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District heating and cooling systems have been present on the European market for more than a century, constantly evolving into more efficient energy infrastructures important for decarbonization of the heating and cooling sectors. With roughly 17,000 operational district heating systems, serving over 70 million citizens, currently, the final energy consumption attributed to district heating in Europe is estimated at over 450 TWh. As the European district heating and cooling sector varies extensively in every analyzed aspect, there are vast differences between European countries regarding technical preferences, technological development, market structure and regulatory frameworks of these systems. The main purpose of this paper is to provide a comprehensive overview of the present status of the district heating and cooling systems in Europe with insight(s) and suggestions into future trends. In addition, the provided data serves as a valuable baseline for future research. Finally, this paper draws attention to the new socio-demographic approach, observed when analyzing the district heating and cooling systems, that has been recently introduced into the scientific community. This new approach also reveals the opportunity for creating new indicators that will influence the modeling of existing and future district heating and cooling systems. • Provides a review on ongoing trends in European district heating and cooling sector. • Analyses European DHC systems from technological, market, and regulatory aspect. • Provides an overview on commonly used performance indicators and energy models. • Discusses the possibility of creating new DHC indicators. • Discusses the trends in future DHC development. [ABSTRACT FROM AUTHOR]

In this paper, a novel combined heating and power (CHP) system is proposed to realize full-scale utilization of geothermal energy and efficient multi-generation, which not only performs preferable overall performance than previous homogeneous system, but also offers an effective energy cascade utilization approach for self-condensing transcritical CO 2 (TCO 2) Rankine cycle. Based on the established mathematical models, the performance comparison is conducted for proving the superiority of the novel CHP system. Then, an overall performance analysis is implemented to reveal the combined effects for six key parameters on system thermodynamic, exergoeconomic and exergoenvironmental performances. Furthermore, multi-objective optimization considering system overall performance is conducted. The results show that for the novel CHP system, the largest relative improvement rate of system exergy efficiency (η exg) and declining rate of total unit product exergy cost (c P , total ) versus the previous CHP system are 15.03 % and 18.89 %, respectively. The final optimization results of η exg , c P , total and total unit product exergy environmental impact (b P , total ) are determined as 51.10 %, 14.12 $/GJ and 9.00 mPts/GJ, respectively. This paper fulfills an elaborate performance analysis and optimization for the novel CHP system, which fills the research gap of efficient and promising CHP system based on self-condensing TCO 2 Rankine cycle. • A novel self-condensing transcritical CO 2 cycle based cogeneration system is proposed. • Full-scale utilization of geothermal energy is realized by the novel system. • Overall performance superiority of the novel system is proved by comparison study. • Combined effects of six key parameters on system overall performance are revealed. • Multi-objective optimization of system overall performance is performed. [ABSTRACT FROM AUTHOR]

The problem addressed in this work is the enhancement of energy efficiency in buildings, primarily focused on heating control. The paper highlights the importance of addressing this challenge, given that HVAC systems are responsible for over 60% of total energy consumption in buildings, making them the largest energy consumers in both the residential and nonresidential sectors. This paper presents a methodology for developing a model predictive control (MPC) system based on artificial neural network (ANN) models, with the aim of improving the energy efficiency of buildings. This approach involves the creation of a training dataset using dynamic thermal simulation tools, enabling the learning of the ANN model that is responsible for predicting future states within an MPC optimization loop. Additionally, the implementation leverages advanced technologies such as Field-Programmable Gate Arrays (FPGAs), specifically the PYNQ board, Wi-Fi modules, and MQTT communication to enhance scalability, deployment, and adaptability. The study evaluates the proposed Neural Network Model Predictive Control (NNMPC) strategy implemented on the PYNQ, reporting a substantial reduction of 38.53% in heating energy consumption in buildings compared to a basic On/Off control approach for 24-hour simulation. This outcome underscores the solutions significant potential for energy savings in building heating systems. [ABSTRACT FROM AUTHOR]

In the context of carbon neutrality, energy conservation and carbon reduction in the heating industry have become the focus of attention. However, severe heat loss is currently occurring in the secondary heating system due to hydraulic imbalance, which is unable to supply heat according to users' needs. In view of this, a thermodynamic-hydraulic model of users' demand for heat and flow rate for the heating system is established. Then, a novel method to regulate hydraulic imbalance is proposed, with the dynamic heat demand satisfied by regulating the valve opening based on NSGA-II. The optimization results show that the comprehensive hydraulic imbalance coefficient has been reduced from 23.08 to less than 0.019, which means that almost 100% of users can get heat supplies corresponding to their needs, while the energy consumption is reduced by about 30%. Additionally, when there are 1000 population and iteration steps, good convergence and high speed are presented using this method. In summary, an on-demand optimized model of hydraulic balance for the secondary heating network is put forward, which provides powerful engineering support and guidance for intelligent heating construction. • This paper presents a method to regulate the hydraulic balance of network using NSGA-II according to the heat demand. • This paper combines the demand flow regulation of users with the resistance analysis of the heating network. • The hydraulic balance can be implemented greatly by using the hydraulic imbalance coefficient as the optimization goal. • The number of iteration steps in the algorithm has an effect on the optimization results. [ABSTRACT FROM AUTHOR]

Reducing building energy consumption and increasing the use of renewable energy are essential to energy conservation. Photovoltaic thermoelectric heat pumps have been considered as a sustainable measure to supply detached houses with hot water, especially those that even do not have access to the power grid. This paper investigates a stand-alone photovoltaic/thermal integrated thermoelectric water heating system (PV/T-TEWH). A dynamic model of PV/T-TEWH is developed and validated. The performance of the system in Lhasa, Beijing, Changsha and Guangzhou is simulated and analyzed respectively, and the economics of the system are compared. Results show that PV/T-TEWH can rely on the electric energy it generates without additional power supply when the current is less than or equal to 1.4 A in Lhasa and 1.0 A in Beijing, Changsha and Guangzhou. The annual total heat gain of the PV/T-TEWH system increases as the operating current increases, but the COP of the system falls with the rise of operating current. When the system is operating at the currents of 0.6 A, 1.0 A, 1.4 A, and 1.8 A, the payback period shortens with the increase of current. Lhasa has the shortest payback period among four cities and it is only 2.2 years when the working current is 1.8 A. The PV/T-TEWH system provides a new method for building hot water supply, especially for detached houses in remote areas. • This paper proposes and investigates a photovoltaic/thermal integrated thermoelectric water heating system (PV/T-TEWH). • A dynamic model suitable for simulating the PV/T-TEWH system is developed and validated. • The annual performance of the system in Lhasa, Beijing, Changsha and Guangzhou is simulated and analyzed. • The economics of the system in different cities are compared. [ABSTRACT FROM AUTHOR]

Heat recovery in industry is limited by thermodynamic and economic factors. Increased heat recovery in an existing heat exchanger calls for higher costs in terms of capital and pumping due to increased exchanger size and pressure drop. One design option to offset the rapid growth of surface area to meet the upgraded heat load is to seek strategies to increase the heat recovery by increasing the heat transfer coefficient with a moderate increase on pressure drop. Compabloc heat exchangers have the construction features that make them suitable for such purposes. This paper presents a new design methodology for this type of exchanger and discusses its application in retrofit projects. The approach exploits the use of utility paths as the simplest and more practical way of identifying energy savings projects. The importance of analysing and quantifying temperature disturbance propagations is discussed. Applications to two case studies demonstrate the economic viability of using compabloc exchangers to achieve large energy recovery and savings. It is demonstrated that with an additional pumping cost of $66,776.12 USD/year, a total surface area of 1140.8 m2 and capital investment of $1062,272.0 USD, 24.8 MW of additional energy can be recovered, saving $5339,675.52 USD/year, giving a payback of 2.8 months. • A practical approach to the use of compabloc heat exchangers in retrofit applications is introduced. • Compabloc exchangers are sized using a new design methodology and new generalised thermohydraulic correlations. • Utility paths and temperature disturbance propagation are important aspects of the approach. • Compabloc exchanger can achieve high heat recovery, energy savings and short payback periods. [ABSTRACT FROM AUTHOR]

