Low-temperature Heating System Research Articles

Resilient energy management of a multi-energy building under low-temperature district heating: A deep reinforcement learning approach

The corrective control of a building-level multi-energy system (MES) for emergency load shedding is essential to optimize the operating cost after contingency. For a Danish case, the heating devices in the building are connected to a developing low-temperature district heating (LTDH) system and operated under a heat market. Due to the coupling between the electrical power and heating system, an electricity outage can be propagated to the heating network, and heat prices as well as tariffs can impact the MES operating cost. In the previous studies, only electrical load shedding is modeled, while the impact of electricity outages on heating system operation and heat load control is ignored. On the other hand, the problem is traditionally solved by model-based optimization methods which are highly nonconvex leading to high computing complexity. Moreover, operating uncertainties can lead to infeasible solutions. To address these challenges, this paper proposes a deep reinforcement learning-based corrective control method for the resilient energy management of a building-level MES. In the method, the proximal policy optimization algorithm is applied, where multiple uncertainties, system dynamics, and operating constraints are considered. A case study of a real-life residential building connected to the LTDH system in Denmark is carried out, where electricity outages are simulated. The results verify the performance of the proposed method in achieving resilient energy management of the MES.

Model of the non-stationary thermal processes in the ground heat pump system

One of the main directions for improving heat supply systems is the tendency to switch to low-temperature heating systems by using heat pump units is the tendency of implementation the low-temperature heating systems based on the use of heat pump units. In the work, the main attention is focused on the improvement of thermal parameters and circuit design features of elements of the heat pump system of heat supply using soil energy. For this purpose, the toolkit of mathematical modelling of processes in ground heat pumps is applied, taking into account the climatic conditions of Ukraine. The paper proves the technical possibility of creating an autonomous system of alternative heat supply for energy-saving technologies with the possibility of using ground energy, taking into account environmental requirements. It is substantiated that the use of the proposed systems is a promising direction for Ukraine, which is experiencing a shortage of its own energy resources, because it provides an opportunity to increase the share of organic fuel substitution and reduce the volume of heat emissions into the environment. A mathematical model of heat processes in the elements of the heat exchange equipment of the heat pump system based on renewable energy (soil energy) and secondary energy (wastewater) was developed, taking into account environmental requirements (preventing hypothermia of the soil during the operation of soil pipes and damage to vegetation, respectively), which allows choosing a rational mode of operation of the system under seasonal climatic changes and technological conditions. Numerical modelling of heat processes in elements of the heat exchange equipment of the heat pump system using groundwater and waste water was performed, and the energy and environmental efficiency of the system under variable climatic and technological factors was determined. Analysis and generalization of the calculation results of the heat pump heat supply systems using alternative energy based on the proposed mathematical model, taking into account environmental requirements (preventing thermal relaxation of the soil) allows to take into account the change in the temperature gradient around the soil heat exchanger and more accurately determine the heat flow from each section of the heat exchanger. It has been established that for heat pumps with soil heat exchangers, the maximum substitution ratio of the traditional fuel is 75 %, and the economically feasible quantity of soil heat exchangers is 9 units. Heat pumps using waste water can completely replace traditional heat supply systems. For individual consumers, it is possible to recommend heat pump units with soil heat exchangers, at the same time, it is necessary to provide a backup source of energy to increase the reliability of heat supply.

Analysis of thermotechnical characteristics of the thermoelectric film heating system

Modern world trends in increasing the energy efficiency of heat supply systems, in particular, are aimed at decentralizing the supply of heat to consumers, and also involve the use of low-temperature heating systems. The Institute of Technical Thermophysics of the National Academy of Sciences of Ukraine together with the specialists of the Department of Thermal and Alternative Energy of the National Technical University of Ukraine “Ihor Sikorskyi Kyiv Polytechnic Institute” carried out scientific research and analysis of the main thermal characteristics of the electrothermal film heating system (model ZHDM-WM-220-180 /225/270) and accessories for it manufactured by ZHONGHUI (HEILONGJIANG) UNDERGROUND HEATING CORPORATION (People's Republic of China). The results of the study of the main thermal technical characteristics of the thermoelectrical film heating system are given. The analysis of the design of the heat-dissipating mat showed relatively high reliability of its components and acceptable operational characteristics for various objects of the housing and communal economy.

