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Energy demand for heating and cooling of buildings can be minimized through usage of thermal energy storage (TES) systems in building materials. TES in microencapsulated phase change materials provides a new solution to thermally regulated energy efficient buildings. This study summarizes the investigations and analysis of microencapsulated PCMs for building applications. Microencapsulated phase change materials (MPCMs) can be incorporated with many materials that are commonly used in building construction. This paper provides overview of various encapsulation techniques, test methods for MPCMs as well as applications of MPCMs in buildings. There are several micro-encapsulation methods by which the microcapsules of a wide range of sizes between 0.05 μm and 5000 μm can be produced. The MPCM incorporated with concrete, mortar, plaster and other materials have a significant potential to increase the thermal capacity of the mixture. Several authors reported testing of building materials with MPCM. Though the increase of thermal capacity with addition of MPCM is significant the decrease of mechanical properties, such as compressive strength, is relatively small. [ABSTRACT FROM AUTHOR]

Phase change materials can be integrated in building walls to reduce heating energy consumption. However, proper design of the composite material requires a lot of complex calculations. In this paper, we present a methodology based on metamodeling in order to properly design phase change material composite solutions. A low-energy house example is chosen to develop our methodology, simulations being carried with TRNSYS. Box–Behnken design of experiments is used for data sampling in order to be able to produce a polynomial metamodel. First, the metamodel allows to have a profound understanding of the parameters influence: melting temperature, thickness, latent heat, density and thermal conductivity. Second, it is possible to extract from the polynomial form the optimal material properties. Third, the metamodel can be used to design or test different material solutions. Based on this methodology, it is possible to build a simple tool that can be used by architects and engineers. [ABSTRACT FROM AUTHOR]

Artificial intelligence techniques have been successfully applied to control dynamic systems looking for an optimal control. Among those techniques, reinforcement learning has been shown as particularly effective at reducing the dimensionality of some real problems and solving control problems by learning from experience. The use of thermal energy storage active systems in the building sector is identified as suitable option to reduce their energy demand for heating and cooling. However, these systems might be expensive and require appropriate control strategies in order to improve the performance of the building. In this paper a ventilated facade with PCM is controlled using a reinforcement learning algorithm. The ventilated facade uses mechanical ventilation during nighttime to solidify the PCM and releases this cold stored to the inner environment during the peak demand period. It is crucial to decide correctly the schedule of charge and discharge process of the PCM according to the weather and indoor conditions. An experimentally validated numerical model is used to test the performance of the control algorithm under different weather conditions. Important improvements on the energy savings due to the use of control strategies were found and supported by the data under the different tested climatic conditions. [ABSTRACT FROM AUTHOR]

The European Performance of Buildings Directive (EPBD) set the regulatory framework for a cost-effective improvement of the existing dwellings in 2002. The transformation of the stock towards higher efficiency is expected to be stimulated by labelling of the dwellings. The certificate itself is required to contain a list of potential cost-effective measures for the dwellings’ thermal retrofit. However, the theoretical heating consumption provided in the certificate is not a good baseline for the calculation of cost effectiveness, as it is based on normalised dwelling conditions. Normalised conditions include a constant occupancy, constant indoor temperature and normalisations of other parameters, which in reality differ in different types of dwellings. The discrepancies between the normalised theoretical and actual heating consumption are also referred to as the performance gap. In this paper, we examined these discrepancies using the example of The Netherlands. Using descriptive statistics and multiple regression, we investigated several parameters thought to have a different effect on actual and theoretical heating energy use – dwelling, household, occupant behaviour, as well as comfort – in order to propose improvements to the current theoretical consumption calculation. Aside from analysing the total sample, the data is regarded separately for overpredicted and underpredicted consumption records. [ABSTRACT FROM AUTHOR]

Passive Houses are buildings which provide comfortable indoor conditions at an extremely low heating and cooling load. The peak daily average heating and cooling loads are typically below 10 W/m 2 and annual useful energy demands are below 15 kW h/(m 2 a). The Passive House standard was originally developed in Germany. In this paper we show by hygro-thermal dynamic simulation that it is possible to realize residential Passive Houses in all of the world's relevant climate zones, represented here by Yekaterinburg, Tokyo, Shanghai, Las Vegas, Abu Dhabi, and Singapore. The window quality, insulation levels, and mechanical services all depend on the climate as well as on the building's shape and orientation. The resulting annual energy demand for space conditioning of the Passive Houses is 75 to 95% lower than that of a traditionally insulated building of the same geometry. In humid climates like Shanghai or Singapore, special attention must be paid to humidity aspects. In climates which are hot and humid all year long, the total useful energy demand for sensible and latent cooling may exceed 70 kW h/(m 2 a) even in a Passive House. Finally, it is shown that the architectural quality is not compromised by the Passive House requirements. [ABSTRACT FROM AUTHOR]

This paper discussed the influence of apartment location on household space heating energy demand per floor area in multi-apartment buildings. According to the actual data, apartment location has a significant impact on space heating consumption per floor area in multi-apartment buildings. Based on average data of each location, a corner unit on the top floor has a space heating consumption per floor area 26.1% higher than a center unit on the middle floor. For multi-apartment buildings, a correction should be made to reflect the effect of apartment location when billing is calculated from space heating consumption instead of floor area. Location correction factors (LCFs) of seven typical cities based on building type and building age were analyzed by calibrated simulation method. The study finds that LCFs for older buildings are smaller than those of younger buildings, varying from 0.8% to 15.3% for seven typical cities. As for different regions, the greater the heating degree day is, the larger the location correction factor (LCF) is, with the deviation among 5.7–14.4%. LCFs can provide a billing-tool to make a fair allocation of heating costs, which may promote the reform of heat metering and billing in China. [ABSTRACT FROM AUTHOR]

This paper evaluates potential energy savings associated with dynamic insulation materials (DIMs) – material assemblies that can change their thermal resistance through a controlled exchange of liquid or gaseous media – in the exterior walls of buildings. In the analysis, a two-step control strategy is considered to modify the R -value of DIMs based on the temperature difference between internal and external wall surfaces. Using a simulation environment capable of modeling DIMs, a comparative analysis is carried out to evaluate the impact of DIMs on the heating and cooling energy end-uses for single-zone residential buildings in three US climates. Several design and operating conditions are considered to assess the performance of DIMs and their potential energy use savings. The results indicated that variable thermal resistance envelope materials (RSI-0.5/RSI-2.5) have the potential to reduce annual cooling energy use in residential buildings on average by 15% and up to 39% for all three US climates and annual heating energy use by 10% on average for mild US climates depending on the window sizes and internal heat gains. [ABSTRACT FROM AUTHOR]

