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This paper focuses on the water-energy nexus in low income households. Water, electricity and gas constitute fundamental resources for households that interplay throughout many daily activities. However, in studies on household poverty, there is a tendency to treat water and energy separately. In this contribution, we argue for the joint consideration of both forms of deprivation and present empirical evidence for the Metropolitan Area of Barcelona (AMB). In Barcelona, the dynamics between water and energy poverty in households widened the scope of institutional measures on energy poverty by incorporating water poverty as part of guaranteeing the 'right to basic utilities'. We document the interactions between the two resources through the water-energy nexus approach by combining quantitative and qualitative methodologies. Apart from presenting the expenditure-based analysis of the Spanish Survey of Income and Living Conditions, which reveals that a significant part of the population is both water and energy poor, with the results from our semi-structured interviews, we are able to demonstrate how much importance and value the affected households give to their thermal and hydric (dis)comfort, which in turn, exerts a direct impact on their daily hygiene and health. The paper also highlights institutional and socio-technical perspective as the differences in ownership and regulatory status of both resources cause discordances in public efforts to alleviate the status of the water and energy poor. [ABSTRACT FROM AUTHOR]

• The paper has a focus on energy consumption habits and trends using statistical methods. • Occupants' behavior is monitored using smart metering system and awareness surveys. • The impact of a serious game on occupant's behavior is evaluated. The paper has a focus on energy consumption habits, trends and intervention strategies in residential buildings, mainly through the serious game approach with a combination of direct consumer feedback through smart metering. More than 150 homes in France and Spain have been involved in the research experiment and the consumption habits of approximately 50 homes were deeply analyzed. The applied methods, processes, results and findings of the monitoring data analysis are presented in the paper with two aims. First, consumption profiles and trends were determined for apartment homes with regard to heating, domestic hot water and electric consumption. Second, the impact of a serious game experiment was assessed comparing energy consumption, indoor air temperature and users' habits (based on questionnaires) before and after launching the experiment. [ABSTRACT FROM AUTHOR]

• A data-informed building energy management (DiBEM) framework was proposed. • It was demonstrated in an office/laboratory building with two-years' experimental data. • The impacts of energy efficient interventions were quantified through data-driven models. • The energy use intensity was reduced from 54.1 kWh/m2 to 42.8 kWh/m2. To support building operations in reaching ultra-low energy targets, this paper proposes a data-informed building energy management (DiBEM) framework to improve energy efficiency systematically and continuously at the operation stage. Specifically, it has two key features including data-informed energy-saving potential identification and data-driven model-based energy savings evaluation. The paper demonstrates the proposed DiBEM with a detailed case study of an office and living laboratory building located in Cambridge, Massachusetts called HouseZero. It focuses on revealing the performance of the energy-efficient interventions from two-years' building performance monitoring data, as well as evaluating energy savings from the interventions based on the data-driven approach. With Year 1 as baseline, several interventions are proposed for Year 2 including improvements to controls and operation settings, encouragement of occupants' behavior for energy savings, and hardware retrofitting. These were deployed to heating/cooling, domestic hot water, lighting, plug and other loads, and photovoltaic (PV) systems. To quantify the impacts of different interventions on energy end uses, several data-driven models are developed. These models utilize linear regression, condition model, and machine learning techniques. Consequently, the heating/cooling energy consumption that was already ultra-low in Year 1 (12.8 kWh/m2) is further reduced to 9.7 kWh/m2 in Year 2, while the indoor thermal environment is well maintained. The domestic hot water energy is reduced from 2.3 kWh/m2 to 1.2 kWh/m2. The lighting energy is only increased from 0.3 kWh/m2 in pandemic operations without occupancy in Year 1 to 0.8 kWh/m2 in partial normal operations in Year 2, while the indoor illuminance level meets occupants' requirements. Combined with other relatively constant loads and the reduction of plug and other loads due to COVID building operation restrictions, the total energy use intensity is thereby reduced from 54.1 kWh/m2 to 42.8 kWh/m2, where 5.4 kWh/m2 of energy reduction for Year 2 is estimated to be contributed by the energy-efficient interventions. PV generation is 36.1 kWh/m2, with an increase of 1.4 kWh/m2 from a new inverter. In summary, this paper demonstrates the use of DiBEM through a detailed case study and long-term monitoring data as evidence to achieve ultra-low energy operations. [ABSTRACT FROM AUTHOR]

• A practical PV/T (Photovoltaic/Thermal) solar panel was developed. • The panel can supply 40–60 °C water by controlling the flow rate. • The panel converts 73.5 % of solar energy at about 40 °C hot-water supply. • The panel surface temperature was about 50 °C even at about 60 °C hot water supply. • The panel's efficiency is compared to other PV/T panels with heat pipes/thermosyphons. The practical efficiencies of existing commercial m-Si and CIS PV modules measured in reality by our group were less than 15 % because of the higher temperatures of the PV modules, and the rest of more than about 85 % of solar energy would be the exhaust heat to the environment. It was already reported in 2020 that the principle of an environmentally-friendly PV/T (Photovoltaic/Thermal) solar panel using an m-Si PV module to utilize 71.3 % solar energy for electricity and 40 °C hot water, as well as suppress heat radiation from the panel. The panel was designed to confirm the principle, i.e., it was an experimental PV/T solar panel. In this paper, a new practical environmentally-friendly PV/T solar panel is proposed for aiming the application to BIPVT (Building-integrated Photovoltaic/Thermal) systems. The new panel uses a CIS PV module, and all the functions, including a heat exchanger using flat aluminum tubes, are placed in the panel box, which is almost the same size as a simple CIS PV panel. The proposed PV/T solar panel converts 73.5 % of solar energy with 13.0 % power generation efficiency and 60.5 % heat collection efficiency at a 40 °C hot water supply in Yokohama, Japan. The efficiency is higher than the previous experimental panel. The proposed panel also can suppress heat radiation at about 50 °C even in the case of 60 °C hot water supply. The proposed PV/T solar panel can supply all residential heat demands, such as domestic hot water (DHW) and space heating or cooling, using solar heat with a lower environmental thermal load. [ABSTRACT FROM AUTHOR]