Quantifying the decarbonization potential of mobile heat battery in low-temperature district heating

This research assesses the potential of a mobile thermochemical storage system, the mobile heat battery (M-HB), for decarbonizing a low-temperature district heating (DH) system in the Netherlands. The assessment is built on a case study where the M-HB is used to transport waste heat from different sources to a neighborhood interface of a DH system. This case study utilizes a simulation-based methodology to calculate the emissions from grid electricity, DH, and M-HB transport and charging. Building performance simulation is used as the main experimental method in combination with both empirical data and theoretical assumptions. Various system operational strategies and uncertain factors are explored, and waste heat sources are screened by different decarbonization targets. Findings indicate that using the M-HB can reduce the operational carbon emissions by up to 80 %, from approximately 60–70 KgCO2/GJ of the system without M-HB to around 13 KgCO2/GJ in optimal scenarios. Emissions from M-HB transport and charging are identified as more influential to the decarbonization potential than other considered factors, which addresses the significance of choosing proper waste heat sources. Despite some limitations from data availability and assumptions, this work identifies both opportunities and challenges for using M-HB to decarbonize DH systems.

Dynamic performance analysis of a new low-temperature nuclear heating system with APROS

ABSTRACT Pool-type low-temperature heating reactor (PLTHR) has attracted considerable attention throughout the world due to its low operating parameters and satisfactory inherent safety in district heating. Exploring the dynamic performance of PLTHR is a prerequisite for designing control systems and developing operation strategies. Until now, the dynamic performance of the district heating system using a 400 MW pool-type low-temperature heating reactor (DHR-400) has not been fully discussed. Based on APROS software, a precise dynamic model for DHR-400 is constructed in this paper. The dynamic responses of DHR-400 under five external variables such as control rod reactivity, first loop flow rate, second loop flow rate, third loop flow rate, and return temperature at the third loop are investigated. The results revealed that the core power variation is not linear with the flow rate variation at the three loops. Core power variations are −16.27, −14.04, and −20.96 MW with a 30% reduction in flow rate at the first loop, the second loop, and the third loop, respectively. Considering safe operation, when there are minor fluctuations in the heating demand, the core power regulation method by adjusting the third loop’s flow rate should be given priority without altering the position of the control rods.

Assessment of the impact of setting the heating curve on reducing gas consumption in a residential building while ensuring thermal comfort

Due to the large share of the residential building sector in CO2 emissions, it is necessary to look for quick-to-implement and cost-free solutions for heating systems aimed at increasing their efficiency and reducing fuel consumption. The aim of the study is a multi-aspect assessment of the proper setting of the heating curve in the weather controller of a low-temperature floor heating system with a condensing gas boiler, and an analysis of the impact of the heating curve slope on the natural gas consumption, the emission of gaseous and dust pollutants and on maintaining appropriate indoor air parameters: air temperature, operative temperature and PMV and PPD. A wide range of simulation tests were carried out using the TRNSYS software for an existing energy-efficient single-family residential building, with mechanical ventilation with heat recovery, located in north-eastern Poland in Bialystok. Changing the heating curve slope by 0.1 can reduce gas consumption and pollutant emissions by 1.6–10.3 %. Low heating curve slopes may result in failure to reach the temperature set by users (difference between the set and achieved indoor temperature up to 1.9 K), while maintaining standard thermal comfort parameters (−0.5<PMV<+0.5; PPD<10 %). Reducing the indoor air temperature by 2 K can contribute to reducing gas consumption by 11 % while maintaining standard thermal comfort parameters. Changing the heating curve slope is one of the effective methods of reducing fuel consumption in the building. Results are useful for users of buildings equipped with low-temperature heating systems with floor heating and installers of these systems.

Decreasing the Return Temperature in District Heating Networks Thanks to a Switch to Alternative Substation Architectures

District heating networks (DHN) are key systems for managing heating and reducing carbon emissions at a large scale. Therefore, increasing their efficiency is a key to reduce climate change. DHNs with centralized production are supplying hot water to building substations (interface between the DHN and the buildings) for domestic hot water (DHW) production and space heating (SH) using heat exchangers. Colder water is returned to the centralized district heating system by the return pipe. One of the crucial factors to improve the efficiency of DHNs is to decrease the return temperature in the network to keep the same amount of energy transferred to the buildings while reducing the thermal losses and the flow rate, leading to more savings. In this paper, we model and simulate two of the most common DHN substation architectures used in a typical third-generation DHN to identify their flaws and propose new district heating substation architectures that can increase the DHN efficiency. The main result from our study is the consistent reduction in the average return temperature across all scenarios when implementing our proposed architectures. The reduction ranged between 3.7 °C and 10.2 °C. We also found that the lower the heating temperature, the greater the reduction. This is particularly beneficial as buildings are increasingly equipped with low-temperature heating systems, especially new constructions. Moreover, these architectures showed optimal efficiency with new buildings that have a high water heating demand compared to heating demand. This is due to the higher impact of cold water preheating.

