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The Covid-19 outbreak raised great attention to the importance of indoor air quality in buildings. Even if the Covid-19 epidemic is nearing an end, all stakeholders agree that increasing outside air flow rates is beneficial for decreasing the likelihood of contagion, lowering the risk of future pandemics, and enhancing the general safety of the interior environment. Indeed, diverse concerns raised about whether the ventilation standards in place are still adequate. In this context, this research intends to assess the suitability of current ventilation standards in addressing the current pandemic scenario and to offer novel criteria and guidelines for the design and operation of HVAC systems, as well as useful guidance for the creation of future ventilation standards in a post-Covid-19 scenario. To that end, a comprehensive analysis of the ANSI/ASHRAE 62.1 is carried out, with an emphasis on its effectiveness in reducing the risk of infection. Furthermore, the efficacy of various ventilation strategies in reducing the likelihood of contagion has been investigated. Finally, because building ventilation is inextricably linked to energy consumption, the energy and economic implications of the proposed enhancements have been assessed. To carry out the described analysis, a novel method was developed that combines Building Energy Modelling (BEM) and virus contagion risk assessment. The analyses conducted produced interesting insights and criteria for ventilation system design and operation, as well as recommendations for the development of future standards.
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Adequate and efficient building ventilation and filtration are key factors that play an important part in controlling the spread of airborne pathogens like SARS-CoV2 virus (Allen and Ibrahim, 2021). However, most public buildings lack the ability to test and verify performance of their HVAC and mechanical systems for airborne pathogens due to limitations in existing diagnostic assessment tools. Carleton University performed air sampling campaigns in 24 different spaces to assist in the assessment of our HVAC systems performance across campus. The sampling campaign collected over 600 aerosol samples using veriDART's patented DNA-tagged tracer particles that simulate airborne pathogen mobility and exposure within and between rooms. The primary goal of the survey was to assess aerosol migration at the floor level as well as the potential dilution rate of COVID-19 aerosols. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.
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This paper presents an evaluation of the impact of changes in building HVAC system operation guidelines, aiming to reduce COVID-19 propagation, on building energy performance. Given the recentness and emergency nature of these responses, there is a gap in the literature addressing the energy performance impact of these new recommendations. Practical measures recommended by ASHRAE and REHVA are implemented in a computer simulation model of an existing building, created using the eQUEST program. Results show the increase of building EUI and operating cost mostly in the range of 20% to 60%. This increase is mainly due to additional: (a) space heating and cooling thermal loads, and (b) ventilation fans and pumps electricity consumption;caused by longer operation hours, increased ventilation rates and the implementation of humidity control. This research showcases the application of modelling tools in the support of public guidelines development, and it serves as an encouragement to consultants and researchers to explore methods for mitigating the impact and increasing feasibility of public health regulations. © International Building Performance Simulation Association, 2022
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Optimising HVAC operations towards human wellness and energy efficiency is a major challenge for smart facilities management, especially amid COVID situations. Although IoT sensors and deep learning were applied to support HVAC operations, the loss of forecasting accuracy in recursive prediction largely hinders their applications. This study presents a data-driven predictive control method with time-series forecasting (TSF) and reinforcement learning (RL), to examine various sensor metadata for HVAC system optimisation. This involves the development and validation of 16 Long Short-Term Memory (LSTM) based architectures with bi-directional processing, convolution, and attention mechanisms. The TSF models are comprehensively evaluated under independent, short-term recursive, and long-term recursive prediction scenarios. The optimal TSF models are integrated with a Soft Actor-Critic RL agent to analyse sensor metadata and optimise HVAC operations, achieving 17.4% energy savings and 16.9% thermal comfort improvement in the surrogate environment. The results show that recursive prediction leads to a significant reduction in model accuracy, and the effect is more pronounced in the temperature-humidity prediction model. The attention mechanism significantly improves prediction performance in both recursive and independent prediction scenarios. This study contributes new data-driven methods for smart HVAC operations in IoT-enabled intelligent buildings towards a human-centric built environment. © 2023 The Authors
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Background: Ventilation system besides other prevention strategies such as surface disinfecting and personal protective equipment (PPE) decrease the risk of coronavirus disease 2019 (COVID-19) infection. This study aimed to examine the ventilation system of an intensive care unit (ICU) in a hospital in Tehran, Iran to evaluate the potency of heating, ventilation, and air conditioning system (HVAC) for COVID-19 spread. Materials and Methods: Contamination of air turnover caves was evaluated in supplier diffuser and extractor grills of negative pressure HVAC by ten samples. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the samples was evaluated by the real time reverse transcription-polymerase chain reaction (PCR). Moreover, air conditioning and sick building syndrome (SBS) was assessed according to MM040EA questioning from health care workers. Results: In the health care workers, respiratory effects were more prevalent compared to other signs. Despite suitable air conditioning, this study highlighted carrier potency of ICU workers for SARS-COV-2. Conclusion: According to our results, although the HVAC of ICU ward had an appropriate air movement, it was not safe enough for health care workers.
