Building Energy Supply Systems Research Articles

Feasibility study with EnergyPlus simulation for solar chemical heat pump unit introduced into building as next-generation energy supply system

From the viewpoint of rising energy demand and energy costs in buildings, there is an urgent need to develop next generation building energy supply systems characterized by improved resource efficiency and environmental friendliness. The solar chemical heat pump (SCHP) unit can provide heating and cooling in buildings with high efficiency and sustainability, positioning it as a potential candidate. A feasibility study is conducted to introduce the SCHP units into a building in Chiba, Japan, to evaluate the operating characteristics and energy-saving potentials. The building and its HVAC (Heating, Ventilation, and Air Conditioning) system featuring the SCHP unit are introduced into the building energy simulation through EnergyPlus software for the first-step examination. 3E (energy, environment, economy) analysis of the distinctions among conventional, chemical heat pump (CHP), and SCHP systems is conducted to enhance the efficiency of building energy supply systems. Furthermore, the effects of different climate zones and heat and electricity storage equipment on operation characteristics are studied. The study reveals that the SCHP system demonstrates a 75% lower energy consumption, 72% decreased CO2 emissions, and 73% reduced running costs than the conventional system in Chiba City. Moreover, it is shown that integrating the heat storage tank and the electricity storage battery into the SCHP system can reduce reliance on external energy, significantly enhancing the system efficiency.

Modeling and exergy-economy analysis of residential building energy supply systems combining torrefied biomass gasification and solar energy

A novel hybrid energy system driven by torrefied biomass gasification and solar energy is proposed for the first time, and their complementarity to enhance the system’s energy efficiency is analyzed and shown. The system mainly combines biomass torrefaction, biomass gasification subsystem, solar heat collection and absorption refrigeration technology. The effects of different operating parameters on the gasification products were studied. The economic analysis is carried out based on the theory of exergy economy. The results show that torrefaction pretreatment of biomass can significantly improve its fuel quality and gasification performance. With the increase of torrefied temperature, the volume fraction of CO2 and H2 decreased while the volume fraction of CH4 and CO increased. The economic analysis shows that the expected annual income is $72,735, and the investment recovery period is 2.89 years. Through the calculation of the energy-saving and environmental benefits, it can be concluded that the hybrid energy system can save 1.05 × 106 MJ of heat per year. This equates to about 358.26 tons of standard coal or a CO2 emission reduction of 550.59 tons, the participation of solar energy is conducive to the system emission reduction. By tuning the parameter sensitivity, the influence of biomass price change on the unit exergy cost of system products was more obvious.

Towards positive energy islands – a Danish case study

The Danish island of “Ærø” has the ambition of becoming the first Danish island to be self-sufficient in renewable energy and CO2 neutral by 2025, as well as fossil fuel free by 2030. This work investigates the feasibility of re-designing part of the island’s energy system to become the first Danish positive energy island (PEI), evaluating various design scenarios and opportunities for improving and modifying the current energy supply and distribution scheme. The district is modelled considering all building specifications and characteristics and the energy supply systems using the urban scale modelling tool City Energy Analyst (CEA). A simulation of the base-case scenario is performed to calibrate the performance. Different energy improvement strategies targeting building envelopes and energy generation and supply systems are created and implemented in CEA. Six improvement packages are created and simulated. It is demonstrated that a PEI could be built in the district under consideration through a comprehensive energy improvement package of envelope-targeting techniques, energy system upgrades, and the expansion of renewable energy systems. The package includes LED lighting, heat pump installation, and photovoltaic-thermal units. This will enable meeting the annual net need for electricity while producing 20% excess heat.

Retracted: Energy Efficiency Improvement of Composite Energy Building Energy Supply System Based on Multiobjective Network Sensor Optimization

Retracted: Energy Efficiency Improvement of Composite Energy Building Energy Supply System Based on Multiobjective Network Sensor Optimization

MANAGEMENT WITH FUZZY LOGIC OF ELECTRICAL ENERGY OBTAINED FROM SOLAR PANELS AND APPLICATION IN SMART HOME SYSTEMS

A smart building's (home) energy supply difficulties are considered, along with potential backup power sources. The components of a smart building's energy supply system and life support subsystem are examined, along with the roles allocated to the energy management system. It is also demonstrated whether such a system might be developed to reduce the amount of electricity and solar energy used in the building. The proposed form of the building automation system considers the properties of alternate power sources and potential use limitations. The use of fuzzy set theory in energy management strategies for smart buildings is demonstrated, along with the characteristics of such intelligent control. Keywords: Smart home, photovoltaic panel (PV), renewable energy, DC/DC converter, DC/AC inverter, fuzzy logic controller.

