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Abstract: This paper presents a heat storage and cooling concept that utilizes a phase change material (PCM) and a thermally activated building system (TABS) implemented in a hollow core concrete deck. Numerical calculations of the dynamic heat storage capacity of the hollow core concrete deck element with and without microencapsulated PCM are presented. The new concrete deck with microencapsulated PCM is the standard deck on which an additional layer of the PCM concrete was added and, at the same time, the latent heat storage was introduced to the construction. The challenge of numerically simulating the performance of the new deck with PCM concrete is the thermal properties of such a new material, as the PCM concrete is yet to be well defined. The results presented in the paper include models in which the PCM concrete material properties, such as thermal conductivity, and specific heat capacity were first calculated theoretically and subsequently the models were updated with the experimentally determined thermal properties of the PCM concrete. Then, the heat storage of the decks with theoretically and experimentally determined thermal properties were compared with each other. Finally, the results presented in the article highlight the potential of using TABS and PCM in a prefabricated concrete deck element. [Copyright &y& Elsevier]

It is known that building performance usually involves different criteria such as the energy consumption, thermal comfort, thermal loads and internal temperatures, which can make its assessment more complex. Thus, this paper aims to describe a decision-making process to improve some criteria related to the energy efficiency of residential buildings considering a multicriteria approach. Computer simulation using EnergyPlus v8.3-2014 was performed to assess the thermal and energy performance of a residential building for four different climates in Brazil (Belém, Campo Grande, Curitiba and Florianópolis). The performance criteria were the degree-hours and energy consumption for air-conditioning (both for heating and cooling) in different decision makers’ preference scenarios. The performances of eight constructive systems were evaluated considering uncertainties related to the operational variables of the building, obtained through field survey. The results showed that some systems had statistically equivalent performance considering the range of uncertainty. The system of masonry with double massive brickwork performed better for three climates; for Belém, however, an adequate system highly depends on the preference scenario. Nonetheless, different preference scenarios would indicate different adequate systems for all climates. This study used a method of decision-making which enables the possibility for future analyses of other performance alternatives, design variables, and performance criteria. [ABSTRACT FROM AUTHOR]

Evaluation methods can be used to determine what constitutes good energy performance in a building. With an increasing focus on energy use of buildings worldwide, this evaluation assumes a fundamental importance. This paper provides a comprehensive review of the available methods for analysing, classifying, benchmarking, rating and evaluating energy performance in non-domestic buildings. Methodologies are grouped in five categories: engineering calculations, simulation, statistical methods, machine learning and other methods. Techniques for evaluating buildings are described, their principal applications are shown and limitations are identified. The use of performance evaluation in energy efficiency programmes and standards is mapped. There is a need to further develop interactions between the main modelling techniques to produce simple, robust and validated models. Also, evaluation techniques must be developed to consider comfort or service provision in the buildings as a factor in energy performance. [ABSTRACT FROM AUTHOR]

A web-based Roof Savings Calculator (RSC) has been deployed for the United States Department of Energy as an industry-consensus tool to help building owners, manufacturers, distributors, contractors and researchers easily run complex roof and attic simulations. RSC simulates multiple roof and attic technologies for side-by-side comparison including reflective roofs, different roof slopes, above sheathing ventilation, radiant barriers, low-emittance roof surfaces, duct location, duct leakage rates, multiple substrate types, and insulation levels. Annual simulations of hour-by-hour, whole-building performance are used to provide estimated annual energy and cost savings from reduced HVAC use. While RSC reported similar cooling savings to other simulation engines, heating penalty varied significantly. RSC results show reduced cool roofing cost-effectiveness, thus mitigating expected economic incentives for this countermeasure to the urban heat island effect. This paper consolidates comparison of RSC's projected energy savings to other simulation engines including DOE-2.1E, AtticSim, Micropas, and EnergyPlus. Also included are comparisons to previous simulation-based studies, analysis of RSC cooling savings and heating penalties, the role of radiative heat exchange in an attic assembly, and changes made for increased accuracy of the duct model. Radiant heat transfer and duct interaction not previously modeled is considered a major contributor to heating penalties. [ABSTRACT FROM AUTHOR]