• A two-layer framework is proposed for building HVAC and associated multi-energy consumption optimization. • 100% renewable complementarities are proposed for building multi-energy supplies. • A R-C thermodynamic network is formulated to model the building HVAC. • AC slow charging and DC fast charging types of EVs are considered and managed via a novel real-time supply–demand pricing. Building heating, ventilation, and air conditioning (HVAC) and associated energy consumption make up the more and more important part of the world, whose reduction provides a cost-effective path to the "dual carbon" goal. This paper proposes a two-layer management of HVAC-based multi-energy buildings under proactive demand response of fast/slow-charging electric vehicles (EVs). In this paper, the building HVAC is mathematically formulated via a R-C thermodynamic model, which coordinates with multi-energy converters and storages to form a 100% renewable building. The building management is a challenging optimization problem due to its severe constraints and strong spatio-temporal couplings. In the first layer, a day-ahead multi-energy dispatch is formulated to economically optimize the electrical, heat, gas energy carriers. In the second layer, alternating current (AC) slow charging and direct current (DC) fast charging types of EVs are considered and managed via a novel real-time supply–demand pricing mechanism. After acquiring the economical dispatch references in the first layer, the second layer implements a model predictive control (MPC)-based real-time scheduling to handle the multi-energy supply–demand fluctuations. The original two-layer optimization is further handled via mixed-integer linear program (MILP) reformulation for high-efficient solving. Comparisons have shown the advantageous performances of the proposed two-layer optimization over economics and practicability. Simulations results show that the overall system operating cost can be reduced by at most 3.01% with a higher operational flexibility in building management. [ABSTRACT FROM AUTHOR]

The construction sector accounts for 40% of total energy consumption and is increasing. To reduce energy consumption of heating and cooling systems during peak demand while maintaining thermal comfort, phase change materials (PCMs) are used more and more. Appropriate application of PCM and design of latent heat thermal energy storage (LHTES) requires in practice an in-depth knowledge of the thermal properties of PCMs. The aim of the paper is to present the results of experimental determination of the properties of two commercially available, organic PCMs – RT22HC and RT28 HC, using T-history method and pipe Poensgen apparatus. Results of experimental tests showed that these low-temperature PCMs could effectivity store heat and cold in a narrow temperature range of approx. 7 K for RT22 HC and about 3–4 K for RT28 HC. The average measured latent heat values are 190 kJ/kg for RT22 HC and 244 kJ/kg for RT28 HC. The distribution of energy stored in RT22 HC shows the peak in the temperature range of 21–23 °C (with 20–50 kJ/kgK for heating, 22–71 kJ/kgK for cooling). For RT28 HC this range is 27–28 °C (75–130 kJ/kgK for heating, 40–125 kJ/kgK for cooling). The diagrams of enthalpy present small hysteresis (0.5–1 K) in these materials. Thermal conductivity measurements using pipe Poensgen apparatus demonstrated that these PCMs have a low conductivity of 0.12–0.33 W/mK. The presented experimental research is intended to provide the data necessary for the correct design of LHTES with RT22 HC or RT28 HC intended to use in heating and cooling systems and to maintain thermal comfort in buildings. • RT22 HC and RT28 HC were tested using T-history method and pipe Poensgen apparatus. • The average measured latent heat is 190 kJ/kg for RT22 HC, 244 kJ/kg for RT28 HC. • Results of T-history method and three-layer calorimeter are in good agreement. • Pipe Poensgen apparatus was used to determine thermal conductivity of PCMs. • Tested PCMs confirmed their potential to reduce peak energy consumption. [ABSTRACT FROM AUTHOR]

The heat pump operated single-stage humidification-dehumidification desalination system, configured with a subcooler and a heat regenerator, has been proven highly effective in improving both freshwater productivity and energy efficiency. To investigate the potential benefits of increasing the number of humidification stages, this paper presents a heat pump operated two-stage humidification-dehumidification desalination system by adding a pre-humidifier. Subcooler and condenser of the heat pump are used as the heat sources of the main humidifier and the pre-humidifier, respectively. Through parametric studies, a comparative analysis is conducted on the thermodynamic and economic performances of both the heat pump operated single-stage system and two-stage system at various operating conditions. The results show that such system modification can greatly improve system performances. Compared to the single-stage system, the maximum freshwater productivity of the two-stage system is 42.89 kg/h, increased by 19.77 %; the peak gain output ratio is 7.93, up by 9.53 %; and the lowest specific electricity consumption is 79.34 kWh/m3, reduced by 15.15 %. Furthermore, the freshwater production cost for the two-stage system, ranging from 7.78 to 13.33 $/m3, is also superior that of the single-stage system, further demonstrating its substantial value in practical product development and market promotion. • A heat pump operated two-stage humidification-dehumidification system is proposed. • Performances of single and two-stage systems are compared at identical conditions. • Freshwater production costs of the two-stage system range from 7.78 to 13.33 $/m3. • The two-stage system is significantly more efficient than the single-stage system. [ABSTRACT FROM AUTHOR]

Industrial steam heating is a significant aspect of energy consumption in China, playing a crucial role in industrial energy efficiency. Historically, demand response research has predominantly focused on the electricity sector, with limited emphasis on steam supply. This study explores a novel Time-of-Use pricing approach for steam heating systems, anchored in the demand response theory of price incentives. It develops a peak-valley segmentation method by considering both the load differences between supply and demand and the thermal storage capacity of the pipeline system. Additionally, the paper delves into user response characteristics to formulate an optimized Time-of-Use pricing model for steam heating systems. Implemented in a Jiangsu-based case study, the model demonstrates significant efficiency improvements: it reduces the peak-valley load difference by up to 68.3% and cuts steam purchasing costs by ¥135,000. Furthermore, the alignment between the users' total steam load curve and the heat source's steam supply is enhanced by 18.8%, illustrating the model's effectiveness in balancing demand and supply. • Cluster analysis to extract steam user load characteristics. • Divide peak/valley times based on network storage and user traits. • Create a multi-objective Time-of-Use model for steam pricing optimization. • Carry out a case validation in an actual industrial park in Jiangsu. [ABSTRACT FROM AUTHOR]

In this paper, TRNSYS is used to simulate the heating systems of air-cooling concentrating photovoltaic/thermal (CPVT) coupled air source heat pump and water-cooling CPVT coupled air source heat pump. Besides, Grasshopper is adopted for multi-objective optimization of air-cooling system. This study not only proposed two hybrid systems and enriched the research of CPVT coupled air source heat pump, but also proposed a multi-objective optimization method, which uses Grasshopper to invoke TRNSYS. Compared with the air source heat pump system, the annual average COP of heat pump in the air-cooling system increases by 22.8%, and that of the water-cooling system decreases by 6%. The primary energy saving rate of the air-cooling system is 1.06 times and 6.67 times that of the water-cooling system and the air source heat pump system. The optimized air-cooling system reduces the annual total cost by 2.83%, and increases the energy utilization coefficient by 4.76%. The proposed air-cooling system has obvious advantages in energy saving and improving COP of heat pump. This study is useful for the cost savings and energy conservation of air-cooling concentrating photovoltaic/thermal (CPVT) coupled air source heat pump systems based on urban public buildings. • Models of different CPVT coupled ASHP systems are established in TRNSYS. • The optimization method integrates the advantages of TRNSYS simulation and the advantages of GH parameterization. • The systems are analyzed and compared from energy utilization coefficient, exergy efficiency, primary energy saving rate, annual total cost and net present value. • The ACPVT-ASHP system performance is best when the ASHP capacity is 9.9 kW and the length of PV cells is 1.819 m. [ABSTRACT FROM AUTHOR]