Wireless sensor network (WSN) for building applications has been considered by many HVAC experts as an efficient tool to promote building energy efficiency and indoor thermal comfort. This paper, therefore, proposes a strategy of using WSN to monitor the temperature distribution in a large-scale indoor space, which aims to (i) improve the quality of the measurements transmitted by wireless signals, (ii) identify the temperature distribution pattern of the large-scale space, and (iii) optimize the allocation of supply air rated flow rate to multiple supply air terminals that serve the space according to the identified temperature distribution pattern. The developed strategy is illustrated by applying it to a real WSN test bed, installed in a typical large-scale space in Hong Kong. Results are presented and discussed, which shows that the phenomenon of temperature uneven distribution was commonly existent in a large-scale space and the developed strategy was able to efficiently improve the quality of measurements by WSN and improve the temperature homogeneity in the large-scale space. [ABSTRACT FROM AUTHOR]

Storage tanks are widely used in heat pump driven heating systems. In this application, storage tanks can: reduce the number of times the heat pump compressor starts; adapt the capacity of heat generation to heat demand; which can offer the possibility to use low rate electricity. This last point will assume increasing importance as smart grids become more prevalent. Floss and Dietrich (Optimierte integration von Pufferspeichern in hydraulische Systeme, in: Proceedings of the International Congress e-nova 2008, Pinkafeld, Austria, 2008, pp. 129–136, ISBN 978-3-9500919-8-4) points out that due to different effects such as mixing or heat conduction inside the tank, the supply temperature at the consumer is lower than the outlet temperature of the heat pump. The average (mass flow weighted) of this temperature drop was named drop of mean temperature (DoMT). It varies between 0.2 °C and 10 °C, depending on the hydraulic integration inside the storage tank, and can reduce the efficiency of the system up to 30%. This paper discusses options to reduce the DoMT, thereby raising the efficiency of the heat pump system through an optimized integration of storage tanks, and a variation of the mass flow rate in the hydraulic system. These results are based on theoretical and practical investigations undertaken at the Institute of Building Energy Systems, University of Applied Sciences, Biberach, Germany. [ABSTRACT FROM AUTHOR]

The damper used for the control of airflow in heating, ventilation and air conditioning systems can constructively be adapted to measure the air velocity with its moment characteristic. It is a device that indirectly determines the air velocity by measuring the position of the blades and the air stream moment acting on it. The subject of this paper is energy consumption of the air torque position damper depending on its structure. The aim is to compare the energy consumption of four possible types of dampers with non-cascading blades: with one blade, with two cross-guided blades, with two parallels-guided blades and with two blades, one of which is a measuring blade and the other remains fixed in horizontal position. The case when there is a straight section of a duct both in front of and behind the damper was considered. Adequacy of the existing mathematical model and energy consumption for all four types of dampers was determined experimentally. It was found that the damper with two blades of which one is a measuring blade and other remains fixed in horizontal position had minimal energy consumption. [ABSTRACT FROM AUTHOR]

Although China's heat metering technology has developed rapidly in recent years, the improvement demonstrates an unbalance in different provinces. It is of great significance to outlook application and sustainability of heat metering technology in various regions technically. Taking the sustainability of heat metering technology as research object, the author establishes a sustainable evaluation model in this paper. Factors in the evaluation model are assigned through a main questionnaire and actual application of typical projects. A pecking-order contrast method is adopted to determine weights of factors in the evaluation model, correspondingly sustainable development of heat metering in various locations is assessed. Sustainability scores in three regions (Northeast, Northwest and North China) are obtained via evaluation model. The model owns high accuracy compared with results of heat metering work assessment by the Ministry of Housing and Urban-Rural Development (MOHURD). The heat metering in the three regions score 60, 62 and 75, respectively, implying that the sustainability in the northeast and northwest is unsatisfactory but in north is somehow better. It is suggested that envelope heat insulation should be increased in the northeast region, while policy support and heat metering technology ought to be enhanced in the northwest. [ABSTRACT FROM AUTHOR]

Conventional weather-compensated heating controllers are often configured to deliver more heating than necessary, resulting in energy losses. Furthermore, they cannot take into account future climate conditions, and yield less than optimal thermal comfort. We have developed a non-invasive add-on module for existing heating controllers that implements an adaptive, model-predictive heating control algorithm. This algorithm helps the heating controller deliver a heating energy just sufficient for maintaining thermal comfort, resulting in energy savings. In this paper we report on the energy savings measured on ten buildings equipped with this device. By monitoring the space heating energy during the 2013–2014 heating season, and by periodically alternating between the new controller and the reference controller, we establish the energy signature of all buildings with both controllers. The comparison of the energy signatures yields the relative energy savings achievable with the new controller. These energy savings are positive for all test sites, with a mean of 28 ± 4% (standard error of the mean). [ABSTRACT FROM AUTHOR]

An experimentally validated numerical model is developed to study the effects of seven design and operational parameters on the heating performance of a solar chimney incorporated with phase change material (PCM) in this paper. It is found that when the latent heat increases from 70 to 170 kJ/kg, the melting time is increased by 103% and freezing time is prolonged by 60%. If heat flux is increased by 33%, the melting time is reduced by 36.4%. Increasing thermal conductivity of the insulation material from 0.02 to 0.06 W/m K, the melting time is prolonged by 47.2%. When absorptivity of the absorber is increased from 0.8 to 1.0, the melting time is decreased by 26.3%. When transmissivity of the glass cover is increased by 25%, the melting time is reduced by 26.7%. For the inlet air temperature, when it decreases from 25 to 15 °C, the freezing time is shortened by 39%. The melting time is only reduced by 8% when thermal conductivity of the absorber is increased by 25 times. Therefore, it can be concluded that the first six parameters have more impact on the system's performance while the thermal conductivity of absorber slightly impacts it. [ABSTRACT FROM AUTHOR]

Temperierung refers basically to wall heating through pipes mounted in or on the inside of the walls. In the context of heritage preservation the Temperierung system was mainly developed by the State Office for Non-State Museums in Bavaria for heating and climatization of museums and exhibit buildings. Based on the ongoing research project “Temperierung as a Tool for Preventive Conservation—An Assessment” a close and interdisciplinary collaboration is established between building physicists, conservators and practitioners from 18 selected museums. The paper highlights the different existing Temperierung systems within the project, main components of the system and different types of application. The main principles of the technique are explained and compared to more commonly known heating systems like convector/radiator heating and wall/floor heating. Preliminary results of the measured indoor climate and effects of the Temperierung heating system of several chosen museums are presented. The impacts of the indoor climate to the conservation of artifacts, influenced by Temperierung heating, are discussed with typical methods of indoor climate assessment and with conservational assessment. The detailed and neutral description of Temperierung heating gives a basis for planners and persons in charge for retrofitting historical museum buildings. [ABSTRACT FROM AUTHOR]