Application Research of PVT in Solar House R-CELLS

The application of PVT (Photovoltaic-thermal) technology is discussed based on R-CELLS, which is a zero-energy solar energy house at Solar Decathlon China 2021. Combined with the actual data, the simulation model of the PVT system, which supplies domestic hot water and heating bathroom, is established in TRNSYS, and the performance evaluation of the whole year and heating season and economic analysis of the whole life cycle is carried out at the same time. Comparing and analyzing the system with or without auxiliary heating in the water tank, the simulation results show that the annual average electrical efficiency of the system is 15.35% and 15.52%, the annual average thermal efficiency is 3.36% and 9.52%, and the payback period is 13.87 years and 12.12 years. By increasing the number of PVT panels, 4 PVT panels can achieve zero energy consumption of the system, and the payback period of the PVT system can be reduced to 6.5 years after continuing to increase. The small-scale PVT system is systematically analyzed based on a case, and the importance of water tank auxiliary heating design and supply-demand matching design in the PVT energy supply system is found through data comparison, which has reference significance for the promotion of PVT building energy supply system in the future.

Mixed-Integer Real-Time Control of a Building Energy Supply System

We present a methodology based on mixed-integer nonlinear model predictive control for a real-time building energy management system in application to a single-family house with a combined heat and power (CHP) unit. The developed strategy successfully deals with the switching behavior of the system components as well as minimum admissible operating time constraints by use of a special switch-cost-aware rounding procedure. The quality of the presented solution is evaluated in comparison to the globally optimal dynamic programming method and conventional rule-based control strategy. Based on a real-world scenario, we show that our approach is more than real-time capable while maintaining high correspondence with the globally optimal solution. We achieve an average optimality gap of 2.5% compared to 20% for a conventional control approach, and are faster and more scalable than a dynamic programming approach.

Operation mode performance and optimization of a novel coupled air and ground source heat pump system with energy storage: Case study of a hotel building

The problem of soil heat imbalance in traditional ground source heat pump (GSHP) systems in cold regions hinders the utilization of geothermal energy. This paper takes a hotel building energy supply system as an example to study the feasibility of a coupled air and ground source heat pump system with energy storage. The design intention of the proposed system was to add an air source heat pump (ASHP) and a water source heat pump (WSHP) as auxiliary heat sources to undertake part of the energy supply function of a GSHP. In winter, the system uses the ASHP as the low temperature heat source of the WSHP, so that its heating performance is basically not affected by extremely low outdoor temperatures, with an average system COP of 2.3. Combined with the energy storage (cold and heat storage), the “peak load shifting” of the power grid and the minimization of the system operation cost are realized. The simulation model of the novel system is established and verified by the monitoring data of the system. The operation mode is optimized to maximize the COP of the system, and the defrosting mode of the ASHP and soil heat balance were analyzed. The results show that the optimized defrosting control can increase the heating capacity of the ASHP by 13.9%. In addition, the proposed system can not only maintain the soil heat imbalance rate to 2.6%, but also reduce the operating cost. The calculation shows that compared with the traditional GSHP system, the annual operation cost of the novel system is only 58%, and the carbon emission can be reduced by 7.14%, which has good economic and environmental benefits. The popularization and application of this form of building system in cold regions has a high value.

