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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]

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]

A technical feasibility study of an innovative hybrid solar-wind-rain eco-roof system with natural ventilation and skylight for electrical energy generation and saving is presented in this paper. The system integrates and optimizes five green technologies: wind turbine, solar photovoltaic system, rain water harvesting and utilization system, natural ventilation and roof sky lighting. The design was conceptualized based on the experiences acquired from meteorological data for Malaysian application. The V-shape top roof which was designed above the wind turbine was able to increase the wind speed by the venturi effect before the wind interacts with the wind turbine located between the roofs, hence improve the performance of the wind turbine. An automatic cooling and cleaning system with a stream of water was designed to clean and cool the roof which can improve the electrical efficiency of the solar photovoltaic modules. The ventilation vents of the system allow warm air inside the building to be ventilated out from the building by the pressure difference caused by high speed wind due to the roof design. The skylighting in the system improve the living comfort level and reduce power consumption of artificial lighting. Technical assessment of the system showed the estimated annual energy generated was 21205.65 kWh, estimated energy savings was 1839.6 kWh, the estimated annual ventilation rate was 2.17 × 10 8 m 3 and reduction of CO 2 emissions was 17767.89 kg/yr. [ABSTRACT FROM AUTHOR]

This paper presents two grid-connected photovoltaic (PV) systems (monocrystalline silicon, c-Si; copper–indium–diselenide; CIS) situated on the rooftop of the solar lab building in the National University of Malaysia, southwestern Malaysia. Various parameters were used to analyze the system performance; including array yield, final yield, capacity factor, and performance ratio. The recordings were noted down under the actual climatic conditions for an entire year. The variables of energy cost and payback period were also considered to calculate the economic feasibility of the system. Variations in the final yield of CIS were as low as 2.98 h/day in July to the highest value of 4.31 h/day in March. The final yield for c-Si power plant ranged from 2.92 h/day in July to 4.14 h/day in March. The calculated capacity factors for CIS and c-Si power plants were 15.6% and 14.4%, respectively, in July as the worst value, and 21.12% and 20.2%, respectively, in March as the best value. In the case of CIS power plant, the performance ratio ranges from 63.8 in July to 84.12 in March, and for c-Si power plant, it ranges from 59.92 in July to 79.14 in March. The energy cost and the payback period of the suggested system were evaluated as 0.045 USD/kWh and 28.44 years, respectively. Finally, this study provides valuable information for those who are interested in PV system installation in the tropical zones. [ABSTRACT FROM AUTHOR]

This paper evaluated the performance of the building integrated solar thermal shading (BISTS) system on building energy consumption and daylight levels through energy and daylighting modeling and simulations. A medium office reference building in Los Angeles defined by the DOE was used in the case studies. The horizontal BISTS louvers on the south windows and vertical BISTS louvers on the east and west windows were modeled and simulated. The final BISTS configuration was achieved by considering the balance between primary energy savings and daylight provision. The results revealed that 1) the BISTS system could effectively improve the daylight condition for a single perimeter room by increasing the useful daylight level and reducing the excessive level. 2) The savings for the building energy consumption were not significant. The final design with the BISTS layouts on three façades could result in 5.3% of total primary energy saving. 3) 90° of slat angle should be avoided for both the horizontal and vertical BISTS louvers. Smaller angles – between 0° and 60° – are preferred. [ABSTRACT FROM AUTHOR]

Residential and commercial buildings account for more than 74% of total annual electricity consumption in the United States. Studies have shown that occupants’ awareness of their behaviors in consuming electricity encourages them to change their unsustainable behaviors and improves the sustainable ones. As behaviors impact the ways that daily activities are performed, in order to develop a personalized appliance level model of an occupant's behavior, precise activity recognition is required. In this paper, we introduce a novel framework to allocate personalized appliance-level disaggregated electricity consumption to daily activities. In our framework, using ontology-based approach, the input appliance usage data is first separated into categories of non-overlapping activity events. The separated data sets are then segmented to detect activity segments, which are next mapped into activity classes using a trained classification model. To evaluate the performance of our presented framework, an experimental validation was carried out in three test bed apartment units. Results of validation showed a total F -measure value of 0.97 for segmentation and an average accuracy of 93.41% for activity recognition. Following the activity recognition, the approximate electricity consumption associated with the recognized activities was estimated and the results of each test bed unit were compared with the others. [ABSTRACT FROM AUTHOR]

