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• Investigation of a solar energy storage system under low-grade solar energy. • Dynamic heat storage and release processes under multiple parameters. • Matched collecting areas for different grades of meteorological conditions. • Performance optimization process of the solar thermal energy storage system. Designed and operational parameters matter greatly in how successful an energy storage system performs. However, a current challenge in matching suitable these parameters lies in the poor understanding of such systems' performance under dynamic weather conditions. In this paper, we investigated a phase change material (PCM) storage unit that is particularly aimed for poor-solar areas, and connected the unit to a flat plate solar collector to establish a complete solar thermal energy storage system (STESS). To optimize the system performance, different grades of solar radiation and outdoor ambient temperatures are introduced, and the effects of heat transfer fluid (HTF) flow rates and solar collecting areas are investigated numerically through multiple performance evaluation parameters. The results indicate that the solar collecting area has a significant effect on the performance of the STESS compared to that of the water flow rate. And different collecting areas of 1 m2, 1.5 m2, and 3 m2 with an optimal water flow rate of 0.06 m3/h are matched to different average daily solar radiation of 203.4 W/m2, 155.2 W/m2, 92.7 W/m2, respectively. Further for the heat release process, different heat release efficiencies from 88.32 % to 97.12 % with different energy consumption of the fan from 0.003 kWh to 0.063 kWh are obtained when the air flow rate is increased from 30 m3/h to 90 m3/h. One of the air flow rates of 60 m3/h is superior for the STESS considering higher heat release efficiency and lower energy consumption of the fan. The findings of this paper will contribute to optimizing the performance of a STESS in practical applications. [ABSTRACT FROM AUTHOR]

New smart building technologies that offer continuous dynamic optimization of Heating, Ventilation, and Air Conditioning (HVAC) control hold promise to advance building operations for efficiency and grid response. These technologies use data from the control system to determine the analytically optimal setpoints, and then write back the optimal setpoints into the control system to minimize system energy consumption or costs. There are limited studies documenting field validations of these technologies. This paper presents the results from a long-term field evaluation of a model-predictive HVAC optimization system that installed in four commercial buildings. Energy savings analysis was conducted based on pre/post submetered energy use. Across the cohort of evaluation sites, HVAC savings following the implementation of the optimization system were mixed, ranging from 0–9%. Analysis of site operational data showed that occupant comfort was neither positively nor negatively impacted. Key technology adoption considerations and recommendations are summarized in the paper. The technology performs best when HVAC systems are in good working condition, and can be exercised to achieve the full range of its optimized setpoints–however it may not provide extensive additional savings over cases where best practice sequences of operation and reset strategies are already comprehensively implemented. [ABSTRACT FROM AUTHOR]

In order to obtain satisfactory effect of air conditioning and ventilation, the floor–supply displacement ventilation has widely applied in many civil buildings. Swirl diffusers mounted on the floor are widely used to provide fresh air into the occupied zone in the floor–supply displacement ventilation system. This paper studied the air distribution performance of swirl diffuser by 2D-PIV (particle image velocimetry). The experiment was implemented in a full-scale room to achieve reliable data of swirl diffusers. Flow visualizations have been carried out to determine the shape of the swirl jet. The whole velocity field was measured by 2D-PIV system, which is very useful to analyze air distribution above the swirl diffuser. With the aid of the flow visualizations and PIV test technology, the macro and micro structure of the air flow above the swirl diffuser is specified in more detail. Moreover, the centerline velocity decay coefficient (K value) and entrainment ratio were obtained. The research work of this paper provides detailed experimental data of air flow above the swirl diffuser, which provide the reference for selection of air terminal devices and a basis for follow-up numerical simulation study. [ABSTRACT FROM AUTHOR]

Building simulation tools have been widely used for performance assessment. However, many studies [1] have reported that a performance gap exists between the reality and simulation output, mainly caused by unknown simulation inputs. Therefore, model calibration needs to be introduced. Calibration attempts can fail for the following reasons: coarse initial simulation model, long sampling time, uncertainty in the model, and sensor errors. The aim of this paper is to address the abovementioned issues. For this study, an existing office building was selected and two calibration approaches were presented: deterministic vs. stochastic. For stochastic calibration, a Gaussian Process Emulator (GPE) was introduced as a surrogate of the EnergyPlus model. The stochastically calibrated model performs better than the deterministically calibrated model. It is concluded in the paper that (1) the calibration quality is influenced by the degree of the details of the initial model, (2) the accumulated measured data under a sampling time of up to one day (e.g. gas energy consumption) might be unsuitable for calibration work due to the lack of ‘time-series trend’, and (3) the calibration quality is also influenced by sensor errors and further calibration needs to take these into account. [ABSTRACT FROM AUTHOR]

Green roofs have been recognized as an effective way to increase urban green space and improve building micro-environment. This paper investigated the thermal and energy performance of an extensive green roof under free-floating 1 1 Free-floating here means no heating or cooling system affecting the internal conditions of the room. and air-conditioned conditions in Shanghai, a coastal city with hot and humid summer. A field experiment was conducted on two full-scale rooms of a building from 30/07/2014 to 31/08/2014. One room was covered by a green roof while the other one was covered by a common roof. The results show that solar radiation has the strongest correlation with green roof’s cooling effect, and the correlation between solar radiation and heat flux through green roof is negative in free-floating condition but positive under air-conditioned condition. Outdoor temperature is the most correlated factor of green roof’s temperatures but the least correlated one for green roof’s cooling effect. Energy balance analysis indicates that evapotranspiration and long wave radiation dissipate most of heat gain for green roof, and soil water content has a significant impact on energy balance. This paper presents the basic thermal characteristic of extensive green roof in Shanghai and also make it possible for further validation of hygrothermal transfer model of green roof system. [ABSTRACT FROM AUTHOR]

The paper is an addendum to the paper entitled “Ancient vernacular architecture: characteristics categorization and energy” that was published at “Energy and Buildings” in 2010 [1] . This addendum provides an explicit list of 114 codes representing vernacular architectural regions across the whole globe defined by climate, culture and continent. Codes are intended to support work in analyzing and memorializing vernacular building characteristics that otherwise may be lost. This addendum will be an important and useful resource for analyzing and studying vernacular architecture. [ABSTRACT FROM AUTHOR]

