaction between solar walls (on the southern side) and different types of building envelopes (on the other exposures) varying the insulation level according to recent standards. The results demonstrated that solar wall provides heating energy savings and thermal comfort in winter and intermediate seasons. A significant improvement of the solar wall''s performances can be obtained using double glazing. In summer solar walls determine an increase in cooling energy needs and risk of overheating. The use of solar wall''s shading and ventilation reduces such drawbacks and leads to indoor conditions within comfort range. [Copyright &y& Elsevier]