• Presentation of innovative Zero-Energy-Sauna concept which solar energy and thermal energy storage. • Development and investigation of numerical models for two thermal energy storages. • Hot water storage allows typical sauna operation during winter in moderate climate region. • Adsorption storage makes manual steam generation as with conventional heater possible. • Optimum storage designs derived by numerical simulation serve as blueprints for the thermal energy storages implemented and experimentally investigated in Zero-Energy-Sauna. As a practical contribution to the energy transition from fossil to renewable energy, this paper addresses a wellness product with high energy demand: the sauna. The overall goal of the presented research project is to develop and demonstrate a so-called Zero-Energy-Sauna. In this paper, the development by means of numerical simulations is discussed. In a preliminary study, multiple concepts have been systematically derived and assessed. One innovative concept has been patented and an extended version of this concept is being implemented in this research project. The implemented concept utilizes solar energy and applies two types of thermal energy storage: a pressurized, stratified hot water storage and a closed low-pressure adsorption storage. The main purpose of the hot water storage is the heat supply, while the purpose of the adsorption storage is to provide steam. We formulate and investigate two numerical models for these thermal energy storages. For the hot water storage, an one-dimensional model is applied which considers the effect of natural convection. With this model, different charging and discharging scenarios are examined, proving the applicability of this type of hot water storage for a Zero-Energy-Sauna. For the adsorption storage, a previously developed and published model is adopted and extended by a metal plate for manual steam generation. Based on this model, various configurations of the adsorption storage are studied, revealing an optimum design for maximum steam generation. The storage designs derived by numerical simulations serve as blueprints for the two thermal energy storages. Both storages are currently being implemented and experimentally investigated in the Zero-Energy-Sauna of the ongoing research project. [ABSTRACT FROM AUTHOR]

• Data about DHW in residential buildings were collected by survey in Southern Italy. • Contextual and personal factors influencing DHW usage were considered. • Descriptive statistics were performed to characterize DHW by climatic zone. • Inferential statistics were conducted to discover DHW usage patterns. • Four clusters of dwellings were identified considering DHW daily usage hours. In European efficient buildings, the share of energy use for DHW is a significant percentage of the heat requirement. The evaluation of DHW energy demand and consumption patterns has been neglected in the past and studies are located in Northern countries. This paper presents a survey conducted in Southern Italy. Descriptive statistics were performed to characterize DHW production by climatic zone. Inferential statistics were conducted to discover significant contextual and personal variables and identify usage groups. The most used energy source was biomass (49.3%), followed by methane gas (37.7%). Fireplaces were installed in the coldest zone, in detached houses, more in small municipalities (36%), and low-income families (32%). Solar systems were in 8% of dwellings having income higher than 28000€. Four clusters of dwellings were identified considering the daily usage hours. The eldest and less numerous households fell into the cluster with the lowest usage (3.5 h). Households with a percentage <25% of unemployed components had more probability to belong to clusters with more DHW usages. The paper contributes to fill the investigation in the Mediterranean area and provides a systematic approach to expand the limited knowledge about the influencing factors on the DHW production and usage. [ABSTRACT FROM AUTHOR]

The energy demand for supplying Domestic Hot Water (DHW) has an important share in the overall thermal energy consumption of commercial buildings. The aim of this paper is to analyze the performance of DHW production in commercial public service, i.e., educational buildings, to subsequently identify frequent inherent shortcomings of centralised DHW installations and to provide measures for optimization or economically more viable solutions. Several buildings of the University of Natural Resources and Life Sciences in Vienna have been investigated in terms of DHW consumption and performance of the installed centralised systems. Referring to the investigated university buildings, it can be stated, that in cases of low to medium consumption figures, typical centralized DHW installations with a hot water circulation pipework achieve only poor efficiencies in the range of 2–12%. As for one particular centralized DHW system in operation, focusing on demand controlled DHW supply through adapted flow control, e.g., reducing the runtime of the circulating pumps at specific time intervals, and, if applicable and feasible, decreasing hot water flow- and storage capacities can reduce annual energy consumption for DHW by 15–25% and improve the overall system efficiency significantly as could be evaluated in a detailed case study. A seemingly economical yet ecologically controversial option for improving centralised DHW systems is the partial or complete conversion to electric point-of-use water heaters. This reduces thermal energy losses almost completely, hereby significantly increasing the efficiency of a DHW supply system. Nevertheless, existing hot water supply systems, energized by district heating, usually consume less primary energy and most likely generate fewer CO 2 emissions compared to electric DHW heaters. [ABSTRACT FROM AUTHOR]

Highlights • Energy use for DHW accounts from 16% to 50% of total heat requirement. • Method to estimate mean hourly and daily profile of DHW from total heating readings. • Method gives good results when DHW share in total heating demand is minimum 50%. • Better understanding of users' practice related to DHW and space heating is crucial. Abstract During recent years, the research in reduction of energy use in buildings has focused primarily on decrease of space heating needs, energy for ventilation and recently cooling, whereas domestic hot water (DHW) has been overlooked. In 2013, the energy use for DHW was estimated at 16% of total heat requirement in EU28 households, but in new energy-efficient buildings this share is documented to be around 40–50%. Generally, however, there is limited knowledge of DHW. This paper presents a simple methodology, which enables calculation of the mean hourly and the daily profiles of DHW demand from hourly values of the building total heat demand, and thus contributes to gaining a better understanding of the DHW usage. The method is validated with data from single-family houses and apartments and afterwards applied to dataset consisting of hourly total heat consumption readings from 38 single-family houses delivered by district heating. The method gives satisfying results when the DHW usage during summer is at least at the same level as the space heating demand, which is the case in apartments and in the energy-efficient houses. The standard deviation was used as preliminary classification criterion for deciding if the method can or cannot be applied. Two limits were found σ > 240 for apartments and σ < 800 for single-family houses. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a study on energy performance of Singapore''s hotel buildings. Energy consumption data and other pertinent information were collected from 29 quality hotels through a national survey. Building features and operational characteristics contributing to the variations in hotel energy performance were discussed. The annual average total energy use intensity (EUI) in these hotels is 427kWh/m2. Electricity and gas are used in all sampled hotels, and some hotels also use diesel to power standby generator or hot water boiler. We also investigated relationships between electricity consumption and number of occupied rooms in individual hotels; the weak correlations found indicate it is necessary to improve energy management when occupancy rate is low. Besides, Pearson correlations between hotel energy use intensity and possible explanatory indicators revealed that three-star hotels differ from high class establishments in energy use. Worker density and years after the last major energy retrofit were also found to be highly correlated to hotel building energy use intensity. Also discussed in this paper is the effect of weather conditions on electricity consumption of the hotels. [Copyright &y& Elsevier]

• First-time transfer and combination of state-of-the-art approaches of electric hot water heaters to hot water heat pumps (model predictive control, system identification, live state estimation, and demand prediction). • An experimental proof of the model predictive control potential of hot water heat pumps by comparison of the standard hysteresis control to the model predictive control, covered in a realistic setting. • Quantification of the savings and the demand side management potential achievable by a state-of-the-art prediction method in a realistic setting. Hot water heat pumps are well suited for demand side management, as the heat pump market faced a rapid growth in the past years with the trend to decentralized domestic hot water use. Sales were accelerated through wants and needs of energy conservation, energy efficiency, and less restrictive rules regarding Legionella. While in literature the model predictive control potential for heat pumps is commonly shown in simulations, the share of experimental studies is relatively low. To this day, experimental studies considering solely domestic hot water use are not available. In this paper, the realistic achievable model predictive control potential of a hot water heat pump is compared to the standard hysteresis control, to provide an experimental proof. We show for the first time, how state-of-the-art approaches (model predictive control, system identification, live state estimation, and demand prediction) can be transferred from electric hot water heaters to hot water heat pumps, combined, and implemented into a real-world hot water heat pump setup. The optimization approach, embedded in a realistic experimental setting, leads to a decrease in electric energy demand and cost per unit electricity by approximately 12 % and 14 % , respectively. Further, an increase in efficiency by approximately 13 % has been achieved. [ABSTRACT FROM AUTHOR]