Energy performance simulation is a generally used method for assessing the energy consumption of buildings. Simulation tools, though, have shortcomings due to false assumptions made during the design phase of buildings, limited information on the building's envelope and installations and misunderstandings over the role of the occupant's behaviour. This paper presents the results of a Monte Carlo sensitivity analysis on the factors (relating to both the building and occupant behaviour) that affect the annual heating energy consumption and the PMV comfort index. The PMV results are presented only for the winter (heating) period which is important for energy consumption in Northern Europe. The reference building (TU Delft Concept House) was simulated as both a Class-A and a Class F dwelling and with three different heating systems. If behavioural parameters are not taken into account, the most critical parameters affecting heating consumption are the window U value, window g value and wall conductivity. When the uncertainty of the building-related parameters increases, the impact of the wall conductivity on heating consumption increases considerably. The most important finding was that when behavioural parameters like thermostat use and ventilation flow rate are added to the analysis, they dwarf the importance of the building parameters. For the PMV comfort index the most influential parameters were found to be metabolic activity and clothing, while the thermostat had a secondary impact. [ABSTRACT FROM AUTHOR]

The paper presents the results of the analysis of the impact of various ventilation systems on the energy consumption performed for one Polish museum building that was built in 1929–1930. Simulations were carried out with the use of two computer codes: CONTAM and ESP-r. Multi-zone models including the exhibition rooms and the staircase were prepared. The simulations were made of synthetic weather data for one of the Polish towns for two months of the heating season. Twenty-four hour variability of internal heat gains was taken into account. The results show clearly that the natural ventilation system (which is currently used in the building) enables the air exchange with fresh air on the first floor only. The air infiltration on the upper levels is close to zero. Rebuilding the ventilation system generates changes in the energy demand of the building. It is presented how the heat demand increases with the increase of the ventilation air flow and what is the impact of the air infiltration on the heat demand for different variants of ventilation. [ABSTRACT FROM AUTHOR]

To foster the transition to more sustainable energy systems, policymakers have been approving measures to improve energy efficiency as well as promoting smart grids. In this setting, building managers are encouraged to adapt their energy operations to real-time market and weather conditions. Yet, most fail to do so as they rely on conventional building energy management systems (BEMS) that have static temperature set points for heating and cooling equipment. In this paper, we investigate how effective policy measures are at improving building-level energy efficiency compared to a smart BEMS with dynamic temperature set points. To this end, we present an integrated optimisation model mimicking the smart BEMS that combines decisions on heating and cooling systems operations with decisions on energy sourcing. Using data from an Austrian and a Spanish building, we find that the smart BEMS results in greater reduction in energy consumption than a conventional BEMS with policy measures. [ABSTRACT FROM AUTHOR]

Climate change has been shown to significantly alter the heating and cooling needed to maintain thermal comfort within a home. However, limited studies have investigated the impact on the design philosophy associated with achieving an energy efficient building envelope with the onset of climate change. Applying robust future TMY for 2070 the change in heating and cooling demand has been studied in this paper for various combinations of external and internal wall insulation, roof insulation, reflective foil, thermally reflective roofs and different floor coverings. A building thermal model was used for the mild temperate climate of Adelaide, Australia, which requires both heating and cooling, but is dominated by heating. Climate change was found to increase and shift this demand to cooling dominated. It was determined that with climate change, heating becomes significantly less important in better insulated buildings and therefore measures which reduce cooling load are more critical. It is concluded that in this climate zone, climate change design approaches need to dramatically change to focus on cooling, contrary to present strategies. [ABSTRACT FROM AUTHOR]

The accuracy in assigning a climatic zone to a city is essential for studying the correct sizing of domestic hot water, heating, and cooling systems, as well as of construction materials. In Spain, the current system for allocating climate zones is one proposed by the Código Técnico de la Edificación (Technical Building Code) (CTE) and includes a method based on Royal Decree 235/2013, Procedimiento Básico para la Certificación de Eficiencia Energética de Edificios de los Edificios (Basic Procedure for Certification of Energy Efficiency of Buildings), as well as on the recognized document CERMA to calculate energy demands, CO 2 emissions, and energy ratings. The climatic data of cities is not always available, so the CTE method has proposed some solutions, but they are not always precise enough. In this paper, we propose an alternative classification of climatic zones as a result of applying a new method based on approximation and interpolation functions, with a maximum error of 5.773e − 15 in summer and 6.661e − 16 in winter. This new method has been applied and tested in Andalusia in Southern Spain, a region with 772 municipalities. According to the climatic data available, the new proposed method has resulted in more precise climatic zones than the two versions of the CTE (2009 version and the 2013 update). The results are closer to reality, and the method is exportable to any region. [ABSTRACT FROM AUTHOR]

The earth–air heat exchangers (EAHE) are promising technology for passive heating/cooling of buildings. The study carried out to evaluate annual thermal performance of EAHE system for hot and dry climatic conditions of Bhopal (Central India) has been presented in this paper. A quasi-steady state, 3-D model based on computational fluid dynamics (CFD) was developed to evaluate the heating/cooling potential of EAHE system. The simulation results were validated against experimental observations taken on experimental set-up installed in Bhopal (Central India). The energy metrics namely energy payback time (EPBT) and seasonal energy efficiency ratio (SEER) for EAHE system were evaluated on the basis of energy analysis of simulation results. The embodied energy for the EAHE system was evaluated as 1663.88 kW h. The maximum heating potential and cooling potential of EAHE obtained in the months of January and May, respectively, were calculated as 191.06 kW h and 247.25 kW h. The total yearly energy output of EAHE system for air flow velocity of 5 m/s was found as 1290.53 kW h. The EPBT of EAHE system was calculated as 1.29 years. The SEER for typical summer and winter months were calculated as 1.34 and 1.10, respectively. The CO 2 emission mitigation potential and the total carbon credits earned from EAHE system were calculated as 101.30 tonnes and Rs 1, 72,817.80 ($2837.60), respectively by considering its life span as 50 years. [ABSTRACT FROM AUTHOR]

The paper presents the results of 1-year measurement of indoor environment parameters (temperature, relative humidity, CO 2 concentration) in exhibition rooms of one Polish museum in various periods of the year, and the results of simulation on thermal model of this building. The influence of a temperature control scheme in museum rooms on heating and cooling demand was analysed. The actual state (poor control of internal temperature) and ideal control of internal temperature were analysed – two cases in the winter and two cases in the summer. Simulations were performed by ESP-r program. The multi-zone model of the building was validated based on measurement data. Measurements and simulations revealed significant variations in the temperature in the rooms of the museum. The analysis showed that the maintaining internal temperature at constant level of 20 °C in winter reduces monthly heat demand in most of the exhibition rooms. Obtained effect is 5–16% depending on the premises. Provision the raise of a temperature by 1 K results in the increase of heat consumption by 6%. Maintenance of a desired internal temperature, which does not exceed 24 °C in the summer, requires the provision of coolness to the museum premises. [ABSTRACT FROM AUTHOR]