Energy performance indices are widely used methods for determining and assessing the efficiency of buildings in operation. However, methodologies for indices that compare heat consumption among buildings and at higher temporal granularity than yearly are needed. This makes it possible for consumers to compare themselves to others to encourage them to improve their energy efficiency. For a district heating system, it also provides the district heating company with an overview of consumers' energy efficiency (and consumers' efficiency must be comparable). This is critical due to the interconnectedness of district heating systems, as consumers can indirectly have negative impacts on each other's operations. Having an overview of the efficiency of consumers can provide useful information for the district heating companies to detect unusual consumption and possible faults. This paper therefore has created a framework for the comparison of heat consumption among buildings, by taking into account various contextualities to make comparisons possible. The framework has been tested on a case study, and its capabilities are showcased. • Leveraging building metadata to allow energy consumption comparison among buildings. • Creation of heating consumption performance indexes for use by end-consumers. • Enabling of higher temporal resolution performance indexes increasing usability. • Fault detection based on performance indexes. • Showcasing of methodology on real consumption data from a suburb in Denmark. [ABSTRACT FROM AUTHOR]

The integrated electricity and heating system (IEHS) can improve energy efficiency and promote renewable energy consumption. When quality-quantity regulation (QQR) is adopted, namely adjusting hydraulic and thermal conditions of heating system, the increase in operation flexibility is more remarkable. However, present IEHS dispatch models considering QQR overlook hydraulic characteristics of valves and variable frequency pumps resulting in inexecutable dispatch results easily and hindering IEHS's flexibility potential. Furthermore, loop networks and the access of multiple heat sources in heating systems may lead to flow reversal, but current research adopts a fixed flow direction which suppresses the potential of flow reversal to improve flexibility. In this paper, we propose an IEHS dispatch model considering QQR to promote renewable energy consumption, which considers hydraulic characteristics of valves and variable frequency pumps, and flow reversal. Specifically, we introduce two binary flow direction labels for every branch in heating system model and then the IEHS dispatch model which can deal with flow reversal is established. A sequential solution process combining linear and nonlinear optimization is formulated to overcome the non-convex feature of IEHS dispatch model. Specifically, piecewise linearization and piecewise McCormick relaxation are combined to handle complex nonlinear terms in the dispatch model. Therefore, a mixed integer linear programming model is obtained and solved, of which results are used as initial values for nonlinear optimization. Results in the case study show that operation cost is decreased by 0.97 % and renewable power consumption rate is increased from 83.31 % to 84.42 % after considering valve adjustment. Operation cost is further decreased by 6.06 % and renewable power consumption rate is increased to 94.04 % after considering flow reversal. • IEHS dispatch model with quality-quantity regulation of heating systems is proposed. • Operation characteristics of pumps and valves in heating system is considered. • Heating system model with flow reversal is constructed. • A sequential method combining linear and nonlinear optimization is formulated. • Impact of valve adjustment and flow reversal on IEHS dispatch is investigated. [ABSTRACT FROM AUTHOR]

Financial issues have been always one of major priorities in scheduling of energy systems. Although these systems are able to serve several types of energy demands but generated emission by these systems is a challenging problem. Since improvement of each one of mentioned issues has negative effects on the other issue therefore a trade-off solution is necessary to be obtained between these issues. In this paper, a multi-objective model has been presented to satisfy both economic and environmental objectives of a hub energy system in the presence of demand response program. In the proposed paper, ε-constraint and max–min fuzzy satisfying methods have been employed to solve and select the trade-off solution. The main reason of implementation of demand response program is to reduce operation cost and improve environmental performance of hub energy system. In fact, demand response program transfers some percentage of load from peak periods to off-peak periods to flatten load curve which leads to reduction of cost and emission. A mixed-integer linear programming has been used to simulate the proposed model and general algebraic modeling system software has been utilized to solve it. A sample hub energy system containing renewable and non-renewable energy resources has been studied and comparison results are presented to validate efficiency of proposed techniques. [ABSTRACT FROM AUTHOR]

Adsorption carbon capture has shown its superiority in energy consumption and cost investment when compared with common amine scrubbing technologies. However, high regeneration energy demand of adsorbents is still a challenge for large-scale application. This paper proposes a temperature vacuum swing adsorption system integrated with auxiliary heating and cooling technology. Absorption chiller and double-stage absorption heat transformer (DAHT) are introduced from the perspective of adsorption and desorption process of CO 2 capture system. Results indicate that when the duration of each step increases from 25 min to 45 min, the CO 2 recovery rate decreases from almost 100 %–75.7 %, and CO 2 purity increases slightly from 89.6 % to 91.1 %. Considering the temperature grade of waste heat, heat consumption of the absorption chiller assisted system is lower than that of DAHT for original and adjusted cases at a generation temperature of 58 °C. If the desorption temperature decreases from 120 °C to 100 °C, heat consumption of the absorption chiller decreases from 1.90 GJ·ton−1 to 1.76 GJ·ton−1, but the average capture capacity decreases from 306.3 ton·ton−1 ad to 272.1 ton·ton−1 ad. It is demonstrated that both absorption chiller and absorption heat transformer could be promising solutions to reducing the energy consumption of CO 2 capture system. Absorption chiller has a priority over DAHT in regions with low temperature heat sources. Moreover, a tradeoff between adsorbent loss and heat consumption should be found when choosing the appropriate heat pump for practical application. [Display omitted] • Adsorption carbon capture integrated with absorption chiller is initially proposed. • Absorption chiller is beneficial for reduction of heat consumption of capture. • Decrease of desorption temperature has great influence on system performance. • Heat pump assisted adsorption capture is a promising way for energy saving. [ABSTRACT FROM AUTHOR]

50–80 °C heat sources are abundant in renewable energy areas and industrial processes. However, they are difficult to be effectively used due to their ultralow grade. In order to solve this problem, this paper presents a high-efficient hybrid adsorption refrigeration system combing with desiccant coated heat exchangers. In this study, the performance of the hybrid system is experimentally investigated and parametric effects are fully discussed. Results indicate that the hybrid system operates efficiently across a wide heat source range of 50–80 °C. A high-temperature hot water facilitates the cooling production of the hybrid system, while a low-temperature hot water is more beneficial to the COP promotion. Also, a lower cooling water temperature, higher air temperature, higher relative humidity and longer switch time can enhance system performance. The optimal cooling capacity is quantified as 4579 W when powered by 80 °C hot water and the COP reaches its maximum of 0.673 under a heat source temperature of 50 °C. Comparison results show that compared with present systems, the hybrid system has greater adaptability as well as higher efficiency in utilizing 50–80 °C ultralow-grade heat sources, and can satisfy the simultaneous demand for cooling and dehumidification, which offers a promising way to high-efficient energy utilization and sustainable development. • A hybrid adsorption system using desiccant coated heat exchangers is presented. • The hybrid system operates efficiently across a wide heat source range of 50–80 °C. • The cooling capacity and COP reach 4579 W and 0.673, respectively. • The hybrid system provides a promising solution for efficient energy utilization. [ABSTRACT FROM AUTHOR]

