Energy Utilization In Buildings Research Articles

Numerical approach for sizing vertical ground heat exchangers based on constant design load and desired outlet temperature

Vertical ground heat exchangers (GHE), as part of a ground source heat pump system, have been utilized for energy extraction/injection from/to the ground, i.e. a renewable source of energy, in the heating/cooling months to reduce building energy utilization. The current available GHE sizing methods are mostly based on several over-simplified one or two dimensional analyses, which cannot predict its thermal behavior with the accurate and realistic boundary conditions or in series configurations. In this study, thermal performance of vertical GHEs is numerically investigated at a given constant load through solving full transient 3D Navier-Stokes equations inside the U-tubes and the energy equation all over the computational domain, i.e. both fluid and solid parts. There are three interconnected parameters, namely GHE load, the heat transfer fluid outlet temperature, and the GHE depth that influence its thermal performance and consequently, the required investment cost. Therefore, the thermal performance of GHEs is computed for different constant loads at different depths, and it is shown that at each constant load, there is a trade-off between the investment cost and the thermal performance. Furthermore, the GHEs thermal performance in parallel and series configuration is investigated at a fixed depth and different loads. In light of the obtained data, the required size of the GHEs for a test building with an imbalanced energy extraction/injection rate is derived and the thermal performance of the proposed cluster of GHEs is numerically simulated for 20 years.

Automated method of calculation of parameters for non-traditional heating technologies and conditioning of buildings

Purpose. Develop an automated method for calculating parameters for heat pump systems for heating, air conditioning and hot water supply, designed for use in domestic conditions with non-standard heat transfer flows. Methodology. Mathematical modeling of thermodynamic processes occurring in heating, air conditioning and hot water supply systems. Findings. The automated method of calculating the parameters of non-traditional technology, which uses standard heat pump equipment of the water heating system for the cooling mode of the air in the warm period of the year, and the discharge of heat dissipated into the ground, was substantiated and developed; and for the needs of hot water supply heat pump air-liquid, acting as a high-speed water heater. The estimation of technologies of the thermal energy utilization in buildings developed earlier by authors is executed. The first technology involved the use of a heat pump and heat accumulator scheme in the cold season, and halved the consumption of conventional fuel compared to a gas column for hot water at the same facility. The second technology involved heat recovery with the help of a heat accumulator in a complex system of air conditioning and hot water supply in the warm period, which saves from 74 to 82% of conventional fuel compared to the scheme with boiler and air conditioner without heat accumulator. Critical conclusions were drawn about the need to use additional dimensional equipment for these technologies and the excess amount of hot water received. Possibilities of realization of such scheme were analyzed. Analytically substantiated recommendations on the design (ribbing of heat exchange surfaces) of heating devices and parameters of their operating modes in the cold and warm periods of the year were given. The condition of invariance of heat exchange areas of heating devices and basic water consumption in the heating system was fulfilled. The need to regulate the air conditioning regime by changing the water flow in the system to maintain a constant indoor air temperature with fluctuations in outdoor air temperature was substantiated. Originality. For the first time, attention is paid to the study of non-traditional methods of using heat pump heating for heating, air conditioning and hot water supply of residential premises. The automated method for determining rational parameters for these technologies was developed. Practical value. The automated method of forming the control dependence of the mass flow of water in the system on the outside air temperature on the condition of constancy of the set comfortable indoor air temperature was developed. The use of air-liquid heat pump for hot water supply in the warm period was analyzed, a high energy conversion factor was noted (14 ... 22). The savings of conventional fuel from the application of the considered technology from 13% to 18% in comparison with the technology using a heat accumulator were substantiated.

Energy Usage Optimization in Zero Energy Building to Reduce Dependency on Conventional Sources

As Net-zero energy buildings (NZEBs) have been proposed as a viable method for reducing building energy utilization and pollutant emissions. To achieve the desired performing goal, the layouts and capabilities of the integrated renewable energy systems in NZEBs should be carefully chosen. The persistent rise in global energy demand as a result of industrial advancement and population expansion is presently a massive source of concern. The goal of this project is to develop an ideal design technique for a zero-energy building that takes into account the building's energy output and usage. Solar power production was determined to be the most significant element.