The Chinese Kang, a traditional heating device, is widely used in northern rural China. It recovers the heat from cooking smoke and provides local thermal comfort to people sitting or lying on it. However the heat supply ability of the traditional Kang is limited due to constraints of the surface temperatures and heat transfer coefficients. In this paper, a new Chinese Kang with forced convection (CKFC), which adopted hot water as the heat transfer medium and added a small fan to enhance convective heat transfer, was developed. A full-scale CKFC system was constructed for actual application in a rural house and its thermal performance was measured. Experimental data show that during the space heating period, the heating power of forced air convection ranged from 625 W to 1170 W, while that through the CKFC surfaces was only 200–500 W in the local heating or space heating mode to maintain local thermal comfort. Meanwhile, the CKFC retained the merits of a traditional Kang by providing local thermal comfort. The measured asymmetry of Kang plate surface temperatures was 6.7 °C. Overall, the CKFC has satisfactory performances as a new heating terminal device in rural houses. [ABSTRACT FROM AUTHOR]

Following the electric load (FE) and following the thermal load (FT) strategies both have advantages and disadvantages for combined cooling, heating and power (CCHP) systems. In this paper, the performance of different strategies is evaluated under operation cost (OC), carbon dioxide emission (CDE) and exergy efficiency (EE). Analysis of different loads in one hour is conducted under the assumption that the additional electricity is not allowed to be sold back to the grid. The results show that FE produces less OC, less CDE, and FT produces higher EE when the electric load is larger. However, FE produces less OC, less CDE and higher EE when the thermal load is larger. Based on a hybrid electric–thermal load (HET) strategy, compromised electric–thermal (CET) strategies are innovatively proposed using the efficacy coefficient method. Additional, the CCHP system of a hotel in Tianjin is analyzed for all of the strategies. The results for an entire year indicate the first CET strategy is the optimal one when dealing with OC, CDE and EE. And the second CET is the optimal one when dealing with OC and EE. Moreover, the laws are strictly correct for different buildings in qualitative terms. [ABSTRACT FROM AUTHOR]

The paper examines implementation of heat saving measures in buildings in 2050, under the assumption that heat and power supply comes solely from renewable resources in Denmark. Balmorel – a linear optimisation model of heat and power sectors in Denmark is used for investigating economically viable levels of heat savings, which can be implemented by reducing heat transmission losses through building elements and by installing ventilation systems with heat recovery, in different future Danish heat and power system scenarios. Today almost 50% of heat demand in Denmark is covered by district heating. A further expansion of district heating network in Denmark is assessed and penetration of heat savings is analysed in this context. If all heat saving measures, included in the model, are implemented, heat demand in Danish buildings in 2050 could be reduced by around 40%. Results show that it is cost effective to reduce from approximately 12% to 17% of future heat demand in buildings depending on assumed lifetime and costs of heat saving measures. Individual heating areas have higher penetration of heat savings than district heating areas. When district heating systems are expanded, an overall penetration of heat savings slightly decreases along with lower capacity investments and system costs. [ABSTRACT FROM AUTHOR]

For military and disaster relief housing, rapidly deployable shelters must be lightweight, be packaged in a small volume for transportability, and be erected without heavy lifting equipment. A critical design criterion is also energy efficiency in heating and cooling. To meet these priorities, the research team has utilized origami as inspiration for a thermally insulated rigid wall deployable shelter that can be erected manually through counterweighting. To enhance energy efficiency, improvements in the shape of a structure (i.e., member lengths and angles) at a design stage can lead to savings throughout its lifecycle. This is magnified in the context of mass-production of deployable shelters, where any improvements are multiplied. Structural efficiency is also critical to achieve lightweight design. This paper presents a multi-objective shape optimization methodology which balances the priorities of structural performance (i.e., minimum deflections) and energy efficiency (i.e., minimum thermal energy load). This is demonstrated for the case study of a deployable shelter. Design variables include geometric parameters. Constraints relate to the package size and capability of interfacing with existing technologies. Structural analysis is performed using a parametric finite element program. Thermal energy is calculated using EnergyPlus. An optimized solution is found and compared against existing military solutions. [ABSTRACT FROM AUTHOR]

The coefficient of performance (COP) of air-source heat pumps (ASHP) decreases toward low outdoor temperatures. This paper presents an auto-cascade heat pump system (ACHPS) with the objective to improve the heating performance of ASHP in cold climate. The auto-cascade process is achieved based on the separation of binary zeotropic refrigerant mixture consisting of pure refrigerants with different boiling points. Fluid selection for the ACHPS is carried out to validate the feasibility for potential application. Based on the performance analysis on COP, 15 qualified binary mixtures are obtained. R143a/R600 (0.8/0.2) tops the potential working fluid with a COP of 2.15. The effects of system parameters, such as circulation composition, heat transfer fluid (HTF) temperature glide and temperatures of heat source and sink on COP and exergy efficiency of ACHPS are thereafter investigated. The simulation results show that there exist a maximum COP of 2.15 and a maximum of exergy efficiency of 37.2% at the R143a mass fraction of 0.8 when the ambient temperature and heating temperature are −10 °C and 50 °C, respectively. Finally, by comparison with the single-stage heat pump operating with commercially available refrigerants, the proposed ACHPS shows an advantage of compressor isentropic efficiency. The compression isentropic efficiency of ACHPS could be increased by 25.5% compared to the single stage cycle working with R407c when the ambient temperature is −10 °C. [ABSTRACT FROM AUTHOR]

Being increasingly insulated, new buildings are more and more sensitive to variations of solar and internal gains. Due to an important use of electrical heating systems, especially in housing, France is facing a growing problem of peak load on its electricity grid. Controlling the heating system often constitutes an efficient solution to shift heating loads while maintaining indoor comfort. The proposed energy management is a predictive set of optimal commands issued from a dynamic programming optimization knowing in advance the weather, occupancy and internal gains for the next 7 days. This method is tested on a low energy house situated in France with an annual heating demand of 14 kWh/m 2 . In this paper, load shifting according to utility rate incentives and carbon emissions are studied. The importance of building models as well as envelope insulation and thermal mass on energy management results is shown. [ABSTRACT FROM AUTHOR]

Several studies have shown that the actual energy performance of buildings can differ significantly from its designed value. An important part of this performance is constituted by the building fabric's thermal performance. A common method to evaluate the latter for an actual building is the co-heating test. The co-heating test comprises a quasi-stationary heating experiment followed by linear regression analysis of aggregated building performance data. This paper reviews related research work and cristallises the current state-of-the-art. The physical phenomena working behind the scenes of the generally assumed simplified heat balance are discussed. Statistical constraints generally prevent these from being uncovered fully during the analysis. Multiple linear regression is proposed as the most sensible method to analyse co-heating measurement data. A novel way to visualise such analysis, deduce building performance data graphically and compare different co-heating test results is presented. [ABSTRACT FROM AUTHOR]

This paper proposes a new method for an optimal control of the heating system at the building scale. This control is a new approach of energy planning that aims to decrease the heating consumption/expenses over a defined prediction horizon while respecting the occupants’ thermal comfort. It employs a simplified building thermal model to simulate the building thermal behavior taking into consideration the weather predictions. This approach is based on the application of Monte Carlo method, i.e., a random generator for the heating system scenarios. The aim is to determine the optimal heating plan for the prediction horizon that fulfills the constraints regarding the thermal comfort of occupants and the minimization of the energy consumption/expenses together with achieving a load shedding. [ABSTRACT FROM AUTHOR]