In times of great transition of the European construction sector to energy efficient and nearly zero energy buildings (nZEB), a market observation containing qualitative and quantitative indications should help to fill out some of the current gaps concerning the EU 2020 carbon targets. Next to the economic challenges, there are equally important factors that hinder renovating the existing residential building stock and adding newly constructed high performance buildings. Under these circumstances this paper summarises the findings of a cross-comparative study of the societal and technical barriers of nZEB implementation in 7 Southern European countries. The study analyses the present situation and provides an overview on future prospects for nZEB in Southern Europe. The result presents an overview of challenges and provides recommendations based on available empirical evidence to further lower those barriers in the European construction sector. The paper finds that the most Southern European countries are poorly prepared for nZEB implementation and especially to the challenge/opportunity of retrofitting existing buildings. Creating a common approach to further develop nZEB targets, concepts and definitions in synergy with the climatic, societal and technical state of progress in Southern Europe is essential. The paper provides recommendations for actions to shift the identified gaps into opportunities for future development of climate adaptive high performance buildings. [ABSTRACT FROM AUTHOR]

Taking current situation of energy regarding winter heating and study on heating as an example, this paper is based on field measurement, investigation and study, discussing the current energy consumption and usage of winter heating of rural areas in Shandong Province, China. The paper reveals that the most regions in Shandong are utilizing furnaces to keep warming which is a relatively primitive method. Most of villagers are satisfied with the indoor environment although this is not the case, which is contributed by the farmers’ strong passive adaptability. With the constant improvement in living standard of Shandong rural people, simultaneously, energy quality and quantity are required higher and higher. Traditional biomass energy cannot meet their needs. Therefore, more effective and cleaner energy are necessary for them to advance daily living quality and level. The heating measure that will save more energy should be adopted. [ABSTRACT FROM AUTHOR]

The living conditions and energy consumption have been gradually increased in rural area of Shandong Province, China. However, the existing heating technology cannot meet the requirement of occupants’ thermal comfort. Therefore, a more promising heating technology needs to be taken into account. With regard to public place in the rural area, this paper draws a comparison of heat source using Air Source Heat Pump (ASHP), gas boiler and biomass boiler in aspects of efficiency and economy, and conducts a simulation for the indoor air temperature field using different heating technologies, such as radiator, radiant floor and tuyere. Regarding the conventional residence, this paper summarizes the advantages of household ASHP in aspects of efficiency, environment, economy, technology and market. The results show that ASHP is suitable for application in Shandong rural area. [ABSTRACT FROM AUTHOR]

Coal-fired heating, mainly used in North China, has caused serious environmental problems. Schemes to replace coal have been established, but they are not suitable for all scenarios. This paper proposes a heating scheme that uses a methanol heating stove (MHS) to meet the demand for clean, low-cost rural heating. The economy, emissions, and energy consumption of the MHS were analyzed. The scheme was compared with five common rural heating methods. The effects of the methanol price, power grid transformation, and gas pipeline construction on the annual cost of each heating scheme were investigated using a theoretical model. The MHS emitted 66 % less CO 2 and 95 % less SO 2 and NO x and consumed 54 % less standard coal than bulk coal heating stoves. The low electricity supply required to vaporize methanol contributed to the cost and emission reduction. Methanol price fluctuations warrant government subsidies to incentivize the implementation of the scheme. For increased adoption, we recommend that the MHS be used in areas with low population densities and methanol prices. This approach can therefore be an ideal substitute for "coal-to-electricity" and "coal-to-gas" methods in areas that lack access to power or gas supplies and can replace air-source heat pumps in severe cold zones. [ABSTRACT FROM AUTHOR]

This paper presents new metrics to measure the effect of thermal mass on the energy required to heat and cool buildings. Previous studies have been flawed as they have not considered the interaction between intermittent occupancy and thermal mass, which has a significant impact on overall energy use. However, existing parameters do not adequately capture these effects, so the new metrics developed in this paper are used to analyse the impact of thermal mass in hot climates with active cooling, and cold climates with active heating. The results agree with existing literature that high thermal mass structures are likely to be effective in hot climates; however, in cold climates the drawbacks of high thermal mass likely outweigh the advantages, and high thermal mass can cause an increase in energy use. This finding has implications for the design of buildings in cold climates, and contradicts the commonly-held assumption that high thermal mass is correlated with low energy use. The new metrics (transient energy ratio and effective U -value) provide a generalisable method to quantify these effects. They are further used here to analyse the dynamic performance of heavily insulated buildings and show that high thermal mass often leads to higher energy use in cold climates. [ABSTRACT FROM AUTHOR]

The purpose of the research was to examine the savings potential and verify how to reduce the energy consumption in new hospitals by about 50%. Our results are also very relevant in other buildings complex with surplus heating, cooling and thermal storage. Conversion and utilization of surplus heat sources represent well known technologies and are under constant development. In large building complexes there is a potential for coordinated production, storage, and distribution of energy. Heat pump, chiller and thermal storage technologies enable re-use of surplus heat/cool energy throughout the year. Energy supply and demand are typically modelled with separate tools and timescales. Through our study new methods are developed for operation of interacting simulating models. These methods provide tools to step into optimization of combinations of integrated energy systems. The main issues focus on hydraulic water flow and storage systems as a basis. The layout is important not only with regards to utilize the energy quality, i.e. the temperature. In addition, control strategies are shown to have a highly relevant impact on the possible savings. Some details of new hydraulic layout and control design will be described and discussed in the paper. Both in combination with heating, cooling and storage system. Our research indicates that it is possible to save between 20-50% of the energy consumption with optimizing the technical installations in Oslo area. Another benefit of integrated thermal modelling is to reduce the risk of permafrost in ground source heat pump installations. This risk is relevant for large buildings in northern Norway, at annual mean temperatures are below 0̊C. This paper shows how integrated simulation and design can be used to avoid permafrost. [ABSTRACT FROM AUTHOR]

PM2.5 concentration in Beijing China has become a focus for government and common people. It has been explored through source apportionment that heating generates significant influence on PM2.5 concentration in Beijing. However, there has still been great difficulty of quantitatively measuring the impact. In this paper, the author, taking PM2.5 in Beijing as research object, establishes a model of heating influence on PM2.5 emission. Data about the city's boiler number, distribution, fuel consumption as well as rural fuel consumption have been obtained through questionnaire. With the adoption of coefficients for producing and emitting pollutants, influence of heating factors in Beijing on PM2.5 concentration is evaluated quantitatively. High accuracy of the model in the paper has been proved through comparison with data of 2014 Beijing PM2.5 concentration monitored by Chinese Ministry of Environmental Protection. According to evaluation result 10.9, heating contributes to 13.7% of PM2.5 emission in Beijing, 9.9% and 3.8% from the six urban districts and rural areas respectively. It has been suggested that measures including decreasing heating temperature should be adopted to alleviate PM2.5 pollutions in Beijing. [ABSTRACT FROM AUTHOR]

Climate change and its consequences are of great concern. Buildings can be affected by climate change in different ways, such as changes in energy needs and thermal comfort. However, the challenge is to quantify and assess the uncertainties involved in future climate data as well as the relevant adoption strategies. The aim of this paper is to demonstrate potential energy consumption changes in high performance building construction systems in a changing climate. In this paper, current and future weather data of three time slices of 2020, 2050 and 2080 were used to simulate the performance of a simple building in Manchester and London using DesignBuilder software which employs Energy Plus as its calculation engine. Five of the most commonly used and high performance construction systems were examined in terms of energy consumption in this model and results are given. In general, this paper provides a useful methodology for simplification in design decision-making for current and future UK housing. It is observed that future climate scenarios do not have major effects in qualitative comparisons of construction systems. [ABSTRACT FROM AUTHOR]