• This paper presents a unique change-point model based on selected time periods. • Time-dependent variations in climate and user behavior are central in the selection of time periods. • The model allows for differentiation between thermal power characteristics. • The selected time period for prediction of Q total corresponds to the highest R2 value, 0.70. The building and service sector accounts for nearly 40% of total energy use in Sweden. The existing, historic building stock accounts for large part of this energy use and comprises an important part of the national pursuit to increase energy efficiency. One main problem for decreasing energy use in the existing building stock is the lack of data describing thermal performance characteristics. This paper presents a novel development of the change-point model for predicting the thermal performance of buildings using selected time periods based on time-dependent variations in climate and user behavior. The predicted thermal power characteristics include total specific heat losses (Q total), energy use for hot water circulation (HWC) and hot tap water (HTW), and balance temperature. A residential district with 73 historic buildings in Linköping, Sweden, has been used as the study object. The developed model is shown to be effective and robust for describing building thermal performance. The average R2 was 0.70 for predictions of specific heat losses. The sensitivity analyses conclude that the selected time steps and months correspond to the highest R2 value. The average variation width for prediction of the balance temperature is 0.9 °C for buildings in the interquartile range based on a three-year comparison of hourly heating power supply data. Moreover, from a property owner perspective, the model is shown to be useful for identifying deviating thermal power characteristics and can easily be used to get an overview of a district. [ABSTRACT FROM AUTHOR]

In ultra-low temperature district heating the supply temperature is less than required to heat the domestic hot water and a heat pump is therefore often proposed to raise the temperature. This paper investigates how this heat pump can be utilized for price based demand response to induce peak reductions and energy cost savings. A model predictive control strategy is proposed and evaluated through co-simulations where a model predictive controller is formulated in MATLAB and connected to an EnergyPlus hot water storage tank. It is demonstrated that the system is capable of reducing the district heating morning peak and the electric grid evening peak as well as providing energy cost savings for the end-user without compromising hygiene and comfort. [ABSTRACT FROM AUTHOR]

• Circulation heat loss data without hot water demand were collected and analyzed. • A novel method for calculating dynamic heat loss was developed and deduced. • The proposed dynamic heat loss-based operation scheduling model minimized energy consumption within comfort constraints. • The proposed solution saved 16.42% in energy consumption and 24.76% in operational costs. Building energy systems with circulation loops have high circulation heat loss, resulting in low energy utilization efficiency. It requires energy-saving operation strategies to eliminate unnecessary circulation heat loss, especially in domestic hot water (DHW) systems. The objective of this paper is to improve the energy efficiency of building energy systems and reduce operational costs. This is done by dynamically adjusting the target temperature set point. This is the first study to present a computationally inexpensive method for accurately predicting the temperature drop of hot water in environments with changing ambient temperatures. The outcome indicates that energy usage efficiency could be increased by approximately 16.42 %, while operational costs could be lowered by approximately 24.76 % for over 90 days in the fall. The proposed model is an implementable approach for predicting temperature drop and optimal operational scheduling as part of robust and reliable building energy management in real-world scenarios. [ABSTRACT FROM AUTHOR]

Smart control of domestic electric hot water cylinders could be used as a relatively inexpensive option to help bridge supply–demand mismatches in highly-renewable electricity grids in many countries. Evaluation of options for the smart control of these cylinders is made difficult by the lack of domestic hot water flow time-series data. In contrast, hot water cylinder electricity demand time-series data, either directly measured or imputed from whole house data, is often much more readily available. In this paper, we propose an inverse-problem approach that uses a physical model of a hot water cylinder to determine hot water flow information from electricity demand data. Once hot water flow information has been determined, it is then possible to simulate smart control of the hot water cylinder element such that it does not interfere with the provision of hot water. We illustrate this approach by using a simple physical model of a hot water cylinder to simulate the hot water flow of 19 houses with electric hot water cylinders from measured time-series electricity data. A smart control case study is then explored where these houses are part of a solar PV microgrid and the cylinder elements are controlled so as to reduce the battery storage needed by the microgrid to reach a certain level of self sufficiency. [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]

• A POE-integrated simulation method is proposed to address energy occupant behavior. • Opening windows and operating AC were found to co-exist which affects simulation accuracy. • The new method improves energy simulation accuracy by 14% for domestic areas. • The method improves energy simulation accuracy by 16% for total building areas. Occupant behavior plays a critical role in building energy consumption, particularly in residential buildings. However, occupant behavior is complicated and varies significantly from case to case. Also, energy modeling of high-rise buildings is far less explored than that of low- or medium-rise buildings. This paper aims to improve accuracy in building energy simulation by utilizing Post Occupancy Evaluation (POE) data to calibrate energy model. Drawing on a review of the literature of occupant behavior and building energy modeling, the paper provides a calibration method of integrating POE data into an energy model, which is demonstrated using a real-life typical 40-storey residential building in Hong Kong. The developed method addresses seven updated input parameters, namely, schedule, devices, air-conditioners, windows, lights, domestic hot water, and cooking. By comparing the two energy modeling processes, i.e. with and without POE input, and their resultant estimated energy consumption, the paper quantifies the impact of occupant behavior on building energy consumption. Annual metered data together with energy bills obtained from the POE were utilized to validate the models. The results show that the use of the developed POE-integrated method helped to improve accuracy in energy consumption prediction by 14% for the total building floor area and by 16% for the total residential area. From examining the impacts of the seven input parameters, the paper reveals the key energy use sensitive occupant behaviors within high-rise residential buildings in Hong Kong. These include: the number of residents in each unit; adoption of window type and split type of air-conditioners; window and air condition operation modes; cooking time on weekdays and weekends; and time spent on hot water showering. The developed method can assist building designers and services engineers to estimate building energy use more accurately and provides a scenario analysis tool for clients and facility managers to develop effective energy conservation strategies. [ABSTRACT FROM AUTHOR]

For a long period, the energy use for domestic hot water (DHW) in non-residential buildings has been neglected. As energy use for space heating, ventilation, and lightning has been reduced through the years, the energy share for DHW production has increased. With today's focus on energy efficient buildings, the DHW systems must not be left behind the other fields to obtain a holistic approach to energy efficient buildings. To develop more energy efficient DHW systems for non-residential buildings, more knowledge is needed regarding draw-off durations, flow rates, and water temperatures from different draw-off types. This paper presents high frequency measurement results in two Danish office and educational buildings, which show that three DHW systems only utilize between 3.4 and 7.5 % of the total energy used for DHW production. Above 85 % of the total energy use is lost from the recirculation circuit to secure a high hot water temperature at the draw-off point. However, temperature measurements at the draw-off points show that a significant share of the heat is lost from pipes not covered by recirculation. One reason is draw-off durations are approximately 50 % of the time below 10 s at washbasins and kitchen sinks. Another reason is actual maximum flow rates are far from the calculated design flow. The high frequency measurements at multiple draw-off points give essential knowledge of use patterns for washbasins, kitchen sinks, and service sinks in non-residential buildings. This knowledge can contribute to developing energy efficient DHW systems and new types of DHW production. [ABSTRACT FROM AUTHOR]