[Display omitted] • In the US, carbon savings are readily achievable by transitioning to heat pump technologies for the vast majority of homes. • The heat pump performance required to achieve carbon and cost neutrality varies by a factor of four across the US. • Energy cost neutrality is much harder to achieve than carbon neutrality. • Achieving carbon and energy costs savings is much easier when replacing older, low efficiency equipment. In order to meet climate goals, it will be necessary to significantly reduce the greenhouse gases emitted by homes. A key factor in the US is to reduce the on-site combustion of fossil fuels for heating end-uses and to replace this with use of electric heat pump technologies connected to a low-carbon grid. The replacement of natural gas furnaces with electric heat pumps is a key home decarbonization strategy. However, the potential for space heating electrification to reduce greenhouse gas emissions depends on the carbon dioxide equivalent (CO 2 e) content of the electricity used by the heat pump. This varies considerably depending on the source of electricity, with large state to state variability. Furthermore, household energy costs are likely to be impacted by the electrification of space heating, because retail energy prices for both natural gas and electricity in each state vary by factors of seven and four, respectively. Contractors, energy programs, government and building code officials, as well as consumers need clear indications of the likely CO 2 e and energy cost impacts of proposed electrification projects, because these will affect decarbonization choices and rationales around scaled heating electrification. Government and utility programs also need to be aware of the likely outcomes of any supported/incentivized measures. In this paper, we investigate these effects by looking at new metrics to analyze the change in CO 2 e emitted and the cost to meet home heating loads when switching from a natural gas furnace to a heat pump for the contiguous 48 states of the mainland US. [ABSTRACT FROM AUTHOR]

• Occupants on-demand heating control behavior in a rural residential building is investigated. • Independently controlled split-type heating equipment were used to elucidate actual demand patterns. • Data collection over three years under an interference avoidance scheme. • Five representative intermittent heating patterns were obtained from a real-world case study. A better understanding of actual heating demands is crucial for optimizing operational heating systems, because disparities between expected load and actual demand are key factors in inefficient heating system design, implementation, and corresponding energy loss. Additionally, the discrete, energy consumption-based billing systems applied to freestanding rural residential buildings encourages reductions in energy waste but produces spatially and temporally distinct heating patterns. Conventional heating systems have only basic controls and slow response times that cannot reflect actual user demand. Hence, this paper presents an experimental scheme for measuring room-wise heating demands, and thus, the actual heating demand patterns of rural residential buildings. A case study was conducted on a typical rural residential building in Beijing to validate the method's feasibility. Real-world usage patterns were obtained using indoor environment sensors and independently-controlled heating devices that collected the operational parameters of each room over three years, in a long-term non-intervention study design. Clustering analysis and various indicators were used to characterize heating demand for each room: heating patterns, usage intensity, and temporal variation. In most case, the occupants heated only a few rooms, rather than the whole building. These results have potential real-word implications for predicting occupant heating behavior and energy conservation. [ABSTRACT FROM AUTHOR]

[Display omitted] The rapid development of urbanization has created high demand for central heating systems. This trend has led to an increase in energy consumption for central heating, which has made China's energy-saving transformation extremely difficult. However, the channel by which urbanization impacts and the future trends of energy consumption for central heating are still unclear. Therefore, this study employs the Logarithmic Mean Divisia Index (LMDI) method to decompose the effect of urbanization on changes in energy consumption for central heating during 2001–2019 in China. We investigate the contribution of urbanization from demographic, economic and spatial perspectives. Additionally, a scenario analysis is used to explore trends in energy consumption for central heating in different projected urbanization scenarios. The results show that urbanization has a positive impact on energy consumption for central heating, particularly in underdeveloped regions. Demographic urbanization has the strongest positive effect on energy consumption for central heating, followed by spatial urbanization and then economic urbanization. Compared with the expansion of area and economic development, population agglomeration will bring more energy consumption for central heating. The forecasting results indicate that energy consumption for central heating will reach 176–189 Mtce in 2030, which is approximately 1.4 times the current level. This work quantifies the energy consumption for central heating in the future under urbanization. The policy recommendations given at the end of the paper will provide a reference for the formulation of energy consumption for central heating. [ABSTRACT FROM AUTHOR]

Network hydraulics play a major role in the design and operation stage of District Heating (DH) systems, considering further hydraulic complexities expected in the near future. This paper presents a mathematical solution procedure that computes the network hydraulics, tailored as unique to the principal basis behind the branched type of DH networks. The procedure makes use of simple input data (i.e., pipe-node list) to obtain the mathematical description of the network layout via detection algorithms for the incidence and the loop matrices (the pseudo-code given). The matrix-based solution procedure was formulised to detect the network flow and pressure distributions either by use of the Newton-Raphson or genetic algorithms, based on the conservations of mass and energy. The problem formulation was maintained as correcting the end-user flow rates that satisfy the energy conservation throughout the closed loops of the network, which sped up the convergence to a solution. The developed model was used in a case study consisting of 220 × 2 pipe segments (supply and return) and 214 end-users, the results being obtained in 35.5 s via the Newton-Raphson algorithm. Despite the sensitivity analysis, the genetic algorithm was found to have premature convergences under various trials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heating system is the most crucial parameter for renovation. • Deep renovation is neither cost-effective nor climate-friendly considering future uncertainties. • Heating system replacement alone has lower overall emissions than solely envelope renovation. Buildings are responsible for a large share of CO 2 emissions in the world. Building renovation is crucial to decrease the environmental impact and meet the United Nations climate action goals. However, due to buildings' long service lives, there are many uncertainties that might cause a deviation in the results of a predicted retrofit outcome. In this paper, we determine climate-friendly and cost-effective renovation scenarios for two typical buildings with low and high energy performance in Switzerland using a methodology of robust optmization. First, we create an integrated model for life cycle assessment (LCA) and life cycle cost analysis (LCCA). Second, we define possible renovation measures and possible levels of renovation. Third, we identify and describe the uncertain parameters related to the production, replacement and dismantling of building elements as well as the operational energy use in LCCA and LCA. Afterwards, we carry out a robust multi-objective optimization to identify optimal renovation solutions. The results show that the replacement of the heating system in the building retrofit process is crucial to decrease the environmental impact. They also show that for a building with already good energy performance, the investments are not paid off by the operational savings. The optimal solution for the building with low energy performance includes the building envelope renovation in combination with the heating system replacement. For both buildings, the optimal robust cost-effective and climate-friendly solution is different from the deep renovation practice promoted to decrease the energy consumption of a building. [ABSTRACT FROM AUTHOR]

