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Clustering algorithms have been successfully applied in analyzing building energy consumption data. It has proven to be an effective technique to identify representative energy consumption patterns as well as being a pre-processing step for other techniques. In this paper, we propose a clustering method based on k-shape algorithm, which is a relatively novel method to identify shape patterns in time-series data. In the experiment, clustering is performed for each individual building according to its hourly consumption. The novelty of this paper is that a new k-shape algorithm is applied to detect building-energy usage patterns at different levels, and the clustering result is further utilized to improve the accuracy of forecasting models. Ten institutional buildings covering three different typologies are used as case studies and a set of hourly and weekly energy consumption data is further analyzed in this paper. The experimental results reveal that this proposed method can detect building energy usage patterns in different time granularity effectively and also proves that the forecasting accuracy of SVR model is significantly improved by utilizing the results of the proposed clustering method. [ABSTRACT FROM AUTHOR]

Concerning the building environment HVAC facilities, even if a great effort has been made in developing components and systems with high nominal efficiencies, less attention has been paid to the problem of system maintenance. The main objective of the thermoeconomic diagnosis is to detect possible anomalies and their location inside a component of the energy system. The second objective, and indeed the one to be achieved in this paper, is indicated as inverse problem. It is associated with the quantification of the effects of anomalies in terms of thermoeconomic quantities. Its rigorous application in building thermal installations has some difficulties relating to the strong interrelation between the different components and the fact that energy supply facilities are continuously changing with time. The way to deal with dynamic circumstances is thoroughly explored in this article. Likewise, this paper’s main goal is to demonstrate an application of two thermoeconomic diagnosis methodologies in the building sector, one based on the malfunction and dysfunction analysis and the other one based on the characteristic curves of the components. The results obtained allow us to point out the advantages and limitations of both methodologies as well as to combine them and then develop a more reliable diagnosis. [ABSTRACT FROM AUTHOR]

This paper presents an online transfer learning framework for improving temperature predictions in residential buildings. In transfer learning, prediction models trained under a set of available data from a target domain (e.g., house with limited data) can be improved through the use of data generated from similar source domains (e.g., houses with rich data). Given also the need for prediction models that can be trained online (e.g., as part of a model-predictive-control implementation), this paper introduces the generalized online transfer learning algorithm (GOTL). It employs a weighted combination of the available predictors (i.e., the target and source predictors) and guarantees convergence to the best weighted predictor. Furthermore, the use of Transfer Component Analysis (TCA) allows for using more than a single source domain, since it may facilitate the fit of a single model on more than one source domain (houses). This allows GOTL to transfer knowledge from more than one source domain. We further validate our results through experiments in climate control for residential buildings and show that GOTL may lead to non-negligible energy savings for given comfort levels. [ABSTRACT FROM AUTHOR]

This paper reviews occupancy based model predictive control (MPC) for building indoor climate control. Occupancy behavior in buildings is stochastic and complex in nature. With better understanding of occupancy presence in rooms and spaces, advanced controls, such as MPC, can be designed to achieve a more energy efficient operation, compared to more traditional control methods, while comfort is maintained. This paper starts with an overview of traditional controls implemented in buildings, and importance of occupancy based controls. Various control-oriented building modeling methods including physics-based and data-driven models are reviewed. Later on, a comprehensive review of MPC in terms of control theory, objective functions, constrains, optimization methods, system characteristics and various types of MPC is presented conducted. In principle, MPC finds an optimal sequence of control commands to optimize an objective function, considering system model, disturbances, predictions and actuation constraints. Lastly, occupancy based controls including commonly used rule-based and latest model-based controls are reviewed. In addition, a few experimental studies are presented and discussed. The paper presents a holistic overview of occupancy-based MPC for building heating, ventilation, and air conditioning (HVAC) systems, and discusses current status and future challenges. The purpose of this paper is to provide a guideline forresearchers who would like to conduct similar studies to have a better understanding of established research methods. [ABSTRACT FROM AUTHOR]

The goal of this paper is to identify the effects of in-pore transport of liquid water and water vapor as well as phase changes on the hygrothermal behavior of earthen buildings. Indeed, one of the main assets used to promote these constructions is their role in moisture buffering hence temperature and relative-humidity quality controlling. However, there is no clear consensus yet concerning the impact of these phenomena on the global energy performance of the buildings. A coupled model is therefore proposed in this paper, based on heat and mass balances inside the earthen walls, in order to clarify this question. This model considers separately the kinematics of each phase (e.g. liquid water, vapor, dry air and solid matrix), in interaction with each other. It also takes into account the impact of pore water confinement on the liquid-to-vapor phase change, in particular on the resulting latent heat released or absorbed. The model is successfully compared to experimental results on instrumented full-scale rammed earth wall subjected to temperature cycles. It eventually allows identifying the singular hygrothermal behavior of earth material by testing the range of applicability of the simplifying assumptions which are commonly made in function of the permeability of the tested material. [ABSTRACT FROM AUTHOR]

The smart grids are modern electric power grid infrastructure for enhanced efficiency and reliability through automated control, high-power converters, modern communications infrastructure, sensing and metering technologies, and modern energy management techniques based on the optimization of demand, energy and network availability. The role of buildings in this framework is very crucial. This paper addresses critical issues on smart grid technologies and the integration of buildings in this new power grid framework. The main objective of this paper is to provide a contemporary look at the current state of the art in the potential of buildings and communities to be integrated in smart grids as well as to discuss the still-open research issues in this field. The challenges for the building sector are discussed and future research prospects are analysed. [ABSTRACT FROM AUTHOR]

The gas turbine capacity and operating strategy selection of Building Cooling, Heating and Power (BCHP) systems play an important role in the system operating performance, leading to different primary energy consumption for the same building load. However, the optimal design problems of those two factors have not been solved very well. This paper presents a new simple method to determine the optimal gas turbine capacity and operating strategy. The gas turbine electricity efficiency, the Coefficient of Performance ( COP ) of absorption heat pumps, and the demand heat/power ratio are found to be the key factors. There exists two values of the critical gas turbine efficiency. More primary energy will be consumed when the selected gas turbine electricity efficiency is below the smaller critical value compared with the separated generation. When the selected gas turbine electricity efficiency is between the two critical values, the hourly optimal operating strategy and the gas turbine capacity can be determined by Following the Thermal Load (FTL). Otherwise, the optimal gas turbine capacity should be sized by Following the Electricity Load (FEL) with the consideration of the actual given conditions. Based on this method, some typical cases with or without TES are analyzed. The results agree well with the conclusions drawn in the current published papers. This method gives a new aspect to understand BCHP analytical design, and can be applied in the engineering area. [ABSTRACT FROM AUTHOR]