The increase in global environmental concerns as well as the advancement of computational tools and methods have had significant impacts on the way in which buildings are being designed. Building professionals are increasingly expected to improve energy performance of their design. To achieve a high level of energy performance, multidisciplinary simulation-based optimization can be utilized to help designers in exploring more design alternatives and making informed decisions. Because of the high complexity in setting up a building model for multi-objective design optimization, there is a great demand of utilizing and integrating the advanced modeling and simulation technologies, including BIM, parametric modeling, cloud-based simulation, and optimization algorithms, as well as a new user interface that facilitates the setup of building parameters (decision variables) and performance fitness functions (design objectives) for automatically generating, evaluating, and optimizing multiple design options. This paper presents an integrated framework for building information modeling (BIM)-based performance optimization, BPOpt. This framework enables designers to explore design alternatives using an open-source, visual programming user interface on the top of a widely used BIM platform, to generate models of building design options, assess the environmental performance of the models through cloud-based simulation, and search for the most appropriate design alternatives. This paper details the process of the development of BPOpt and also provides a case study to show its application. The case study demonstrates the use of BPOpt in minimizing the energy consumption while maximizing the appropriate daylighting level for a residential building. Finally, strengths, limitations, current adoption by academia and industry, and future improvements of BPOpt for high-performance building design are discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] The paper investigates the summer time performance in Nucleus-type hospital ward. [•] The spaces were reasonably within the thermal comfort threshold set by NHS. [•] The paper demonstrates the complexity in the calibration of dynamic thermal models of hospitals. [•] Light touch low carbon interventions could bring in comfort into the 2050s in UK Midlands. [•] 6ach−1 requirements set by NHS may not be necessary to achieve comfort in UK Midlands. [Copyright &y& Elsevier]

Abstract: This paper analyzes the operating principle and the advantages of the parallel-type hybrid-power gas engine-driven heat pump system (PHGHP) and builds test systems to test the performance of the system in the heating conditions and cooling conditions. PHGHP used heat pump system's cooling capacity, heat capacity, fuel-consumed flow, fuel consumed-rate, thermal efficiency and reclaimed heat as the economic analysis parameters. In addition, this paper puts forward the concept of the equivalent fuel-consumed flow and the equivalent output power of engine. The test results show, the speed and torque of gas engine which used the baseline control strategy and combined with a gas engine optimization curve control strategy are always in the designated economic. Fuel-consumed flow changes in 280–340g(kWh)−1. With compressor speed increasing, the drive system thermal efficiency is maintained between 0.23 and 0.28. [Copyright &y& Elsevier]

Abstract: Significant energy savings can be achieved by optimizing chiller operation and design in heating, ventilation and cooling (HVAC) systems. In terms of optimization, various metaheuristics have been proposed to the optimal chiller loading problem. New metaheuristics are also emerging recently, between them the firefly algorithm. Firefly algorithm is a nature inspired algorithm based on the idealized behavior of the flash pattern and characteristics of fireflies. This study proposes a new improved firefly algorithm (IFA) based on Gaussian distribution function to the optimal chiller loading design. To testify the performance of the proposed method, the paper adopts two case studies comparing the results of the developed model using IFA with those of traditional firefly algorithm and other optimization methods in literature. In this paper, the optimization problem is minimize energy consumption of multi-chiller systems, where the objective function is energy consumption and the optimum parameter is the partial loading ratio of each chiller. The results of both case studies show that the proposed IFA outperform several optimization methods of the literature in terms of minimum energy consumption solution of the optimal chiller loading problem. [Copyright &y& Elsevier]

Abstract: In the last years many studies concerning the evaluation of the thermal conductance of building elements via measurements have been carried out; this value has to be ensued from the analysis of recorded temperature and heat flux profiles. The determination of this property in situ would allow a more accurate a more accurate evaluation of the real heating energy demand of a building. Papers discussing different data analysis methods are present in literature and measurements on test components under real conditions and evaluations on different theoretical aspects by means of numerical simulations have been already developed. This paper aims at widening the existent literature of the in situ evaluation of the thermal conductance, through the discussion of the results of a measuring campaign which lasted four years on real buildings, and by comparing the reference specific thermal conductance (C) values with those computed on the basis of the measurements. Various tests on the same elements are discussed. Finally an analysis on the influence of the C value on the evaluation of the net heating energy demand of a building in different climates is presented. [Copyright &y& Elsevier]

Abstract: Reducing the energy consumption of air-conditioning systems is becoming increasingly important. This paper focuses on the air-conditioning system in Terminal 3 in Xi’an Xianyang International Airport, the first airport terminal to adopt radiant cooling in China. In the large spaces of this airport terminal, a temperature and humidity independent control (THIC) system has been adopted instead of a conventional nozzle air supply method, which significantly reduces the energy consumption of the air supply. The radiant floor is the main mechanism for indoor temperature control, while a liquid desiccant outdoor air processor combined with displacement ventilation is responsible for humidity control. Ice storage is adopted to reduce operating costs, and the supplied chilled water temperature can be as low as 3°C. This paper examines the performance of the THIC system in detail. The indoor environment is determined through measurements to be comfortable, and the on-site performances of key components in both the airport terminal and the cooling plant are investigated. The outdoor air processor supplies air of appropriate temperature and humidity ratio; two kinds of radiant floors are used for temperature control, both with measured cooling capacities of about 30–40W/m2; and the energy efficiency ratio (EER) of the cooling plant is 2.62. [Copyright &y& Elsevier]

Abstract: Slightly more than a decade ago, reflective multi-foil insulations were introduced onto the building market as a highly promising new type of thermal insulation material. These materials consist of several layers of thin metallic foil or metallised polymer film with a low emission coefficient combined with spacer materials in-between. Because of the low emission coefficient of the foils, radiation through the insulation material is significantly reduced as a result of which these materials are claimed to have very high thermal resistance, even up to 5 or 6m2 K/W. However, debate is still ongoing into whether these claims are correct. In contrast to some in situ measurements, hot box and hot plate measurements performed in laboratories result in much lower thermal resistance values. Based on a review of research reports and journal papers, this paper identifies the causes for the different results among different research institutes. From this analysis, conclusions are drawn about the thermal performance that can likely be expected from reflective multi-foil insulations. [Copyright &y& Elsevier]