• Machine Learning is used for energy use prediction of a solar-assisted heat pump. • Attention mechanism and time series decomposition is used to improve model accuracy. • Various combinations of input features are compared. • Results can provide valuable insights for developing Neural Network models. With improved insulation of building envelopes and the use of low-temperature space heating systems, the share of energy use for domestic hot water (DHW) production in buildings has increased significantly, and nearly become the most energy-expensive service in modern buildings. Early prediction of the energy use for DHW is required for many advanced applications such as smart control, demand-side management, and optimal operation of electric or heat storage. However, predicting energy use of the solar-assisted water heating system is more challenging than typical DHW systems, as it is strongly affected by two stochastic phenomena, demand pattern and solar radiation. Given the increasing use of solar-assisted water heating systems, this paper aims to evaluate the potential to predict energy use in such systems using a novel machine learning approach. In this novel model, a Long-Short Term Memory (LSTM) neural network is enhanced by (1) implementing the attention mechanism, a recent development in deep learning inspired by human vision to pay selective attention to the input data, and (2) decomposition of input data into sub-layers. The performance of simple LSTM neural network, Attention-based LSTM neural network (ALSTM) and Attention-based LSTM using decomposed data (ALSTM-D) are compared to a Feed-Forward neural network as a baseline model. Results show that LSTM, ALSTM and ALSTM-D models have a Mean Absolute Error (MAE) of 25%, 28% and 41% lower than Feed-Forward model, respectively. These results indicate the superior performance of the proposed ALSTM-D model over conventional models for solar-assisted DHW systems. [ABSTRACT FROM AUTHOR]

• Propose a CCHP system integrated natural gas reforming system with solar energy. • Design and construct models of the PAFC-CCHP hybrid system. • Present the energy and exergy analysis of the proposed system. • Discuss the effects of key parameters on thermodynamic performance. Hybrid natural gas combined cooling, heating, and power (CCHP) systems integrated with solar technologies offer the efficient use of distributed energy resources for reducing the use of fossil fuels and greenhouse gas emissions. This paper proposes a novel CCHP system, using the phosphoric acid fuel cell (PAFC) as the prime mover, integrated with the natural gas reforming with solar energy assistance. Their respective thermodynamic models are constructed for simulation of the system thermodynamic performance. The simulation results demonstrate that the energy efficiencies of the hybrid system with solar energy assistance are 55.12% for the heater mode and 66.77% for the chiller mode, while the exergy efficiencies are 32.87% and 31.59%, respectively. Similarly, when solar energy is not available, its energy efficiencies are 59.24% and 69.18%, while its exergy efficiencies are 40.09% and 39.01%, respectively. In the PAFC–CCHP hybrid system, the exergy efficiencies are key components in the overall efficiency, and the efficiencies with and without solar energy are 29.34% and 36.95%, respectively. Solar energy and exergy share is employed to analyze the solar energy contribution, and they are 36.1% and 35.6%, respectively. Meanwhile, the parametric analysis is also carried out to evaluate the effects of key parameters on the performance. The results show that increasing the reforming temperature, influenced by solar energy, improves the natural gas conversion and boosts the hydrogen concentration of the syngas fed into the PAFC, which increases the overall exergy efficiency. However, the effect of the reforming temperature is reduced when the reforming temperature is higher than 1073.15 K. [ABSTRACT FROM AUTHOR]

To improve the defrosting accuracy and the energy efficiency of the air-source heat pump (ASHP) under frosting and defrosting conditions, a novel Temperature–Humidity–Time (T–H–T) defrosting control method, based on a frosting map for the ASHP unit, is proposed in this paper. A field test was conducted for two heating seasons, to verify the feasibility and applicability of the T–H–T method. The advantages of the T–H–T method, compared to the conventional Temperature–Time (T–T) defrosting control method, are presented. In total, eight cases are shown in this paper. Cases 1 to 4 were chosen to reveal the T–H–T performance under different frosting conditions. It was found that no matter what kind of frosting conditions, defrosting was always initiated in a similar situation: ∼90% of the outdoor coil surface was covered by frost; the temperature difference between the compressor suction and discharge increased by ∼20%; and the heating capacity decreased by ∼30%. These results indicate that the T–H–T method can make an accurate decision under different frosting conditions. Cases 5a, 5b and Cases 6a, 6b were two groups of cases to compare the advantages of the T–H–T method against the conventional T–T method. Cases 5a and 5b were chosen for the non-frosting condition. It was found that the T–T method initiated the defrosting operation 31 times within 24 h. However, none of the defrosting operations was conducted for the T–H–T method. Cases 6a and 6b were chosen to compare these two methods under consecutive and variable frosting conditions. For the T–T method, 63% of the defrosting processes were found to be executed under conditions where defrosting was not necessary. However, for the T–H–T method, all the defrosting controls were found to be accurate and reasonable. These results indicated that the novel T–H–T method is suitable for the defrosting control of the ASHP, and has a more competitive performance than the conventional T–T method. [ABSTRACT FROM AUTHOR]

• Advanced climate-resilient energy retrofit technology reduces the use of non-renewable energy in the building sector. • Renewable District Heating as an optimal technology in deep energy renovation strategies. • Sustainable cities and buildings are feasible by Centralised District Heating system powered by biomass. • Key Performance Indicators (KPIs), to achieve nZEB performances established in the European legislations. This paper presents the implementation of a biomass-fuelled District Heating System (DHS), as a part of a deep energy renovation exercise to achieve a climate-resilient campus with minimum carbon dioxide emissions. The case study is carried out for the University of Valladolid, an average-sized university in Spain, with a continental weather climate. Prior to renovation, the different building blocks had a wide-ranging level of fossil fuel consumption for space heating and domestic hot water ranging between 60 and 430 kWh/m2·year. The application of this centralised heating system allows to achieve the minimum threshold for near zero-energy buildings (nZEB) of 100–120 kWh/m2, in accordance with the Spanish Standards. These values correspond to the maximum European indicators for offices in continental weather conditions. Results of this comprehensive study show that 15 out of the 19 buildings reached the nZEB target, due to the proposed strategy. The overall carbon dioxide emissions have dropped by 92.69% as compared to the original fossil-fuel powered boiler, thus bringing carbon dioxide emissions down to 1.57 kgCO 2 /m2·y. Therefore, it is shown that deep energy renovation strategies through renewable energy DHS have the potential of achieving nZEB for universities in continental weather conditions. [ABSTRACT FROM AUTHOR]

• A constraint equivalent model for heat networks is proposed. In this model, the operational constraints of heat networks are mapped to the feasible region of CHP units, which protects the privacy of heat networks. • A boundary point search method is further developed to efficiently solve the constraint equivalent model and construct a high-accuracy approximation of actual feasible region. • A cooperation method with the rolling horizon strategy is proposed considering the uncertainties of heat and power loads. In the proposed cooperation method, the feasible region of CHP units is provided to the power system only once, which alleviates the communication burden. • Compared with other cooperation methods, simulation results show the advantages of the proposed cooperation method in balancing privacy protection and the quality of the solution. • The impact of heat storage tanks and uncertainties of heat loads on the boundaries of the feasible region is further analyzed. The cooperation of combined heat and power (CHP) systems can improve efficiency in energy utilization by fully utilizing the complementarity between heat and power. However, heat and power systems are operated by different companies where data sharing is restricted for privacy reasons, thus posing significant obstacles to collaboration. This paper proposes a coordinated operation method for CHP systems based on the constraint equivalent model. To preserve the operational constraints of heat networks and protect data privacy, a boundary point search method is firstly developed, where the operational constraints of heat networks are mapped to the feasible region of CHP units. Then, a multi-period cooperation model considering uncertainties of both networks is established based on the proposed constraint equivalent model and the rolling horizon strategy. Moreover, the impact of heat storage tanks and uncertainties of heat loads on the boundaries of the feasible region for heat networks is further analyzed. Simulation results demonstrate the effectiveness of the proposed constraint equivalent model and the cooperation method. [ABSTRACT FROM AUTHOR]