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: The velocity of wind in an urban location is comparatively lower than in rural or semirural locations. This paper deals with the study of a new methodology to increase the wind speed and power output of small turbines located in urban areas. The new methodology is adopted based on TRIZ (Theory of Solving Inventive Problems) principles. This idea was obtained from the different shapes adopted for the Roof Tops of Buildings at various locations. The methodology used here studies the impact of monoslide roof shape on wind speed using CFD. Majority of buildings in India have Flat Roofs. So, the paper suggests the use of adjustable roof so that the roofs could be tilted at various angles. The present study gives a diagrammatical representation of the new method and an analysis using CFD. Measuring the velocity of wind at an urban location at various altitudes and at various locations of the buildings is a complex task. Computational Fluid Dynamics (CFD) is already a necessary tool for modelling the wind over complex urban terrains. This study underlines a system to reduce the passiveness and idle time of wind turbines located in buildings. That could make the urban wind turbine more agile and active for higher power generation and resource utilization. [Copyright &y& Elsevier]

Abstract: Accurate understanding of the thermal behaviour of building components is essential for predicting heating or cooling needs and facilitates the implementation of more successful energy saving strategies and retrofits. This paper focuses on a specific measure commonly introduced through the residential energy efficiency retrofit programmes in Ireland–insulation. Traditionally, assessments of the performance of building envelopes have been based on assumed thermal resistances of the materials involved, laboratory tests and computer modelling. The aim of the present work is to investigate the in situ thermal behaviour of a case study building and its components under transient and quasi-steady environmental conditions, comparing data before and after the fixing of cavity wall and ceiling insulation. The paper concludes by proposing that predicted values of heat loss using standardised assumed material properties of the existing structure do not reflect the actual values achieved in situ for this test case. These values greatly overestimated the impact of the retrofitted insulation on heat loss through the ceiling and wall. [Copyright &y& Elsevier]

Abstract: Voltage rise is one of the main factors which limits the capacity of Low Voltage (LV) network to accommodate more Renewable Energy (RE) sources. This paper proposes a robust and effective approach to coordinate customers’ resources and manage voltage rise in residential LV networks. PV is considered as the customer RE source. The suggested coordination approach in this paper includes both localized control strategy, based on local measurement, and distributed control strategy based on consensus algorithm. This approach can completely avoid maximum permissible voltage limit violation. A typical residential LV network is used as the case study where the simulated results are shown to verify the effectiveness of the proposed approach. [Copyright &y& Elsevier]

Abstract: Liquid desiccant cooling system (LDCS) is an alternative air-conditioning system with promising energy-saving potential. To further explore the potential of LDCS, it is important to reveal the mass transfer mechanism of dehumidification process. The classical mass transfer model does well in theoretical analysis, but failed to explain the dehumidification reverse phenomenon in experiments. Therefore, this paper proposes a mass transfer model based on the kinetic theory for improvement. Through theoretical and experimental research, it proves the new model clearly describes the dehumidification mechanism and did better in predicting the dehumidification reverse phenomenon. This paper also gives a method through which we can get some important parameters of the new model from the mass transfer coefficient of the classical model. [Copyright &y& Elsevier]

Abstract: This paper summarizes a study undertaken to reveal potential challenges and opportunities for integrating optimization tools in net zero energy buildings (NZEB) design. The paper reviews current trends in simulation-based building performance optimization (BPO) and outlines major criteria for optimization tools selection and evaluation. This is based on analyzing user''s needs for tools capabilities and requirement specifications. The review is carried out by means of a literature review of 165 publications and interviews with 28 optimization experts. The findings are based on an inter-group comparison between experts. The aim is to assess the gaps and needs for integrating BPO tools in NZEB design. The findings indicate a breakthrough in using evolutionary algorithms in solving highly constrained envelope, HVAC and renewable optimization problems. Simple genetic algorithm solved many design and operation problems and allowed measuring the improvement in the optimality of a solution against a base case. Evolutionary algorithms are also easily adapted to enable them to solve a particular optimization problem more effectively. However, existing limitations including model uncertainty, computation time, difficulty of use and steep learning curve. Some future directions anticipated or needed for improvement of current tools are presented. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to contribute to the knowledge about energy use in residential buildings. Field measurements were carried out in 57 electrically heated Swedish single-family houses, where the total energy use (i.e. electricity use for space heating, household electricity and electricity use for hot water production), indoor temperatures and water use were recorded during four winter days. Some of the findings were that differences for households’ total energy use of similar houses were large. The characteristics of load curves clearly differ between weekdays and weekend days. The water use differs greatly for the households. This paper is part of a larger project where time use diaries were used in order to further link the energy use to residents’ every day energy related behaviours. To get a better understanding of the energy use in our homes is a prerequisite to be able to both recognise the problems as well as the potentials of reaching energy goals of our society, leading to a decreased impact on the environment from the building sector. [Copyright &y& Elsevier]

Abstract: Nowadays designers have to create energy efficient systems. Besides, they have to provide thermally comfortable environments for occupants. These, sometimes conflicting requirements lead to the development of such systems like surface heating and cooling systems that affect occupant''s heat exchange with his surroundings via radiation. With regards to the above described systems, combined effect of two local discomfort parameters is studied in this paper, namely radiant temperature asymmetry and warm floors. The European standard CR 1752 deals with these parameters separately and no data are available on how many people are dissatisfied due to combined exposures. The paper summarizes the results of climate chamber experiments conducted with a thermal manikin as well as human subjects that were exposed to cold wall and warm floor simultaneously present. The results show that equivalent homogenous temperature (EHT) of the manikin decreased by 2°C at the hands and face due to the cold radiating surface regardless of the warm floor. It was found that the thermal sensation and skin temperatures of human subjects were affected more by the radiation from the vertical cold surface than by the warm floor. Furthermore, genders showed significant differences regarding skin temperature change during sessions. [Copyright &y& Elsevier]