• The cascaded PCMs charge–discharge processes and cycle entransy models are studied. • To run stably and efficiently, the charge–discharge cycle model is recommended. • The thermal performance of cascaded PCMs may be worse than that of single PCM. • The cascaded PCMs is suitable for scenes with large temperature differences. • In heating systems, the total NTU of cascaded PCMs is recommended between 4.5 and 6. Thermodynamic analysis can guide the application of the cascaded latent heat storage system (CLHSS) for space heating. However, in previous studies, the CLHSS charge–discharge process and the cycle are not distinguished, and the applicability of the corresponding models is not analyzed. In addition, the technical advantages of CLHSS in heat utilization are still unclear. This paper solved the above three problems to provide theoretical guidance of the CLHSS integrated into heating systems. First, the CLHSS charge–discharge cycle is the special charge–discharge processes in which the initial and final states of each PCM are consistent. The CLHSS charge–discharge processes and cycle models are established and optimized. Second, the optimization results of charge–discharge processes model cannot ensure the same initial and final states of each PCM, which leads to unstable operation and performance degradation of the CLHSS. Thus, the CLHSS charge–discharge cycle model is recommended. Third, when the total number of heat transfer unit (NTU) of CLHSS is less than that of single-stage latent heat storage system (SLHSS), the thermal performance of CLHSS may be worse than that of SLHSS. Besides, the use of CLHSS instead of SLHSS is suitable for scenes with large temperature differences between heating equipment and heating terminals. Finally, parameters effects on optimization results are analyzed. From the perspective of improving entransy efficiency, it is recommended that the total NTU of CLHSS during charge process and discharge process are between 4.5 and 6, and as close as possible. [ABSTRACT FROM AUTHOR]

• Sleeping thermal comfort using a bed-based ASHP was numerically studied. • A digital thermal manikin (DTM) was used to simulate a sleeping person. • The PTS - WPD model was used to evaluate sleeping thermal comfort. • Four factors affecting sleeping thermal comfort were numerically analyzed. Sleeping is an important human activity and heating system is needed for a comfort sleeping thermal environment in winter. By combining the merits from both an air source heat pump (ASHP) and a Chinese-Kang heating system, a prototype bed-based ASHP (B-ASHP) system has been proposed, and several design/operating parameters were experimentally and numerically studied previously. A numerical study using a digital thermal manikin (DTM) on the impacts of four influencing factors, i.e., operating mode, bed surface temperature (t bed), thermal resistance of mattress (R mat), and thermal resistance of quilt (R q) on sleeping thermal comfort was carried out, and the study results are reported in this paper. The numerical study results suggested that firstly, to maintain a suitable sleeping thermal environment, the use of only the Horizontal section (H-Section) of the bed-based heating terminal of the B-ASHP system was adequate; however using the Horizontal and Vertical section (H + V-Section) could minimize the temperature difference between the micro-climate close to the bed and outside environment, although with a higher energy consumption. Secondly, t bed of the bed-based terminal should be carefully selected, and a t bed of 44 °C could both meet the requirement of thermal comfort and acceptable operating efficiency of the B-ASHP system. Thirdly, the use of a mattress would reduce the heat transfer from the bed-based terminal to a sleeping person and indoor space, however an excessively higher R mat of mattress would reduce the heating capacity and operating efficiency, leading to a cold sleeping environment. Finally, the use of a quilt would help prevent the heat loss from a sleeping person, thereby maintaining a warmer sleeping thermal environment, however a higher-than-necessary R q of quilt would decrease the sleeping thermal comfort. [ABSTRACT FROM AUTHOR]

• The comprehensive survey on individual household heating in Serbia. • Results reveal barriers and opportunities for the successful energy transition. • The obsolescence of HSs, low efficiency, and lack of funds are evident. • Noticeable potential for achieving energy and GHG savings. • Subsidies and raising environmental awareness are recognized as policy measures. This paper presents the results of the household survey on individual household heating systems in Serbia. The survey was conducted in the period October to December 2020 with the participation of 1100 households with individual household heating systems. The information collected in the questionnaire can be separated into three main parts: basic household data, current heating system characteristics, and households' perceptions and attitudes. The survey results provide unique and comprehensive information concerning individual household heating systems and the main barriers and drivers for a successful energy transition in the future. The results show the obsolescence of household heating systems, low efficiency, insufficient investment in thermal insulation in the past, and lack of financial resources for investing in sustainable heating. On the other hand, this survey highlights the positive attitude of about half of households towards potential subsidizing of the cost of new heating systems. This survey presents a valid starting point for defining instruments aimed to improve energy efficiency in the household sector, diminish its influence on climate change, and secure energy transition towards sustainable heating systems. The obtained results should be indicative for middle-income developing countries at the beginning of the energy transition process. [ABSTRACT FROM AUTHOR]

• A comprehensive overview of various modeling methods for BTES is presented. • Validated against the TRNSYS DST model and real-life monitoring data. • Three operation strategies of BTES in DH system are investigated. • Six building insulation and weather scenarios to increase the results' robustness. • The time-scheduled combined control strategy is more beneficial among all scenarios. This paper presents a modeling and simulation method that supports energy performance assessment and operation strategy investigation of borehole thermal energy storage in the Chifeng district heating (DH) system. A living laboratory in Chifeng, China that integrates a 0.5 million m3 borehole thermal energy storage system, an on-site solar thermal plant and excess heat from a copper plant is presented. The research adopts Modelica models from open source libraries to evaluate the system. The validity of the borehole thermal energy storage model is evaluated through an inter-model comparison study and an empirical validation test. We used the validated model to investigate three operation strategies. We conclude that the time-scheduled combined operation strategy is more beneficial for the studied system regarding CO 2 emission reduction. [ABSTRACT FROM AUTHOR]

In the current economic situation in Ukraine, the operation of heat supply systems occurs at a reduced temperature of circuit water. The increased temperature graph of 95/70 °C due to the high cost of fuel is impractical. The experience of such countries as Denmark, Germany, Finland, Sweden and Holland with developed centralized heat supply indicates the need for the first-class equipment of an individual heating point (IHP) of a building with an automatic control system, and then the transition to technology with a reduced temperature graph is carried out. Therefore, the modernization of heat supply systems in Ukraine aimed at the use of a reduced temperature graph will require a transition to closed independent heating systems, to qualitative and quantitative regulation and to automation of consumer IHP systems. A lot of district heating systems in Poland also require modernization to meet the requirements of the European Directive EED 2018/2002. This paper presents the results of numerical study of the influence of design and operating parameters of the heat supply network on the choice of the optimal temperature and flow- rate of circuit water of a distric heating system (DHS). [ABSTRACT FROM AUTHOR]