Abstract: Recent results show that a predictive building automation can be used to operate buildings in an energy and cost effective manner with only a small retrofitting requirements. In this approach, the dynamic models are of crucial importance. As industrial experience has shown, modeling is the most time-demanding and costly part of the automation process. Many papers devoted to this topic actually deal with modeling of building subsystems. Although some papers identify a building as a complex system, the provided models are usually simple two-zones models, or extremely detailed models resulting from the use of building simulation software packages. These are, however, not suitable for predictive control. The objective of this paper is to share the years-long experience of the authors in building modeling intended for predictive control of the building''s climate. We provide an overview of identification methods for buildings and analyze their applicability for subsequent predictive control. Moreover, we propose a new methodology to obtain a model suitable for the use in a predictive control framework combining the building energy performance simulation tools and statistical identification. The procedure is based on the so-called co-simulation that has appeared recently as a feature of various building simulation software packages. [Copyright &y& Elsevier]

Abstract: In this paper the energy and exergy performance of a social dwelling of a multi-family building from the 1960s in Bilbao (Spain) is presented and various improved energy concepts based on exergy principles are proposed and investigated. The aim of this paper is to explore and demonstrate the usefulness of the exergy approach in the assessment and development of an energy system for the dwelling under consideration. The total energy supply system is analysed, including the demand (space heating, domestic hot water and electricity), the system components (for conversion, storage and distribution) and the energy input from energy resources (primary energy and renewable resources). The study includes a comparison of the primary energy input of all cases considered and an analysis of the energy and exergy losses of each system component. The study has shown that the exergy analysis reveals thermodynamic losses that are not revealed using energy analysis and secondly, that the development of an improved energy system based on exergy principles has resulted in a significantly reduced primary energy input compared to the reference situation. [Copyright &y& Elsevier]

Abstract: Although absorption cooling has been available for many years, the technology has typically been viewed as a poorly performing alternative to vapour compression refrigeration. However, rising energy prices and the requirement to improve energy-efficiency is driving renewed interest in the technology, particularly within the context of combined cooling, heat and power systems (CCHP) for buildings. In order to understand the performance of absorption cooling, numerous models are available in the literature. The complexities involved in the thermodynamics of absorption chillers have, however, so far restricted researchers to creating steady-state or dynamic models reliant on data measurements of the internal chiller state, which require difficult-to-obtain, intrusive measurements. The pragmatic, yet fully dynamic model described in this paper is designed to be easily calibrated using data obtained from the measurements of inflows and outflows to a chiller, without resorting to intrusive measurements. The model comprises a series of linked control volumes featuring both performance maps and lumped mass volumes, which reflect the underlying physical structure of the device. The paper describes the modelling approach, theory and limitations, along with an example of the implementation of the model in the ESP-r code complete with calibration and an application to a specific example. [Copyright &y& Elsevier]

Abstract: This paper compares several different simplified methodologies for building energy performance assessment during winter time selected based on its large application and/or its user friendly characteristics. Hourly values for energy demand are calculated by a detailed comparison tool based on hourly weather data. A simplified building procedure spreadsheet to evaluate energy demand is also presented. It gives reliable results, needs only a little input data to describe the building design and low time consumption. The spreadsheet is therefore useful for preliminary design tasks in the early design stages where rough estimates of the building design and preliminary energy use are needed for primary decision support. The method is based on a seasonal heating calculation of heat losses and usable heat gains for the building, where the heat-accumulating capacity of the building is considered. The seasonal mean values of the solar radiation and degree days are applied. This paper describes the applied calculation technique and the assumptions made to carry out heating calculation. [Copyright &y& Elsevier]

Abstract: Photovoltaic (PV) connected systems are experiencing rapid market growth. This is due to the continually downward trend in PV cost together with government support programs. A scenario has been assumed to analyse the geographical market of PVs. The results provide clear evidence of the influence that some variables have on the profitability of PV investments. This study presents a model for minimising investment risk and maximising the return of a renewable energy portfolio in Italy. The value of the paper is in showing that the energy and CO2 reduction potential that can be reached through consumer-oriented policy measures, but the paper also looks at the effectiveness and social implications of such measures. Private households possess immense unused potential for energy reductions (and climate protection) that could be realised through gains in energy efficiency, behavioural changes, and extended use of low-emission energy. The focus of energy policy has been on businesses rather than on private households, which are only partly captured by direct policy measures. To achieve the goals of climate policies, the current political and scientific discussion increasingly considers measures that aim to reduce energy consumption in the private sector. Quantitative estimates are presented for economic indicators and will show the various effects of policy measures on the implemented household types. [Copyright &y& Elsevier]

Abstract: The microclimate around a building, establishing through the interaction with other buildings or the natural environment, is a significant factor in the building energy consumption. This paper presents a method for the quantitative analysis of building energy performance under any given urban contexts by linking the microclimate model ENVI-met to the building energy simulation (BES) program EnergyPlus. The full microclimatic factors such as solar radiation, long wave radiation, air temperature, air humidity, and wind speed have been considered in the proposed scheme. A case study has been conducted to analyze the effects of different microclimatic factors on the energy balance of an individual building. The method outlined in this paper could be useful for urban planning and building design. [Copyright &y& Elsevier]

Abstract: This paper applies the Analytical Hierarchy Process (AHP) in calculating the weights and uses Cause–Effect Grey Relational Analysis (CEGRA) to rank system performance based on multiple criteria evaluation. AHP is compared with CEGRA in ranking the alternatives, thus achieving improved environmentally friendly system performance. This paper uses the TFT-LCD chiller in Taiwan to measure the model''s reliability and validity through comparison with the traditional strengths and weaknesses assessment. Businesses should cooperate with collaborative vendors and apply the service science management concept to improve performance and reduce energy waste. [Copyright &y& Elsevier]