Abstract: The adaptive approach to thermal comfort has gained unprecedented exposure and rising status recently among the thermal comfort community at the apparent expense of the heat balance approach for the evaluation of naturally ventilated buildings. The main appeal of this adaptive approach lies in its simplicity whereby the comfort temperature is expressed as a function of the outdoor air temperature only. The main responsibility for attaining thermal comfort is given to the individual, who is supposed to have some degree of control over the personal thermal environment. The adjustment of expectation enables a wider comfort temperature range in which occupants feel comfortable. Arguments in favor of the adaptive approach have been based on the results from a large number of field studies conducted across the globe involving the occupants of various types of buildings. It is not surprising, therefore, to watch proliferation of papers on the adaptive approach in the scientific domain and the incorporation of adaptive findings into standards and guidelines. However, there are a number of issues in the advancement of this approach, which have had little exposure in the literature. This paper looks critically at the foundation and underlying assumptions of the adaptive model approach and its findings. [Copyright &y& Elsevier]

Abstract: In this paper, we develop an agent-based model which integrates four important elements, i.e. organisational energy management policies/regulations, energy management technologies, electric appliances and equipment, and human behaviour, to simulate the electricity consumption in office buildings. Based on a case study, we use this model to test the effectiveness of different electricity management strategies, and solve practical office electricity consumption problems. This paper theoretically contributes to an integration of the four elements involved in the complex organisational issue of office electricity consumption, and practically contributes to an application of an agent-based approach for office building electricity consumption study. [Copyright &y& Elsevier]

Abstract: Growth in peak period electricity demand has driven the requirement for a significant expansion of Sydney''s electricity network. Energy efficiency and demand management activities in office buildings may be an alternative to electricity network augmentation, with significant economic and environmental benefits. This paper identifies and characterises trends in electricity peak demand in Sydney''s office buildings, comparing a range of high and low energy consuming buildings. The paper assesses the potential for energy efficiency and demand management strategies in office buildings to reduce peak loads and hence defer electricity network augmentation. Base building electricity load data was analysed for a sample of 25 Sydney office buildings, along with Sydney electricity substation and temperature data. Peak loads for buildings with best practice energy performance were found to be 26% lower than for buildings with average energy performance, while annual electricity consumption was 57% lower. With these findings, this paper has assessed the effectiveness of current energy efficiency policy for peak demand management and has recommended strengthening energy efficiency policies in order to capture coincidental peak load reductions, as well as new policies specifically targeting peak demand management. It was found that these measures could offer significant potential to defer network investment. [Copyright &y& Elsevier]

Abstract: This paper takes an overall energy system approach to analysing the mismatch problem of zero energy and zero emission buildings (ZEBs). The mismatch arises from hourly differences in energy production and consumption at the building level and results in the need for exchange of electricity via the public grid even though the building has an annual net-exchange of zero. This paper argues that, when looked upon from the viewpoint of the overall electricity supply system, a mismatch can be both negative and positive. Moreover, there are often both an element of levelling out mismatches between individual buildings and an element of economy of scale. For these three reasons mismatches should be dealt with at the aggregated level and not at the individual level of each building. Instead, this paper suggests to compensate the mismatch of a building by increasing (or decreasing) the capacity of the energy production unit. Based on historical data for the electricity supply area in western Denmark, this paper makes a first attempt to quantify mismatch compensation factors. The results indicate that such compensation factors are a little below one for buildings with photovoltaics (PV) and a little above one for buildings with wind turbines. [Copyright &y& Elsevier]

Abstract: Building designers are often limited in their ability to reduce the environmental impact of buildings, due to a lack of information on the environmental performance of building components as well as inconsistencies in the way in which this information is derived. Whilst numerous tools exist to help facilitate the low-energy building design process, these typically require large investments of time and money that are often beyond those available within any particular project. This paper describes an approach for streamlining the design process to reduce building life cycle energy consumption. Building assemblies are ranked based on an assessment of the life cycle energy requirements associated with their use within a building. This facilitates early stage assessment, negating the need for a resolved design before the relative energy requirements of alternate design solutions are known. Previous work assessed the initial and recurring embodied energy as well as the operational energy requirements for heating and cooling associated with the use of a range of building assemblies, using a simplified house model. This paper presents a sensitivity analysis of variations to the floor area, shape and orientation of this model, to test the reliability and applicability of the ranking approach across a broad range of circumstances. It was found that these variations did not influence the ranked order of the assemblies in terms of their life cycle energy requirements. Thus, the ranking of assemblies appears to provide an appropriate approach for streamlining the selection of construction elements during the building design process. [Copyright &y& Elsevier]

Abstract Vacuum Insulation Panels (VIPs) are super-insulating products that can be used for different applications. When they are used for building thermal insulation, they have to maintain a very high thermal performance in long-term. The initial thermal conductivity of VIPs is around 4 mW.m − 1.K − 1. This very low value will increase in time, depending on the nanoporous property of the core material and on the barrier envelope efficiency which prevents the increase of moisture and internal pressure. To estimate the long-term thermal performance of VIPs, modelling is required. Simulations have shown the very great importance of the core material characteristics, and the external temperature and humidity conditions. That is why it is necessary to study the VIPs behaviour with realistic solicitations in service life for each VIP configuration. This paper proposes a methodology for determining the long-term thermal performance of VIPs when they are installed in envelope components for various building thermal insulation applications. All the methodology including the climate conditions, the building modelling and the insulation systems, is described. Severity criteria and performance indicators are proposed in order to estimate the thermal efficiency of VIPs in various applications and climates. [ABSTRACT FROM AUTHOR]