Water flow rates are key operating variables in chilled and hot water systems. The water flow rate through a pump can be virtually measured using available motor power and pump head with projected motor and pump efficiencies. In general, motor efficiency is implicitly determined by motor power while pump efficiency is given as a function of water flow rate. As a result, the water flow rate has to be calculated through a numerical method, which is difficult to apply in building automation systems (BAS). The objective of this paper is to develop a virtual pump water flow meter, which can be implemented in BAS with an explicit expression of motor power and pump head. First, motor efficiency is regressed as a function of motor power by consolidating multiple dependent factors, then pump efficiency function is reconstructed with pump shaft power and head, and finally experiments are conducted to develop and validate a virtual pump water flow meter on a chilled water pump. The experimental results show that the virtual flow measurements agree well with the flow measurement by a physical meter. The measurement standard deviation is 0.5 L/s for a pump with the design flow rate of 37.9 L/s. [ABSTRACT FROM AUTHOR]

The modeling and simulation of domestic hot water systems, including solar thermal and co-generation technologies, relies on accurate, high time-step resolution water consumption profiles. Due to the expensive nature of field studies, previous profiles have been limited in number of participants, or have been generated synthetically using probabilistic modelling techniques. The Solar City program in Halifax has measured hot water flow rate and temperature data in 119 homes at a time-step of 1 min; and includes a survey of occupancy rates and other relevant meta-data. In this paper, we discuss the data acquisition and processing (with a focus on flow rate data), and conduct analysis to reveal consumption trends and produce a new set of time-step profiles for modeling and simulation. Average hot water consumption per household is 172 L/day with a strong dependency on number of occupants. The hourly profile peaks twice daily, and shifts by several hours on Sunday. The average draw temperature was found to be 51.8 °C, which is lower than the default value of 55 °C applied by many building modeling/simulation packages. The average cold water supply temperature was found to be roughly sinusoidal about 12.4 °C with approximately one-month lag compared to ambient air temperature. [ABSTRACT FROM AUTHOR]

A ground-coupled heat pump (GCHP) is a clean and energy-saving approach to providing air conditioning and domestic hot water. For buildings with a dominant heating load, more heat is extracted from the soil and thermal imbalance becomes a crucial problem, in turn reducing efficiency and impeding the wide application of GCHP. Due to the disadvantages of the existing solutions, a multi-mode air-source heat compensator (AHC) integrated with a GCHP system to make a hybrid AHC-GCHP system is proposed in this paper. The principles and operating strategy of AHC-GCHP are illustrated in detail and its performance is simulated in the transient system simulation tool TRNSYS. AHC can not only compensate heat into the ground but also supply heat for space heating and domestic hot water in different modes through full use of the energy in the air with the average coefficient of performance (COP) ranging from 4.49 to 15.09. The AHC-GCHP system effectively keeps the soil thermal balance, and saves 23.86% energy compared with a traditional “boiler + split air conditioner” system, and costs less than half as much as a “hybrid GCHP assisted with solar collector” system. Consequently, the AHC-GCHP system is a potentially efficient and economic approach for buildings in cold regions. [ABSTRACT FROM AUTHOR]

Washing machine and dishwasher appliance use accounts for approximately 10% of electricity demand in EU households. The majority of this demand is due to the operation of electric heating elements inside appliances. This paper investigates the potential benefits that can be realised by adding a hot fill connection to washing appliances, with respect to carbon emissions, demand side management and renewable energy integration. Initial laboratory testing of new hot and cold fill appliances has resulted in modifications to optimise hot fill intake, and a novel numerical model presents a method of characterising appliance electricity use in different configurations. In order to validate model findings and test the use of new hot fill appliances in situ, a pilot study has recorded appliances’ resource consumption at one-minute resolution in fourteen households. The addition of hot fill reduced the total dishwasher and washing machine electricity consumption by 38% and 67% respectively. Depending on how hot water is supplied to appliances it is estimated that hot fill use results in an annual household carbon saving of up to 147 kgCO 2 . Further to direct electricity reduction, hot fill appliances can offer a method of time shifting demand away from peak periods without inconveniencing occupants’ lifestyles. [ABSTRACT FROM AUTHOR]

In the residential sector, heat pumps are applied for domestic hot water and space heating. Simulations are widely used for general research in the field of heat pumps and to some extend to plan such installations. The advantages are low expenditure of time and costs compared to laboratory or field tests. Validation of simulation models is mandatory to guarantee a sufficient quality. In the presented paper, the field monitoring results of five ground-source installations are utilised for the validation of a black-box heat pump model. The model is similar to TRNSYS Type 201, but implemented in IDA ICE and then modified to handle the difficulties caused by non-standard mass flow and rampant polynomials. As overall result, deviations between 1% and 32% regarding modelled and measured efficiency are seen on monthly basis. The overall result appears as convincing, taking into account typical inaccuracies of laboratory and field tests as well as tolerances during heat pump production. As a side effect, the influence of standby consumption was quantified. For the five presented installations, standby amounts to fractions between 2 and 5% of the annual electricity consumption of the heat pump units. [ABSTRACT FROM AUTHOR]

Lighting is necessary for all kinds of buildings and consumes a large amount of electricity. Tubular daylighting devices (TDDs) can serve as an alternative, but they may also have thermal effects on the indoor environment, which has not been studied yet. In this paper, a lighting-heating coupled TDDs system was designed and built, to improve the use of TDDs for building energy savings and sustainability, where antimony tin oxide (ATO) nanofluids were introduced to absorb extra unexpected heat and then supply domestic hot water. Meanwhile, a new method was developed to calculate the annual amount of energy output of TDDs under different mass concentrations of ATO nanofluids. Results showed that the ATO nanofluids of 100 ppm can absorb ∼ 50% solar radiation coming along with more efficient visible lighting. Furthermore, in the case study in Beijing, TDDs with 100 ppm ATO nanofluids could generate over 10 tons of domestic hot water while saving 30.9 kWh of electricity for refrigeration, resulting in a ∼ 10% improvement on total energy-saving performance. This research work demonstrates the high potential of using the designed lighting-heating coupled TDDs system in buildings for both energy savings and daylighting benefits. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents the methodology for the risk-based dimensioning of domestic hot water (DHW) and heating demands. It is demonstrated that they are stochastic variables. DHW demands are specified on the basis of hot water consumption statistics in Hungary. The standard values of heat demands for heating are based on the duration curve of external air temperatures. This study discusses daily mean temperature distribution in the heating season – between 15 October and 15 April in Hungary – and the description of its duration curve sorted by time. The authors verify the assumption that the duration curve can be described by normal distribution mathematically with high precision. Thereby they somewhat put an end to the process of mathematical experimentation on what function should be used to describe the frequency and duration curve of external daily mean temperatures in the heating season. [Copyright &y& Elsevier]