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In the last years, the Covid-19 outbreak raised great awareness about ventilation system performance in confined spaces. Specifically, the heating, ventilation, and air conditioning system design and operating parameters, such as air change per hour, air recirculation ratio, filtration device performance, and vents location, play a crucial role in reducing the spread of viruses, moulds, bacteria, and general pollutants. Concerning the transport sector, due to the impracticability of social distancing, and the relatively loose requirements of ventilation standards, the SARS-COV-19 outbreak brought a reduction of payload (up to 50%) for different carriers. Specifically, this has been particularly severe for the railway sector, where train coaches are typically characterized by relatively elevated occupancy and high recirculation ratios. In this framework, to improve the Indoor Air Quality and reduce the Covid-19 contagion risk in railway carriages, the present paper investigates the energy, economic and environmental feasibility of diverse ventilation strategies. To do so, a novel dynamic simulation tool for the complete dynamic performance investigation of trains was developed in an OpenStudio environment. To assess the Covid-19 contagion risk connected to the investigated scenarios, the Wells-Riley model has been adopted. To prove the proposed approach's capabilities and show the Covid-19 infection risk reduction potentially achievable by varying the adopted ventilation strategies, a suitable case study related to an existing medium-distance train operating in South/Central Italy is presented. The conducted numerical simulations return interesting results providing also useful design criteria.
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In a larger educational building in Slovenia, we examined the efficiency of ventilation systems by analysing the operation of the heating, ventilation, and air conditioning (HVAC) system in several classrooms. Using the Federation of European Heating, Ventilation and Air Conditioning Associations (REHVA) COVID-19 ventilation calculator, the probability of infection due to the spread of coronavirus through aerosol particles and the reproduction number were calculated based on the classroom occupancy, ventilation rates, and other parameters (i.e., classroom characteristics, preventive measures). Firstly, different levels of ventilation capacity (50 % and 80 %) were applied. Considering the distance between occupants 1.5 m and wearing the masks of all participants, the probability of infection during lectures was always lower than 1 %. Secondly, the maximum number of students that can attend lectures is about 30 %, as calculated according to the legal requirements, recommendations, and given conditions.
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The author has been conducting research on UV based photocatalytic air purifier systems for the past 5 years to eliminate living organic germs, bacteria, pathogens, etc. from the cabin air. An HVAC system has been developed by using a filter impregnated by titanium di-oxide (TiO2) with UV lights to improve and maintain cabin air quality. The designed system can be used for conventional vehicles, EVs, ride sharing and for autonomous vehicles. The author has designed and constructed a 3rd generation HVAC unit for cabin air purification for automobiles that is based on UV photocatalytic process by using UV-C LEDs to eliminate viruses that typically exist in conditioned space. The author has conducted tests with the following viruses and bacteria that are typically encountered in a conditioned environment:(i)Staph Epidermititus: Infections in wounds (Anthrax)(ii)Erwinia Herbicola: Bacteria (Infection in soil and water)(iii)MS2: RNA, COVID-19(iv)Phi-174: DNA, Herpes and HIV(v)Bacillus Globigii: Virus - influenza(vi)Aspergillus Niger: Mold spore (Black mold) Percentage destruction rates for the above viruses and bacteria at 15, 30, 45 and 60 minute intervals are presented in this paper. The developed system is able to reduce the viruses by almost 99.99#x00025;(log 4 reductions) in first 15 minutes of unit operation. Aspergillus Niger destruction rates were lower - approx. 90.3#x00025;in 15 minutes (log 1 reduction). The developed system out performs the industry standard of log 4 reductions in 60 minutes! Using a UV-C and UV-A LED light sources with titanium dioxide filter makes this a unique application for automobile HVAC systems. Additional tests have been planned in 2022 to ensure the developed system is able to eliminate Omicron, a variant of COVID-19. © 2022 SAE International. All Rights Reserved.