• Novel energy conservation measure yields up to 12% of energy savings. • Grey-box data-driven model efficiently models monozone building. • Building energy consumption optimized while satisfying thermal comfort constraints. • Energy consumption of a commercial building is optimized during winter and summer. This paper proposes a novel energy conservation measure that optimizes the planning of heating and cooling systems for tertiary sector buildings. It consists of a model-based predictive control approach that employs a grey-box model built from the building and weather data that predicts the building heat load and indoor temperature. Different from classical optimization approaches where the discretized differential algebraic equations are integrated into the optimization formulation, our model is calibrated using black-box multiobjective optimization, which allows for decoupling the predictive model from the optimization problem, thus having more flexibility and reducing the total computational time. Moreover, rather than requiring the angle of solar radiation, solar orientation and solar masks to calculate the radiation data, our approach requires only a simple model of the solar irradiance. The calibrated model is then used by heating and cooling optimization strategies that aim at reducing the energy consumption of the building in the next day while satisfying the indoor thermal constraints. The proposed approach was applied in a case study of a commercial building during heating and cooling seasons and the results show that it was able to yield up to 12% of energy savings while having a mean power forecast error of 8%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Waste heat seasonally stored in the subsurface provides a source of renewable energy. • Borehole thermal energy storage (BTES) can reduce space heating GHG emissions. • BTES integrated with heat pumps has a potential to deliver building heat economically. On average, fossil fuel space heating constitutes 56% of a building's total energy usage in Upstate New York due to the cold winter climate. Similar levels of fossil fuel heating pertain in at least 15 states in the U.S. northern tier. To meet aggressive carbon reduction goals in this tier, decarbonizing the heat supply in the residential and commercial sector must be pursued. Using Borehole Thermal Energy Storage (BTES) to seasonally store excess thermal energy in the subsurface for later heating use is an innovative way to increase heating efficiency and lower carbon emissions. This paper investigates the technical and economic feasibility of heating Snee Hall on Cornell campus with unused summer steam from Cornell's Combined Heat and Power Plant stored in an optimized BTES array. Snee Hall is a 6855 m2 building with an annual total heating load of 3040 GJ. A standard 2-D transient subsurface conductive heat transfer model is coupled to a high temperature heat pump (delivering > 60 °C) that can supply Snee Hall's existing radiators with 70 °C water. For local geological parameters, 94% of Snee Hall's winter space heating demand can be supplied by a 37-borehole array (90 m depth, 3 m spacing) and a 250-kW high temperature heat pump capacity with average coefficient of performance of 3.85. The calculated storage efficiency is 68.7% and the system has a 30-year net present value of about $526,400, an internal rate of return of 13%, and a payback period of 10 to 11 years. The system offsets about 6900 MMBTU (7280 GJ) of natural gas combustion and saves 250 MT CO 2 emissions annually. The results of the single building analysis can be applied to other buildings on campus or in similar geologic settings in the U.S northern tier. [ABSTRACT FROM AUTHOR]

• Three inverse modelling approaches are used to create radiant heater virtual meters. • Zone models using steady-state and transient greybox approaches are developed. • Zone models using water side load disaggregation approach are developed. • Virtual meters accuracy is used to evaluate the performance of the models. • Modelling approaches' data requirements, data processing, and accuracy are compared. Virtual metering at the equipment level provides a non-intrusive tool to understand energy flows in commercial buildings and monitor building energy performance. The accuracy of virtual meters depends on the modelling approach and its ability to capture the underlying physical processes. This paper presents a novel comparison and provides guidance for the selection of inverse modelling approaches used to create virtual meters to estimate the heat supplied by zone-level hydronic perimeter heaters. The approaches investigated are: steady-state inverse greybox modelling, transient inverse greybox modelling, and water-side load disaggregation. Models that represent these three approaches are trained using data from a highly instrumented academic building in Ottawa, Canada. Model parameters are identified using the genetic algorithm and used in creating virtual meters that can estimate the heat added by perimeter heaters into building variable air volume zones. The accuracy of these virtual meters is assessed by comparing them to physical meters installed in these zones. The results indicate that the three modelling approaches can estimate the daily heating energy supplied by perimeter heaters at a normalized root-mean-square error between 16% and 18%. However, the accuracy of the virtual meters declines as the number of zones increases. The performance of the three modelling approaches is evaluated through illustrative examples that compare modelling assumptions, data requirements, data processing, and model prediction accuracy. [ABSTRACT FROM AUTHOR]

• A hybrid optimization algorithm in online optimization of MPC is proposed. • A distributed MPC for multi-zone buildings existing input coupling is studied. • Nash-optimization acts on enhancing the control performance in distributed MPC. • The redefined global performance index provides the possibility to save energy. To meet demands of smart heating development, the novel dynamic regulation methods of heating systems need to be pursued. This paper presents a model predictive control (MPC) approach for room temperature regulation in multi-zone buildings. Among them, a) For heating systems with nonlinearity and large time delay, a hybrid optimization algorithm consisting of the improved particle swarm optimization (IPSO) algorithm and Newton-Raphson (NR) method in online optimization of MPC for a single zone building is proposed. Compared with the quadratic programming method, it can identify successfully the optimal control vector. b) A distributed MPC approach is presented for multi-zone buildings existing hydraulic coupling. Firstly, Nash-optimization acts on searching the global equilibrium point in the distributed structure, then the hybrid optimization algorithm works in the online optimization of these local MPCs. Compared with the decentralized MPC, the control performance is improved through co-operating and communicating between subsystems via network to share information related to their future behavior. Besides, the global performance index in the distributed MPC is redefined as the weighted sum of energy consumption and thermal comfort, which provides the possibility to eliminate quickly the most unfavorable thermodynamic loop in heating systems and reduce energy consumption. [ABSTRACT FROM AUTHOR]

• Control strategy of the heating of an all-air system in an educational building is optimized. • A nearly zero energy educational building in Belgium is used as case study. • Winter monitoring campaign is analysed and a building energy simulation is calibrated. • Climatic control of the boiler causes a decrease of comfort hours up to 23%. • Climatic control of the storage tank determines energy saving until up to 47%. The optimal control of the HVAC system in the nearly zero energy buildings (nZEBs) can be considered as a challenge. Indeed, the lack of data given by monitored data does not allow understanding what are the implications of different strategies on thermal comfort and energy consumptions. This paper determines an approach for the evaluation of the management of the heating system in an existing educational nZEB. The aim is to understand how the energy efficiency of the heating system is sensitive to controls strategies and the important role played by the control systems. The test lecture rooms on KU Leuven Ghent Technology Campus (Belgium) have been chosen as case study. A deep analysis, starting from an in-field monitoring, was carried out during the winter period of 2019, in order to assess the actual operation and the energy use of building systems under real conditions. Then, a building energy simulation (BES) model of the building and its systems was developed and calibrated against the real monitoring data. Control strategies of the heating system are simulated and compared to the current configuration. The simulation results show that strategies based on a definition of a heating curve for the boiler can reduce the comfortable time (−23%). Controlling the temperature inside the storage tank as a function of the outdoor temperature together with the control on the activation of the air handling unit result in an energy savings from 32% to 46%, with a correspondent increase of comfort time in the period from 0.6% to 3.4% compared to the baseline scenario, depending to the relationship between the external temperature and water temperature inside the water storage tank. [ABSTRACT FROM AUTHOR]