Possibility assessment of the low-temperature district heating systems implementation in Ukraine

These researches concern the application of renewable energy sources in district heating systems. In Ukraine, district heating systems cover approximately 50% of the demand for thermal energy in the residential and communal sector. District heating systems 2G are most often used, which are characterized by high temperatures of the heat coolant, the lack of accounting for heat energy consumption during transportation of the heat coolant, and the use of fossil fuels. In the countries of the European Union, the introduction of district heating systems is considered one of the key directions for the transition to a decarbonized, environmentally safe and efficient energy system. The development of district heating systems technologies makes it possible to lower the temperature of the heat coolant in heat networks and increase the use of renewable energy sources. Ukraine will eventually become a full-fledged member of the European Union, and this determines the need to find ways to bring Ukraine's heat supply systems to the 4G level, in particular to low-temperature district heating systems with the most efficient use of renewable energy sources and waste heat. This article examines climatic, physical-geographical and social features, regulatory, technical and financial-economic opportunities and barriers to the implementation of low-temperature district heating systems in Ukraine. As a result of analytical studies, it was established that there are prerequisites for the introduction of low-temperature heat supply systems in Ukraine, however, a number of technical, regulatory, social and financial and economic measures need to be implemented to bring district heating systems up to 4G indicators. These studies allow establishing measures that require further research for the possibility of introducing low-temperature district heating systems in particular and environmental safety of heat supply systems in general.

Impact of Flexibility Implementation on the Control of a Solar District Heating System

Renewable energy sources, distributed generation, multi-energy carriers, distributed storage, and low-temperature district heating systems, among others, are demanding a change in the way thermal networks are conceived, understood, and operated. Governments around the world are moving to increase the renewable share in energy distribution networks through legislation like the European Directive 2012/27 in Europe, and solar energy integration into district heating systems is arising as an interesting option to reduce operation costs and carbon footprint. This conveys an important investment that adds complexity to the management of thermal networks and often delays the return on investment due to the unpredictability of renewable energy sources, like solar radiation. To this end, this paper presents an optimisation methodology to aid in the operative control of an existing solar district heating system located in the northwest of France. The modelling of the system, which includes a large-scale solar field, a biomass boiler, a gas boiler, and thermal energy storage, was previously built in Dymola. The optimisation of this network was performed using MATLAB’s genetic algorithm (GA) and running the Dymola model as functional mock-up units, FMUs, using Simulink’s FMI Kit. The results show that the methodology presented here can reduce the current operation costs and improve the use of the daily storage of the DH system by a combination of mass flow control and the implementation of a flexibility function for the end-users. The cost-per-kWh was reduced by as much as 16% in a single day, and the share of heat supplied by the solar field on this day was increased by 5.22%.

Modeling of thermal processes in vertical heat exchangers of ground-source heat pump

The basic directions for perfection heat supply systems are the tendency of transition to the low-temperature heating systems based at application heat pump installations. We consider heat supply systems with ground-source heat pump. The paper considers modeling the efficiency of ground-source heat pumps with the account of Ukrainian climate conditions. The paper presents the energy performance criteria which show the way to rational implementation of ground-source heat pumps for heating. A computational model based at non-stationary heat exchange processes in elements of ground-source heat pumps is developed. Generalization and analysis of theoretical and experimental dates allow establishing nature of dependence thermophysical properties on temperature insoil around ground heat exchangers during long term operation of the system. Numerical simulation of thermal processes in vertical ground pipes for ground-source heat pump working with low-temperature heating systems has been worked out. The results of numerical modeling demonstrated perfection and technical adaption of ground-source heat pump for low-temperature heating systems with rational using ground energy potential. The novelty of our method is complex usage theoretical and experimental results which enable to prevent freezing in the ground during long term exploitation This provides insights at effects of different resource mixes and may serve as a new approach to analysis of future heat pump systems using ground source energy development.The proposed method contributes to the field of creation and implementation the sustainable heating technologies using renewable energy sources. The ground heat exchange pipes quantities that are necessary for effective operation heat pump installation, capacity and coefficient of performance with the account of climate conditions are calculated.