Emergy analysis and optimization for a solar-driven heating and cooling system integrated with air source heat pump in the ultra-low energy building

In this paper, a solar-driven heating and cooling system integrated with air source heat pump is designed and applied to the ultra-low energy building. The heat and electricity from the compound parabolic concentrated-photovoltaic thermal collector are fed to air source heat pump to increase the efficiency of the air source heat pump. Integrating energy, social, environmental, and economic benefits of the system in the whole life cycle, an emergy-based optimization method is adopted to obtain the optimal configuration of the compound parabolic concentrated-photovoltaic thermal collector. Under the optimal configuration, the emergy performance of the designed system is analyzed, and the monthly emergy performance and the influence of investment cost and solar irradiation on the emergy performance are discussed. The optimization results show that when the photovoltaic coverage ratio is 1.0, the total emergy consumed by the designed system is the lowest, 2.64 × 1016 seJ/y, which saves 9.96% of emergy compared with the reference system. The environmental load ratio, emergy sustainability index, emergy investment ratio, and emergy yield ratio under optimal configuration are 126.62, 0.021, 0.62, and 2.64, respectively. The emergy investment ratio and environmental load ratio in January are the highest, which are 0.28 and 100.09, respectively, while the emergy yield ratio and emergy sustainability index in May are the largest, which are 15.02 and 0.179, respectively. The environmental load ratio and emergy investment ratio are positively correlated with the annual investment cost, while the emergy sustainability index and emergy yield ratio are negatively correlated with the annual investment cost. The emergy optimization facilitates a better selection of building energy supply systems.

Study on the multitime scale rolling optimization operation of a near-zero energy building energy supply system

The combined cooling, heating and power system of near-zero energy buildings can provide cold energy, heat energy and electricity to users at the same time, realizing combined cold, heat and power generation. However, the randomness of renewable energy output and the volatility of user loads lead to an imbalance between energy supply and demand. Therefore, a three-stage multitime scale optimization operation method is proposed. This method establishes a three-stage optimization model of ‘day-ahead, day-in rolling, real-time feedback’ to optimize the output of the unit step by step. In the day-ahead phase, the optimization goal is to take the lowest daily operating cost while considering the environmental cost. In the day-in rolling stage, the optimization goal is to control the minimum cost of energy purchase in the time domain and the minimum penalty cost of unit output change. The real-time feedback phase optimizes with the minimum total device power adjustment. The results show that the cost saving rates of multitime scale optimization strategies on typical winter days, typical transition season days and typical summer days are 0.90%, 2.32% and 2.12%, respectively. Compared with the ideal cost of different typical days, the cost deviation rates are 0.21%, 0.51% and 1.97%, respectively. Compared with the optimization of the previous day, the total power of the grid connection line on different typical days is −8.0%, −10.65% and −6.23%, respectively. Therefore, this novel optimization method has good economy, stability and accuracy and has a guiding effect on the formulation of each equipment operation plan.

Performance and optimization of a novel solar-air source heat pump building energy supply system with energy storage

In order to solve the problem that the traditional heat pump system in the cold area of North China cannot supply heat efficiently and stably, a novel solar-air source heat pump system is proposed to meet the needs of building energy consumption. In winter, the latent heat of water in the ice tank is used as the main low-temperature heat source for the heat pump, and the outdoor air is used as the auxiliary heat source. During the day, the solar energy is used to restore the heat of the ice tank, so as to realize the complementary utilization of renewable energy. The air source heat pump can be used for cooling in summer. In addition, combined with night energy storage (cold storage and heat storage), the “peak load shifting” and the minimization of building operation energy consumption and cost are realized. The experimental platform and simulation model of the system are established, and the operation and design scheme of the system are optimized with the optimal economy. The optimization results show that the system can still maintain efficient operation under continuous extreme weather in winter and summer, and the SPF of the system in winter and summer are 2.93 and 2.6, respectively. Solar photovoltaic power generation meets part of the power demand of the system, which can save about 1.85 t of standard coal compared with thermal power generation. Compared with a conventional air source heat pump system, the novel system has better economy and a dynamic investment payback period of 3.86 years. The proposed system presents a way to meet building energy supply that is worthy of popularization and application in cold areas.

Energy Efficiency Improvement of Composite Energy Building Energy Supply System Based on Multiobjective Network Sensor Optimization

In order to solve the problem of improving the energy efficiency of the energy supply system, the author proposes a method for improving the energy efficiency of the energy supply system of composite energy buildings based on multiobjective grid optimization, the method solves the energy efficiency improvement of the grid-optimized composite energy building energy supply system, with the increasing material needs of people, the traditional fossil energy consumption is increasing, and the environmental pollution problem is also becoming more and more serious, and people will face serious energy crisis. Due to the high proportion of coal in China’s energy, most thermal power plants use coal as fuel to generate electricity. In the process of coal combustion power generation, a large amount of air pollutants such as CO2, SO2, and Nox are produced, which destroys the ecological environment. In order to alleviate the energy crisis and reduce the emission of polluting gases, the development of renewable energy sources such as wind energy and solar energy is extremely important. Electricity supply and heat supply account for the main part of China’s energy consumption, 40% of China’s energy consumption is used for electricity supply, and 25% is used for heat supply. In terms of electricity supply, 12% of electricity is used for residential use, about 74% is used for industrial production, and 14% is used for commercial development.