• Listed dwellings of southern Spain were monitored in winter to evaluate IEQ and EP. • Lengthy high rates of IRH were observed. • High levels of CO 2 concentration were recorded in bedrooms at night. • Thermal comfort is only achieved through a constant use of the heating systems. • Heat losses are entirely building-driven. Although European heritage buildings are excluded from energy efficiency targets, it would be beneficial to include the largest group, that of listed housing, in energy retrofit plans, in order to encourage its occupation and contributing to the sustainable maintenance of historic cities. This requires reliable experimental studies, which have been rare so far, in order to establish energy rehabilitation plans that do not jeopardize the conservation of their values. This paper aims to contribute to addressing this gap. It evaluates the energy performance and indoor environmental quality of dwellings within listed buildings of the conservation area of Seville, Spain, in the Mediterranean climate zone, under actual winter use and occupation conditions. An experimental campaign was conducted, generating energy models and measuring rates of indoor air temperature to validate them. The findings highlight important health and environmental issues: despite the mild winters of southern Spain, intensive use of the heating system is needed to maintain thermal comfort indoors, increasing polluting emissions; CO 2 concentration in bedrooms is usually excessive overnight and, regularly, indoor relative humidity remains too high; heat losses depend entirely on the physical condition of the constructive elements (walls, roofs, air leakage and glazing) which occupants cannot easily improve. [ABSTRACT FROM AUTHOR]

• Wall-type heat recovery units are solution for improving ventilation in refurbishment. • Assessment of air stream mixing by visualization and CO 2 measurements was conducted. • The risk of air mixing when using wall-type heat recovery units is low. • The analysis of the annual energy demand for residential buildings was conducted. • Wall-type heat recovery units are helpful in achieving low energy buildings. In the cold and moderate climates the energy demand for heating of fresh ventilation air is crucial. The mechanical ventilation systems with heat recovery are used to decrease the peak power of the heating system and to save the energy. In a case of wall-type heat recovery units there is a doubt about the possibility of mixing fresh and exhausted air in the combined intake-outtake device. In this paper experimental investigations were conducted to assess their hygienic safety. The original set-up containing test chamber and the equipment for CO 2 concentration measuring has been used. Visualization of airflows mixing with the usage of smoke is presented. The results show that the risk of the exhausted air return to the building is low. At the same time the ventilating efficiency of such systems is high. The analysis of the annual energy demand for the sample single-family and multi-family buildings has been conducted to present the possible energy benefits of usage such devices. Concluding, the wall-type heat recovery units should be considered as hygienic safe and helpful devices in achieving the standard of low energy buildings in a case of existing and refurbished ones. [ABSTRACT FROM AUTHOR]

• Solar assisted heat pump coupled to a seasonal storage allows heating production. • Seasonal storage of thermal energy is technical and economically feasible. • Seasonal storage is able to be implemented in middle latitude. • PVT panels performance increase with the inclusion of a seasonal storage tank. • Key sizing factors are solar field area, volume of storage and capacity of heat pump. A water-water solar-assisted heat pump (SAHP) is projected on an under construction academic building at the University of Zaragoza (Spain). It integrates a heat pump heating system with photovoltaic/thermal collectors and seasonal storage. Because of its innovative design, considerably higher performances than a conventional type air-source heat pump are expected. This paper shows the simulation of the system performed in TRNSYS, a graphically based software used to simulate the behavior of transient systems. In addition, starting from the current design of the energy system, different sensibility analysis are simulated in order to study alternative configurations of the heating system. The solar coverage of the current installation design is about 60% and the expected savings yield to a payback period of 15,4 years. Three alternative configurations are proposed in this work, reaching up to around 98% of solar coverage. The study results show the technical and economic feasibility of the heating installation based on a solar assisted heat pump with implementation of seasonal storage in an educational building located in a middle latitude. [ABSTRACT FROM AUTHOR]

• Demand-Side-Management with air-to-water heat pump in a Nearly-Zero-Energy-Building. • Model Predictive Control with Artificial Neural Network for heat demand prediction. • Variation of storage capacity and heat pump power shows cost savings up to 24.3% • Market based concepts need further incentives to exploit the flexibility potential of heat pumps. The rollout of the supply dependent generators wind turbines and photovoltaics leads to a flexibility demand that can be adressed from the consumer side, via Demand-Side-Management, as well. In single family houses, the heat pump, in combination with thermal energy storage, can shift their energy comsumption according to price signals in order to reduce consumer costs. This paper analyses the impact of different heat storage sizes and heat pump powers on cost savings and shifting potential, focussing on the Luxembourgish context, when variable electricity prices based on the electricity market are applied. A model predictive controller determines the cost-optimal operating cycles of the heat pump. The building's heat demand is predicted with the help of a neural network. The results of the parametric study show significant differences in energy efficiency and cost savings. Furthermore limitations of taking advantage of variable electicity prices due to the price structure are disclosed. The cost savings however do not give a sufficient incentive for the consumer to invest in optimizing the heating system for Demand-Side-Management purposes. By consequence, the potential and the efficiency of Demand-Side-Management are limited and further incentives are necessary. [ABSTRACT FROM AUTHOR]

• An optimized operation strategy is proposed for ASHP heating of school buildings. • Effects of different combinations of start-up times and return water temperatures on power consumption are compared. • A longer warm-up time with a lower water temperature can save more energy. Air-source heat pump (ASHP) has been widely applied in heating systems of school buildings. In order to achieve building energy efficiency while ensuring indoor thermal comfort, the paper compared the effects of different operation strategies including intermittent heating mode in non-working hours and setpoint of return water temperature in working hours. A middle school building in Tianjin, China is chosen as a case study and its physical model is developed by using the EnergyPlus tool. After verifying the validity of the model, the article simulated 64 different operation conditions produced by combining 8 start-up times with 8 return water temperature setpoints to find a better operation mode of the intermittent heating. Results indicate that running at a lower water temperature with an earlier start-up time is more energy efficient compared with running at a higher water temperature with a later start-up time while meeting the thermal comfort requirement. In addition, by changing the return water temperature setpoints hourly based on the outdoor air temperatures, the situation of overheating and undercooling during working hours has been well improved and the energy saving rate is about 17% during the entire heating season. [ABSTRACT FROM AUTHOR]

The paper analyses effects of changes in temperatures on heating and cooling demands in Europe until 2050. Specifically, the study addresses changes in trends (10-year mean) and extremes (10-year min/max). The analysis is based on two GHG emission climate scenarios (RCP2.6 and RCP4.5) and eight high-resolution regional climate models and results are provided as relative and absolute changes on grid and country scales. Population density is used as proxy for spatial distribution of demands. Projected future temperatures are proportional with RCP scenario and distance into the future and the highest relative changes occur towards north-eastern Europe and for high-altitude areas. The temperature changes lead to general decreased heating demands and corresponding increased cooling demands. In general, higher spreads are seen between demand change ratios for individual models when addressing extremes as opposed to trends: The general 2010–2050 change ratios for heating between countries are 0.85–95 for model means and average 0.69 for the extreme analysis. For cooling, corresponding ratios are 1.25–1.5 for model means and average 2.76 for model maxima. For absolute demand changes, some countries are projected to experience significant changes e.g. exceeding a doubling in cooling demands. The results are suggested as a basis for energy system analyses. [ABSTRACT FROM AUTHOR]