Abstract: As dehumidification is one of the most important tasks of environment control of the building, it is necessary to know the energy efficiency of dehumidification processes. The energy efficiency can give the energy cost of drawing moisture from indoor air to the outside environment. This paper presents analysis of the ideal cost of dehumidification process by a liquid desiccant cycle. Formulas to calculate ideal efficiency of dehumidification process are obtained, which is determined by indoor temperature, outdoor temperature, and the temperature of the intersection point of the iso-relative humidity line of indoor air and the iso-humidity ratio line of outdoor air. The ideal efficiency of the condensing dehumidification method is lower than the ideal dehumidification process, due to the fact that condensing dehumidification method must dehumidify the air at the temperature of dew point. Results from this paper can be used as theoretical foundation for the further analysis of various dehumidification methods and the development of new dehumidification processes. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents the evaluation of the current HVAC components and indoor climate of a high tech Naval Depot when the system fails. The methodology of the research was: first, implementation of the heat, air & moisture models of the building and HVAC components. Second, validation of the models using measured data from the existing building control system. Third, simulation of the current and new HVAC systems designs. Fourth, discussion of the usability of the approach. For this specific case, we concluded that the current system design performs well if, in case of a fault, the air supply to the depots is switched off automatically. The construction of the depots has sufficient thermal inertia to maintain a stable indoor climate for a period long enough to allow it to be repaired. The design could be further improved by controlling the indoor climate surrounding the depots instead of inside the depots itself. In such a case, even if the system did not detect a fault and continued supplying uncontrolled air to the surroundings of the depot, the indoor climate in the depot would remain stable. We conclude that the approach presented in this paper has a wider application than this single case study. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a calculation method for the floor surface temperature in radiant floor heating/cooling system is proposed, a new formula is derived to estimate the floor surface temperature. The floor is divided into two layers. The correlation for the thermal conductivity of the lower layer is developed based on the numerical model of the radiant floor system built in this paper. The results show that the floor surface temperature values from the proposed method are in agreement with the experimental and numerical values. [ABSTRACT FROM AUTHOR]

Abstract: Combined cooling, heating, and power (CCHP) systems use waste heat from on-site electricity generation to meet the thermal demand of the facility. This paper models a CCHP system for a large office building and examines its primary energy consumption (PEC), operational costs, and carbon dioxide emissions (CDE) with respect to a reference building using conventional technologies. The prime mover used in this investigation is a load share turbine, and the CCHP system is evaluated under three different operation strategies: following the electric demand of the facility, following the thermal demand of the facility, and following a seasonal strategy. For the various strategies, the percentages of total carbon dioxide emissions by source are presented. This paper explores the use of carbon credits to show how the reduction in carbon dioxide emissions that is possible from the CCHP system could translate into economic benefits. In addition, the capital costs available for the CCHP system are determined using the simple payback period. Results indicate that for the evaluated office building located in Chicago the CCHP operation reduces the operational cost, PEC, and CDE from the reference building by an average of 2.6%, 12.1%, and 40.6%, respectively, for all the different operational strategies. [ABSTRACT FROM AUTHOR]

Abstract: The building sector is responsible for a great share of the final energy demand and national CO2 emissions in countries like Germany. Nowadays, low quality thermal energy demands in buildings are mainly satisfied with high-quality sources (e.g. natural gas fired in condensing boilers). Exergy analysis, pursuing a matching in the quality level of energy supplied and demanded, pinpoints the great necessity of substituting high-quality fossil fuels by other low quality energy flows, such as waste heat. In this paper a small district heating system in Kassel (Germany) is taken as a case study. Results from preliminary steady-state and dynamic energy and exergy analysis of the system are presented and strategies for improving the performance of waste-heat based district heating systems are derived. Results show that lowering supply temperatures from 95 to 57.7°C increases the final exergy efficiency of the systems from 32% to 39.3%. Similarly, reducing return temperatures to the district heating network from 40.8 to 37.7°C increases the exergy performance in 3.7%. In turn, the energy performance of all systems studied is nearly the same. This paper shows clearly the added value of exergy analysis for characterising and improving the performance of district heating systems. [ABSTRACT FROM AUTHOR]

Abstract: Energy recovery ventilators (ERVs) transfer energy between the air exhausted from building and the outdoor supply air to reduce the energy consumption associated with the conditioning of ventilation air. In this paper, the applicability of ERVs with sensible and latent effectiveness values in a practical range is studied using TRNSYS simulation program. The impact of ERV on annual cooling and heating energy consumption is investigated by modeling a 10-storey office building in four American cities as representatives of major climatic conditions. The results show that heat and moisture recovery can lead to a significant reduction in the annual heating energy consumption (i.e., up to 40%, which is 5% higher than heat recovery). Also, an ERV with the capability of moisture recovery may reduce the annual cooling energy consumption by 20% provided the ERV is properly controlled. Since the un-controlled operation of ERVs during the summer may increase the cooling energy consumption, an optimum control strategy is developed and verified in the paper. This optimum control strategy depends on ERV''s latent to sensible effectiveness ratio. For instance, an ERV with equal sensible and latent effectiveness should be operated when either the outdoor enthalpy or temperature is greater than that of the indoor air. [Copyright &y& Elsevier]

Abstract: This paper describes a large-scale wireless and wired environmental sensor network test-bed and its application to occupancy detection in an open-plan office building. Detection of occupant presence has been used extensively in built environments for applications such as demand-controlled ventilation and security; however, the ability to discern the actual number of people in a room is beyond the scope of current sensing techniques. To address this problem, a complex sensor network is deployed in the Robert L. Preger Intelligent Workplace comprising a wireless ambient-sensing system, a wired carbon dioxide sensing system, and a wired indoor air quality sensing system. A wired camera network is implemented as well for establishing true occupancy levels to be used as ground truth information for deriving algorithmic relationships with the environment conditions. To our knowledge, this extensive and diverse ambient-sensing infrastructure of the ITEST setup as well as the continuous data-collection capability is unprecedented. Final results indicate that there are significant correlations between measured environmental conditions and occupancy status. An average of 73% accuracy on the occupancy number detection was achieved by Hidden Markov Models during testing periods. This paper serves as an exploration to the research of ITEST for occupancy detection in offices. In addition, its utility extends to a wide variety of other building technology research areas such as human-centered environmental control, security, energy efficient and sustainable green buildings. [Copyright &y& Elsevier]