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What can the hospitality industry do to reduce the risk of transmission of COVID-19? Part is recognizing that HVAC systems play a role in mitigating the risk of airborne transmission of COVID-19.1 At the beginning of the pandemic, hospitality facilities, including hotels and restaurants, quickly aligned with guidance from the CDC,2,3 WHO4 and other credible organizations such as ASHRAE5,6 by adjusting operating guidelines to increase outdoor air dilution and improve filtration, where possible, while maintaining guest and associate comfort. This article discusses a comprehensive study recently conducted by the authors to investigate the efficacy of portable air purifiers to improve air quality in public spaces. © 2021 Amer. Soc. Heating, Ref. Air-Conditoning Eng. Inc.. All rights reserved.
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Objective/Scope: One of the main concerns of Oil & Gas Plants and associated Buildings is how to improve indoor air quality (IAQ) and tackling viruses. IAQ can be affected, or may become under high risk by some of nearby gases, microbial contaminates or energy stressor that affect the HSE condition. This paper presents the main factors that been considered to provide practical solutions to achieve high IAQ and tackling viruses (such as COVID-19). Methods, Procedures, Process: IAQ refers to the air quality within and around the plants/buildings. IAQ can usually be affected, or may become under high risk by nearby gases, particulates, microbial contaminates or any mass that affect 100% HSE. Inadequate air quality in building will increase the risk and impact on transferring viruses to people (such as COVID and Flue) and equipment performance (such as equipment failure, components corrosion and short circuits on control board). Survey and data was recorded to evaluate air quality performance in atmosphere instead of assuming it. Accordingly, the impact of inadequate IAQ was studied and evaluated. Results, Observations & Conclusions: The international standard set a good IAQ in respect of gas concentration and human who works inside buildings in a way that less than 50% people should not detect any odor, 25% should not experience discomfort, 10% should not suffer from mucosal irritation and 5% should not experience annoyance. Study concluded that inadequate IAQ inside the building will affect people performance/health and installed equipment performance. In addition, improper HVAC system operation will be become breeding site for odor causing mold and bacteria, specifically on cooling coil. Hence, several technics were studied to improve IAQ, by installing Ultraviolet (UV) light to stop growing bacterial inside the HVAC system, installing chemical filter in air intakes to remove atmospheric dust, gases and bacteria by 100%, upgrading filtration efficiency to MERV-13 or highest achievable to capture at least 75 - 95% of airborne particles between 0.3 and 1.0 micron, increase outdoor air ventilation and temperature/humidity control. The performance of HVAC system and quality of air inside building were monitored by simulating IAQ based on ISO 16890, filters life cycle, energy consumption, and the results were found 100% satisfactory and provided solutions that are now successfully implemented in all new and some of the existing buildings. Novel/Additive Information: There are several buildings with similar issues and these approach/technics now being adopted in new constructed/existing buildings to protect human and asset integrity, which will support ADNOC Way by sustaining safe environment operation, lower health risk, reduce of equipment failure, reduce maintenance cost and 100% HSE. There are numbers of occupied buildings across the world were surrounded by aggressive gases/pollution with poor IAQ and above approaches it can be followed to realize larger benefits. © Copyright 2021, Society of Petroleum Engineers
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In this paper, the use of HVAC systems and non‐HVAC control measures to reduce virus-laden bioaerosol exposure in a highly occupied indoor space is investigated. A simulation tool was used to model the fate and transport of bioaerosols in an indoor space in the hotel industry (bar or pub) with three types of HVAC system (central air handling system (CAHS), dedicated outdoor air system (DOAS), and wall unit system (WUS)). Non‐HVAC control measures such as portable air cleaners (PAC) and local exhaust fans were considered. Occupant exposure was evaluated for 1 μm bioaerosols, which transport SARS‐CoV‐2, for 3 h/day of continuous source and exposure. The combined effects of ventilation (400 l/s of outdoor air), recirculated air filtration (90% efficacy), and a PAC with a capacity up to 900 m3/h mitigated the (normalized) integrated exposure of the occupant by 0.66 to 0.51 (CAHS) and 0.43 to 0.36 (DOAS). In the case of WUS, the normalized integrated exposure was reduced by up to 0.2 when the PAC with a capacity of up to 900 m3/h was used. The corresponding electricity consumed increased by 297.4 kWh/year (CAHS) and 482.7 kWh/year (DOAS), while for the WUS it increased by 197.1 kWh/year. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.