• Long term field evaluation of forecast control of heating. • Easy integration with existing installations in buildings. • Widely applicable measure for energy savings around 10%. • Payback time below one heating season. The priority for reaching carbon neutral buildings by 2050 is to first increase energy efficiency in existing buildings by use of easily and widely applicable measures that are verified based on long-term field research. One such solution is a forecast control of heating systems, which can be quickly and easily integrated to existing weather based controls. However, there are still no long-term field evaluation and detailed analyses of the main features of such a system, which would provide a clear picture about the system's energetical and economical features and thus increase their wide application in existing buildings. This paper provides the data from a long term field evaluation of an innovative forecast control of heating systems (forHEAT), which can be easily installed (in less than 2 h) and integrated with existing installations in millions of existing buildings in Europe and throughout the world. The energy consumption for heating was evaluated in seven residential buildings and three public office buildings before and after the installation and use of the forecast control. The resulting energy savings averaged 13.4% in the residential and 10.7% in the public buildings located in continental European climate, with very cold winters. The payback time averaged a 0.6 heating season and in most case studies does not exceed a single heating season. [ABSTRACT FROM AUTHOR]

This paper proposes a compound parabolic concentrating (CPC) vaporized desalination system with preheating and heat recovery. In the preheating and CPC heating subsystems, the water and heat-conducting oil are respectively employed as the working medium. The seawater is heated by circulating water and heat-conducting oil in the heat exchangers, thereby preventing collector corrosion. The latent heat recovery of the steam improves the energy utilization rate, and the spraying of the feedwater onto the vaporized plate enhances the heat and mass transport and the vaporization efficiency. The influences of the feedwater temperature and ambient temperature on freshwater production under various levels of solar irradiance are illustrated by calculation. The system freshwater production, heat loss, heat efficiency, and heat recovery efficiency are experimentally explored. The preheating and heat recovery increase the average inlet temperature of the CPC heating subsystem to 60.6 °C, thereby an energy savings of 6720.68 kJ/d. The maximum hourly production and the daily freshwater production of the system is 4.55 kg/h and 15.72 kg, respectively. The average heat recovery utilization rate of the system is 0.39. • A novel desalination system with preheating and heat recovery. • More than 6720.68 kJ/day energy saving with preheating and heat recovery. • Enhanced heat and mass transport transfer by spraying. • Daily freshwater yields of 15.72 kg/day. • Preheating, heat recovery and spraying increase the freshwater yields by 25.2% and 61%, respectively. [ABSTRACT FROM AUTHOR]

This paper investigates factors associated with variation in daily total (electricity and gas) energy consumption in domestic buildings using linked pre-COVID-19 smart meter, weather, building thermal characteristics, and socio-technical survey data covering appliance ownership, demographics, behaviours, and attitudes for two nested sub-samples of 1418 and 682 British households selected from the Smart Energy Research Laboratory (SERL) Observatory panel. Linear mixed effects modelling resulted in adjusted R2 between 63% and 80% depending on sample size and combinations of contextual data used. Increased daily energy consumption was significantly associated (p -value < 0.05, VIF < 5) with: households living in buildings with more rooms and bedrooms, that are older, more detached, have air-conditioning, and experience colder (more heating degree days) or less sunny weather; households with more adult occupants, more children, older adult occupants, higher heating temperature setpoints, and that do not try to save energy. The results demonstrate the value of smart meter data linked with contextual data for improving understanding of energy demand in British housing. Accredited UK researchers are invited to apply to access the data, which has recently been updated to include over 13,000 households from across Great Britain. This paper provides guidance on appropriate methods to use when analysing the data. [ABSTRACT FROM AUTHOR]

Abstract: Microturbines offer new perspectives in small-scale heat and power production however their profitability depends strongly on the yearly amount of running hours. The non-continuous heat demand often leads to a reduction in running hours. This paper proposes an alternative by recuperating the lost thermal power through the injection of heated water in the micro Gas Turbine (mGT). Water injection is considered a successful way to increase power and efficiency in industrial gas turbines and similar effects are expected for microturbines. This paper reports on a series of simulations of water injection performed on a Turbec T100 mGT. The goal of this study was to investigate the potential of water injection in the mGT cycle using an adiabatic black box method in the Aspen® process simulation tool. Past experiments with steam injection on the T100 demonstrated the potential of introducing steam/water in the microturbine cycle. Calculations revealed that the key parameters for maximum heat recuperation are stack and pinch temperature. Simulations showed that most of the exhaust heat can be recovered through injection of heated water after the compressor, resulting in an 18% decrease in fuel consumption and an absolute increase in electrical efficiency of 7%. [Copyright &y& Elsevier]

[Display omitted] • Dynamic evaluation of economic and energy benefits due to thermostatic valve installation. • Dynamic evaluation of economic and energy benefits due to heat metering installation. • The adoption of both thermostatic valves and heat metering least to a payback period lower than 2 years. • Analysis carried out considering several shapes of typical building. The aim of this paper is to propose a novel approach in order to accurately calculate the energy and economic savings due to the use of heat metering and thermostatic valves in residential buildings. The paper aims at proving that the present simplified approaches used in European Legislation may lead to significantly underestimate the profitability of this technology. The study is developed for four different typologies of buildings located in the city of Naples (South of Italy), including their geometrical and thermophysical properties. The buildings are first modelled in Google Sketchup and subsequently linked to the TRNSYS environment, which also includes a detailed model of the piping systems. The models allow one to evaluate, for every period of the year, energy demand, energy supplied by radiators, heat gains, transmission, etc. The developed models are used to calculate energy demands for three scenarios for each type of building: centralized heating systems not equipped with heat metering; thermostatic valves without heat metering; heat metering and thermostatic valves. The possible savings related to thermostatic valves and heat metering are estimated using the developed model. The results are compared with the ones provided by the Italian Standards. Results show that the thermostatic valves adoption leads to a significant reduction, up to 50%, of the thermal energy demand of the residential buildings and that all the proposed systems exhibit a remarkable economic profitability, with a payback period lower than 1.7 years. [ABSTRACT FROM AUTHOR]

• The system engineering based on photovoltaic thermal heat pump was constructed. • A new idea for the energy-saving reconstruction of district heating was introduced. • The prediction model of system heating performance was established and optimized. • The equivalent electricity consumption of heating was defined. • The economic performance of energy-saving reconstruction was studied. Actively promoting the reconstruction of clean heating is the key direction of the "Planning for clean heating in winter in northern China (2017–2021)". The photovoltaic thermal heat pump system was introduced in this paper to improve the comprehensive energy efficiency and reduce the operation energy consumption of the heat source system, which provided a new idea for the energy saving reconstruction of clean district heating. In order to verify the feasibility of the energy saving reconstruction by photovoltaic thermal heat pump, following studies were carried out in this paper: First, the integrated energy system engineering based on photovoltaic thermal heat pump was constructed to study the heating performance of the system in winter. Subsequently, the prediction model of heating performance based on back propagation neural network was established and optimized to simulate the heating performance throughout the year. Then, the calculation model of district heating system was established and the evaluation method of system operation energy efficiency and economic performance based on "equivalent electricity consumption of heating" was introduced. Finally, a residential area of Dalian was taking as an example to study the economic performance of energy saving reconstruction of district heating system based on three conventional heat sources by photovoltaic thermal heat pump. The results showed that after the capacity expansion and energy saving reconstruction based on photovoltaic thermal heat pump were conducted, the payback period of energy saving reconstruction investment was 5 years. Besides, with the increase of the configuration ratio of photovoltaic in the system from 1 to 2, the payback period was further shortened to 3 years. [ABSTRACT FROM AUTHOR]