A practical building energy consumption anomaly detection method based on parameter adaptive setting DBSCAN

In order to realize the Building Energy Consumption Anomaly Detection (BECAD) for the green building assessment, the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) is adopted for data clustering. To deal with the parameter setting difficulty of the DBSCAN, a practical parameter adaptive setting method is proposed. The presented method determines values of the DBSCAN parameters, MinPts and ε, according to four distribution characteristics (average data distance, data local densities, cosine similarity, and equivalent space radius) of data, and does not need prior knowledge of the datasets. Furthermore, parameter values determined by the proposed method can improve the clustering effect of the DBSCAN on datasets with various data densities. After testing the proposed method with open datasets, DBSCAN with the parameter adaptive setting method is applied to the BECAD. Experiment results show that identified building energy utilization patterns and abnormal buildings are reasonable and the results can offer the management departments a clear understanding of building energy consumption patterns, as well as decision supports to make subsequent improvement measures.

Parametric Study on Residential Passive House Building in Different Chinese Climate Zones

With the increasing of building energy consumptions, the related issues of energy crisis and environmental pollution become more and more prominent. As an effective energy-saving technology, the passive house (PH) has been widely applied in China to reduce the building energy utilization. However, the design and application of PH vary with different climate conditions. Therefore, it is significant to conduct the parameterization of PH and propose a suitable design zoning of PH in China. In our study, a comprehensive feasibility analysis of the implementation of PH is performed, which chooses 31 representative cities covering 5 climatic regions. The sensitivity analysis firstly filters the key parameters that heavily affect energy consumption. The results indicate that the key parameters include external wall heat transfer coefficient (WU), basement ceiling heat transfer coefficient (BCU), solar heat gain coefficient (SHGC), glass G value (UG), heat recovery efficiency (HERE) and humidity recovery efficiency (HURE). Then, with the multiple regression approach, the values of key parameters are optimized. Based on the determined values of sensitive parameters, the design zoning of PH in China is finally proposed, which can guide the design of PH as well as enhance the application of PH in China.

Deep Learning in Energy Modeling: Application in Smart Buildings With Distributed Energy Generation

Buildings are responsible for 33% of final energy consumption, and 40% of direct and indirect CO2 emissions globally. While energy consumption is steadily rising globally, managing building energy utilization by on-site renewable energy generation can help responding to this demand. This paper proposes a deep learning method based on a discrete wavelet transformation and long short-term memory method (DWT-LSTM) and a scheduling framework for the integrated modelling and management of energy demand and supply for buildings. This method analyzes several factors including electricity price, uncertainty in climatic factors, availability of renewable energy sources (wind and solar), energy consumption patterns in buildings, and the non-linear relationships between these parameters on hourly, daily, weekly and monthly intervals. The method enables monitoring and controlling renewable energy generation, the share of energy imports from the grid, employment of saving strategy based on the user priority list, and energy storage management to minimize the reliance on the grid and electricity cost, especially during the peak hours. The results demonstrate that the proposed method can forecast building energy demand and energy supply with a high level of accuracy, showing a 3.63-8.57% error range in hourly data prediction for one month ahead. The combination of the deep learning forecasting, energy storage, and scheduling algorithm enables reducing annual energy import from the grid by 84%, which offers electricity cost savings by 87%. Finally, two smart active buildings configurations are financially analyzed for the next thirty years. Based on the results, the proposed smart building with solar Photo-Voltaic (PV), wind turbine, inverter, and 40.5 kWh energy storage has a financial breakeven point after 9 years with wind turbine and 8 years without it. This implies that implementing wind turbines in the proposed building is not financially beneficial.