Heat losses of low-temperature radiant heating systems

There is a consensus among stakeholders that nearly zero energy buildings (nzeb’s) represent a step forward towards low-carbon societies. The envelope of nzeb’s is well insulated, so there are cases when the external building elements are used as radiant heating surfaces (floor, ceiling, and walls). There is little information about the heat losses of the low-temperature radiant heating systems installed on the inner surface of the external opaque building elements. The purpose of this study was to quantify and compare the energy used for heating in the case of traditional radiator heating and three different radiant heating modes. The calculation methodology was validated by laboratory measurements. Three different thermal requirements related to the building envelope have been assumed and two different heat sources, so 24 different cases have been analyzed in detail and the energy used was compared. The switch-on and switch-off temperatures were determined using the heat gains utilization factor calculated on a daily basis. It was shown that the energy used for heating in the case of radiant heating (taking into account the delivered heat and the heat losses) exceeds the energy used in the case of radiator heating. In the case of nzeb’s the difference is the highest and may reach even 23.2%–24.8%.

Small-scale experiments on the operational performance of a lightweight thermally active building system

Thermally active building systems (TABS), which are integrated with the structure of a building, provide a robust approach for utilising renewable energy. However, reinforced concrete, where TABS are typically placed, is responsible for a significant proportion of initial embodied energy and related greenhouse gas emissions. Therefore, combining lightweight structural elements and thermal systems reduces initial embodied energy usage while retaining the active material’s thermal storage and heat transport benefits. The present experimental work explores the operational performance of a prototype of a lightweight TABS at ceiling level. A small-scale climate chamber was constructed and equipped to evaluate the prototype in the key operating modes. The study investigated the relationship between the supply temperature of the lightweight TABS and the climate chamber’s internal air temperature for active heating, active cooling and natural ventilation modes. The experiments compared the reaction time in active heating mode for a range of supply temperatures. In addition, we examined the dynamic characteristics of the thermal mass of the lightweight TABS in passive natural ventilation mode and passive cooling mode in the presence of an internal thermal load. The results provide insights into the dynamic performance in operation. In heating mode, we identified the time lag between the radiant surface achieving a steady state and the conditioned air reaching its target temperature. This feature emphasises the significance of refining control strategies when designing comfortable environments with low-temperature heating systems at ceiling level. Further, we highlighted the importance of balancing decisions on minimising embodied energy with the suitability of the selected material to leverage renewable energy sources. The experimental data can be used for validating high-resolution numerical models, which support the development of multifunctional elements with renewable energy sources for building heating and cooling.

New multi-energy sources coupling a low-temperature sustainable central heating system with a multifunctional relay energy station

Due to short cost-effective heat transportation distance, the existing geothermal heating technologies cannot be used to develop the deep hydrothermal type geothermal fields situated far away from urban area. To solve the problem, a new multi-energy source coupling a low-temperature sustainable central heating system with a multifunctional relay energy station is put forward. As for the proposed central heating system, a compression heat pump integrated with a heat exchanger in the heating substation and a gas-fired water/lithium bromide single-effect absorption heat pump in the multifunctional relay energy station are used to lower return temperature of the primary network step by step. The proposed central heating system is analyzed by using thermodynamics and economics, and matching relationships between design temperature of return water and main line length of the primary network are discussed. The studied results indicate that, as for the proposed central heating system, the cost-effective main line length of the primary network can approach 33.8 km, and the optimal design return temperature of the primary network is 23 ℃. Besides, annual coefficient of performance and annual exergy efficiency of the proposed central heating system are about 3.01 and 42.7%, respectively.

Analysis of a small-scale modified beam-down solar concentrator system for low temperature applications

A small-scale beam-down solar concentrator (BDSC) without a receiver concentrator (RC) was studied for the first time for its applicability to low-temperature heating systems. A comprehensive theoretical model was developed that combines solar ray tracing with existing BDSC models to include solar angle variations for different days in a year at any location. The model allows the estimation of image magnification based on the heliostat area and the resultant uniform solar enhancement area on the RR. A test setup with a footprint area of 2.25 m2 and a tower height of 1.5 m, consisting of 11 heliostats, a single hyperbolic central mirror, and a RR, was built and tested to validate the model. It was found that cosine efficiency is an essential factor that dictates the system's performance. Increasing the number of mirrors from 11 to 41 showed the number of suns on the RR will increase from 1.45 to 4.5. A 22% reduction in total insolation on the RR was observed at solar noon due to the shadow of the central mirror, suggesting a prominent effect of shadow in small-scale BDSC systems. The system analyzed could achieve temperatures up to 200 °C, making it suitable for low-temperature applications.