Abstract: Energy flow from the primary energy to the final energy use varies depending on which device is used for the heating and cooling energy service. This paper presents economic analyses of medium capacity space heating and cooling systems from three perspectives – primary energy, final consumer, and social cost perspective. From the analysis results of primary energy and final consumer perspective, electric heat pump (EHP) system is found to be superior to the gas engine driven heat pump (GHP) system for the energy consumption and cost-effectiveness due to its higher system efficiency. However, the result of social cost perspective shows the GHP system is superior to the EHP system considering incurred incremental electricity generation capacity construction cost and avoided gas storage tank construction cost due to a new installation of each system. And this paper suggests three analysis methodologies – the primary energy, final consumer, and social cost perspective – can be used for developing various measures and policies for integrated demand side management. [Copyright &y& Elsevier]

Abstract: During pyrolysis of waste tyre, the operating parameters such as tyre composition, the process temperature, the heating rate and the particle size affect the result of the pyrolysis. Some of these parameters have been closely considered but the particle size of the waste tyre is often ignored. The goal of this paper is to study the effect of particle size in waste tyre pyrolysis under different heating approaches and to use optimization techniques to determine the optimized particle size for each scenario. In this paper, the size of the waste tyre particle is considered as a major factor in determining the magnitude of the overall energy used as well as the completion time of the pyrolysis reaction. Simulations were conducted to compare the effects of the particle size on the completion time and the overall energy usage under different heating rates and operational strategies. Shredding energy needed to reduce waste tyre particles was also included into the calculation of the overall energy consumption. Optimisation of the particle size was conducted under a number of specified maximum completion times and heating rates. This study confirms the trade-off between the overall energy used and the completion time. It also shows the impact of using some optimisation techniques to determine the optimized particle size for different heating approaches. [Copyright &y& Elsevier]

Abstract: An important performance in building thermal control is to ensure thermal comfort with minimal energy consumption. Model Predictive Control (MPC) is considered to be one of the most suited solutions for this due to its ability to use occupancy schedule and weather forecasts for optimal temperature control. MPC relies on a dynamical model of the building, which is the main difficulty of applying it. Therefore, this paper treats the problems related to building modeling and model parameters identification. A robust model of the building is obtained in two stages: firstly physical knowledge is used to determine the structure of a low-order model, then least squares identification method is applied to find the numerical values of the model parameters. In order to perform the identification usually there are required input/output data records having variations which generally are not accepted in inhabited buildings because of imposed comfort conditions. Also inhabited buildings contain unmeasured disturbance sources which may degrade the identified model quality. Therefore this paper proposes to use detailed building models, implemented in dedicated simulation tools, to generate the required input/output data records instead of measuring them on real buildings. This allows us to apply desired input signals and to eliminate disturbance sources. Additionally, the paper presents a method to identify the nonlinearity existing in building thermal behavior, which permits to represent the building by separated linear and nonlinear blocks. This model representation, used along with the linearization method proposed in Part II, permits to design the temperature controller without resorting to the nonlinear system theory. [Copyright &y& Elsevier]

Abstract: This paper presents the results of a computational study on the energy consumption and related CO2 emissions for heating and cooling of an office building within the Urban Heat Island of London, currently and in the future. The study developed twenty weather files in an East-West axis through London; the weather files were constructed according to future climate change scenario for 2050 suitable for the UK which have been modified to represent specific locations within the London UHI based on measurements and predictions from a program developed for this purpose (LSSAT). The study simulated an office with typical construction, heat gains and operational patterns with an advanced thermal simulation program (IESVE). The predictions confirm that heating load decreases, cooling load and overheating hours increase as the office location moves from rural to urban sites and from present to future years. It is shown that internal heat gains are an important factor affecting energy performance and that night cooling using natural ventilation will have a beneficial effect at rural and city locations. As overheating will increase in the future, more buildings will use cooling; it is shown that this might lead to a five-fold increase of CO2 emission for city centre offices in London in 2050. The paper presents detailed results of the typical office placed on the East-West axis of the city, arguing the necessity to consider using weather files based on climate projections and urban heat island for the design of current buildings to safeguard their efficiency in the future. [Copyright &y& Elsevier]

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

Abstract The goal of this paper is to evaluate the advantages achieved through the adoption of low impact energy saving strategies for an independent natural gas fired boiler heating system in a recently built residential building in Rome. For this purpose, an existing apartment was selected as a case study and dynamically simulated in TRNSYS with which the model was validated. Low impact retrofit solutions and heating system management were considered as possible solutions to achieve energy savings. The chosen retrofit solutions consist of envelope elements replacements and building automation controls improvement while heating system management depends on occupants' behavior. Overall, 36 scenarios were considered, starting from the combination of 3 comfort temperature set-points, 2 insulation levels for transparent components, 2 types of zone comfort set-point control with 3 dead-band temperatures. Each case is evaluated in terms of energy results and economic results. The simulation results provide energy savings up to 44% when windows are replaced lowering their transmittance nearby 32%. The choice of a proportional control for zone temperature set-point compared to a simple on-off control guarantee energy saving up to 39% when temperature set-point is low (19 °C) and controls dead-band is 0.5 °C. The effect of different temperature control dead-bands is higher when proportional controls are adopted (up to 40% passing from 2 to 0.5 °C dead-band for 19 °C set-point). Energy consumption reductions up to 63% are achieved if the indoor temperature set-point is lowered 2 °C, underlining the importance of occupants' behavior. At last, an analysis on socio-economic impacts was performed, based on the results of a previous study focused on the externality costs due to pollutants emissions. Highlights • Energy advantages achieved through the adoption of low impact energy saving strategies for an independent gas fired boiler were evaluated. • An existing apartment of a modern residential building in Rome was selected and dynamically simulated in TRNSYS. • 36 energy saving scenarios were considered. • Each case was evaluated in terms of energy and economic results. • An analysis on socio-economic impacts was performed, based on the externality costs due to pollutants emissions. [ABSTRACT FROM AUTHOR]

Abstract The coupling between heat pumps and renewable energy sources is a recognized strategy to reduce primary energy consumption at the household level. This paper contributes to the present-day discussion concerning solar-assisted heat pumps for heating/cooling and to produce domestic how water. In particular, this study presents the results of a field study concerning a novel solar-assisted dual-source multifunctional heat pump, installed in a detached house in Milan. The proposed system couples hybrid photovoltaic/thermal (PVT) panels with a multifunctional and reversible heat pump. The heat pump is equipped with " air-source " and " water-source " evaporators, connected in series and operated alternatively, based on the ambient conditions, system parameters and operating modes. In addition, the PVT panels are used, by employing two storage tanks, to produce domestic hot water and to provide a heat source to the " water-source " evaporator. The proposed system has been tested experimentally, showing interesting and promising results: the system has been able to maintain high efficiencies in the different seasons and has been able to use the solar energy to support the production of domestic hot water. It was found that the use of the " water-source " evaporator allowed to significantly increase the performance of the system and to avoid the defrost cycles. Highlights • We present a novel solar-assisted dual source multifunctional heat pump. • We summarize the results of a field trial. • We provide seasonal performances of unit installed in a detached house. • We provide daily performances of unit installed in a detached house. • We relate seasonal and daily performances. [ABSTRACT FROM AUTHOR]