Integrated Design of Solar Energy Utilization and Building Based on PLC

At present, fossil energy consumption still occupies a dominant position in China’s energy consumption structure, and problems such as low energy consumption efficiency, high degree of carbonization and large environmental pollution persist for a long time. Under the background of advocating environmental protection and energy saving, the combination of solar energy and building is the inevitable trend of building energy saving development, and the integrated design of solar energy and building has become a concern of the architectural circles. With the deepening of people’s understanding of environmental problems and the further deterioration of energy problems, more and more buildings begin to use clean and energy-saving solar energy devices. At present, the construction and development of urban residential buildings in China are mainly multi-storey and high-rise buildings. Therefore, higher requirements are put forward for the application form and scale of solar water heating system in residential buildings. In this paper, according to the current situation of solar energy utilization in buildings in China, based on PLC (programmable logic controller), the paper puts forward some suggestions to promote the integrated design of solar energy buildings.

Assessment and parametric analysis of solar trigeneration system integrating photovoltaic thermal collectors with thermal energy storage under time-of-use electricity pricing

The solar trigeneration system based on coupling photovoltaic thermal (PVT) collectors with an absorption-subcooled compression hybrid cooling configuration has the potential for enhancing solar energy utilization in buildings. Considering time-of-use electricity pricing, the availability of solar cooling often does not coincide with on-peak periods during which electricity prices are high. To benefit from time-of-use pricing for greater economic profitability, sensible heat thermal storage is potential options. However, changeable storage tank temperature affects not only solar cooling capacity but also the electrical output of PVT collectors. Thus, in this work, three operation schemes (i.e., a conventional scheme, heat energy storage and cool energy storage schemes) are compared, and the effect of key design parameters on system performance is analyzed. Models for different system layouts and a conventional photovoltaic (PV-only) system are developed by programming with MATLAB. Annual (8760-hour) simulations are performed based on a case study for a high-rise hotel in subtropical cities. The results for Guangzhou show that the system layout, integrating cool energy storage and glazed PVT collectors with low-emissivity coatings, achieves the highest total electricity cost saving, which is 16% higher than that of the PV-only system. Its total solar energy utilization efficiency is 0.321, which is 2.4 times that of the PV-only system. The novelty of this work is that it provides an appropriate energy storage strategy and the design guidelines of key parameters for PVT-based solar trigeneration systems. This work is helpful for PVT-based solar trigeneration systems to improve operating cost savings under time-of-use electricity pricing.

Building Energy Utilization with LED Lighting and Occupant Sensing System

Building Energy management systems (BEMSs) are needed to monitor and regulate energy consumption in buildings, thus, contribute in reducing the environmental challenges facing our planet. A new energy saving method based on BEMS is proposed in this paper. The proposed method is a smart LED lighting system based on an Arduino microcontroller, a simple motion sensor, and a camera. A complete design and implementation of the smart lighting system is presented in the paper. In addition, the proposed smart system is validated in the paper under various experimental conditions. The results show that simple installation of commercially available motion sensors and cameras can contribute significantly to reduce the electricity bill and CO2 emission.

A review of net zero energy buildings in hot and humid climates: Experience learned from 34 case study buildings

Sustainable development in the building sector requires the integration of energy efficiency and renewable energy utilization in buildings. In recent years, the concept of net zero energy buildings (NZEBs) has become a potential plausible solution to improve efficiency and reduce energy consumption in buildings. To achieve an NZEB goal, building systems and design strategies must be integrated and optimized based on local climatic conditions. This paper provides a comprehensive review of NZEBs and their current development in hot and humid regions. Through investigating 34 NZEB cases around the world, this study summarized NZEB key design strategies, technology choices and energy performance. The study found that passive design and technologies such as daylighting and natural ventilation are often adopted for NZEBs in hot and humid climates, together with other energy efficient and renewable energy technologies. Most NZEB cases demonstrated site annual energy consumption intensity less than 100 kW-hours (kWh) per square meter of floor space, and some buildings even achieved “net-positive energy” (that is, they generate more energy locally than they consume). However, the analysis also shows that not all NZEBs are energy efficient buildings, and buildings with ample renewable energy adoption can still achieve NZEB status even with high energy use intensity. This paper provides in-depth case-study-driven analysis to evaluate NZEB energy performance and summarize best practices for high performance NZEBs. This review provides critical technical information as well as policy recommendations for net zero energy building development in hot and humid climates.