[Display omitted] • The occupancy modeling approaches with a particular focus on UBEM are discussed. • Occupant-related inputs required for UBEM and the correlation between them are emphasized in the review. • Challenges in accommodating the variations in occupancy at the urban scale are reviewed. • Potential data sources for extracting building occupancy at urban scale are discussed. • UML diagram and co-simulation required to represent occupancy are discussed. Occupant-related inputs are significant parameters that influence energy simulation accuracy at both the building and urban levels. In most previous research works, fixed occupant schedules were used in urban-scale building energy modeling. The main reason is the lack of data availability to model the dynamic occupancy schedules. In recent years, urban data sets and modern estimation and detection techniques were introduced to increase the availability of occupant-related data sets. Yet, using these data to model the detailed occupancy at the urban scale is challenging and not much explored. Also, it is unclear how detailed the input regarding the occupancy should be. Addressing these research questions is the main objective of this study. This paper presents a comprehensive review of the occupant behavior (OB) modeling approaches, occupant-related input parameters with particular focus on the occupancy schedule, lighting, appliances use schedule, temperature set-point schedule, and domestic hot water usage for urban building energy modeling (UBEM). Strategies to consider the occupancy sub-models as co-simulation connecting to urban building energy simulation are discussed. Some potential datasets that could be used to derive occupant-related inputs at the urban scale are presented and highlighted. Further, the correlation between occupants' activity level, plug, and lighting loads is discussed in detail. Finally, the limitations and challenges of the occupant-related data connecting to building energy modeling are discussed, along with the research gaps and future directions of occupant-centric UBEM. [ABSTRACT FROM AUTHOR]

• Estimation of annual electricity consumption (EC) of more than 1,700,000 buildings. • EC models based on top-down, bottom-up, regression analysis, GRU and GIS mapping. • Contribution of building and socio-demographic variables on EC. • Effect of temperature on actual and predicted EC used for heating and cooling. • EC is spatialized on different territorial scales. This study financed by ERDF and the Wallonia Region estimates the annual electricity consumption (EC) of building stock, including the 3 building sectors namely residential, tertiary and industrial building. The estimation takes into account appliances, electrical heating, cooling, lighting, cooking and EC by m2 on a building level. The results are spatialized on different territorial scales. Using cadastral data of more than 1,700,000 Walloon buildings and annual EC data from a sample collected in 2012 from the energy reports, the paper assesses the EC of the whole building stock and tests to what extent different types of variables (building factors and socio-demographics) explain annual EC. It then shows which individual variables have the highest explanatory power. In contrast to many other studies, the research recognizes the problem of multicollinearity between predictors in regression analysis and uses Lasso regression to address this issue. Three separate regression models were used to study the predictors of annual EC of residential, tertiary and industrial buildings. EC building factors (appliances, auxiliary and main heating, domestic hot water and cooking) explained the largest share which is 66.46% of the variability in EC for residential buildings whereas the EC usages share for tertiary buildings (lighting, heating and domestic hot water, air conditioning, cooling, etc.) is about 50.53% and 38.55% for industrial buildings. Socio-demographic variables on their own explained about 61.59%, 26.34% and 3.41% of the annual EC, respectively for residential, tertiary and industrial buildings. Hence, the building variables present the highest explanatory power for EC, presumably because heating and cooling EC are included in this study. The study highlights that when attempting to explain EC related to Walloon households, including heating and cooling EC, appliances usage has the strongest predictive power in residential buildings. On the other hand, the projected decrease in EC use for heating in existing residential buildings is −8.82% and −10% for existing tertiary buildings while the projected increase in EC use for cooling in existing tertiary buildings is + 11.94% from 2012 to 2050 on a regional scale. These trends follow the predicted regional heating degree-days (HDD) of −11.76% and cooling degree-days (CDD) of 14.04% for the same period based on the gated recurrent unit (GRU) an implemented deep learning (DL) model. In addition, the produced EC maps on different territorial scales show that the highest EC is seen in large and main cities in general. [ABSTRACT FROM AUTHOR]

Abstract: This paper outlines the development and application of a domestic heat pump model for space heating and cooling energy. The model is intended to bridge the gap between the single coefficient of performance parameter currently used in the UK procedures for the assessment of the energy efficiency of dwellings and the dynamic simulation models frequently developed for the academic estimation of heat pump energy use. It is responsive to variations in source and sink temperatures whilst being simple enough to be embedded in a spreadsheet model. The model was developed by: building a regression model, using heat pump performance test results, relating heat pump coefficient of performance to the differential between source and sink temperatures – “lift”; deriving estimating rules for monthly supply temperature estimates for commonly-used heat pump sources and for demand temperatures for normal wet central heating sinks to give a monthly estimate for the source/sink differential; embedding the regression model in the UK standard model for domestic energy estimation, with additional routines to estimate energy consumption for additional heat and for space cooling. The model developed was validated by comparison with the existing BREDEM model. Compared with the standard BREDEM estimates, the resulting model showed correct response to changes in ambient temperatures, allowing correct estimating of consumption for additional heat under conditions of climate change. It showed variation of heat pump coefficient of performance across the year, allowing better estimation of winter peak load. [Copyright &y& Elsevier]

Abstract: The nexus of water and energy and greenhouse gas emissions is now well recognised, however, quantifying the energy savings from (hot) water-efficient technologies has been largely based on modelled or assumed consumption data from water use appliances and fixtures. The aim of this paper is to determine water, energy and greenhouse gas emission savings from resource-efficient household stock using empirical water end-use data and detailed stock specifications for homes in Queensland, Australia. Hot water system type is considered with comparisons made between intervention scenarios with and without inclusion of a low energy heating system. The results confirm the significant impact that coal-fired electricity water heating has on total household energy consumption. Further, it appears that substantial savings can be achieved by substituting water (e.g. high star rating appliances) and energy (e.g. solar hot water system) efficient appliances in the home. The findings also suggest that retrofitting cheaper resource-efficient technologies are still an effective means of reducing both water and energy consumption, regardless of hot water system type. Future work in this area is needed to expand the current research outcomes, such as the consideration of all thermal losses from heating systems and the use of empirical energy end-use data. [Copyright &y& Elsevier]