Abstract: This paper reviews crucial role of building performance simulation (BPS) – dynamic analysis of the inextricable linkage of building''s energy demand for HVAC and other building''s technical systems sustainable energy supply and renewable energy sources (RES) availability to reach building''s zero energy status. Reviewed are BPS advances in buildings energy efficiency optimization, solar, geothermal and other renewable energy sources integrated implementation, as well as hybridization and mixed distributed energy generation, co- and tri-generation for building''s greening and sustainable neighborhoods, settlements, as well as “high performance” Zero Energy Cities Planning. As an introduction, outlined is the intrinsic harmony of the traditional village houses balanced use of renewable materials and energy sources and presented are feasibility study results on the sustainable Zero Energy ECO Settlement at the Mediterranean Sea proceeded by the description of the site''s sustainability''s constrains assessment. Architectural design and building''s dynamic behavior and energy efficiency optimization resulting in minimization of thermal and lighting loads, precede to the multidisciplinary engineering investigation and preliminary design of sustainable Zero Energy Buildings confirming feasibility of settlement''s sustainable energy and water supply by the reliable implementation of solar PV and wind technologies, including PV powered sea water desalination. Further, interwoven with presentation of a few case studies, paper outlines advances in BPS and Co-simulation. Reviewed are optimization of mixed, natural and mechanical ventilation via CFD integrated with architectural modeling; BPS and Co-simulation approach to the “total building performance optimization” encompassing multifunctional facades, day-lighting, IE&AQ and HVAC systems operation offering an enormous potential for energy saving by residential/municipal RES integrated renovation. Stressed has been that it is impossible to reach sustainability without harmonious interdisciplinary interacting, without balance between materiality and spirituality, science and art, technology development and cultural and other human values improvement, without ethics of sustainability. [Copyright &y& Elsevier]

Abstract: An understanding of the energy performance in buildings in an entire municipality or an entire district is important for sustainable energy planning strategies that accelerate the energy renovation process in existing buildings that are not energy efficient. The methodology described in this paper is largely based on information that is already available on building stock (i.e., cartographic documentation, thematic maps, geometric data and others). Data regarding the energy performance of buildings are collected using energy audits on sample buildings, which are selected using a statistical approach. Using the tools in a GIS platform, the integration of two data sources allows for a low cost, comprehensive framework of the energy performance of buildings. This methodology was tested in a medium sized town in the Lombardy region (Italy), and the results are discussed in this paper. [Copyright &y& Elsevier]

Abstract: The thermal performances of walls have great influences on the energy consumption and the thermal comfort of the room. Because the heat flux through the wall is the direct reason to cause the variations of the indoor air temperature, it directly affects the cooling/heating load and the thermal comfort of the room, the effect of the wall on the wall heat flux should be researched. In this paper, two parameters, which are the heat flux time lag and the heat flux decrement factor, are proposed to evaluate the thermal performance of the wall. Based on the one-dimensional numerical model built in the paper, the effects of the thermal properties of the wall and the thickness of the wall on the heat flux time lag and heat flux decrement factor are investigated. In addition, the heat flux time lag and heat flux decrement factor for several building materials are obtained. This research is useful for knowing the thermal performances of the wall better. [Copyright &y& Elsevier]

Abstract: The article described the dilatancy technology of district heating system with high-temperature heat pump (HTHP). For the exploitation of low-temperature return network sources, a high-temperature heat pump with a heat exchanger was planned. As the core technology of the dilatancy district heating system, HTHP units and heat exchanging systems had been described detailedly through theoretical and experimental analysis. The model was proved to be in good agreement with the experiment data. It could be used for engineering design. In this paper the district heating system in Datong was taken as a case study. The main characteristics of the dilatancy district heating system had been presented in the form of diagrams. The principal advantage of dilatancy technology in the district heating system lies in increasing the temperature difference, reducing the diameters and the initial investment of primary side network. This paper shows clearly the analysis of the dilatancy technology for characterising and improving the performance of district heating systems. [Copyright &y& Elsevier]

Abstract: The paper presents a PI tuning strategy for air handler discharge air temperature control in building comfort application. It recommends using a 5min settling time with no overshoot as the design criterion to select PI gain values, and recommends that a PI controller should be retuned when the settling time is larger than 20min. This tuning strategy avoids unnecessary tuning while providing acceptable control performance for building comfort control. The paper further concludes that PI tuning can be done by adjusting proportional gain only and keeping the reset time constant for air handler discharge air temperature control. The proportional gain can be calculated based on the system sum of time constant and delay, and system static gain in typical applications. Inclusion of the time constant in the equation is recommended for uncommon applications where the delay is large. Regression equations are given based on simulation results for both typical applications and uncommon applications. The PI tuning strategy proposed in the paper can be reliably used in PI auto tuning since it uses less model information and adjusts less gain values than existing tuning algorithms. [Copyright &y& Elsevier]

Abstract: Currently, several whole-building simulation tools (e.g., esp-r, EnergyPlus, TRNSYS, TAS, IES VE, IDA ICE, VA114, BSim, etc.) are used to assess the energy performance of double-skin façade (DSF) buildings. The aforementioned tools are well suited to assess energy performance of conventional building systems or whole buildings; however, it is questionable whether such tools can accurately describe the transient heat and mass transfer phenomena that occur in the complex three-dimensional geometry of DSFs. This paper describes an empirical validation of the EnergyPlus simulation tool for performance simulation of a DSF. A series of experiments were conducted for cavity airflow and thermal behavior of the DSF and then compared with simulation outputs. In this paper, it is shown that there are significant differences in both thermal and airflow behavior of DSFs between the measurements and simulation predictions by EnergyPlus. This study investigates three cases causing the differences and elucidates what should be considered when modeling DSFs using EnergyPlus. [Copyright &y& Elsevier]

Abstract: GeoCool plant was the result of a EU project whose main purpose was to adapt ground coupled heat pump technology to cooling dominated areas. The execution of this experimental plant was completed at the end of year 2004, starting on February 2005 the regular operation of the air conditioning system. Since then, GeoCool facility has been monitored by a network of sensors characterizing its most relevant parameters. Several aspects of the performance and behaviour of the system during its first operational year were presented on a previous paper. This paper presents the energy performance measurements of GeoCool ground coupled heat pump system acquired during five years of operation as well as the evolution of the return water temperature from the ground as a representative of the ground temperature. The analysis of the experimental results shows that the system energy performance is maintained through the years with no appreciable impact on ground thermal response. [Copyright &y& Elsevier]