A multi-scenario life cycle impact comparison of operational energy supply techniques for an office building in Thailand

This study provides a life cycle assessment (LCA) of a sustainably designed office building to be built in Thailand. The building has a gross floor area of 6300 m2 and a lifetime of 50 years. An analysis of four different energy supply scenarios was performed to evaluate methods for reducing grid electricity demand with the goal of optimizing renewable energy usage and minimizing environmental impacts. The scenarios included: (1) the conventional, grid-dependent building, followed by (2) the addition of a rooftop photovoltaic (PV) system, (3) a PV system with lithium-ion battery storage, and (4) a PV system with an ice storage system. Scenarios 3 and 4 were included in this study as 16% of the electricity from PV was overproduced during the weekends when the building was unoccupied. The results show that scenarios 2, 3, and 4 reduced operational grid consumption by 33%, 37.8%, and 37.9% but increased metal depletion potential by 23.9%, 34.4%, and 29.0%, respectively. Ice storage led to the greatest reduction in lifetime environmental impacts. Efficient production and utilization of renewable energy in buildings is vital to reducing nonrenewable fuel dependence; however, it is necessary to minimize metal depletion in the implementation of such technologies.

Effect of gender difference on sleeping comfort and building energy utilization: Field study on test chamber with thermoelectric air-cooling system

In this study we have examined the gender-wise differences in sleeping behavior of volunteers subjected to thermo-electric air conditioning test-room conditions. For this purpose, fifteen males and fifteen female subjects were recruited. After filling the Pittsburgh Sleep Quality Index (PQSI) questionnaire, each subject was required to sleep in the room under all the three study conditions i.e. normally ventilated room (NH), thermoelectrically cooled room at input power supply of 600 W and thermoelectrically cooled room at power input of 720 W. Each subject was required to complete one night's sleep in each of the study conditions. Objective sleeping parameters such as body movement, heart rate, sleeping quality were measured using a Fitbit Alta HR watch. A subjective assessment of the sleep quality was also done after each session. The observed findings were compared for all the three conditions for each subject. It was found that male subjects had an overall better sleep quality at a lower surrounding temperature as compared to the female subjects. For female subjects the indoor environment was found to be comfortable to slightly cold when the thermoelectric cooling system was operated at 600 W. On the other the male subjects had a better sleep quality at 720 W. Based on these cooling requirements, males are estimated to consume 485 kWh more energy annually (which would result in CO2 emissions in excess of 6 tons) as compared to females to maintain comfortable sleeping environment.

Roof Planting as a Tool for Sustainable Development in Residential Buildings in Egypt

Roof has direct influence on thermal ease and energy preservation in and around buildings. Roof Planting is a strategy that can be a beneficial solution in diverse climates to decrease energy utilization in buildings, proposes enriching the aesthetic potentials and architecture presentation of buildings and for enhancing the built environment and increasing investment opportunity. It helps to tackle the shortage of green space in numerous areas and delivers the city with open spaces that aids ease heat effect and offers human population with a correlation to the outside. The research problem presented in the demonstrations of the confronts presented by quick urbanization and expansion, many environmental problems as pollution, dense urbanization and heat effect that creates a negative impact on the environment. The fast growing population in Cities undergo from vanishing of green areas which lead to dispossession of open space. The paper assumes that by applying roof planting to the case studies in Residential buildings in Egypt can improve quality of life, as an effective tool for sustainable development goals represented in social, economic and environmental factors. The paper methodology focuses on the analysis of some international examples and the lessons learned and applicability in Residential buildings in Egypt. The research aims to present the potentials of roof planting in abiding electricity utilization and decreasing CO2 releases in hot environments. The paper studies the impact of roof planting on the performance of buildings. The results demonstrate the sustainable development goals of using roof planting under diverse design conditions and postulate assistance for design of roof planting in alike climates.