Abstract: This paper examines the efficiency (in terms of energy use and carbon emissions) with which 5 different types of domestic water heating systems employed in the UK are able to produce hot water for sanitary use. A method of normalisation is employed allowing results from case studies with different systems and usage levels to be compared. Water heating appliances studied include gas boilers, a micro CHP, heat pumps, an immersion heater, and a solar thermal system. It is found that instantaneous production of hot water is much more efficient than delivery via tank storage for gas-fuelled systems. For electrical systems, an immersion heater is found to perform better in some circumstances than heat pumps and also has advantages when combined with a solar thermal system leading to the proposal that this combination offers the most potential as a low carbon method for domestic hot water provision in the long term. Opportunities are identified to improve the performance of all systems with storage through better control of heat inputs. Inconsistencies in, and problems of compliance with, established standards for mitigation of Legionella in hot water systems are also identified. [Copyright &y& Elsevier]

Abstract: This paper presents the results of experimental research on 8 plate heat exchangers. Their purpose is to heat water for radiator heating system and domestic hot water. Measurements were carried out in 4 substations in district heating system in Belgrade (Serbia). The main achievement of this research was that the fouling factors were determined experimentally, and the found values can be used further on in design of plate heat exchangers in district heating systems. [Copyright &y& Elsevier]

Abstract: This paper evaluates the solar water heating systems for the U.S. typical residential buildings, from the energetic, economic and environmental perspectives, and includes two different types of solar collectors (i.e. flat-plate and evacuated-tube solar collectors), two types of auxiliary systems (i.e. natural gas and electricity), and three different locations (i.e. Los Angeles, Atlanta, and Chicago). The performance of solar water heating systems is also compared with conventional systems that use either natural gas or electricity. The results showed that the flat-plate solar water heating systems using natural gas auxiliary heater has the best performance among all the types and at all locations. The energetic and environmental payback periods for solar water heating systems are less than half of a year, and the life cycle cost payback for solar water heating systems vary from 4 to 13 years for different cities and different configurations when using the conventional electrical water heating system in each city as the benchmark. For a representative case, i.e. flat-plate solar water heating system with natural gas auxiliary heater in Atlanta, sensitivity analysis shows that the daily hot water use has the most significant effects on energetic, environmental and economic performance. [Copyright &y& Elsevier]

Abstract: Evacuated tube solar water heaters are increasingly in use in Hong Kong because of their good thermal efficiency and high water temperature achievable as compared to the flat-plate solar water heaters. But so far their thermal performance has not been systematically evaluated and therefore not well known to the users. This paper reports our experimental and numerical works on evaluating the performance of the two common types of evacuated tube solar water heaters for domestic hot-water applications. These are the single-phase open thermosyphon system and the two-phase closed thermosyphon system. Our results show that the daily and annual thermal performance of the two-phase closed thermosyphon solar collector is slightly better than the single-phase open thermosyphon design. But the payback periods of the two are relatively the same because of the higher initial costs of the two-phase closed thermosyphon collector system. Although economically they are less attractive than the flat-plate type collector system, they are suitable for applications in advanced systems with higher temperature demands. [Copyright &y& Elsevier]

Abstract: This paper introduces a solar-assisted ground-coupled heat pump (SAGCHP) system with heat storage for space heating and domestic hot water (DHW) supply. The simulation results of the system''s detailed operating performance are presented. The optimization of the system design is carried out by the TRNSYS and a numerical simulation is performed for continuous operation of 20 years under the meteorological conditions of Beijing. Different control strategies are considered and the operational characteristics of each working mode are studied. The simulating results show that the long term yearly average space heating efficiency is improved by 26.3% compared to a traditional ground coupled heat pump (GCHP) system because the solar thermal collecting system is used to elevate the thermal energy in the soil and to provide direct space heating with heat storage. At the same time, the underground heat load imbalance problem for a heating load dominated GCHP is solved by soil recharging during non-heating periods, while extra solar energy is utilized to supply DHW. The flexibility and high efficiency of the SAGCHP system could offer an alternative for space heating and DHW supply by heat pump technology and solar energy in cold winters of northern China. [Copyright &y& Elsevier]

Abstract: This paper examines the thermal performance of a roof-integrated solar concrete collector for reducing heat gain to a house and providing domestic hot water. The solar concrete collector is made of PVC pipes embedded in deck slab or concrete roof. No glazing on the top of the solar concrete collector or insulation at the back has been used as in conventional solar water heaters. To compare the energy saving, two test rooms of 2.3m width, 2.5m length and 2.5m height were built. In the first room, the reinforced cement concrete (R.C.C.) slab was used as deck slab whereas the second room was equipped with a cement concrete solar collector. The experimental results showed that the cement concrete solar collector is extremely interesting as it can produce up to 40l of hot water per day at water temperatures ranging from 40 to 50°C. A mathematical model based on the conservation equations of energy is developed to predict the performance of the cement concrete solar collector. There is reasonable agreement from the comparison between measured data and predicted results. The economic analysis indicates that the payback period is rather fast. [Copyright &y& Elsevier]

Abstract: Data gathered from energy audits, phone surveys and smart meter readings are used to derive regression models of the electricity consumption of housing units in Oshawa (Ontario, Canada). The database used comprises 59 predictors, for 62 observations. To address the problem of multi-collinearities among the predictors and at the same time reduce the number of needed predictors, a methodology is developed based on the latent root regression technique of Hawkins . Contrary to other variable selection techniques such as the stepwise method, the technique used in this paper allows an easy identification of alternative subsets. Using this technique, a reduction of 85% in the number of predictors is obtained, leaving only nine of them in the final subset. These nine variables are the number of occupants, the house status (owned or rented), the number of weeks of vacation per year, the type of fuel used in the pool heater, the type of fuel used in the heating system, the type of fuel used in the domestic hot water heater, the existence or not of an air conditioning system, the type of air conditioning system, and the number of air changes per hour at 50Pa. A regression with these nine predictors leads to an R 2 of 0.79, with an adjusted R 2 of 0.75 and all regression coefficients statistically significant at the 95% confidence level. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a novel indirect-expansion solar-assisted multifunctional heat pump (IX-SAMHP) which integrates a domestic heat pump with a solar water heater. The IX-SAMHP can not only work in operation modes included in the two household appliances, but also operate in four new energy-saving operation modes for the space cooling, space heating and water heating. All operation modes have functioned successfully and can be switched to each other smoothly on a purpose-built experimental setup. Experiments of the heat pump water heating mode at outdoor air temperatures of 8°C and 15°C and the solar-assisted space heating mode at indoor air temperatures of 20°C have been investigated in detail. Electric heaters were used to simulate solar radiation intensity in different weather conditions. The experimental results show that the IX-SAMHP can produce hot water with much less electric consumption in cloudy days compared with a solar water heater and can operate in much higher coefficient of performance than a domestic heat pump in cold winter. The IX-SAMHP is especially suitable for the regions abundant in solar radiation where the space heating, space cooling and water heating are required all the year round. [ABSTRACT FROM AUTHOR]