Abstract: This paper discusses how to optimize pre-cooling strategies for buildings in a hot California climate zone with the Demand Response Quick Assessment Tool (DRQAT), a building energy simulation tool. This paper outlines the procedure used to develop and calibrate DRQAT simulation models, and applies this procedure to eleven field test buildings. The results of a comparison between the measured demand savings during the peak period and the savings predicted by the simulation model indicate that the predicted demand shed match well with measured data for the corresponding auto-demand response (Auto-DR) days. The study shows that the accuracy of the simulation models is greatly improved after calibrating the initial models with measured data. These improved models can be used to predict load reductions for automated demand response events. The simulation results were compared with field test data to confirm the actual effect of demand response strategies. Results indicate that the optimal demand response strategies worked well for most of the buildings tested in this hot climate zone. [Copyright &y& Elsevier]

Abstract: This paper presents general guidelines for the required cooling capacity of an entire office building using thermally activated building systems (TABS). By activating the thermal mass of the building using pipes embedded in the floor, peak loads can be reduced. On-site measurements were performed to obtain the required cooling power of an entire building as well as individual zones. Beside this, the internal climate conditions of rooms and surface temperatures of the TABS were measured. The measured data were used to analyze the predictive performance of a simulation model. In order to acquire general guidelines for the required cooling capacity of a standard office building, simulations of an entire building were used to determine the impact of variable internal heat gains and different sized windows. The required cooling capacity was compared to the cooling capacity of a system without energy buffering (e.g. chilled ceiling panels). It was found that reductions up to 50% of the cooling capacity for a chiller can be achieved using TABS. The presented results within this paper can be used as design guidelines in the first stage of a design process. The results focus on temperate climates and were derived using Dutch climate conditions. [Copyright &y& Elsevier]

Abstract: To maintain ultra-low particle concentrations, cleanrooms can require several hundred air changes per hour. These ventilation rates make cleanrooms 30–50 times more energy intensive than the average U.S. commercial building. There are an estimated 12millionm2 of cleanroom space in the U.S., consuming over 370PJ of energy each year. This paper explores opportunities to improve the energy efficiency of cleanrooms while maintaining or improving operating conditions. This paper documents the modeling of a 1600m2 cleanroom in upstate New York. The TRNSYS model includes TMY2 weather data; building geometry and material properties; empirical data on occupancy, lighting and process equipment; and sophisticated HVAC systems. The model was validated based on metered steam, chilled water and electricity usage. Under 8% error was achieved in all fields. Four strategies were simulated: a heat recovery system for exhaust air, resulting in an 11.4% energy reduction with a 2.7-year simple payback; solar preheating of desiccant dehumidifier regeneration air (2.4% energy reduction, 11.5-year payback); improved lighting controls (0.3% energy reduction, 1.5-year payback); and demand-controlled filtration (4.4% energy reduction, 3.1-year payback). Implementation of recommended strategies is predicted to save 9TJ, 862tonnes of CO2, and $164k annually. [Copyright &y& Elsevier]

Abstract: The efficiency of heating systems is increasingly important because of the increasing need to save energy and protect the environment. This paper presents an innovative technique for modeling multi-zone hydronic heating systems in buildings in an easier and more user friendly manner. An original approach is described in which the thermal and hydronic systems are solved simultaneously by simulating the dynamic behavior of pipe water flow rates, water temperatures, and room air temperatures. The simulation uses mathematical models that apply a Newton–Raphson method (NRM) developed in Matlab© and Simulink© environments. A user friendly graphical user interface (GUI) enables the designer to analyze any multi-zone hydronic heating system from the point of view of improving its efficiency. A laboratory heating system was used to validate this modeling technique. A series of trials were conducted in a multi-zone laboratory heating system located within the R&D division of a leading Italian boiler manufacturer, and the results presented in this paper validate the model. [Copyright &y& Elsevier]

Abstract: With the actual environmental issues of energy savings in buildings, there are more efforts to prevent any increase in energy use associated with installing air-conditioning systems. The actual standard of thermal comfort in buildings ISO 7730 is based on static model that is acceptable in air-conditioned buildings, but unreliable for the case of naturally ventilated buildings. The different field studies have shown that occupants of naturally ventilated buildings accept and prefer a significantly wider range of temperatures compared to occupants of air-conditioned buildings. The results of these field studies have contributed to develop the adaptive approach. Adaptive comfort algorithms have been integrated in EN15251 and ASHRAE standards to take into account the adaptive approach in naturally ventilated buildings. These adaptive algorithms seem to be more efficient for naturally ventilated buildings, but need to be assessed in field studies. This paper evaluates different algorithms from both static and adaptive approach in naturally ventilated buildings across a field survey that has been conducted in France in five naturally ventilated office buildings. The paper presents the methodology guidelines, and the thermal comfort algorithms considered. The results of application of different algorithms are provided with a comparative analysis to assess the applied algorithms. [Copyright &y& Elsevier]

Abstract: The latest (4/04 and 5/04) versions of the Hong Kong Building Environmental Assessment Method (HK-BEAM), one covering new buildings and the other existing buildings, have been formally launched in 2005. The paper describes the building energy performance assessment method in these latest HK-BEAM versions. With the use of the energy budget approach, the assessment framework is applicable to a wide range of buildings that may comprise different mixes of premises types. The new scheme provides bonus credits for provisions that allow utilization of renewable energy sources. For existing buildings, it makes allowances for plant performance degradation and constraints to implementation of improvement measures in existing buildings. So far, the new assessment method has been applied to six building developments, including commercial complexes and residential developments. The assessment results are presented and discussed in the paper. [Copyright &y& Elsevier]