Occupant behavior is now widely recognized as a major contributing factor to uncertainty of building performance. While a surge of research on the topic has occurred over the past four decades, and particularly the past few years, there are many gaps in knowledge and limitations to current methodologies. This paper outlines the state-of-the-art research, current obstacles and future needs and directions for the following four-step iterative process: (1) occupant monitoring and data collection, (2) model development, (3) model evaluation, and (4) model implementation into building simulation tools. Major themes include the need for greater rigor in experimental methodologies; detailed, honest, and candid reporting of methods and results; and development of an efficient means to implement occupant behavior models and integrate them into building energy modeling programs. [ABSTRACT FROM AUTHOR]

A deep three-years survey of the existing social housing stock in Emilia Romagna, Italy, has been completed helping to accomplish a full acknowledgement of more than 70 buildings in terms of both their envelopes and heating system characteristics. Analysing the outcome data, a simplified parametric calculation protocol has been created to operate a preliminary audit and energy retrofit simulation on the entire social housing stock of the Region. The results of the study, initial data about the energy state-of-the-art of the building cluster and feasible retrofit solutions, are useful to identify where to focus for a further and more accurate energy diagnosis. This paper represents a synthesis of a three-years research work, demonstrating the potential of the parametric assessment method in terms of evaluating environmental and energy benefits, deriving from scheduled retrofit actions, to assist technicians in endeavouring interventions priority. [ABSTRACT FROM AUTHOR]

This paper demonstrates the use of benchmarking methods for residential buildings in an energy rich economy. Three bottom-up methods were used, ordinary least square (OLS), support vector machines (SVM), and engineering modelling (EM). EM highlighted the energy inefficiency in these buildings, where the EM simulations showed the potential of halving the average measured consumption of 20.5 MWh/year. SVM could demarcate buildings and households with consumption of >16.0 MWh/year which are considered to be inefficiency. OLS is simple to use and the non-linear least square, showing R 2 > 0.8, performs better than linear least square fit. This work allows two EUI benchmark measures to be determined and they have average values of 2035 kWh/person/year and 56 kWh/m 2 /year. [ABSTRACT FROM AUTHOR]

Abstract: Thermal mass combined with other passive strategies can play an important role in buildings energy efficiency, minimizing the need of space-conditioning mechanical systems. However, the use of lightweight materials with low thermal mass is becoming increasingly common. Phase Change Materials (PCMs) can add thermal energy storage benefits to lightweight constructions. There are many studies about the use of PCM in buildings, but there are still some difficulties for effective use and practical application of these materials. The study of applications used in real buildings could help us find solutions to these difficulties. This paper analyzed different PCM applications presented in highly efficient lightweight construction houses that have participated in the American Solar Decathlon, an international competition organized by U.S. Department of Energy. These houses have been tested and monitored in Washington DC, place with suitable climate conditions for short term thermal storage systems. The study started with a classification of the PCM applications and included an analysis of the systems, materials, switching temperatures, containments and design strategies used to improve the houses energy performance. Also, it included results of numerical simulations and experimentation that the participant team had done, complemented with information available in the literature about similar materials or applications. [Copyright &y& Elsevier]

Abstract: Active transparent façades constitute a building envelope component that is becoming more and more common in high-rise office buildings. Many designers have opted for a ventilated façade, claiming that this technology is sustainable, reduces energy consumption and enhances indoor comfort conditions, but these claims have often proved to be wrong. From the thermofluid-dynamic analysis point of view, few design procedures or sufficiently detailed, reliable and easy to use simulation software are available for ventilated façades. A numerical model that has been developed to simulate the thermal behaviour of mechanically ventilated active transparent façades is presented in this paper. The model, developed in the Simulink/Matlab® environment, simulates the façade in both steady-state and transient conditions and provides the temperature of the different layers of the façade structure and the corresponding heat fluxes as output data. The model has been validated by comparing the simulation results with experimental data obtained in the laboratory. A test has also been performed on a real façade under actual operating conditions. The model performance has resulted to be quite promising. The accuracy of the prediction of the temperature is good, while the simulations of the heat fluxes are slightly less reliable for some operative conditions. [Copyright &y& Elsevier]