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A cooperative control strategy is proposed for the air conditioning (AC) system and ventilation system to reduce the risk of COVID-19 infection and save the energy of the AC system. This strategy integrates the dynamic model of the AC-cabin system, infection risk assessment, model predictive control (MPC) of the thermal environment inside the cabin, and ventilation control that considers passengers' sneezing. Unlike other existing AC system models, the thermal-health model established can describe not only the system performance but also the virus concentration and risk of COVID-19 infection using the Wells-Riley assessment model. Experiments are conducted to verify the prediction accuracy of the AC-cabin model. The results prove that the proposed model can accurately predict the evolution of cabin temperature under different cases. The cooperative control strategy of the AC system integrates the MPC-based refrigeration algorithm for the cabin temperature and intermittent ventilation strategy to reduce the risk of COVID-19 infection. This strategy well balances the control accuracy, energy consumption of the AC system, and the risk of COVID-19 infection, and greatly reduces the infection risk at the expense of a little rise in the energy consumption.
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Data from an online survey conducted in January 2021 by 464 participants living in London and working from home (WFH) after the COVID-19 outbreak were analysed, focusing on: (1) types of building services at home, (2) perceived sound dominance of building services, and (3) the perception of the indoor acoustic environment (i.e. the indoor soundscape) in relation to two main activities, i.e. WFH and relaxation. Results show that most of participants' houses had radiators for heating and relied on window opening for ventilation and cooling. Air systems (e.g., HVAC systems) resulted in higher perceived dominance compared to other systems, but only when evaluated for WFH. Sound dominance from building services was in turn related to soundscape evaluation. Spaces with less dominant sounds from building services were more appropriate for both WFH and relaxation, and spaces with fewer dominant sounds were assessed better, but just for WFH. Participants' evaluations generally did not differ according to building service typology. The presence of air-cooling systems was associated with better perceived sound environments, most likely due to better acoustics conditions in newly built or retrofitted dwellings, more probably equipped with air cooling systems. Preliminary findings point out the importance of carefully considering the dominance of sounds by building services, especially for air systems, in relation to traditional and new uses of residential buildings. © 2021 Institute of Physics Publishing. All rights reserved.
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With the sudden outbreak and rapid spread of COVID-19, global economic development and social stability have been seriously affected. The virus mainly spreads infection among people on a large scale through the air. People are gradually focusing on how to use HVAC system, so that it can play a more efficient and positive role in epidemic prevention and control. Consequently, we designed an intelligent purification and disinfection apparatus for air-conditioning units. The apparatus integrates rapid virus detection and high-efficiency disinfection functions. It uses a modular design and different operating modes for different levels of epidemic periods. This apparatus is not only suitable for daily life, but also can meet the prevention and control requirements during the epidemic period, which takes the economy, energy saving, and environmental protection into account. © 2021 Institute of Physics Publishing. All rights reserved.
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In this research paper, an analysis is developed on the performance of a hybrid ventilation system that combines Earth-to-Air Heat eXchangers (EAHX), free cooling and evaporative cooling Air Handling Unit Heat eXchanger (AHU-HX), all being controlled by a Building Management System (BMS) in a net Zero Energy Building (nZEB), called LUCIA. LUCIA nZEB is the first safe-building against Covid-19 in the world, certified by the international organisation WOSHIE, and located in Valladolid, Spain. The main aim is to optimize the performance of the three systems in such a way that the Indoor Air Quality (IAQ) levels remain within the allowable limits, while maximizing the use of natural resources and minimizing energy consumption and carbon emissions. The approach to satisfy the heating and cooling demand and IAQ levels through zero emissions energy systems is developed, thus anticipating the zero-energy target, set by the European Union for 2050. Results showed that the installed hybrid ventilation system uses heat exchangers for 70% of the operational time, in order to achieve the set parameters successfully. Also, the analysis made by monitoring data, have shown that the control and optimal operation of the hybrid ventilation system allows high energy recovery values with minimum additional electricity consumption. Significant reduction of carbon emissions and operational costs have been achieved.