Abstract: The intent of this paper is to describe and compare the two different two-dimensional frame/spacer heat transfer calculation methodologies used in North America (FRAME [EEL. The FRAMEplus Toolkit for Heat Transfer Assessment of Building Components, Version 3.0, Enermodal Engineering, Kichener, Ontario, Canada, 1995], THERM [LBNL. THERM 2: PC Program for Analyzing Two-Dimensional Heat Transfer Through Building Products, LBL-37371, Windows and Delighting Group, Lawrence Berkeley National Laboratory, Berkeley, CA, 1998], ASHRAE SPC 142P [ASHRAE. Standard Method for Determining and Expressing the Heat Transfer and Total Optical Properties of Fenestration Products, Public Review Draft of Standard 142P, American Society of Heating, Refrigerating and Air Conditioning Engineers, Atlanta, 1998]) and in Europe [ISO 10077-2. Thermal Performance of Windows, Doors and Shutters–Calculation of Thermal Transmittance—Part 2: Numerical Method for Frames, International Standards Organization, Geneva, 2003]. The two approaches, called the ASHRAE and ISO methods, are different in the way they treat the effect of the glazing spacer on the heat transfer through the frame and the glazing unit near the frame. The ASHRAE method assumes that the spacer effects both the heat transfer through the frame and the heat transfer through the glazing in an “edge-of glass” region 63.5mm (2.5in.) from the glazing/frame sight line. The ISO method assumes that the additional heat transfer due to the existence of the spacer is proportional to the glazing/frame sightline distance that is also proportional to the total glazing spacer length. An example calculation of the overall heat transfer and thermal transmittance (U-value or U-factor) using the two methods for a thermally broken, aluminum framed slider window is presented. The fenestration thermal transmittance calculations analyses presented in this paper show that small differences exist between the calculated thermal transmittance values produced by the ISO and ASHRAE methods. The results also show that the overall thermal transmittance difference between the two methodologies decreases as the total window area (glazing plus frame) increases. Thus, the resulting difference in thermal transmittance values for the two methods is negligible for larger windows. This paper also shows algebraically that the differences between the ISO and ASHRAE methods turn out to be due to the way the corner regions of the window frame and glazing are treated in the assembly of the overall thermal transmittance for a three-dimensional window from the two-dimensional calculations. Three-dimensional heat transfer calculations can be made and correction factors can be applied to both the ASHRAE and ISO two-dimensional results to bring them into agreement with the three-dimensional results. [Copyright &y& Elsevier]

Abstract: The paper presents the basic parameters and the energy flows of a ground source heat pump system (GSHP) used for air conditioning the New City Hall of Pylaia (Thessaloniki area—Northern Greece). The building is a typical public one, with an air-conditioned area of 1350m2. The ground source heat pump installation is the largest in Greece, and its operation is monitored with the aid of a DAQ system. The energy flows presented in the paper are based on DAQ recordings of the first 3 years of system''s operation. It is proved that the energy demand of the system is significantly lower, compared to that of conventional heating and cooling systems. The seasonal COP of the system has not yet been stabilized, gradually increasing, as it is expected due to the operation of the ground heat exchanger. [Copyright &y& Elsevier]

Abstract: The paper deals with the optimization of building energy efficiency in tropical climates by reducing the period of air-conditioning thanks to natural ventilation and a better bioclimatic design. A bioclimatic approach to designing comfortable buildings in hot and humid tropical regions requires, firstly, some preliminary, important work on the building envelope to limit the energy contributions, and secondly, an airflow optimization based on the analysis of natural ventilation airflow networks. For the first step, tools such as nodal or zonal models have been largely implemented in building energy codes to evaluate energy transport between indoor and outdoor. For the second step, the assessment of air velocities, in three dimensions and in a large space, can only be performed through the use of detailed models such as with CFD. A new modelling approach based on the derivation of a new quantity—i.e. the well-ventilated percentage of a living space is proposed. The well-ventilated percentage of a space allows a time analysis of the air motion behaviour of the building in its environment. These percentages can be over a period such as 1 day, a season or a year. Twelve living spaces with different configuration of openings have been studied to compare the performance of ventilation function of the opening distribution. Results and discussion are presented in the paper. This method is helpful for an architect to design the rooms according to their use, and their environment. Finally, the developed models can be used in building projects to estimate the period of the natural ventilation and to reduce the energy consumption due to air-conditioning. [Copyright &y& Elsevier]

Abstract: Predicting the performance of natural ventilation is difficult, especially for large scale naturally ventilated buildings, due to the lack of accurate and efficient prediction tools. This paper presents a strategy, integrating a multi-zone model and computational fluid dynamics (CFD), to improve natural ventilation prediction and design methods. Large openings and atrium configurations are broadly used in naturally ventilated buildings to promote buoyancy force and optimize air movement. How to properly deal with this typical configuration for a multi-zone model and integrated simulation is discussed and compared in this paper. In order to validate a newly developed multi-zone model program, MMPN, this paper investigated both buoyancy ventilation and wind-buoyancy combined ventilation. Integration strategies, transferring data (velocity or pressure) from a multi-zone model program to CFD as boundary conditions, are also studied. [Copyright &y& Elsevier]

Abstract: The methodology to predict building energy consumption is increasingly important for building energy baseline model development and measurement and verification protocol (MVP). This paper presents support vector machines (SVM), a new neural network algorithm, to forecast building energy consumption in the tropical region. The objective of this paper is to examine the feasibility and applicability of SVM in building load forecasting area. Four commercial buildings in Singapore are selected randomly as case studies. Weather data including monthly mean outdoor dry-bulb temperature (T0), relative humidity (RH) and global solar radiation (GSR) are taken as three input features. Mean monthly landlord utility bills are collected for developing and testing models. In addition, the performance of SVM with respect to two parameters, C and ε, was explored using stepwise searching method based on radial-basis function (RBF) kernel. Finally, all prediction results are found to have coefficients of variance (CV) less than 3% and percentage error (%error) within 4%. [Copyright &y& Elsevier]

In a conventional construction, the ventilation air enters the building through a combination of pathways, such as windows and vents, via cracks around external openings, joints between building materials, etc. By contrast, in a dynamic insulation construction, the ventilation air is drawn into the building through the insulation material of the building envelope. Structures with dynamic insulation incorporate porous insulating material in the envelope and air passes through the porous material.The aim of this paper is to present the experimental work carried out on a wall component that is a combination of dynamic insulation panel and a ventilated façade, tested under real weather conditions. The wall component consisted of two main sub-layers: the ventilated external envelope and the dynamic insulation (DI) sub-layer. The DI component consisted of layers of breathing materials that let the air enter the room at a reasonable pressure difference between the interior and exterior.The paper describes the experimental work carried out and the results drawn from the tests performed in the linked wall component under: (i) various differential pressure regimes between the interior and the exterior of the test cell and (ii) controlled and floating internal air temperature. In summary, the performance of the component was effective, since conduction losses were decreasing. [Copyright &y& Elsevier]

