As the proportion of building energy consumption in total energy consumption continues to rise, traditional energy scheduling strategies and building load regulation methods are improved to reduce energy consumption and enhance the flexibility of building scheduling. In this study, a two-stage optimization strategy for energy-efficient buildings incorporating electric vehicles (EVs) based on user satisfaction is proposed. First, a source–load–storage coordinated energy optimization system for buildings, including photovoltaic (PV) generation, energy storage systems (ESSs), EVs, light-emitting diode (LED) lights, and heating, ventilation, and air conditioning (HVAC), is established. Second, the satisfaction levels of users with multiple flexible loads are used as indicators of comfort to dynamically adjust energy consumption in buildings. Then, a multiobjective energy optimization model is formulated to minimize daily operational costs while simultaneously maximizing user satisfaction, with an emphasis on balancing comfort and economic efficiency. Third, a two-stage energy optimization model of day-ahead and intraday is constructed to reduce the impact of source–load forecasting errors on the operation of building energy systems, and an incentive demand response strategy is introduced to guide users to participate in scheduling in the intraday stage. Finally, different cases are created to test the effectiveness of the proposed strategy. The overall simulation results validate the proposed approach with operational cost reduction of 12.9% while maintaining a user satisfaction level above 0.95 and grid volatility reduction of 7.56% as compared to the traditional energy optimization strategy.
Data center computer room air-conditioning equipment operates for prolonged periods, and its performance must be tested and evaluated annually to ensure safe and efficient operation. This study conducts field measurements on the server layout, blind plate structure, and working condition adaptability in the rack. The thermal environment of a data center using the closed cold aisle underfloor air distribution system is studied, and the thermal environment safety and energy efficiency throughout the year are evaluated through thermal performance indicators and energy efficiency indicators. The results show that it is recommended to install a rack with a power of more than 2 kW in the middle area of the cold aisle. Installing a blind plate in the gap between the racks can promote the circulation of cold air inside the server, reduce the backflow interference of hot air, and reduce the maximum outlet temperature by 3.32 °C. The average supply air speed was reduced by approximately 24%. Under summer operating conditions, the PUE, WUE, and CUE of the data center were approximately 1.2, 3.5, and 0.84, respectively, and the WUE exhibited strong seasonality. Under winter operating conditions, free cooling can effectively reduce the energy consumption of data centers. In addition, the overheating problem of the racks at the end of the cold aisle of the data center is significant. The cabinet cooling index of the 16 racks was less than 90%, and the heat loss was high.
Heating and ventilation. Air conditioning, Low temperature engineering. Cryogenic engineering. Refrigeration
Yu. E. Geints, I. Yu. Geints, Ya. V. Grudzin
et al.
Filamentation of high-power femtosecond laser pulses in air is accompanied by a fairly strong release of optical energy into the propagation medium due to laser-induced ionization of air molecules and production of an underdense plasma of charged species. We present the results of our laboratory experiments and numerical simulations aimed to the estimation of energy deposition amount by laser filament upon propagation in air depending on the conditions of spatial focusing, pulse energy, and radiation wavelength. For the first time to our knowledge, our study reveals a more than 50% decrease in the filament energy deposited in air in the range of moderate numerical aperture values, approximately from 0.003 to 0.007, at the carrier wavelengths of 740 nm and 470 nm. We attribute such a considerable reduction in the laser pulse energy release for femtosecond plasma to the competing effects of Kerr self-focusing and geometric divergence of focused laser pulse.
Commuter buses have a high passenger density relative to the interior cabin volume, and it is difficult to maintain a physical/social distance in terms of airborne transmission control. Therefore, it is important to quantitatively investigate the impact of ventilation and air-conditioning in the cabin on the airborne transmission risk for passengers. In this study, comprehensive coupled numerical simulations using computational fluid and particle dynamics (CFPD) and computer-simulated persons (CSPs) were performed to investigate the heterogeneous spatial distribution of the airborne transmission risk in a commuter bus environment under two types of layouts of the ventilation system and two types of passenger densities. Through a series of particle transmission analysis and infection risk assessment in this study, it was revealed that the layout of the supply inlet/exhaust outlet openings of a heating, ventilation, and air-conditioning (HVAC) system has a significant impact on the particle dispersion characteristics inside the bus cabin, and higher infection risks were observed near the single exhaust outlet in the case of higher passenger density. The integrated analysis of CFPD and CSPs in a commuter bus cabin revealed that the airborne transmission risk formed significant heterogeneous spatial distributions, and the changes in air-conditioning conditions had a certain impact on the risk.
Angalaeswari Sendrayaperumal, Somyak Mahapatra, Sabuja Sanket Parida
et al.