Abstract: An experimental system was developed and tested in order to investigate the exergetic performance of a solar photovoltaic system (PV) assisted earth-to-air heat exchanger (under ground air tunnel) that is used for greenhouse cooling at the Solar Energy Institute, Ege University, Izmir, Turkey. This system was under operational conditions successfully during the 2010 summer cooling season. This paper provides the experimental results obtained between 18th of August and 26th of August of in 2010. Exergy destruction in the system was calculated and presented in this paper using a reference temperature of 15°C. Results are discussed and interpreted in the paper for various performance metrics, such as the effect of climatic conditions and operating conditions on the system performance. Results show that the system may be satisfactorily used for greenhouse cooling in the Mediterranean and Aegean regions of Turkey. [Copyright &y& Elsevier]

Abstract: The paper suggests a multi-criteria approach for the energy refurbishment of historical buildings, proposing methodologies for the performance analysis, coupling several experimental and numerical studies. The target consisted in a rigorous evaluation procedure, in order to guarantee the necessary reliability of a numerical model of the system “building envelope/technical plants”, on which testing the technical and economical convenience of energy retrofit solutions. The paper collects the long work carried out by several Institutions during the last years, on Building “Palazzo dell’Aquila Bosco-Lucarelli”, a historical building located in Benevento (Southern Italy), currently analyzed in order to define the technical adoption of possible improving actions. The carried out studies, beyond the proposition of an operational methodology, are aimed to evidence a best-practice specified for the Italian territorial context, which has several historical buildings needing restoration. Carefully applied investigations, based on various methodologies and through several instrumentations, allowed the definition of a numerical model correspondent to the real building, defined also comparing the results with the historical requests of gas and electricity. Moreover, dynamic energy simulations tested the effectiveness, singularly and coupled, of several solutions for the building energy optimization. A significant potentiality of energy and economic optimization has been demonstrated. [Copyright &y& Elsevier]

Abstract: In this paper, an attempt is made to evaluate the exergetic performance of a solar photovoltaic thermal (PV/T) air collector. A detailed energy and exergy analysis is carried out to calculate the thermal and electrical parameters, exergy components and exergy efficiency of a typical PV/T air collector. Some corrections are done on related heat loss coefficients. An improved electrical model is used to estimate the electrical parameters of a PV/T air collector. Further, a modified equation for the exergy efficiency of a PV/T air collector is derived in terms of design and climatic parameters. A computer simulation program is also developed to calculate the thermal and electrical parameters of a PV/T air collector. The results of numerical simulation are in good agreement with the experimental measurements noted in the previous literature. Finally, parametric studies have been carried out. It is observed that the modified exergy efficiency obtained in this paper is in good agreement with the one given by the previous literature. It is also found that the thermal efficiency, electrical efficiency, overall energy efficiency and exergy efficiency of PV/T air collector is about 17.18%, 10.01%, 45% and 10.75% respectively for a sample climatic, operating and design parameters. [ABSTRACT FROM AUTHOR]

Abstract: The paper deals with an innovative natural gas combined heat, cooling and power (CHCP) system with electrical, heating and cooling capacities of 126/220/210kW, respectively. The trigeneration plant is composed of a cogenerator which uses an automotive derived gas fired internal combustion engine (ICE), coupled to a liquid LiCl–water desiccant cooling system which recovers heat from the flue gases and from the ICE cooling water. The paper describes the energetic and economic analyses of the plant and it makes some evaluations of the effects of fuel and electric prices and of the subsides and plant costs on the economic indices of the system. [Copyright &y& Elsevier]

A concept of exhaust air insulation (EAI) is proposed for application in cooling dominated buildings. The EAI wall in basic form is composed mainly of an air-permeable porous material layer, a ventilated cavity, and an external protection structure. The excessive indoor air pressure or mechanical ventilation forces the exhaust air from the conditioned space to flow through the porous layer firstly, and eventually to ambient through the ventilated cavity. The outflowing exhaust air makes the temperature of the inner surface of the porous layer very close to that of the indoor air. And consequently, the heat gain through the building envelope wall can be dramatically reduced in the cooling season. In this paper, an unsteady-state heat transfer model is developed to predict the temperature distribution of the EAI wall. Experimental measurements are carried out for validating the heat transfer model. Numerical simulations are performed to simulate the transient heat transfer of the EAI wall in cooling season. The exfiltration heat recovery efficiency of the EAI wall is quantitatively investigated. Effects of the airflow velocity, the thickness of porous layer, and the thermal conductivity of porous material on the thermal performance of EAI wall are analyzed. Performances of a conventional brick wall and an external insulation wall are also calculated and compared with that of the EAI wall. Results show that the EAI wall can reduce 84.7% and 67% of the daily total heat gains in cooling season compared with the brick wall and the external insulation wall, respectively. Excellent thermal performance can be achieved by employing thicker porous layer or higher airflow velocity. At a velocity of 0.003 m/s with porous layer thickness of 50 mm, the heat flux entering indoor spare can be decreased to practically zero. [ABSTRACT FROM AUTHOR]

In hot humid climates, a major portion of air conditioning energy is used for dehumidification. In traditional centralized air conditioning systems, air is cooled below the dew point to remove the moisture. This process is energy intensive. Liquid desiccant dehumidification systems (LDDS) provide a promising alternative as they use low grade or free energy like solar energy. Majority of the existing direct-contact liquid desiccant dehumidification modules adopt the concept of low influx rates which ensures high residence time resulting in improved dehumidifier performance. There is limited knowledge with respect to high influx rates which is the topic of this paper. The overall objective of this study is to evaluate the performance of a high-influx, bubble dehumidifier. A prototype dehumidifier employing aqueous Lithium Chloride (LiCl) as desiccant that could accommodate high-influx rates was developed and experiments were conducted to evaluate its performance. Results of the experiments are analyzed in terms of performance parameters namely moisture removal rate (MRR) and dehumidifier effectiveness. The apparatus could achieve a maximum MRR of 0.28 g/s resulting in 66% dehumidifier effectiveness. Empirical equations to predict the MRR were developed through linear regression using experimental data. The input variables used in regression are the inlet depth, the inlet air vapor pressure, the desiccant solution vapor pressure and the diffusion coefficient of water in LiCl solution, along with the design parameters. The diffusion coefficient parameter which was ignored in other dehumidifier models was found to be imperative in this research. The developed empirical equations were validated by comparing the predicted and measured values on a new set of experiments, the data for which were not used for regression. It is found that the time-dependent nonlinear response of the system is predicted accurately by the empirical model. The root mean square errors of the observed and predicted values are less than 8%. [ABSTRACT FROM AUTHOR]