Abstract A Trombe wall (T-Wall) is widely applied to buildings due to the advantage of saving fossil energy and improving indoor environment, etc. However, a traditional T-Wall usually has the drawbacks of low thermal efficiency and thermal inertia, which lead to poor heating performance and significant energy loss at night. To overcome the above drawbacks, in this paper, an improved T-Wall was designed and its heating performances were experimentally investigated. Firstly, a detailed description on the improved T-Wall, test-bench and measurement system were reported. Then, the experimental procedures, conditions and data reduction were given. Finally, the experimental results were analyzed and discussed. The results revealed that the air temperature in the test room was higher than 16.0 °C during more than half of the testing time, and the minimum air velocity was 0.35 m/s at the vent outlet, which could circulate the indoor air to improve the thermal environment. Furthermore, the daily thermal efficiency of the improved T-Wall was higher than 50% during the daytime. Therefore, the results of this study provided valuable insights for improving the heating performance of T-Wall. Highlights • A Trombe wall with novel configuration is proposed. • An experimental study of the novel designed Trombe wall is conducted. • The novel Trombe wall is able to heat the indoor space effectively and rapidly. • The daily thermal efficiency of the novel T-Wall is higher than 50% during the daytime. [ABSTRACT FROM AUTHOR]

Abstract Beyond the definition and measurement of energy poverty, which have mainly attracted research interest over the last decades, attention has recently begun to turn to a broader notion of energy vulnerability. So far, this has mostly been approached on a theoretical base, suggesting the incorporation of broader socio-economic aspects into the energy poverty framework. However, the quantitative measurement of energy vulnerability is still an unexplored field of research. In this paper, the "Vulnerability Index" is developed, which, based on stochastic analysis, quantifies the vulnerability of a population to the energy poverty ratio, compared to a reference population. Moreover, Sensitivity Analysis quantifies the particular contribution of various parameters to the problem, by determining their weighting factors. As case study, the vulnerability of Greek mountainous regions with respect to the country level was studied. The results showed that households living in mountainous regions are more vulnerable versus those of the whole country, at 89.7%. It was also found that energy policy should focus on raising incomes of mountainous population and, afterwards, on energy saving measures and reduction of heating cost in mountains. The methodology suggested can address social inequalities of vulnerable population groups, in terms of energy poverty. [ABSTRACT FROM AUTHOR]

Abstract: Daily maximum temperature can be used a good indicator of peak energy consumption, since it can be used to predict the massive use of heating or air conditioning systems. Thus, the prediction of daily maximum temperature is an important problem with interesting applications in the energy field, since it has been proven that electricity demand depends much on weather conditions. This paper presents a novel methodology for daily maximum temperature prediction, based on a Support Vector Regression approach. The paper is focused on different measuring stations in Europe, from which different meteorological variables have been obtained, including temperature, precipitation, relative humidity and air pressure. Two more variables are also included, specifically synoptic situation of the day and monthly cycle. Using this pool of prediction variables, it is shown that the SVMr algorithm is able to give an accurate prediction of the maximum temperature 24 h later. In the paper SVMr technique applied is fully described, including some bounds on the machine hyper-parameters in order to speed up the SVMr training process. The performance of the SVMr has been compared to that of different neural networks in the literature: a Multi-layer perceptron and an Extreme Learning Machine. [Copyright &y& Elsevier]

Abstract: Evaluating a building’s performance usually requires a high number of sensors especially if individual rooms are analyzed. This paper introduces a simple and scalable model-based virtual sensor that allows analysis of a buildings’ heat consumption down to room level using mainly simple temperature sensors. The approach is demonstrated with different sensor models for a case study of a building that contains a hybrid HVAC system and uses fossil and renewable energy-sources. The results show that, even with simple sensor models, reasonable estimations of rooms’ heat consumption are possible and that rooms with high heat consumption are identified. Further, the paper illustrates how virtual sensors for thermal comfort can support the decision making to identify the best ways to optimize building system efficiency while reducing the building monitoring cost. [Copyright &y& Elsevier]

Abstract: The performance of different HVAC systems varies when coupled with different buildings. This paper examines the relationship between building heating and cooling load and subsequent energy consumption with different HVAC systems. Two common HVAC systems in use throughout the UK office building stock, variable air volume (VAV) system and fan coil (FC) with dedicated outside air system, have been coupled with a typical narrow plan office building with and without daylight control and for both cellular and open plan. The results presented in this paper clearly indicate that it is not possible to form a reliable judgment about building energy performance based only on building heating and cooling loads. For the two investigated systems, variable air volume system and fan coil with dedicated outside air system, the difference between system demand and building demand varied from over −40% to almost +30% for cooling and between −20% and +15% for heating. If a heat recovery unit is used, the difference in heating performance is even greater, rising to −70%. [Copyright &y& Elsevier]

Abstract: The building industry uses great quantities of raw materials that also involve high energy consumption. Choosing materials with high content in embodied energy entails an initial high level of energy consumption in the building production stage but also determines future energy consumption in order to fulfil heating, ventilation and air conditioning demands. This paper presents the results of an LCA study comparing the most commonly used building materials with some eco-materials using three different impact categories. The aim is to deepen the knowledge of energy and environmental specifications of building materials, analysing their possibilities for improvement and providing guidelines for materials selection in the eco-design of new buildings and rehabilitation of existing buildings. The study proves that the impact of construction products can be significantly reduced by promoting the use of the best techniques available and eco-innovation in production plants, substituting the use of finite natural resources for waste generated in other production processes, preferably available locally. This would stimulate competition between manufacturers to launch more eco-efficient products and encourage the use of the Environmental Product Declarations. This paper has been developed within the framework of the “LoRe-LCA Project” co-financed by the European Commission’s Intelligent Energy for Europe Program and the “PSE CICLOPE Project” co-financed by the Spanish Ministry of Science and Technology and the European Regional Development Fund. [ABSTRACT FROM AUTHOR]

Abstract: Building energy regulations, also referred to as building energy codes, emerged in the 1970s as an essential tool for improving energy efficiency and minimising energy consumption in buildings. Basically they aim at setting minimum energy efficiency requirements to achieve energy efficient design in new buildings. This paper analyses the development of building energy codes concerning Heating, Ventilation and Air-Conditioning (HVAC) energy efficiency, along with their scope and compliance paths. The paper focuses on the synthesis of energy efficiency requirements on HVAC systems of non-residential buildings in different regulations. Critical issues for the development of prescriptive and performance regulatory paths for this type of systems in non-residential buildings are discussed in order to improve the understanding of HVAC energy efficiency topics and to provide policy makers with a menu of options to strengthen the HVAC section of building energy codes. [ABSTRACT FROM AUTHOR]

Highlights • Increase of self-consumption of photovoltaic electricity for heating by factor six. • Simple control algorithm to use building mass as thermal battery with heat pump. • Operation cost of the heat pump can be cut in half. • Building overheating up to 26 deg C is equivalent to 2 m3 water heat capacity. • Electricity grid consumption 40% less with only 10% additional building heat loss. Abstract The purpose of this paper is to show the possible increase of self-consumption of photovoltaic (PV) electricity production for a building by intelligent use of thermal masses in the building. TRNSYS simulations were carried out for an electrically driven ground heat pump in combination with PV, thermally activated building systems and water storage (TES) in small single-family buildings. Several different control strategies adapting set-temperatures in combination with different building types and heat capacities were investigated. For a single-family house with 8900 kWh space heating and domestic hot water demand per year and a 20 m2 PV system, the solar fraction (SF) increased from 11% for a standard configuration up to 61% with maximized use of overheating of the TES (2000 L tank) and the building mass. The running cost for the heat pump due to grid electricity consumption (0.18 EUR per kWh) decreased from 420 EUR per year – in the reference case without PV – to 373 EUR (SF = 11%) with PV, but in the standard configuration without PV self-consumption optimization, and to 69 EUR per year (SF = 61%) with PV self-consumption optimization, if the remaining PV electricity was completely sold at 0.05 EUR per kWh. [ABSTRACT FROM AUTHOR]