The ideology of ensuring energy-efficient design and construction of buildings by providing minimum requirements is the core objective of this work. Energy audit was conducted to improve the design of the building with incremental requirements to further enhance the energy efficiency. The Energy Conservation Building Code (ECBC) has been modified extensively over the years, starting from its initial deployment in the year 2011 to its latest modifications in the year 2019. The energy conservation standards in ECBC apply to building envelope, heating ventilation, air conditioning, lighting, service water heating, and electric power distribution. It should also be ensured that all-electric systems, transformers, energy-efficient motors, and diesel generators must meet the regulated set of mandatory requirements. From among the various software types that have been approved for ECBC design and application, this study has employed Energy Plus software to simulate the design based on the given input and the selected location. The location that has been chosen for this study was Bhubaneshwar, India. All necessary details ranging from latitude, longitude, weather, time zone, elevation, building area, lighting, heating, cooling, and much more have been covered in the simulation. Utilizing ECBC regulated standards for an energy-efficient building design has resulted in an increase in the energy savings by 27.4%, and thus, the building qualifies to be regarded as an ECBC compliant building.
Abstract Commercial and residential buildings consume 20% of the world's total energy usage and forecasts indicate a growing trend of 1.5% per year by 2040. Share of energy consumption in the heating ventilation and air conditioning (HVAC) reached to 40–70% of the building energy usage. Reduction in the heat exchange between the interior and exterior spaces is an energy-efficient technique for lowering HVAC energy demand. In this study, the thermal performance of a PCM-based wall was numerically examined in the winter. The main purpose of this research was to investigate the efficacy of installing PCM inside the envelope on reducing heat loss from the conditioned space and at the same time its effect on air handling unit (AHU) energy usage. For this, seven different PCM layers at melting temperatures of 276.15–293.15 K with a thickness of 1 cm were loaded into the envelope. Based on the results, among the PCMs thermophysical properties, thermal conductivity has more manifest efficacy. Under the best conditions, owing to installing PCM of A3 inside the envelope, the energy-saving in December, January and February diminished by 11.25%, 11.23% and 10.35%, respectively. Also, thermodynamic calculations affirmed that the maximum reduction in AHU power usage owing to PCM loading was 11.73%. Using payback time technique, the economic analysis was performed and it was found that under the best conditions, the payback time is 18.6 years.
Sadi Alawadi, David Mera, M. Fernández-Delgado
et al.
The international community has largely recognized that the Earth’s climate is changing. Mitigating its global effects requires international actions. The European Union (EU) is leading several initiatives focused on reducing the problems. Specifically, the Climate Action tries to both decrease EU greenhouse gas emissions and improve energy efficiency by reducing the amount of primary energy consumed, and it has pointed to the development of efficient building energy management systems as key. In traditional buildings, households are responsible for continuously monitoring and controlling the installed Heating, Ventilation, and Air Conditioning (HVAC) system. Unnecessary energy consumption might occur due to, for example, forgetting devices turned on, which overwhelms users due to the need to tune the devices manually. Nowadays, smart buildings are automating this process by automatically tuning HVAC systems according to user preferences in order to improve user satisfaction and optimize energy consumption. Towards achieving this goal, in this paper, we compare 36 Machine Learning algorithms that could be used to forecast indoor temperature in a smart building. More specifically, we run experiments using real data to compare their accuracy in terms of R-coefficient and Root Mean Squared Error and their performance in terms of Friedman rank. The results reveal that the ExtraTrees regressor has obtained the highest average accuracy (0.97%) and performance (0,058%) over all horizons.
The outbreak of pneumonia caused by 2019 Novel Coronavirus arises significant concern for virus transmission and control. The control of the indoor environment or public-enclosed environment is crucial to reduce the risk of infection. Heating, ventilation, air-conditioning (HVAC) systems are used to create a healthy, thermal-comfort indoor environments. Thus, the rational use of HVAC systems is of great importance for the environmental control to reduce infection risk and to improve human wellbeing in the pandemic. In order to satisfy the requirement of better healthy environment and more thermal comfort performance of indoor ventilation system, prevention of indoor pollution is essential, especially considering the purpose of disease transmission resistance. This paper investigated the collective contagion events in enclosed spaces as well as engineering control against virus spread with ventilation systems for health-care facilities and public vehicles. Future challenges of HVAC design and control were discussed.
Jayanthi Vajiram, Negha Senthil, Nean Adhith. P
et al.
The rapid growth of air and space travel in recent years has resulted in an increased demand for legal regulation in the aviation and aerospace fields. This paper provides an overview of air and space law, including the topics of aircraft accident investigations, air traffic control, international borders and law, and the regulation of space activities. With the increasing complexity of air and space travel, it is important to understand the legal implications of these activities. This paper examines the various legal aspects of air and space law, including the roles of national governments, international organizations, and private entities. It also provides an overview of the legal frameworks that govern these activities and the implications of international law. Finally, it considers the potential for future developments in the field of air and space law. This paper provides a comprehensive overview of the legal aspects of air and space travel and their implications for international and domestic travel, as well as for international business and other activities in the air and space domains.