In hot and humid climate such as in Japan and south east Asia, dehumidification in summer is really important for air conditioning. Temperature and humidity independent control (THIC) of air conditioning system can handle sensible heat and latent heat separately, and provide good indoor environment and achieve energy conservation. Desiccant air handling unit is one of the major solution for THIC of air conditioning system. It needs hot water to regenerate sorbent which absorbs moist in the air. Combined heat and power can supply hot water at almost constant temperature for desiccant air handling system and also contribute to the business continuity plan of commercial buildings. However, there are still uncertainties about the factors which affect energy performance of desiccant air handling unit and the optimum design and operations in hot and humid climate. The objectives of this paper are to prove factors which affect energy performance of desiccant air handling unit by measurement analysis and show optimum condition of the desiccant air handling unit under various room conditions by simulation. Measurement analysis shows that energy performance of desiccant air handling unit depends not only on the inlet air condition to dehumidification wheel but also on designed supply air humidity. Furthermore, simulation results show the optimum inlet air condition entering dehumidification wheel under various supply air absolute humidity which is determined by design room conditions. These results provide useful information of desiccant air handling unit during design and operation phase of buildings in hot and humid climate. [ABSTRACT FROM AUTHOR]

An investigation of building performance through a comfort and operational quality standpoint is not too often discussed for Net-Zero Energy Buildings (NZEB). It would seem important that predications and claims for reducing energy-use in buildings and the move towards NZEB does not compromise comfort in buildings. A high school in Essendon, Victoria (near Melbourne) Australia undertook a retrofitting process to improve its existing library from a functional as well as an environmental standpoint. In the process, several pre- and post-measurements were made of building performance. An advanced packaged unit mechanical system applies a demand control ventilation system with a specialised control that promises uniform air temperature throughout the volume of the conditioned space. This system utilises staged compressors with variable speed drive fans and results in minimal background noise. For the mechanical system to deliver as promised, the building envelope was air pressure sealed to an international standard and double glazed (from single glass) and zoned according to orientation and spatial function. Efficient LED lighting was also applied to a dimming control responsive to occupancy and daylight. This level of building improvement requires before and after measurement procedures to assure and prove a quality performance for a near NZEB. Various measurements of pressurisation, air exchange rates through tracer gas, air temperature stratification, IAQ, as well as a continuous and localised comfort survey measurement all contribute to a pre and post assessment of building performance. This paper discusses several measurement processes considered useful to characterize the performance of an HVAC system in a retrofitted library space. As a result of the building envelope quality, subsequent monitoring of the mechanical conditioning system showed that it could have been reduced to half its specified size. Furthermore, sub-metering of the space indicates that the attention given to the lighting and conditioning systems has reduced their impact, so that plug loads are beginning to dominate and require attention if net zero energy building is to be targeted. [ABSTRACT FROM AUTHOR]

External fixed shading devices are generally used to adjust solar influx radiation and save energy in summer. However, they could block the beneficial solar radiation in winter. In this paper, a photovoltaic thermal-compound thermoelectric ventilator (PVT–TEV) system is proposed and investigated. The PVT–TEV system not only could prevent direct solar radiation from going into buildings in summer, but also could heat fresh air by the air-type PVT coupled with a thermoelectric ventilator system in winter. A PVT–TEV system was built in a room for testing the system. Results demonstrate that the performance of the PVT–TEV system is mainly affected by solar radiation when the system works in the sunny days of winter. The stronger the solar radiation is, the more the heat of PVT–TEV system gains and the higher the fresh air temperature is. The average electrical efficiency of PVT is 10%, the average thermal efficiency of PVT–TEV is 26.7% and the average COP h of PVT–TEV is 6.4. In the rainy day, the outdoor fresh air is heated when it flows through heat pipe exchangers of the thermoelectric ventilator. The higher the working voltage is, the more the heat TEV system gains and the lower the COP h of the TEV system is. The average COP h of PVT–TEV system is 1.73 when the operating voltage is 24 V. The PVT–TEV system provides an active and green method for building exterior shading device and supplying fresh air. [ABSTRACT FROM AUTHOR]

Buildings subject to Energy Performance Contracts (EPCs) are usually quite complex public buildings, sometimes relatively old and usually barely documented from the technical standpoint. Gathering comprehensive and reliable technical information is a time consuming and expensive process that has to be carried out within the submission deadline. In these conditions, the standard approach to energy performance forecasting which uses detailed simulation is practically unfeasible. This paper proposes a reduced-order modeling approach that is tailored to the EPC tendering phase. The proposed methodology extends a third order building model, introducing explicit, albeit still abstract, representations of the heating/cooling system, of the weather influence and of the end-user gains. The extended parameter set reflects to a large degree the information that is readily available in practical on-site surveying, or that can be easily calculated from that information. As a consequence of the simplified physics, a knowledge driven, practical calibration procedure, which provides an effective way of reducing uncertainty, is proposed. The calibration procedure analyses the uncertainty present in the available knowledge and uses the constraints imposed by the implemented physics on the parameters’ dynamic to assess their value estimation. The modeling approach is exemplified through three case studies: the first one provides the comparison of the reduced-order model predictions with the outcomes of a detailed model of a small hospital, the second one is used to compare the reduced-order model predictions with the detailed measurements of energy consumption of a real building, and the third case study exemplifies the use in operational context with scarce information. [ABSTRACT FROM AUTHOR]