Smart heat tariffs in transition to free market

Innovative pricing mechanisms should motivate heat suppliers and consumers to move toward more sustainable energy systems and introduce low-temperature district heating systems and sector coupling in smart energy systems. Therefore, district heating regulation regimes should also be changed to stimulate transformations in the energy sector. The district heating tariffs depend on many factors, including fuel prices, operational parameters, taxes, investments, and other criteria. Therefore, an analysis of the DH tariffs has been implemented to find solutions to motivate DH enterprises towards energy efficiency and climate neutrality. The analysis results are based on the decision-making assessment approach by selecting various criteria and evaluating them from five significant aspects: engineering, environmental, climate, economic and socioeconomic. The central elements within the developed fuzzy cognitive mapping model are investment costs, heat production costs, and primary energy consumption. Considering the set boundary conditions, the most beneficial method for smart heat tariff definition could be heat tariff benchmarking with integrated energy efficiency standards for DH operators.

Multiobjective optimization and analysis of low-temperature district heating systems coupled with distributed heat pumps

Developing district heating can help decarbonizing energy systems. Modern concepts of district heating revolve around low operational temperature to reduce heat losses and enhance the efficiency of the supply plants with technologies such as cogeneration, condensing boilers or geothermal heat pumps. However, temperature reduction in district heating networks may be limited by technical requirements on the building side. Booster heat pumps on the end-users’ side can be a solution to bridge the network-building temperature gap. However, the current state-of-the-art on such systems does not provide ways for optimizing in real-time the operating temperature, which is needed to fully exploit its benefits, and proposed control strategies focus solely on reducing costs without considering environmental aspects. This article proposes a new multi-objective optimization framework to determine the real-time supply temperature for low-temperature district heating with booster heat pumps. The optimization approach uses rolling horizon and both operating costs and GHG emissions are minimized simultaneously. The model on which the optimization relies includes efficiency curves for equipment and water transport delays in the network. Many scenarios are simulated to understand how key factors affect the optimal supply temperature, such as the fuel type (i.e., wood chips or natural gas), price of electricity, emission factor of electricity, and relative weight of costs and emissions in the objective function. Results show that the proposed framework can indeed reduce costs and emissions, but the viability of the system depends strongly on the above-mentioned factors. In the case-study with typical electricity costs and emissions for Quebec (Canada), the average operating temperature could be reduced to 42 and 66 °C depending on the type of boilers in the system. While emissions were always smaller than with a conventional network, operating costs could be higher (with wood chip boiler) or lower (with natural gas boiler). This work can contribute to the deployment of efficient low temperature networks.

Capacity and operation optimization of a low-temperature nuclear heating system considering heat storage

Integrating heat storage devices with the pool-type low-temperature heating reactor (PLTHR) can improve the flexibility of PLTHR for load following. A novel low-temperature nuclear heating system (HST-NHS) is proposed, which combines the DHR-400 heating reactor system, a heat storage tank (HST), and a gas boiler (GB) to achieve real-time matching between heating supply and demand. A mixed integer nonlinear programming (MINLP) optimization model with the annual cost (AC) as the optimization objective is established. An operation strategy that considers the device priority is proposed. The capacity and operation of HST-NHS are simultaneously optimized using the CPLEX solver. The optimization results indicate that an HST with a rated capacity of 1324.14 MWh and a GB with a rated capacity of 201.69 MW can provide the operational flexibility needed for the HST-NHS throughout the heating period. When compared with comparison schemes 1 (DHR-400 and HST), 2 (DHR-400 and GB), and 3 (pure gas boiler heating system), HST-NHS achieves significant annual cost savings. Finally, a sensitivity analysis of device price and fuel price is conducted, revealing that the unit price of the DHR-400 heating reactor system and natural gas price are the main factors affecting the AC and dynamic payback period (DPP) of HST-NHS. This work offers theoretical guidance for the subsequent engineering application of the DHR-400 heating reactor system.