In variable air volume (VAV) systems, conventional control methods reset the supply air static pressure based on the exact mathematics model of the controlled objects which are often difficult to be founded, because the VAV controlled systems have the characteristics of nonlinear, multivariable and long delay times. In order to develop a simple inference process for real-time applications, this paper presents a novel fuzzy control method for static pressure reset with no using of the mathematics model. The proposed fuzzy control method is developed based on the maximum damper position feedback using Mamdani-type fuzzy rule and functioning fuzzy subset inference (FFSI). This study provides the detail implement process of the proposed fuzzy control method. Supported by the experimental data, the proposed method is compared with optimal fixed changing step method in an integrated control test rig for a VAV air conditioning system. Experimental results show that the proposed method has better energy efficient and control performance. A minimum of 7% energy saving of the proposed fuzzy control method is shown through experimental study. [ABSTRACT FROM AUTHOR]

In many modern buildings, different monitoring and control systems are used, but majority of them are not directly connected with the energy consumption optimisation. This paper presents a concept of an integrated performance monitoring system for promotion of energy awareness in buildings. The reference architecture of the envisioned system evolved from the traditional management structure, plan-do-check-act model. Traditional plan-do-check-act model has been upgraded with the integration of prediction engine, knowledge repository and modern scientific approaches for supporting energy awareness including early warning, optimisation and supervision. The proposed concept is constituted upon three modules: (1) data acquisition and processing, (2) knowledge repository, (3) performance monitoring system including prediction engine, consumption modelling, emissions calculation and decision support. The concept of three modules evolved from the idea to enrich existing solutions with the awareness about possible future abnormal situations and to enable preventive actions. Presented case study represents a repeatable application of the energy cost centres based modelling of energy consumption in educational and research buildings by using neuro-fuzzy modelling approach. Initial testing results are indicating the potential of electricity savings up to 15% enabled by visualisation and awareness about electricity consumption. [ABSTRACT FROM AUTHOR]

The paper describes a study developed to estimate the energy savings potential of a radiant cooling system installed in a commercial building in India. To evaluate thermal performance and energy consumption, simulations were carried out using FLUENT and EnergyPlus software, respectively. The building model was calibrated using the measured data for the installed radiant system. Then this calibrated model was used to simulate the energy consumption of a building using a conventional all-air system to determine the proportional energy savings. For proper handling of the latent load, a Dedicated Outside Air System (DOAS) was used as an alternative to Fan Coil Unit (FCU) that was installed in conjunction with the radiant cooling system. A comparison of energy consumption calculated that the radiant system was 17.5% more efficient than a conventional all-air system and that a 30% savings was achieved by using a DOAS system compared with a conventional system. The Computational Fluid Dynamics (CFD) simulation showed that a radiant system offers more uniform temperatures, as well as a better mean air temperature range, than a conventional system. To further enhance the energy savings in the radiant system, different operational strategies were analyzed based on thermal analysis using EnergyPlus. [ABSTRACT FROM AUTHOR]

This paper establishes the methodology used for lighting system planning in underground mining, shows local data and lighting levels required by the mining industry, and examines and compares the results of the technical and economic evaluation of using fluorescent and LED luminaires in underground mining in Chile. A case study for a new expansion of the mine called “New Mine Level” of El Teniente, Codelco, the biggest underground copper mine in the world, is analyzed, where a large amount of luminaires are used to illuminate work and transit areas in the mine. Technical comparison among different brands and both technologies is performed using DIALux software. Cost-effectiveness and sensitivity analysis is calculated using prices and economic data from this case study. [ABSTRACT FROM AUTHOR]