Performance analysis of a prototype solar photovoltaic/wickless heat pipe embedded aluminum curtain wall-heat pump water heating system

In this study, a novel glazed photovoltaic heat pipe based curtain wall (PV-HPCW) heat pump system composes of the wickless heat pipe embedded aluminum veneer curtain wall as solar thermal collecting system and heat pump water heating system is proposed. This system assists in heat redistribution on the outer wall of the room to increase solar collection rather than transmission, and in which the collected heat is then transferred to the cold feed of the domestic hot water heating system. A dynamic model is developed to analyze the energy conversion and heat transfer process in the entire system by utilizing the energy balance approach to understand inter-connection and definition of the sorted equations. An experiment is executed and tested under the real outdoor weather conditions in Hong Kong, which is done by measuring the operational parameters, such as solar radiation, PV power generation, temperature at various points and compressor consumption. The simulation results reflect good consistency with the observation data, and indicating that the established model has reasonable accuracy to predict system performance. In outdoor condition, the results indicate that the average electrical and thermal efficiency of PV-HPCW module are around 9.44% and 20.22%, respectively; Similarly, the overall thermal efficiency and overall electrical efficiency (exergy) of the system are 44.6% and 12.8%, respectively; whilst the mean coefficient of performance, COP and the comprehensive coefficient of performance, COPpvt of the system are 3.64 and 5.12 respectively. The PV-HPCW heat pump system has a significant potential and benefits relating to solar heat and electricity. Thus, this innovative PVT technology based building envelop could be a promising building energy supply system with the advantage of proper resource utilization and compact structure, and all these positive implication would encourage the development of such high performance technology, which will contribute to the reduction of carbon emissions in the building sector and ultimately to reduce the urban heat island effect.

Building Energy Performance Evaluation of a Norwegian single-family house applying ISO-52016

In the following work, we have implemented a version of the hourly method in the ISO 52016-1:2017 standard, informed by the central input table in the SN/TS 3031:2021 specification, including a building energy supply system modelled according to the specification. A case study shows that the model compares well to measurements in unoccupied periods and that openly available gridded weather data can substitute data collected by the weather station on site. A more refined representation of boundary conditions and additional user inputs may be needed for other housing typologies than what can be recreated from the table, but we find that some of this information can be stipulated using open spatial datasets and tools. The results are presented in a web-service dashboard, maintaining continuity with operation phase data collection.

Solar Decathlon Europe – A review on the energy engineering of experimental solar powered houses

The Solar Decathlon is a competition for universities from all over the world to design, build and operate small experimental solar powered houses. Its first edition took place in the US in 2002. Since 2010 it is in practice in Europe with four competitions and 65 net zero or net energy plus houses build and tested in 10 disciplines (decathlon). This paper provides an overview and analysis on the European edition of the competition. The work was carried out within the framework of Annex 74 “Competition and Living Lab Platform” of the International Energy Agency and an EC funded project named “Solar Decathlon Europe - Analysis of the Results”. The analysis was based on the development of a web based knowledge platform, providing a large set of information and monitored data from past competitions. Based on the availability of information and data, the comparative evaluation is centred on the building energy supply systems and their performance. Starting with very large PV systems, the latest competitions rules trigger the teams to apply systems sized comparable to small buildings in net zero energy building practice. As a result not all houses succeed in a positive energy balance. Due to the wider introduction of batteries the self-consumption of the solar yield and the degree of self-sufficiency increases. New developments of the competition rules stimulate the energy flexibility in operation with the power grid. Modifications for the rules and the monitoring procedure for the next edition intend to further link the competition to building science.