Abstract: This paper identifies the impact of thermostat strategies on heating and cooling energy consumptions in buildings, thus suggesting the importance of a database for understanding the effect of thermostat settings and for deciding energy-conscious strategies. Using computer simulation, diverse thermostat strategies – change of setback period, change of set-point temperature, and change of setback temperature – were tested parametrically in a typical USA single-family homes, located in two climate zones, namely cold (Detroit, Michigan) and hot-humid (Miami, Florida). Analysis revealed that heating and cooling systems were significant energy-consuming components in each climate zone. Accordingly, heating energy in cold climate zones and cooling energy in hot-humid climate zones have potential for matchingly significant saving. Diverse thermostat strategies (changes of setback period, of set-point, of setback temperature) demonstrated their obvious impacts on such saving. In the cold climate in particular, the heating system showed the most significant energy-saving effect via proper thermostat strategies. Proper setback period, set-point and setback temperature need to be established to achieve energy efficiency in residential buildings. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the energy performance of a central atrium is investigated and compared with the energy performance of a courtyard with the same geometric proportions. The atrium and the courtyard design used for the analysis are square in plan and surrounded by the building on all four sides. The glazing type and percentage for the courtyard walls and atrium skylight are varied in the analysis. Weather data from four cities representative of climatic conditions of cold, temperate, hot-humid and hot-dry were used. The results show that, in general, the open courtyard building exhibits a better energy performance for the shorter buildings. As the building height increases, however, at some point the enclosed atrium exhibits a better energy performance. This “break even” point for the number of stories depends on different factors like glazing and climate parameters discussed above. [Copyright &y& Elsevier]

Abstract: Through a case study, this research explores an approach, which uses computer simulation technology, to evaluate different energy conservation alternatives and to assist facility managers to select reliable and feasible solutions. The subject facility is located in the Southeast region of the United States. One of the major challenges and operation goals of the General Services Administration, who manages the facility, is for that facility to achieve the Energy Star designation. However, due to the complexity of the facility, the requirements from building occupants, as well as other difficulties, finding a path for optimizing the operation of the facility in order to achieve the Energy Star designation is not always easy. This project uses eQuest, a simulation software tool, to create a “virtual environment”, in which the operations of the HVAC (heating ventilation air-conditioning) system and the lighting of the facility are studied. Subsequently, recommendations initially made by experts through traditional energy audit approaches are evaluated in the “virtual environment” in order to determine the best solution to achieve the goal of the facility managers. This paper discusses major aspects of the project, including the challenges, the values and the limitations of applying computer simulation techniques in such a facility with complicated structural, occupancy and operation features. [Copyright &y& Elsevier]

Abstract: Glass façades, particularly in high-rise buildings, increase in energy consumption for heating, cooling and ventilation. This causes too high running cost of mechanical systems. Double skin glass façade is a system that decreases these disadvantages, by providing natural ventilation, preventing solar heat gain, controlling daylight, etc. This paper aims to investigate the appropriateness of double skin glass façades in moderate climate, such as Istanbul, in terms of the energy and cost efficiency when compared to single skin glass façades. For this purpose, an approach is proposed to determine the efficient alternatives. It comprises to generate standard façade alternatives by considering the objectives, constraints and performance criteria, and to evaluate their energy and cost efficiency for both single and double skin glass façades. In conclusion, the most energy efficient double skin glass façade is about 22.84% more efficient than the most energy efficient single skin glass façade is. Additionally, the most cost efficient single skin glass façade is about 24.68% more efficient than the most cost efficient double skin glass façade is. [Copyright &y& Elsevier]