Abstract Electric demand flexibility in buildings has been deemed to be a promising demand response resource, particularly for large commercial buildings, and it can provide grid-responsive support. A building with a higher electricity flexibility potential has a higher degree of involvement with the grid response. If the electricity flexibility potential of a building is known, building operators can properly alleviate peak loads and maximize economic benefits through precise control in demand response programs. Previously, there was no standard way to quantify electricity flexibility, and it was difficult to evaluate a given building without experiments and tests. Thus, a systematic approach is proposed to quantify building electricity flexibility. The flexibility contributions include building thermal mass; lights; heating, ventilation, and air conditioning (HVAC) systems, and occupant behaviors. This proposed model has been validated by the instantiation of an office building case on the Dymola platform. For a typical office building, the results show that the electricity flexibility resource not only comes from the HVAC system, but also thermal mass and occupant behavior to a large degree, and buildings with energy flexibility can cut down much of their load during peak load time without compromising on the occupant's comfort.
Heating, ventilation, air conditioning and refrigeration (HVAC&R) systems provide physical environment comfort for the occupants at a possible expense of large amount of energy consumption [...]
A conceptual design of a novel UVC-LED air-cleaner is presented as part of an international educational-research study. The main components are a dust-filter assembly, a UVC chamber and a fan. The dust-filter aims to suppress dust accumulation that will hamper the UVC chamber operation. The innovation is in the UVC chamber that includes a novel turbulence-generating grid to enhance air mixing in the chamber and a novel LEDs layout to achieve sufficient kill of the SARS-CoV-2 virus and TB bacterium aerosols with a reasonable power consumption. Both diseases have hit hard low to medium income countries and this study is part of an effort to offer non-pharmaceutical solutions to mitigate the air-transmission of such diseases. Low to high fidelity methods of computational fluid dynamics and UVC ray method are used to show that the design can provide a kill above 97% for Covid and TB, and above 92% for influenza-A. This is at a flow rate of 100 l/s, power consumption of less than 300W and a device size that is both portable and may also fit into ventilation ducts. Research and educational methodologies are discussed, along with analysis of the inexpensive dust-filter performance and the irradiation and flow fields.
Air pollution causes widespread environmental and health problems and severely hinders the life quality of urban residents. Traffic is a critical for human life and its emissions are a major source of pollution, aggravating urban air pollution. However, the complex interaction between the traffic emissions and the air pollution in the cities has not yet been revealed. In particular, the spread of the COVID-19 has caused various cities to implement different traffic restriction policies according to the local epidemic situation, which provides the possibility to explore the relationship between urban traffic and air pollution. Here we explore the influence of traffic to air pollution by reconstructing a multi-layer complex network base on traffic index and air quality index. We uncover that air quality in Beijing-Tianjin-Hebei (BTH), Chengdu-Chongqing Economic Circle (CCS) and Central China (CC) regions are significantly influenced by the surrounding traffic conditions after the outbreak. Under different fights against the epidemic stages, the influence of traffic in other cities on the air pollution reached the maximum in stage 2 (also called Initial Progress in Containing the Virus). For BTH and CC regions, the impact of traffic on air quality becomes larger in the first two stages and then decreases, while for CC, the significant impact occurs in Phase 3 among regions. For other regions, however, the changes are not evident. Our presented network-based framework provides a new perspective in the field of transportation and environment, and maybe helpful to guide the government to formulate air pollution mitigation and traffic restriction policies.
Alfonso González-Briones, Javier Prieto, Fernando De la Prieta Pintado
et al.
At present, the domotization of homes and public buildings is becoming increasingly popular. Domotization is most commonly applied to the field of energy management, since it gives the possibility of managing the consumption of the devices connected to the electric network, the way in which the users interact with these devices, as well as other external factors that influence consumption. In buildings, Heating, Ventilation and Air Conditioning (HVAC) systems have the highest consumption rates. The systems proposed so far have not succeeded in optimizing the energy consumption associated with a HVAC system because they do not monitor all the variables involved in electricity consumption. For this reason, this article presents an agent approach that benefits from the advantages provided by a Multi-Agent architecture (MAS) deployed in a Cloud environment with a wireless sensor network (WSN) in order to achieve energy savings. The agents of the MAS learn social behavior thanks to the collection of data and the use of an artificial neural network (ANN). The proposed system has been assessed in an office building achieving an average energy savings of 41% in the experimental group offices.
Abstract The need to achieve energy efficiency standards in new and existing buildings has triggered both research and design practice aimed at reducing their carbon footprint and improving their indoor comfort and functionality conditions. In this view, a dedicated scientific effort has to be spent while dealing with historical architectures needing to preserve their key testimonial knowledge into the society. Therefore, tailored retrofit strategies have been investigated and implemented without compromising their architectural value, especially when new uses are foreseen in those buildings. This review classifies different examples of the use of energy efficiency approaches and the integration of renewable energies in historical buildings, including solar and geothermal energy, and the use of heat pumps and other high-efficiency heating ventilation and air conditioning systems.