Performance and operation strategy optimization of a new dual-source building energy supply system with heat pumps and energy storage

The use of renewable energy is an important technical way to achieve building energy conservation and environmental protection. In this study, a new type of dual-source building energy supply system with heat pumps and energy storage, which can solve the problems of unstable operation and low reliability of a single-energy system and high investment and operation cost of existing multi-source energy systems, is proposed. In this system, photovoltaic–thermal water is used as the low-temperature heat source of the water source heat pump and the air source heat pump as the auxiliary energy supply device to realize cascade utilization of energy. “Peak load shifting” and minimization of building energy consumption and operation costs are realized by storing energy (cold and heat) at night when electricity prices are low. On the basis of the long-term monitoring data of the energy supply system for an office building, load-forecasting and system performance models are established, and the operation strategy in winter and summer is optimized. Then, the whole-year operation of the system is simulated and analyzed. Results show that the optimized system runs efficiently and can save approximately 10% of operating costs compared with the situation before optimization. The operating cost of the system is 55% of that of the conventional air source heat pump system, and its dynamic payback period is 3.66 years. The proposed system is a form of building energy supply system worthy of popularization and application in cold regions.

Research and development of ice storage in building energy supply system

In this work, the most suitable type of heat exchanger for an ice accumulator was determined based on studies of the dynamics of ice growth on heat exchange surfaces of various shapes and its configuration was determined. The calculation of the accumulating capacity of the ice accumulator has been made. The task is set to create a mathematical model in the Ansys Fluent and TRNSYS environment, as well as BIM and BEM models of the main elements of the system. A ready-made design solution for the introduction of an ice storage device into the existing heat supply system of an energy-efficient house with an assessment of the cost of costs and required materials has been developed. An assessment was made of the cost of various solutions for heating a house with a load of 10 kW. A test bench layout has been developed for monitoring and analyzing the operation of the system, as well as the impact on the environment. The functionality of the current system for recording and processing the operating parameters of the equipment allows not only to confirm the correctness of calculations and the operability of the mathematical model, but also to assess the impact of the ice accumulator on the environment.

Comparative Study on Performance of Renewable Energy Building Energy Supply System

The air source heat pump water system test bench and the compact all-glass vacuum tube solar water heating system test bench are (were) built on the roof of two adjacent teacher’s apartment buildings with the same structure, shape and material were constructed to study the performance of energy supply systems for different types of renewable energy buildings. The energy supply system performance and the performance parameters are comprehensively and systematically analyzed in the same environment conditions of the same period. The results show that the weight coefficients of the performance parameters of the two energy supply systems are equal by means of extension theory analysis. At the last, the comprehensive correlation degree Kj(1) of water outlet temperature on the performance of renewable energy power supply system is 2.07, the comprehensive correlation degree Kj(2) of water inlet temperature is 2.04, the comprehensive correlation degree Kj(3) of air temperature is 2.14, the comprehensive correlation degree Kj(4) of solar radiation is 4.97, and the comprehensive correlation degree Kj(5) of sunshine hours is 3.78.

Performance of building energy supply systems using renewable energy

Performance of building energy supply systems using renewable energy

Synergetic cascade-evaporation mechanism of a novel building distributed energy supply system with cogeneration and temperature and humidity independent control characteristics

Low and medium grade heat sources, such as geothermal energy, solar energy, and various waste heat sources, can only usually meet the independent demand of electricity, cooling or heating in the building. However, the demand for different forms of energy exists simultaneously. Therefore, a novel distributed building energy supply system is presented and cascade evaporation is used for combined cooling, heating and power. Two-stage evaporation is adopted to realize the temperature and humidity independent control. The coupling effect of the cascade evaporation and the building energy supply ability is illustrated through the multi-parameter optimization of system power generation and refrigeration performance as well as the simulation analysis of cooling and power control strategies. The results show that the organic Rankine cycle (ORC) as the power source of the vapor compression cycle (VCC) eliminates the mechanical work and electrical energy conversion process between the ORC and VCC. The low-temperature stage of VCC dehumidifies the outdoor fresh air, while the high-temperature stage cools the indoor return air, realizing the independent control of temperature and humidity and increasing the equivalent evaporation temperature of VCC. The proposed energy supply system can simultaneously meet the cooling, heating and electricity demand of the building, so it can be promoted in practical engineering applications.