A great number of low carbon technologies have been developed in the last decades. The use of such technologies promises good indoor environment for the building's occupants, lower energy consumption and carbon emissions. However, there are uncertainties related to payback periods and usability constraints of low carbon technologies. In addition, past and current research has shown differences between the expected and the actual performance of buildings, both in terms of energy consumption and indoor comfort. For a better understanding of differences between expected and actual performance of buildings, it is necessary to investigate the energy consumption, the behaviour of the occupants and their interaction with new technologies, and the resulting indoor comfort. Monitoring building performance can help to reduce the uncertainties related to the building performance of buildings. This paper presents an overview and classification of data collection methods to monitor the energy consumption, thermal comfort of occupants and the operation of buildings in use. Data collection methods and techniques are categorised and linked to specific methods to evaluate building performance and recommendations are made to set up building monitoring research. By identifying the most effective methods to monitor buildings, this research aims at embedding performance monitoring in standard practice. [ABSTRACT FROM AUTHOR]

The building envelopes are exposed to the hot-humid climate with high humidity in hot summer and cold winter zone (HSCW) of China. The moisture transfer may severely influence the conduction loads through exterior walls. In this paper, a coupled heat and moisture transfer model is developed and validated to investigate the thermal performance of exterior walls. The conduction loads through a typical exterior wall are used to evaluate the effect of moisture transfer on the thermal performance of exterior walls in HSCW zone of China. The results show that the peak cooling and heating loads are overestimated by 2.1–3.9% and 4.2–10.1%, respectively, when ignoring moisture transfer. In cooling season, the sum of the latent load accounts for 14.3–52.2% of the sum of the total load and the yearly latent load accounts for 4.9–6.1% of the yearly total load when considering moisture transfer. The total cooling, heating and the yearly load are underestimated by 9.9–34.4%, 1.7–4.0%, and 5.2–6.8%, respectively, when ignoring moisture transfer. The results indicate that ignoring moisture transfer causes significant discrepancy in predicting the conduction loads. A detailed model considering moisture transfer in building envelope is essential to accurately evaluate the building energy performance in HSCW zone of China. [ABSTRACT FROM AUTHOR]

Appropriate design and control strategies are crucial for the implementation of certain complex active systems in the building sector. Suitable and user-friendly numerical tools have to be available to architects and engineers, so they can incorporate innovative active systems in their building designs. The thermal response of a ventilated facade with phase change material in its air chamber for cooling applications is studied in this paper. The system makes use of low temperatures at night to solidify the phase change material, and store it solid for a later cooling supply to the interior of the building. This active technology is very sensitive to the weather conditions as well as to the defined operational schedule (charge, storage and discharge periods definition). Two different numerical approaches have been developed to better understand this system and to define different control strategies, as well as to determine their potential to reduce the energy consumption in the building for cooling purposes. First, a finite control volume approach was applied to describe the ventilated facade with latent heat storage. The important computational cost and complexity of this numerical methodology leaded the authors to develop a simple numerical model based on the assumption that the exchange between the air and phase change material inside the ventilated facade occurs at isothermal conditions. Both models were validated against experimental data, and even though the isothermal model presented slightly higher deviation from the experimental results than the finite control volume one, it is presented as a suitable numerical tool for architects and engineers because of its light computational cost and versatility. [ABSTRACT FROM AUTHOR]

A numerical simulation model of a two-stage compression refrigeration system with vapor injection using R-32 as refrigeration is newly presented in this paper. The middle chamber state of the twin rotary compressor with vapor injection was simulated. Based on that, the whole system model was set up and it was validated by comparing the predictions with measured data. The results show that, compared with No-injection cycle, R-32 vapor injection system provides very significant performance improvements for cooling performance. The most suitable volume ratio of the high-pressure cylinder to low-pressure is between 0.65 and 0.78; Compared with the single-stage compression system, the cooling capacity and COP of the two-stage compression system can improve 5–15% and 10–12%, respectively; The optimum vapor injection pressure corresponding to the comprehensive cooling performance was 1.3–1.8 MPa. [ABSTRACT FROM AUTHOR]