This paper presents the development of a symbolic transformation based strategy with interpretability and visualisation for building energy performance assessment. The strategy was developed using shape definition language based symbolic transformation and hierarchical clustering. Advanced visualisation techniques including dendrogram, heatmap and calendar view were used to assist in understanding building energy usage behaviours. A comparison of this proposed strategy with a Symbolic Aggregate approXimation (SAX) based strategy was also performed. The performance of the proposed strategy was tested and evaluated using the three-year hourly heating energy and electricity usage data of a higher education building. The result demonstrated that the proposed strategy can identify distinct building energy usage behaviours. The visualisation techniques used also assisted the information discovery process. The discovered information helped to understand building energy usage patterns. The comparison of the proposed strategy with the SAX based strategy showed that the proposed strategy outperformed the SAX based strategy for the case building tested in terms of the variations in building energy usage. This proposed strategy can also be potentially used to evaluate the operational performance of building heating, ventilation and air-conditioning (HVAC) systems. [ABSTRACT FROM AUTHOR]

The paper presents a novel method developed for energy efficient heating of domestic hot water (DHW) with a ground source heat pump (GSHP) system. The method is based on step-based heating of DHW, where the DHW is gradually heated from the inlet temperature of domestic cold water to the target temperature of DHW using a specifically designed GSHP system concept. The developed method was tested and validated using experimental and computational performance analyses and the energy efficiency, operation and potential limitations of the developed application were also studied in existing apartment buildings. To demonstrate the efficiency of the developed application, the performance of the new concept was compared to the performance of a conventionally used GSHP system. The results demonstrated that the developed GSHP concept delivered up to 45–50% improvement in energy efficiency of the DHW heating process over the conventional GSHP application. The measured Seasonal Performance Factors were 2.5–2.6 for the conventional application and as high as 3.7–3.8 for the developed application, when DHW was heated from 7.5 °C to 55 °C. The case study demonstrated that the developed concept is also well applicable in existing buildings, but there is still room for improvement. [ABSTRACT FROM AUTHOR]

The present paper describes a holistic energy efficient retrofit of low income multiple social housing located in Athens, Greece. A holistic analysis was conducted in order to determine the optimum retrofit plan that includes innovative and state of the art commercially available technologies, passive techniques as well as renewable energy sources, aiming to reduce its energy consumption and carbon footprint, improve indoor environmental conditions and be cost effective at the same time. An extensive experimental campaign including air leakage measurements, thermal imaging, energy consumption and indoor environmental quality measurements was conducted before and after the implementation of the retrofit. In addition, advanced building simulation, occupant surveys and socioeconomic analyses were performed in order to evaluate the impact of the retrofit and estimate specific performance indicators. [ABSTRACT FROM AUTHOR]

This paper describes the operational performance results of 6 kW grid-connected building integrated photovoltaic system (BIPV) applied in laboratory building, installed in Colombia (in Bogotá, at 4°35′ latitude and 2.580 m altitude) after one year of monitoring (September 2015-August 2016). The BIPV system is operating in the building “Researching Center of the Engineering Programs − CIPI” at Universidad de Bogotá Jorge Tadeo Lozano. The photovoltaic array is installed on the building’s roof and it has been operating properly since the month of January 2015. The BIPV system is composed of 24 photovoltaic modules connected to the electrical grid through a 5000 W inverter. A monitoring system was implemented using virtual instrumentation to measure irradiance, environment temperature and DC-AC variables of the photovoltaic system. A one-year monitoring process of the system and the meteorological variables allowed us to assess the energy performance and correlate power production with solar radiation. The results indicated that the average of AC energy generated by the pv system was 471,083 kWh/month; the average of irradiance was 4048 kWh/m 2 -day; the average of the photovoltaic arraýs efficiency was 13,68% and the maximun final yield of the system’s performance (YF) was 88,6 kWh/kWp-year. The grid-connected BIPV plant fulfills the specifications demanded for such systems by National and International standards. [ABSTRACT FROM AUTHOR]

As a building component with long history, green envelope has received much attention for its thermal and energy benefits in the past decades. However, few studies have taken into account the two-way effect of green envelope on indoor and outdoor environment during thermal performance evaluation. In this paper, a coupled hygrothermal transfer model of green envelope is developed and validated against field measurements, and the results demonstrate that the model could reasonably reproduce temporal variations of temperature and moisture in green envelope. Then the green envelope model is implemented into an urban canopy model to predict its thermal performance under urban canopy context in Shanghai area. The simulations for a district of office buildings indicate that green envelope decreases sensible heat getting into the indoor and outdoor space significantly, and the maximum indoor temperature difference between buildings with and without green envelope is up to 0.34 °C under free-floating condition. Meanwhile, for outdoor environment, the maximum differences for air temperature, mean radiant temperature and SET* are up to 0.1,0.9 and 0.2 °C respectively under air conditioning condition. What’s more, sensitivity analysis shows that building density has a significant effect on the relative cooling benefit of green envelope against common envelope. [ABSTRACT FROM AUTHOR]

The area of projected shadow on building facades may play a role of paramount importance in the prediction of solar energy conversion and building thermal and energy performance. Algorithms for solar shading calculations may directly affect the accuracy of results obtained by building energy simulation tools. In addition, the consideration of uncertain design parameters imply an estimative of a confidence interval of solar fraction results that determine the reliability as well as the improvement of shading calculation models. In this way, this paper presents a methodology for uncertainty and sensitivity analysis applied to the prediction of sunlit area on building exterior surfaces with shading devices. From a single building model, the solar fraction was investigated for two cities and four typical days. According to the obtained results, more than 20% of all simulation time steps have uncertainties equal or higher than 5% on the solar fraction calculation at 95% confidence level. The maximum values of the uncertainties occur in warmer months, which could significantly impact the building energy balance. Three inputs have higher influence on the uncertainties on solar fraction results: (1) latitude, (2) orientation and (3) width of overhang fins. Perturbation of only 5° on the building orientation may imply important uncertainties on solar fraction, which is normally neglected by designers. The results highlight the importance of assessing the uncertainty of inputs in algorithms such as the one to calculate the surface solar fraction that is an important prerequisite of the final building energy balance. [ABSTRACT FROM AUTHOR]