Abstract: This paper develops a bottom-up model of space and water heating energy demand for new build dwellings in the Irish residential sector. This is used to assess the impacts of measures proposed in Ireland''s National Energy Efficiency Action Plan (NEEAP). The impact of the housing construction boom, which resulted in 23% of occupied dwellings in 2008 having been built since 2002, and the subsequent bust, are also assessed. The model structure treats separately new dwellings added to the stock after 2007 and pre-existing occupied dwellings. The former is modelled as a set of archetype dwellings with energy end use affected by the relevant set of building regulations that apply during construction. Energy demand of existing dwellings is predicted by a simpler top down method based on historical energy use trends. The baseline scenario suggests residential energy demand will grow by 19% from 3206ktoe in 2007 to 3810ktoe in 2020. The results indicate that 2008 and 2010 building regulations will lead to energy savings of 305ktoe (8.0%) in 2020. Had the 2008 building regulations been introduced in 2002, at the start of the boom, there would be additional savings of 238ktoe (6.7%) in 2020. [Copyright &y& Elsevier]

Abstract: The paper presents an extended method for exergy analysis of buildings and Heating Ventilation Air Conditioning (HVAC) systems, according to an energy demand build-up model from the building side to the energy supply side. The HVAC systems comprise a thermal energy emission and control system, a thermal distribution system, an electricity distribution system and an energy conversion system. Energy and exergy that are required by a building and a HVAC system are posed into the external part and classified by different forms of energy carriers. The external part is out of the boundary of the study. The method is illustrated with an office building equipped with low-temperature heating and high-temperature cooling systems situated in the Netherlands. Thermal exergy and thermal energy demands of the building and thermal energy and thermal exergy losses occurring in the HVAC systems are discussed. The building and the HVAC systems to be considered meet standard Dutch energy performance regulations. Nevertheless their overall exergy efficiencies are low in both cases (17.15% and 6.81% subsequently). The exergy analysis also pinpoints that the thermal energy emission and control system and the energy conversion system are the main causes of the exergy inefficiencies in the heating and cooling cases, respectively. [Copyright &y& Elsevier]

Abstract: Complex, inconvenient and badly arranged push buttons and menus on domestic heating controls often cause users to enter unsuitable settings that result in impaired comfort and poor operating efficiency. This paper proposes a novel approach to the human interface of home heating systems that greatly simplifies the input required from the user. Time settings are derived automatically from electricity consumption and hot water use, also a temperature set point is provided that adapts to user activity levels and external temperature. Practical results from a prototype control system incorporating these methods are reported, showing useful energy savings. It is argued that this increased automation of control allows the benefits of low carbon technologies such as micro-combined heat and power, and solar hot water heating, to be fully exploited. [Copyright &y& Elsevier]

Abstract: In this paper we compare our estimate of energy consumption for domestic hot water production in a building with the measured value. The energy consumption for hot water production is estimated from the measured total power consumption. The estimation method was developed using computer simulations, and it is based on the assumption that hot water production causes rapid and detectable changes in power consumption. A comparison of our estimates with measurements indicates that the uncertainty in estimation of hot water energy consumption is ±10%. Thus, the estimate is comparable to class 3 energy meter measurements, which have an uncertainty of ±2–10%. [Copyright &y& Elsevier]

Abstract: A hybrid ground-coupled heat pump (HGCHP) with domestic hot water (DHW) supply system has been proposed in this paper for space cooling/heating and DHW supply for residential buildings in hot-climate areas. A simulation model for this hybrid system is established within the HVACSIM+ environment. A sample system, applied for a small residential apartment located in Hong Kong, is hourly simulated in a typical meteorological year. The conventional GCHP system and an electric heater for DHW supply are also modeled and simulated on an hourly basis within the HVACSIM+ for comparison purpose. The results obtained from this case study show that the HGCHP system can effectively alleviate the imbalanced loads of the ground heat exchanger (GHE) and can offer almost 95% DHW demand. The energy saving for DHW heating is about 70% compared with an electric heater. This proposed scheme, i.e. the HGCHP with DHW supply, is suitable to residential buildings in hot-climate areas, such as in Hong Kong. [Copyright &y& Elsevier]

Abstract: A simple approach and practicable prediction method of transmission heat loss would significantly benefit to the comprehensive applications in the hot water system design. This paper proposes an empirical prediction method and defines new parameters to simplify the equation to calculate energy consumption in hot water system. The temperature drop mechanism is established by empirical approach to replace multiple factors in the theoretical heat loss equation developed in air conditional technology. As a result, it is proved that the proposed empirical prediction approximates to the results of theoretical calculation in the range for practical applications. [Copyright &y& Elsevier]

Abstract: In this paper, the initial considerations and the first results of the development of the supervision system for the air-conditioning plant of the testing station with variable orientation of the Mechanical Engineering Department of the University of Calabria are presented. This station is provided with the air-conditioning plant able to operate with air and water for cooling and heating; the heating plant using hot water supplies different terminals, including the radiator, fancoil and radiant floor. The plant is endowed with the flexibility to allow opportune analyses of the performances and of consumption by varying the control action. This first study phase attempts to identify the best match among the plant types and the control systems, on the basis of experimental data obtained for the different control actions, with the aim of providing useful indications to the designer. For the testing station plant, the optimum control action proved to be the proportional-integral-derivative (PID) one. The instruments used, thanks to the ease of implementation and flexibility, enabled the realisation of a control system guaranteeing good plant performances. Moreover, the software developed makes an intuitive graphic display possible of the plant situation at any moment. [Copyright &y& Elsevier]

Abstract: The paper presents a mathematical model for the numerical simulation of a substation for the supply of hot water which operates without auxiliary energy. The introduced original mathematical model has been verified experimentally, enabling a direct comparison with real conditions. While the approach to the mathematical modelling is traditional, the main innovation is the selection and derivation of suitable mathematical models, which are able to deliver the results which are as close as possible to real conditions, thus enabling an excellent accordance of both models, i.e. the mathematical simulation and the test line results. The simulated system is modular to allow analysis of the influence of each parameter. The non-linear model was applied for the heat exchanger, while the temperature sensor has been modeled as the second order system to account for its heat conducting protective pocket. When modelling the valve, its dynamic characteristics have been considered, being an additional advantage over existing mathematical models. The reason for research is to optimize water heaters, a common solution for hot water services in Nordic countries. [Copyright &y& Elsevier]

• Innovative micro CAES – TES trigeneration system powered by the extra-production of green energy. • Compressed air energy storage instead of electrochemical batteries for small and residential use. • No typical electrochemical battery recovery and disposal problems. • Energy storage with extremely long lifetime, absence of hysteresis cycles. • Micro CAES – TES trigeneration system coupled with HVAC system. This paper proposes the application on microscale of an innovative trigeneration system with micro CAES (Compressed Air Energy Storage) – TES (Thermal Energy Storage) and the integration of renewable energy production, focusing on the potential use for air conditioning and domestic hot water systems. The system allows storing mechanical energy in the form of elastic and thermal potential of compressed air through two thermal storage units, HTTES (High Temperature Thermal Energy Storage) and LTTES (Low Temperature Thermal Energy Storage). The proposed system is tested on a single-family building in a warm climate. The analysis is carried out for integrated and independent operating modes. In integrated mode, the LTTES refrigerant charge and the vapor compression chiller operate simultaneously to cover the building's thermal load. In this case the energy expenditure is only related to the power supply of the chiller. In independent mode, the cold storage and the chiller work alternately during evening operation to limit the absorption of energy from the distribution network. The results show that, in integrated operating mode with partial recirculation and internal temperature conditions of 26 °C and 50% of relative humidity, the system reaches, in relation to the peak thermal load, a maximum operating time of 236 min. The minimum operating time of 26 min is reached using the full external air operating mode with an internal temperature of 26 °C and relative humidity of 40%. In independent operation mode, it is possible to sustain the evening thermal load for up to a maximum of 5 h without electricity absorption from the distribution network. [ABSTRACT FROM AUTHOR]