This paper describes two field studies of thermal comfort conducted in Ilam, a city located in western Iran. The first study consisted of two short-term surveys carried out during two climatically extreme periods—a hot summer and a cold winter—in 1998. The second study consisted of a long-term survey that collected data throughout the whole of 1999. Both studies were performed in naturally ventilated buildings. This paper shows some comparative analysis between the findings from the short-and long-term studies. For the hot season the neutral temperatures from the short-and long-term studies were 28.4 and 26.7 °C, respectively. For the cold season the short-and long-term neutral temperatures were 20.8 and 21.2 °C, respectively. The results show a very good agreement between both studies in Iran. The main points of interest from the studies were the variability of acceptable conditions, a good relationship between neutral temperature and room temperatures and also, more importantly, between indoor comfort and outdoor conditions. The findings reveal that the people in the study could achieve comfort at higher indoor air temperatures compared with the recommendations of international standards such as ISO 7730. [Copyright &y& Elsevier]

In heating, ventilation and air-conditioning (HVAC) systems, early detection and diagnosis of faults are of critical importance to save energy and improve the performance of system components. The challenge is developing an automatic fault detection and diagnosis algorithm for monitoring of multi-mode nonlinear systems. This paper proposes a novel adaptive Gaussian mixture model (AGMM) approach for automatic fault detection and diagnosis in nonlinear systems. The concept of this method relies on developing a time-varying probabilistic machine-learning model for non-linear systems. In this study, Gaussian mixture model regression (GMMR) technique is used to model a nonlinear system based on measurement data. Unscented Kalman filter (UKF) is then integrated with GMMR for adjusting the model parameters based on the feedback of residuals between observation and model prediction. The proposed algorithm is able to detect and diagnose simultaneous faults in systems from monitoring variations of key GMMR parameters. The application of AGMM method is demonstrated for detection and diagnosis of common faults in a water-cooled multi-chiller plant system. Faults including energy efficiency degradation in chillers were tested with the proposed method. Results indicate that the AGMM approach is successful in detection and diagnosis of simultaneous faults. [ABSTRACT FROM AUTHOR]

Prior knowledge of occupants’ thermal comfort can facilitate informed control decision of ambient thermal-conditioning in a building environment. This paper investigates the possibility to predict human thermal state (Comfort/Discomfort) from the information of physiological parameters. As gender difference has been widely linked with thermal comfort perception, a four-fold objective is adopted: first, investigating gender differences in subjective thermal perception; second, investigating gender differences in physiological response under different thermal states; third, identifying those physiological features that have the potential to predict thermal state, and fourth, establishing a data-driven thermal state prediction model for each gender group using the identified features. Human subject experiments were conducted, during which five physiological responses (hand skin temperature ST h , hand skin conductance SC h , pulse rate PR, blood oxygen saturation SpO 2 , blood pressure BP) and four subjective responses (thermal comfort, thermal preference, humidity sensation, airflow sensation) were recorded in conjunction with a thermal sensation survey while environmental conditions varied from cold/cool to neutral levels (18°C − 27 ∘ C). Additionally, derivative features namely change rate (FOG) and mean squared gradient (MSG) of each physiological parameter were examined. Rigorous statistical analysis and subsequent predictive modeling utilizing Random Forest algorithm were implemented. Results demonstrate significant gender difference in several subjective and physiological responses. The features identified for males (SpO 2 -MSG/ST h /ST h -FOG/ST h -MSG/SC h /SC h -FOG/SC h -MSG) and females (ST h -FOG/ST h -MSG/SC h /SC h -MSG/PR/PR-MSG) could accurately predict 92.86% and 94.29% of thermal states, respectively. This study indicates that the thermal state of a person can be identified by monitoring physiological parameters from non-intrusive body locations using wearable sensing technology. [ABSTRACT FROM AUTHOR]

A major challenge facing the buildings sector is the absence of continuous commissioning and the lack of performance monitoring and evaluation leading to buildings energy performance gaps between predicted and actual measured performance. Aiming to better characterize, evaluate and bridge these gaps, the paper proposes an online building energy performance monitoring and evaluation tool ObepME, serving as a basis for fault detection and diagnostics and forming a backbone for continuous commissioning. A calibrated building dynamic energy model is developed and employed to automatically run on a daily basis and simulate the building transient performance for the previous day. The simulated energy consumption results form a baseline to which the actual collected data are compared to evaluate the dynamic energy performance gap. The OU44 University building in Denmark is considered as a case study to implement the proposed framework. A holistic energy model was developed in EnergyPlus and calibrated employing data from various building meters, collected weather conditions, generated occupancy schedules and systems operational parameters and set-points. The calibrated model was employed in the ObepME tool to automatically and continuously monitor and evaluate the OU44 building energy performance, on the level of the whole building and individual energy systems consumption, throughout the period from February to mid-March 2017. The reported dynamic energy performance gap was around −2.85%, −3.47% and 5.48% for heating, total electricity and ventilation system electricity consumption. In addition, specific observations were made on a daily basis in terms of the overall electricity, heating, lighting and ventilation energy consumption as highlighted by the ObepME tool. The ObepME tool is currently running automatically as a part of the OU44 building continuous commissioning and performance evaluation aiming to identify possible discrepancies and deviations paving the way for a methodical preventive fault detection and diagnostics process on various levels in the building. [ABSTRACT FROM AUTHOR]

This paper depicted the novel data mining based methods that consist of six models for predicting accurate future heating and cooling load demand of water source heat pump, with the objective of enhancing the prediction accuracy and the management of future load. The proposed model was developed to ease generalization to other buildings, by making use of readily available measurements of a comparatively small number of variables related to water source heat pump operation in the building environment. The six models are - tree bagger, Gaussian process regression, multiple linear regression, bagged tree, boosted tree and neural network. The input parameter comprised the prescribed period, external climate data and the diverse load conditions of water source heat pump. The output was electrical power consumption of water source heat pump. In this study, simulations were conducted in three sessions - 7-day, 14-day and 1-month from 8th July to 7th August 2016. The forecast precisions of data mining models were measured by diverse indices. The performance indices which were used in assessing the prediction performance were - mean absolute error, coefficient of correlation, coefficient of variation, root mean square error, mean square error and mean absolute percentage error. The mean absolute percentage error results for 7-day future energy demand forecasting from tree bagger, Gaussian process regression, bagged tree, boosted tree, neural network and multiple linear regression were 3.544%, 0.405%, 1.703%, 1.928%, 2.592% and 13.053%, respectively. Moreover, when the proposed data mining model performance was compared with the existing studies, the mean absolute percentage error of 2.515% was found out for the first session, 7-day. The results also showed that the six models were efficient in foreseeing the abnormal behavior and future cooling and heating load demand in the building environment. [ABSTRACT FROM AUTHOR]