Commercial office buildings represent the largest in floor area in most developed countries and utilize substantial amount of energy in the provision of building services to satisfy occupants’ comfort needs. This makes office buildings a target for occupant-driven demand control measures, which have been demonstrated as having huge potential to improve energy efficiency. The application of occupant-driven demand control measures in buildings, most especially in the control of thermal, visual and indoor air quality providing systems, which account for over 30% of the energy consumed in a typical office building is however hampered due to the lack of comprehensive fine-grained occupancy information. Given that comprehensive fine-grained occupancy information improves the performance of demand-driven measures, this paper presents a review of common existing systems utilized in buildings for occupancy detection. Furthermore, experimental results from the performance evaluation of chair sensors in an office building for providing fine-grained occupancy information for demand-driven control applications are presented. [ABSTRACT FROM AUTHOR]

A double ventilated window is formed by two parallel windows in the same facade opening with a ventilated air-channel between them. Under inward flow conditions and incident solar radiation this works as a solar collector. The solar radiation absorbed by the outer and inner windows heats up the passing air in the air channel before it is delivered inside. Still, part of the solar radiation reaches directly the indoor environment through the glazed part. This paper is a presentation of an experimental and analytical study of the solar heat gain coefficient (SHGC) of a ventilated double window under different working conditions and for several types of glasses and different glass to frame ratios. The variation of SHGC values with each influent factor is provided which can be useful for a dynamic whole building energy analysis. [ABSTRACT FROM AUTHOR]

The condensing heat recovery in air conditioner is attractive because of its great economical and environmental value. This paper presents theoretical and experimental investigations of a novel solar thermoelectric air conditioner with hot water supply (STACHWS). The system can implement different working modes according to the building users’ requirement. Experiments were carried out under different operating conditions in order to investigate the performance of the system. Results show that the STEACWS can reliably be used to heat hot water without losing its cooling capacity when it is controlled well in different operation conditions. The system has relatively remarkable coefficient of performance (COP int ) which can be as high as about 4.51 in space cooling and water heating mode. When the system works as a water source thermoelectric heat pump, the coefficient of performance (COP) of the system can be about 2.59 in cooling mode and 3.01 in heating mode. This simple and environmentally friendly system can reduce indoor cooling and heating load and provide a continuous hot water supply for householders. [ABSTRACT FROM AUTHOR]

For certain temperate climate types, cooling towers have the potential to produce high temperature chilled water, which when used in conjunction with radiant and displacement cooling technologies, have prompted interest in this concept as a potential approach for the conditioning of buildings. The feasibility of the proposed system depends largely, on achieving low approach water temperatures within an appropriately designed cooling tower, at acceptable levels of energy performance. Using a validated mathematical model, the current paper examines the performance of such a cooling tower for four different temperate climate conditions. The current assessment shows for building water return temperature of 22 °C, for temperate climates that are considered warm and humid, the limitations on cooling tower operation are when ambient conditions exceed 25 °C and 75% RH. Two strategies were investigated to allow the smallest practicable approach to the wet bulb temperature to be achieved: (i) increasing the tower air flowrate, (ii) decreasing the tower water flowrate. For a temperate climate that is warm and humid, operating the cooling tower with an approach of 1.0 K was found to be not practicable for all encountered weather conditions, but use of a 2.0 K approach was found to be practicable for all conditions. [ABSTRACT FROM AUTHOR]

This paper exposes a HVAC system installed and tested during the Solar Decathlon Europe 2012 competition at the SMLsystem prototype. This system is focussed to improve the performance of a heat pump based HVAC system with two thermal storage tanks using phase change materials (PCM). A cold tank is used to take advantage of the low outside temperatures at night to cool the PCM with a high COP and it is used later to cool the building when the outside temperature rises. The second tank is operated as an alternative hot reservoir which provides the system the flexibility to dissipate the heat to the tank at a constant temperature granting never to reduce the COP from a minimum value. Different functioning strategies to evaluate the efficient use of the HVAC system for cold accumulation and heat dissipation are shown and implemented. [ABSTRACT FROM AUTHOR]