• An IoT-based monitoring system platform for a solar water heating system. • A comprehensive audit procedure for a solar water heating system through IoT-data. • A number of control strategies for energy efficiency and savings improvement. • Verification of control strategies via experiment on a solar water heating system. This paper studies a mechanism to investigate and to improve the energy efficiency of a solar water heating system (SWH) in a hospital building located in Singapore. We utilize the data collected from Internet-of-Things (IoT) to gain information on different environmental and operational aspects of the considered system, that determine opportunities for improving the efficiency of various sub-systems of the SWH, and develop control strategies for efficient operation of the overall system. Through the data collected by IoT, such as water flow, heat pump and water pump operational schedule, availability of solar, and electricity consumption, we perform a comprehensive energy audit to analyze the efficiency of sub-systems and the performance of overall system as well. Based on the insights obtained from data analysis, corresponding control strategies for various sub-systems are developed to improve the efficiency of the overall system and reduce the operational cost of the SWH. Finally, the effectiveness of the proposed control strategies is confirmed through experiment on the site of the considered SWH. [ABSTRACT FROM AUTHOR]

• Definition of the grey water profile of a dwell. • Estimation of potential energy to recover in the grey water generated by dwells. • Definition of the basic componets to recover energy efficiently. • Definition of the optimum size and operation control strategy in these systems. • Evaluation of the influence of the sizing on the system performance. Passive houses linked to more efficient heating and cooling technologies have been one of the focus in last years. However, to close the loop of the building sector, there is still one open source: wasted heat from grey water. This paper addresses the potentiality of the wasted heat from grey water as a heat source to produce domestic hot water (DHW) based on a heat pump system (HP). A heat pump optimized for these applications, a heat recovery heat exchanger and two variable volume storage tanks compose the system. The main objective of this work is to determine the potential recovery of the wasted heat in order to minimize the building energy consumption. Design guidelines of the components and the analysis of an optimum operation algorithm of the system have been performed in order to minimize CO2 emissions. In addition, an evaluation of the potential heat recovery of the wasted heat is included. As an example, that methodology has been applied to 20 dwellings. Based on that case, the obtained results demonstrate that by recovering 80% of the available recovery heat, the total demand of DHW is satisfied with high levels of comfort and efficiency. [ABSTRACT FROM AUTHOR]

This paper presents a multi-criteria assessment approach for a wide range of energy efficient measures and their combinations applied for a residential building retrofit in Norway. A number of passive, active and renewable energy efficient measures (EEMs) have been selected and defined. Based on the level of energy saving potentials, these EEMs have been combined into 18 retrofit combination packages (COMBs) and grouped into various retrofit levels (Moderate Retrofit-I, II, III and Extensive Retrofit). The annual primary energy consumptions (heating, hot water and electricity) for the proposed combination packages were simulated in IESVE building energy simulation software. This is then followed by two levels of assessments: i) the comprehensive assessments of the key retrofit priorities including primary energy reduction, global costs, payback period and the carbon emission reduction and ii) social assessment with the aim to represent various stakeholders' views on the selected COMBs using a metric of weighting factors. Based on this, a multi-criteria assessment approach featuring a novel ranking factor (EEES) taking into account of energy, economic, environmental and social aspects during retrofit process was adopted. This approach quantifies different stakeholders' perspectives on the proposed COMBs, which could enable various stakeholders' involvement in the retrofit decision making process. It was concluded that COMB 05 and 06, which include only 2–3 passive and active EEMs have been ranked and chosen as the most favourable retrofit solutions, with EEES value equalled to 25.6 from various stakeholders' perspectives. The impacts of changing renewable energy prices and PV generated feed-in tariff rates on the global costs, carbon reductions and primary energy consumptions of the proposed COMBs, which have rarely been analysed in literature, are numerically investigated in this research. Such renewable EEMs which are greatly recommended by the European Commission, are expected to gain further support from national level government renewable incentives. Therefore, it is envisaged that in the long term, Extensive Retrofits incorporating mostly renewable EEMs could become more affordable and cost effective. [ABSTRACT FROM AUTHOR]

The South Korean government is presently conducting a research project to provide measurement-based building energy consumption data for individual end uses, such as space heating, space cooling, domestic hot water (DHW), and other uses. From 2014 to 2019, energy consumption measurement systems for each end use were installed in sample buildings, and the measured data are being statistically processed with the objective of constructing an information system for energy use and CO 2 emission intensities by end use. This paper presents the statistical data for the site and primary energy use intensities (EUIs) and the CO 2 emission intensities by end use for the period of May 2017–April 2018; the data were obtained from measurements in 71 sample apartment units located in Seoul. The average site EUIs display the following order: space heating > electrical appliances > DHW > cooking > lighting > space cooling > air movement. Electrical appliances have the largest average primary EUI and CO 2 emission intensity. The average site EUIs exhibit the same order as those of the US Residential Energy Consumption Survey 2015 data: space heating > electrical appliances, etc. > DHW > space cooling. [ABSTRACT FROM AUTHOR]

This paper presents the results from a real residential field test in which one of the objectives was to maximize the instantaneous self-consumption of the local photovoltaic production. The field test was part of the REnnovates project and was conducted in different phases on houses in several residential districts located in Soesterberg, Heerhugowaard, Woerden and Soest, the Netherlands. To maximize self-consumption, buffered heat pump installations for domestic hot water and stationary residential battery systems were chosen due to their respective thermal and electrical storage capacities. The algorithm used to tackle the associated sequential decision-making problem was model-based reinforcement learning. The proposed algorithm learns the stochastic occupant behavior, uses predictions of local photovoltaic production and considers the dynamics of the system. The results show that this algorithm increased the average self-consumption percentage of the local PV generation (used instantaneously in situ) on average by 14%, even if only buffered heat pump installations for domestic hot water were used. This increase was achieved without causing any perceived discomfort to the residential end users. The average energy shifted per day from the solar production period to the night by the 2 kW/3.6 kWh batteries was 1.5 kWh. The main contribution of this work was therefore the real field implementation of the proposed algorithm. The results demonstrate that it is possible to improve even further the integration of local production using flexible loads. [ABSTRACT FROM AUTHOR]