Experimental performance evaluation of a novel anti-fouling wastewater source heat pump system with a wastewater tower

Using wastewater source heat pumps to recover heat from the sewage discharged from buildings could help improve building energy utilization efficiency remarkably, which is a promising technology in near-zero energy buildings and should be widely used. However, fouling deposit would occur on a heat exchanger surface due to the poor water quality of wastewater, which would affect the heat transfer performance and may even block the heat exchanger, reducing the reliability of a wastewater source heat pump unit. Fouling poses a challenge for the wider application of wastewater source heat pumps. A novel anti-fouling wastewater source heat pump system with a wastewater tower was proposed in this work and its operational performances were experimentally investigated based on a long-term test of 41 days (492 h). Experimental results showed that the heat transfer rate in the evaporator of the novel wastewater source heat pump was stable during the 41-day test at an average of 3.80 kW. Unlike in the evaporator of a conventional wastewater source heat pump unit, the total thermal resistance in the evaporator of the novel wastewater source heat pump unit was not increased but only fluctuated around an average of 0.0267 K m2/W throughout the entire 41 days test. The evaporating temperature of the refrigerant stayed stable around an average of 2.74 °C. Furthermore, the coefficient of performance of the unit was also stable at an average of 3.32 and the coefficient of performance of the system maintained an average of 2.13. The condensate drained away from the bottom of the evaporator did not contain any foulant. In addition, the photos for the evaporator showed that its surface was still clean after the 41-day test. Therefore, the experimental results suggested that the novel wastewater source heat pump system not only had superior performance of heat recovery but also achieved effective anti-fouling on its evaporator surfaces.

Model predictive control under forecast uncertainty for optimal operation of buildings with integrated solar systems

In this paper, we explore intelligent operation strategies, based on stochastic model predictive control (SMPC), for optimal utilization of solar energy in buildings with integrated solar systems. Our approach takes into account the uncertainty in solar irradiance forecast over a prediction horizon, using a new probabilistic time series autoregressive model, calibrated on the sky-cover forecast from a weather service provider. In the optimal control formulation, we model the effect of solar irradiance as non-Gaussian stochastic disturbance affecting the cost and constraints, and the nonconvex cost function is an expectation over the stochastic process. To solve this complex optimization problem, we introduce a new approximate dynamic programming methodology that represents the optimal cost-to-go functions using Gaussian process regression, and achieves good solution quality. In the final step, we use an emulator that couples physical system models in TRNSYS with the SMPC controller developed using Python and MATLAB to evaluate the closed-loop operation of a building-integrated system with a solar-assisted heat pump coupled with radiant floor heating. For the system and climate under consideration, the SMPC saves up to 44% of the electricity consumption for heating in a winter month, compared to a baseline well-tuned rule-based controller, and it is robust, imposing less uncertainty on thermal comfort violation.

A Review of Internet of Energy Based Building Energy Management Systems: Issues and Recommendations

A building energy management system (BEMS) is a sophisticated method used for monitoring and controlling a building’s energy requirements. A number of potential studies were conducted in nearly or net zero energy buildings (nZEBs) for the optimization of building energy consumption through efficient and sustainable ways. Moreover, policy makers are approving measures to improve building energy efficiency in order to foster sustainable energy usages. However, the intelligence of existing BEMSs or nZEBs is inadequate, because of the static set points for heating, cooling, and lighting, the complexity of large amounts of BEMS data, data loss, and network problems. To solve these issues, a BEMS or nZEB solution based on the Internet of energy (IoE) provides disruptive opportunities for revolutionizing sustainable building energy management. This paper presents a critical review of the potential of an IoE-based BEMS for enhancing the performance of future generation building energy utilization. The detailed studies of the IoE architecture, typical nZEB configuration, different generations of nZEB, and smart building energy systems for future BEMS are investigated. The operations, advantages, and limitations of the existing BEMSs or nZEBs are illustrated. A comprehensive review of the different types of IoE-based BEMS technologies, such as energy routers, storage systems and materials, renewable sources, and plug-and-play interfaces, is then presented. The rigorous review indicates that existing BEMSs require advanced controllers integrated with IoE-based technologies for sustainable building energy usage. The main objective of this review is to highlight several issues and challenges of the conventional controllers and IoE applications of BEMSs or nZEBs. Accordingly, the review provides several suggestions for the research and development of the advanced optimized controller and IoE of future BEMSs. All the highlighted insights and recommendations of this review will hopefully lead to increasing efforts toward the development of the future BEMS applications.