The thermal habits of Odoo were examined and energy consumption data were also predicted. Special tests were performed for the time of the competition, and whole year was also analysed. The climatic data were of Madrid as the competition took place there. The modelling environment was MATLAB's Simulink with a built-in module of Simscape. It is for especially examining thermal behaviours. MATLAB itself is capable of solving differential equations by time, for this reason dynamic simulations can be performed. First the building structure was created, and then the heatflows affecting the internal temperature were added. In this paper detailed process of creating the model is presented, and some results are discussed, including some possibilities of further improvements. [ABSTRACT FROM AUTHOR]

Highlights: [•] This paper gives the first reported research about heat exchanger issues for ACB. [•] Four different circuitry arrangements are investigated. [•] The effectiveness of circuitry adjustment to ACB terminal unit is confirmed. [•] The unexpected conclusion indicates much potential improvement of ACB system. [Copyright &y& Elsevier]

• Performance assessment of CdTe-based STPV for saving façade buildings power. • Calculation, evaluation, and comparison of different glazing and its effect on the air conditioning power and temperatures. • Estimation the lighting energy consumption for different glazing. Façade buildings are generally highly glazed and energy-intensive especially in countries with hot weather. Power consumption in these buildings is even more significant when air conditioning (AC) is added to the figures. Building with semi-transparent photovoltaic (STPV) materials is bringing advantageous energy-saving features to these façade structures. Energy is saved by more heat being reflected resulting in less AC power consumption with the STPV thermal properties. In addition, the optical and electrical properties provide indoor sunlight with power generation. This paper investigates the net potential energy saving via applying cadmium telluride (CdTe) in Façade buildings. The analysis has been carried out using indoor and outdoor experiments considering different orientations and transparencies. Compared to a single glazing case as a reference, the application CdTe achieved a net energy saving to be as high as 20%. Furthermore, a trade-off between saving energy and environment comfort has been discussed as less transparency windows lead to more artificial light consumption. The findings indicate that STPV is a promising solution for sustainable buildings. [ABSTRACT FROM AUTHOR]

• Thermal performance is assessed for a wall module from bio-based materials. • Numerical models are compared to measurements from a full-scale prototype. • The effect of framing profiles on thermal resistance is specifically investigated. • A workmanship defect is linked to a 5x increase in additional heat flow of profiles. • When suitably mounted the component achieves a U -value of 0.27–0.30 W/m²K. Building envelope systems are rapidly evolving, driven by increasingly stringent requirements for limiting energy consumption. Current trends favour lightweight, prefabricated wall assemblies with high levels of insulation, which have been shown to be particularly sensitive to thermal bridging through anchoring and framing elements. This paper presents a self-supporting multi-layer wall component made from bio-based materials, where novel biocomposite profiles are used instead of conventional metallic frames. The thermal performance of the proposed solution is calculated from numerical modelling and characterised through in-situ measurement of a full-scale prototype. For the plane areas of the wall with continuous insulation, theoretical calculations are broadly in line with results from experimental monitoring (7–15% deviation). Additionally, an area along a framing profile was specifically monitored, and it was found that the numerical model overestimated thermal resistance with a deviation of 121%. The presence of air gaps between the rigid insulation and framing elements, linked to the fabrication process of the prototype, was identified as a plausible cause. A subsequent explanatory numerical assessment, considering the effect of such cavities in the numerical model, provided results that are consistent with measurements from the experiment and previous literature. The study aims at demonstrating the insulation levels achievable with the use of novel bio-based materials of low thermal conductivity, and more generally, contributing to a better understanding of the thermal performance of framed lightweight insulated assemblies in service conditions, by monitoring and modelling the impact of thermal bridges and workmanship at framing elements. [ABSTRACT FROM AUTHOR]