Greenhouse gas emissions have been recognized as one of the major cause of the global warming phenomena. The built environment accounts for more than 40% of the overall energy consumption and 36% of the overall CO2 emissions in Europe. Recent studies show that housing is one of the most responsible sector for world ecological impacts. The European Parliament developed the concept of Nearly Zero Energy Buildings (NZEB), characterized by a very low energy demand and a high renewable energy on-site production. In fact, energy efficiency is the first step towards the ambitious aim to reduce of 80% by 2050 the EU carbon emissions. The zero-energy building target is an achievable goal, which relies on a careful design that encompasses a synergy between passive and low-energy strategies. However, considering the whole life cycle of buildings, NZEBs reduce the operational energy close to zero, increasing the relevancy of the embodied energy, which occurs during the construction phase. Balancing the values of the operational and embodied energy is necessary to minimize buildings footprint on the environment. In this paper the renovation and re-use of the Atika building, a demonstrative energy-efficient building, is presented as case study of an environmental efficient methodology for energy retrofitting. The case relies on the methodology developed by Active House, a holistic vision for sustainable buildings labeling. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated a potential reduction in cooling load and improvement in comfort from the implementation of night ventilation. This paper describes the performance, in terms of indoor environmental conditions, of three buildings from both the U.S. and India that use night ventilation as their primary cooling method. The research methods used the following approach: (1) Assess the cooling strategy in relation to the adaptive comfort model; (2) Develop a hybrid model, using both first principle equations and the collected data, to predict the instantaneous air and mass temperatures within each building and use the model to assess performance of the cooling strategy; (3) Determine an optimized ventilation control strategy for each building to minimize energy and maintain comfortable temperatures. (4) Develop a statistical model using collected data to predict the window opening pattern for occupants of a building using natural night ventilation. The study yielded the following results: (1) The buildings in the mild climate are successfully keeping the indoor temperature low, but also tend to be overcooling; (2) The night ventilation strategy has very little impact on indoor conditions of the buildings in the mild climate; (3) The impact of night ventilation is less significant when there is low internal loads and heavy mass; (4) The building in the hot and humid climate is keeping the indoor temperature within the comfort bounds for 88% of the year; (5) The night ventilation strategy has advantageous impact on indoor conditons of the building in the hot and humid climate, but not enough to cool the space on its own; (6) Model predictive control has the potential to further improve the performance of night ventilation. (7) Window opening behavior for the building using natural night ventilation is most heavily dependent on indoor air temperature and mass temperature. [ABSTRACT FROM AUTHOR]

Thermal stratification in large warehouses is a common phenomenon in winter, especially for cold climates. Buoyancy-driven warm air tends to move upwards towards ceilings creating vertical temperature gradients with upper higher temperatures, and consequently leading to excessive heat losses through roofs. These warehouses therefore require thermal destratification through certain air mixing strategies, the selection of which often relies on engineering rules of thumb and experiences but can be better determined through combined experimental and numerical approaches. This paper investigated different thermal destratification methods in two industrial warehouses based on field measurements and CFD simulations with the focus on the quantification of thermal stratification, and the suitable methods modeling air mixing devices, e.g. ceiling rotating fans and bucket fans. The numerical models were first validated by field measurements and then used to simulate different destratification strategies and to compare associated energy impacts. The CFD methods for modeling air mixing devices and their performances can be applied to other similar cases. [ABSTRACT FROM AUTHOR]

This paper focuses on the jointly operational optimization of a network of buildings while considering energy exchange among them. Based on the operation model of each individual building, coordinated information and strategies of the energy exchange among all buildings are used to maximally reduce the energy cost of all the buildings while reducing the complexity of the network operation. The optimization problem of a network of multiple buildings is formulated as a stochastic mixed integer programming problem, and a Lagrangian relaxation-based decentralized algorithm is developed to solve this problem. Based on this method, a price mechanism for the energy exchange among buildings which can guarantee the fairness of all the buildings is developed by introducing Lagrangian multipliers as the coordinated signals for the decentralized optimization. The performance of the proposed method is discussed based on case studies of a network of four buildings in Singapore. Numerical results show that the method can not only achieve significant energy cost savings for all the buildings, but also provide huge ability to accommodate the uncertainties in the network. It is also found that the proposed price mechanism for the energy exchange provides incentives for the buildings to participate in the joint optimization. [ABSTRACT FROM AUTHOR]

External movable shading devices are mainly used to improve the thermal and lighting environment of an interior space by preventing overheating during the cooling season as well as by preventing glare. An external movable shading device can be controlled using various methods, where parameters related to the lighting environment, such as daylighting and glare, are commonly adopted as major variables associated with the control of the shading device. In this paper, an algorithm is provided with which an external movable shading device can be operated in any one of three control modes as selected according to the operation purpose preferred by the occupant. The algorithm can be applied to external movable shading devices of various shapes. The shaded fraction is adopted as a major control element, and the control purpose of the external shading device is configured to include energy conservation, illuminance satisfaction, and glare protection. The algorithm includes an hourly evaluation procedure for obtaining the range of allowable shading device movement that satisfies each of the three operation purposes. Real-scale mockup tests for the three control modes were conducted during different time periods in summer to verify the performance of the control strategies. The test results regarding the energy and environment performance for each control mode show that the control algorithm can be selected to provide satisfactory compromises between energy and visual comfort factors. The result of this study can provide users with options for controlling movable shading devices on a building according to their preferred operation purposes. [ABSTRACT FROM AUTHOR]