This paper addresses quality and impact issues concerning Energy Performance Certificates (EPC) by means of a dataset based upon the Swedish EPCs for single-family houses. Assuming that the quality of the certificates plays an important role for their impact, we examine to what extent various characteristics of the firms and experts issuing the certificates are influencing their assessments of energy consumption and energy conservation. Exploiting the information on biased assessments, we also investigate the relationship between the transaction price of a house and its EPC label. Doing so, we distinguish the attributes that can be observed by visiting the house and those that a buyer only can inform herself about through the EPC. Applying regression analyses we find that firm and expert characteristics matter quite a lot implying that the EPC-quality could be improved considerably by increasing the inter-rater reliability. The results also show that the price impact of the energy label is related to information that the buyers can obtain by visiting the house rather than to information uniquely provided by the EPCs. Hence, the EPCs per se are unlikely to stimulate energy conservation through the price mechanism. [ABSTRACT FROM AUTHOR]

Children spend the majority of their weekdays in classrooms that often have low indoor air quality and limited financial resources for the initial and running costs of mechanical ventilation systems. Designing effective natural ventilation (NV) systems in schools is difficult due to the intense use of the classroom spaces and the dependence of NV on building geometry and outdoor conditions. Building thermal and airflow simulation tools are fundamental to predict NV system performance in the design phase. These predictions of these tools must be validated (preferably with data from real buildings). This paper presents a set of detailed measurements of buoyancy driven natural DV systems of three classrooms located in two buildings in Lisbon (Portugal). The rooms are located in two educational buildings, a kindergarten and a university, and have different buoyancy driven natural DV systems (with and without chimneys). The experimental measurements are used to validate a three-node DV model implemented on the open-source thermal building simulation software EnergyPlus. The validation results show that the building thermal simulation model tested is able to predict bulk airflow rate with an average error of 16%. In addition, a good agreement is also obtained for the vertical temperature prediction: an average error of 4% corresponding (average deviation of 0.7 °C). Analysis of the kindergarten rooms results revealed, that as expected, increasing chimney height from 1 to 4 m has a significant positive impact in NV system performance. The performance of natural DV systems depends on the number of thermal plumes in the room. For the same sensible heat load, increasing the number of plumes lowers the average occupied zone air temperature and increases the bulk airflow rate. In light of the complexity of the cases tested, NV with uncontrolled boundary conditions, the results of the comparisons performed between measurements and simulations should contribute to increase confidence in the use of EnergyPlus to simulate buoyancy driven natural DV systems. [ABSTRACT FROM AUTHOR]

Energy-efficient buildings, made of ecologically acceptable materials, are result of a worldwide ecological awareness induced by ever growing concern in regard to climate changes and economic aspects of long term energy savings. Complexities regarding energy-efficiency, economy and traditional construction of residential family homes led to acceptance of new building materials and forming of several typical wall types in south-eastern European region. This paper offers an energy performance analysis and a life cycle assessment of three common outer wall types: prefabricated timber-frame, an aerated autoclaved concrete and a solid brick wall with two model heating regimes. In order to verify energy and environmental performance of each wall type in a complete building, a detached house model was determined with the same parameters used for comparison. Model performances were determined for the selected life cycle stages and system boundaries during an eighty year period taken as a service life of family houses and compared to conventional and passive houses performances found in literature. Analysis results show that the model with aerated autoclaved concrete wall has the best environmental performance and that model with masonry brick walls has the best thermal performance in discontinuous heating mode of the three analysed walls. [ABSTRACT FROM AUTHOR]

With increasing concern for building energy efficiency, domestic hot water (DHW) supply systems, which have significant energy-saving potential, have drawn more attention from both practitioners and academia. In this study, we conducted a field study on seven centralized hot water supply systems in Beijing, measuring the water temperature and flow rate in primary or secondary pipes and collecting the operating records of hot water usage, gas consumption, and electricity consumption. In addition, we discuss the main problems existing in the current centralized DHW system. Based on measured data, this paper further analyzes energy losses from each link in the hot water supply system. A mathematical model is then proposed for simulating the energy consumption of hot water supply systems under various conditions such as various boiler efficiency, thermal insulation thickness, water pipe network structure, and hot water usage. The model is also used to explore the main factors that lead to low performance of centralized DHW systems in China. Finally, we analyze the applicability of diverse heat sources (e.g., electricity, gas, and heat pumps) in centralized DHW systems in China. [ABSTRACT FROM AUTHOR]

The main purpose of ventilation systems is to satisfy the need of occupants in terms of thermal comfort and air quality. In the case of mixing ventilation, based on the use of jets from one or from multiple diffusers placed in the room, the fresh air and the thermal loads should be distributed in the entire occupied zone. Therefore, the design of the diffusers must aim, beyond aesthetic aspect, the ability to provide a good mixing between the jet and the ambient air. Enhancement of jet induction by means of lobed inserts into a diffuser, was recently proposed in an European patent as a promising and low-cost solution for improving the performance of HVAC systems. In this paper, an experimental investigation on jet characteristics and thermal comfort generated by a classical multi-cone ceiling-mounted diffuser is proposed. Its performance is compared with the same diffuser equipped with lobed inserts. A simplified heated manikin simulates the presence of a human body in the test room. Airflow pattern from the diffuser and its interaction with the manikin were analyzed with whole-field PIV technique. Thermal comfort was analyzed based on traditional pointwise measuring probes and on the standard ISO 7730. It is revealed that the thermal comfort was significantly improved using the lobed diffuser compared to the conventional one, without increase of pressure drop and sound pressure levels. [ABSTRACT FROM AUTHOR]

Temporary housing is crucial to disaster recovery, due to the demand for large numbers within a short period. The short life cycle and unique functional requirements associated with temporary housing could lead to significant environmental impacts. However these have not been adequately investigated. This paper focuses on the life cycle performance of light-framed temporary housing in China with local technologies, taking Chinese electricity mix of each process and domestic transportation distances into consideration. The research selects four popular temporary housing in China, calculates the material requirements and compares the life cycle impact of different wall assemblies based on Future House built in Nanjing. While energy consumption and greenhouse gas emissions are used as surrogate indicators of environmental impact, total life-time impact is established by including construction energy, operating energy, maintenance energy and end-of-life energy and corresponding greenhouse gas emissions. It was found that the life cycle energy of post-disaster temporary housing is much higher in comparison to low energy buildings with construction energy contributing 65% to life cycle energy due to unique requirements. The results also show that life cycle energy of post-disaster shelters could be reduced by using recycled materials, lighter structural materials and light wall cladding materials. [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]