Energy, exergy analysis and optimization of insulation thickness on buildings in a low-temperature district heating system

In the study, energy and exergy analysis of the buildings on a campus in Turkey are conducted by using actual operating data and taking measurements in the district heating system as a case study. The energy and exergy demands, losses that stem from all buildings are calculated according to average daily outdoor temperature data. Due to the high heat losses in the buildings, determining the optimal insulation thickness for the exterior wall should be investigated. Therefore, optimal insulation thicknesses, energy savings, fuel consumptions and payback periods of the insulation material on the exterior wall of the building are examined by using Life Cycle Assessment and P1–P2 method for natural gas. Optimal insulation thicknesses are calculated for different insulation materials such as XPS, glass wool, rock wool and EPS for the climatic regions (HDD=800–4250°C days). According to average exergy losses from the building components per unit area, the average total exergy loss is calculated as 2.39×10-2 kW/m2.year and 1.42×10-3 kW/m2 (5.92%) of this loss stems from the exterior walls, 1.93×10-3 kW/m2 (8.07%) from the floors, 7.37×10-4 kW/m2 (3.08%) from the roofs, 1.58×10-2 kW/m2 (65.99%) from the windows and doors, 4.04×10-3 kW/m2 (16.92%) from the ventilation with infiltration. Energy requirement values of the building are found between 2.68–25.70 kWh/m3 towards from the warmest to the coldest climatic region for the uninsulated wall. In the un-insulated state, fuel consumption varies between 1.93-18.48 m3/m2 from the warmest to the coldest region. The optimal insulation thickness values of the building’s exterior wall are calculated as between 2.3–10.0 cm according to different climatic regions. In-state of exterior wall insulation of 3 cm, fuel consumption decreases by 46.63%–53.46% compared to different insulation materials and climatic regions compared to the un-insulated state.

Comparative Study on Boiling Heat Transfer Characteristics and Performance of Low-Temperature Heating System of R744 and Its Azeotropic Refrigerant

R744 is the most competitive and ideal natural refrigerant when flammability and toxicity are strictly limited. However, there are still some problems when it is applied to a heating system. For example, the discharge pressure of the system exceeds 10 MPa, it increases the cost of the system, and the cycle efficiency is also low. To solve these problems, this paper proposes to replace R744 by mixing R744 and ethane at a ratio of (77.6/22.4) to form an azeotropic refrigerant. At present, there is little research on R744 azeotropic refrigerant. Therefore, this paper first establishes the CFD model and compiles the UDF program to focus on flow boiling heat transfer characteristics, and then, it analyzes the performance of R744 and its azeotropic refrigerant in a low-temperature heating system. The results show that the heat transfer coefficient of R744 and its azeotropic refrigerant decreases with an increase in mass flux and increases with an increase in heat flux and saturation temperature; the heat transfer coefficient of azeotropic refrigerant is greater than R744; and there is no dryness under the same conditions. Under a given operating condition, there is a critical point that makes the performance of azeotropic refrigerant better than R744, and this critical point is related to the outlet temperature of a gas cooler, and the system discharge temperature of azeotropic refrigerant is significantly lower than that of R744. In conclusion, azeotropic refrigerant has certain advantages in heat transfer and system performance compared with R744, which will also play an important role in promoting the replacement of refrigerant in the future.

Predictive control of low-temperature heating system with passive thermal mass energy storage and photovoltaic system: Impact of occupancy patterns and climate change

With the increasing energy prices and growing concerns over energy security, an accelerated transition to net zero carbon built environment has never been more important. Many studies have shown the capabilities of advanced control strategies such as model predictive control (MPC) to achieve energy efficiency, balance with thermal comfort and air quality. It has also shown its capability to provide demand flexibility, minimising peak load demands and maximising the production of renewable energy sources in buildings. This work investigates the potential of integrating price-responsive MPC with a low-temperature heating system and passive structural thermal energy storage (STES). Integration with a photovoltaic (PV) system is also explored. The system performance under future climate conditions is evaluated considering different design and operating conditions, including different thermal mass, occupancy patterns and internal heat gains, setpoint strategies and operation temperatures of the low-temperature heating system. The coupled model developed has been verified and validated with numerical and experimental data, and good agreement is observed. The results showed that mediumweight thermal mass and a medium-temperature (45 °C) under-floor heating inlet temperature provided a higher load shifting ability, based on a realistic occupancy profile for a residential building and a high tolerance setpoint strategy during unoccupied periods. The result also showed that higher low-price energy usage and lower heating energy usage could be achieved in future climate conditions. Finally, an increase in the load shifting ability was observed after the integration of rooftop solar PV system.