Active chilled beams support high temperature cooling which enables the opportunities of direct ground-coupling and self-regulation. Direct ground-coupling implies cooling through a ground heat exchanger without use of a chiller and self-regulation refers to the elimination of individual room control systems. This paper presents the operation and indoor air temperatures in such an office building located in Stockholm, Sweden, and the analysis includes the unprecedented hot summer of 2018. The results show that the system is capable of supplying the building with enough cooling to not exceed desired indoor air temperature levels. It is also concluded that the self-regulation kept the indoor air temperature satisfactory uniform. The difference between the highest and lowest temperature is 1.9 K on average and below 2.4 K during 90% of the time. Regarding stability, the least stable temperature recorded has a standard deviation of 0.8 K while the average standard deviation is less than 0.5 K. The indoor air temperature during summer is about 2 K lower than suggested by standards. This calls for conducting a thermal comfort survey and may be remedied by increasing the chilled water temperature. To increase the performance of the system, the ground is cooled during winter by preheating the supply air. During 2018, slightly more cooling was extracted in the summer than recharged during winter. [ABSTRACT FROM AUTHOR]

• System-level key performance indicators are missing in the literature yet important. • A suite of system key performance indicators (KPIs) are defined. • The system KPIs cover four major end use systems and their eleven sub-systems. • A database of system KPIs is developed using simulation results of 16 prototype building models. • Potential applications of system KPIs include system performance benchmarking and diagnostics, code compliance, and M&V. Quantifying building energy performance through the development and use of key performance indicators (KPIs) is an essential step in achieving energy saving goals in both new and existing buildings. Current methods used to evaluate improvements, however, are not well represented at the system-level (e.g., lighting, plug-loads, HVAC, service water heating). Instead, they are typically only either measured at the whole building level (e.g., energy use intensity) or at the equipment level (e.g., chiller efficiency coefficient of performance (COP)) with limited insights for benchmarking and diagnosing deviations in performance of aggregated equipment that delivers a specific service to a building (e.g., space heating, lighting). The increasing installation of sensors and meters in buildings makes the evaluation of building performance at the system level more feasible through improved data collection. Leveraging this opportunity, this study introduces a set of system-level KPIs, which cover four major end-use systems in buildings: lighting, MELs (Miscellaneous Electric Loads, aka plug loads), HVAC (heating, ventilation, and air-conditioning), and SWH (service water heating), and their eleven subsystems. The system KPIs are formulated in a new context to represent various types of performance, including energy use, peak demand, load shape, occupant thermal comfort and visual comfort, ventilation, and water use. This paper also presents a database of system KPIs using the EnergyPlus simulation results of 16 USDOE prototype commercial building models across four vintages and five climate zones. These system KPIs, although originally developed for office buildings, can be applied to other building types with some adjustment or extension. Potential applications of system KPIs for system performance benchmarking and diagnostics, code compliance, and measurement and verification are discussed. [ABSTRACT FROM AUTHOR]

Natural materials, such as straw bale and earth, have substantially less embodied energy than processed materials, so that their use in building construction can give a valuable contribution to sustainability. This paper presents a natural multi-sheet wall package (named straw wall, SW) consisting of straw bale layer and innovative natural plasters, giving a rational evaluation of its potential of use in the sustainable building construction. The new building component was investigated by analyzing its environmental impact through the Life Cycle Assessment (LCA) from "Cradle to Gate" and its energy performance using dynamic simulation of a building case study; the energy saving potential of SW was assessed in different climate conditions in Italy. The innovative package highlighted excellent energy performance with respect to the NZEB reference, as prescribed by the Italian regulation, for all climates. Considering only the production and construction phases, the Embodied Energy associated to the innovative wall system is about the half of the value related to a traditional wall package and the CO 2 equivalent emissions differ by more than 40%(Pescara site). [ABSTRACT FROM AUTHOR]