Numerical Modelling of Thermal Performance of Active-passive Ventilation Wall with Phase Change Material

Abstract In order to improve the utilization of solar energy in buildings, a new system combining an active-passive ventilation wall with phase change material (PCM) and solar concentrators was proposed, and a two-dimensional unsteady numerical heat transfer model of the proposed wall was established and validatedusing data collected from field measurement. Using this model, influencing factors, namely, velocity and inlet temperature of air, thickness and length of air tunnel, have been identified to have influence on its thermal performance. Then optimum operational conditions have also been identified to guide the optimal design of the proposed wall and the application of solar energy in buildings.

An Optimization Model Applied to Active Solar Energy System for Buildings in Cold Plateau Area

The large-scale utilization of solar energy in buildings is one of the most promising technologies to solve the global energy shortage problem and reduce the carbon dioxide emissions. The present paper has proposed an optimization model coupled with solar thermal and photovoltaic systems. Optimization results of active solar energy system from the energy saving view and economical view have been obtained for typical hotel and office buildings in cold plateau area, respectively.

Sustainable Technologies for Cutting down Energy Requirements for Lighting and Air Conditioning in Buildings

In the current scenario of increasing population and rapid urbanization, energy requirements in human habitats are exponentially increasing which is nearly 40% of the total energy produced. Therefore technologies and methods for reducing energy utilization in buildings are being developed throughout the world. Energy efficiency and conservation are two important aspects as it takes a larger stack in running the buildings, which is being highlighted in the „Green Building‟ concept. In urban buildings, energy is required mostly for lighting and air conditioning. In terms of lighting, daylighting and less energy intensive lighting devices like LED, CFL etc. are being used. Use of renewables like solar energy for power generation and also for air conditioning were also found to be used in buildings. Recent researches are based on using the building itself or its parts like roofs, facades, windows etc. for utilizing solar powers using technologies like Building Integrated Photovoltaics (BIPV) and Building Integrated Solar Thermal (BIST). Similarly building integrated thermal energy storage using phase change materials along with construction materials for space cooling and heating were also been used. This paper highlights such sustainable technologies which are used to reduce the

A thermo-activated wall for load reduction and supplementary cooling with free to low-cost thermal water

A building envelope serves as a thermal barrier and plays an important role in determining the amount of energy used to achieve a comfortable indoor environment. Conventionally, it is constructed and treated as a passive component in a building thermal energy system. In this article, a novel, mini-tube capillary-network embedded and thermal-water activated building envelope is proposed to turn the passive component into active, therefore broaden the direct utilization of low-grade thermal energy in buildings. With this proposed approach, low-grade thermal water at a medium temperature close to the ambient environment can be potentially utilized to either counterbalance the thermal load or indirectly heat and cool the space. With the revealing of the idea, effects of water temperature and flow rate on the envelope's thermal performance are investigated using a transient model. The results indicate that the thermo-activated wall can be effective in stabilizing the internal surface temperature, offsetting the heat gain, and supplying cooling energy to the space in summer. Utilization of the innovation should take the cost of total energy, energy benefit and efficiency into consideration. This article illustrates how low-grade energy can be actively used as a means for achieving net-zero energy buildings.