Effective Ventilation Strategies for Mitigating Infection Risks in Hospitals (C5108-20GF)
Collaborative Research Fund (CRF) COVID-19 and Novel Infectious Disease (NID) Research Exercise, Research Grants Council of the Hong Kong Special Administrative Region, China
Amount awarded: HKD$ 4,429,517
Collaboration: The Hong Kong Polytechnic University, City University of Hong Kong, The University of Hong Kong
Layman Summary
Healthcare-associated infections (HAIs) impose excessive burden on existing healthcare systems. The outbreak of Coronavirus Disease (COVID-19) pandemic worldwide once again reminds us the potential threat of airborne transmission within a hospital. A number of viruses and bacteria are known to be spread by air, for example, Tuberculosis, influenza virus and SARS-CoV-1. Guidance for airborne precautions has been provided to healthcare workers (HCWs) taking care of patients with known or suspected viral infections. Nonetheless, risk of in-hospital airborne transmission remains if a patient with unidentified airborne infection of novel virus or asymptomatic infection of known airborne diseases is not handled correctly in General Human Occupied Areas (GHOAs) (i.e. general inpatient ward, outpatient clinic, accident and emergency (A&E) room and washrooms). Studies indicated ventilation systems in mechanically ventilated enclosure could improve virus removal capacity and energy efficiency, however, barely any study has addressed the temporal influence of infection risk, medical cost and energy consumption in respect of ventilation control parameters and airborne pathogen emission scenarios.
In this proposed study, computational modelling of expiratory droplet dispersion, transportation and deposition will be employed to evaluate the infection risk of various ventilation strategies in mechanically ventilated GHOAs. The fluid dynamics inside the drainage systems, the indoor dispersion from ingress of contaminated aerosols in washroom, the outdoor emission disposal of pathogenic bioaerosol from the ventilation stack and associated medical cost and energy impact will also be studied. Based on two respiratory viruses, namely SARS-CoV-2 and H1N1 influenza virus, exposure risks and an exposure assessment indicator will be developed. Moreover, annual energy consumption of different ventilation strategies will be calculated via a building energy simulation tool. By understanding the association between exposure risk and energy expenditure, strategic ventilation schemes for a general hospital area and washroom that could strike a balance between cross-infection risk (in terms of reduced medical cost) and energy consumption will be proposed to the hospital management.
Research activities
Micro Environment
Updating indoor air quality (IAQ) assessment screening levels with machine learning models
IAQ standards have been evolving to improve the overall IAQ situation. COVID-19 has raised public concerns about ventilation and indoor air quality, especially in dense cities like Hong Kong. It is of utmost importance to develop IAQ screening strategies to ensure healthy and comfortable indoor environments. To enhance the performances of IAQ screening models using surrogate parameters in identifying unsatisfactory IAQ, and to update the screening models such that they can apply to a new standard, a novel framework for the updating of screening levels, using machine learning methods, was proposed. With carefully selected model hyperparameters, the IAQ assessment made by the models achieved high test accuracy of 0.807–0.820, indicating that machine learning models are suitable for screening unsatisfactory IAQ. The updating framework was presented using the updated IAQ standard in Hong Kong as an example, demonstrating the feasibility of updating a machine learning IAQ model when a new standard is being adopted, which shall provide an ultimate method for IAQ assessment prediction that is compatible with all IAQ standards and exposure criteria.
Reference:
Wong, L. T., Mui, K. W., & Tsang, T. W. (2022). Updating Indoor Air Quality (IAQ) Assessment Screening Levels with Machine Learning Models. International Journal of Environmental Research and Public Health, 19(9), 5724.
CFD simulations for airborne dispersion and deposition of Methicillin-resistant Staphylococcus aureus (MRSA) in general inpatient ward environment
The study describes the use of computational fluid dynamics simulations to evaluate four airflow change rate scenarios with different bioaerosol particle sizes emitted by sneezing or coughing, and validated the established models using actual field environmental data of MRSA collected from a general inpatient ward. This study provides a new piece of empirical evidence to support the airborne MRSA transmission in the hospital ward environment, which give insights into the interdisciplinary research approach for investigating the effect of airflow on airborne transmission with the support of field measurements.
(left) Layout of a general inpatient ward; (right) Air velocity distribution across a horizontal plane located at y = 1.35m under 3, 6, 9 and 13 ACH.
Reference:
A journal article titled “Computational fluid dynamics simulation for airborne dispersion and deposition of Methicillin-resistant Staphylococcus aureus in general inpatient ward environment” was submitted to Heliyon.
The role of ventilation system in airborne transmission in hospitals
Throughout the years, building researchers and medical experts have conducted a lot of studies to identify the effect of hospital ventilation on airborne transmission in order to provide a better understanding of HAIs and recommend ventilation improvement strategies. Despite the efforts, a general agreement on the optimal ventilation strategy for hospitals has not been reached. In this study, we comprehensively reviewed the current research approaches and focuses of CFD studies on hospital ventilation and airborne transmission was conducted. A total of 95 journal articles and conference papers published between the years 2003 and 2021 were reviewed. We discussed the trend of research throughout the review period, the main research focuses, benefits and drawbacks of using CFD techniques, the conclusions or suggestions drawn from existing research and the future research directions in the field.
Reference:
Tsang, T. W., Mui, K. W., & Wong, L. T. (2022). Computational Fluid Dynamics (CFD) studies on airborne transmission in hospitals: A review on the research approaches and the challenges. Journal of Building Engineering, 105533.
Development of a novel wireless tracer gas system
The tracer gas experiment is one of the comment approaches to study airborne transmission under the influence of ventilation. Prevalent commercial tracer gas measuring instruments are rather expensive, have a long sampling cycle and are limited in the number of sampling points. This study developed a novel R134a tracer gas system using small sensors incorporated in a wireless module. The system has a sampling cycle of 10 seconds, and the measurement data are transmitted to and stored in a cloud database through Wi-Fi for real-time analysis and data retrieval. The novel system gives quick response, detailed spatial and temporal profiles of the tracer gas levels, and comparable air change rate analysis. The system can serve as an affordable alternative to traditional tracer gas systems for evaluating ventilation performance. With multiple units deployed as a wireless sensing network, the system can identify the dispersion pathway of tracer gas, thus aiding the estimation of transmission risks.
Photos of the novel tracer gas system.
Reference:
Tsang, T. W., Mui, K. W., Wong, L. T., Law, K. Y., & Shek, K. W. (2023). A Novel IoT-Enabled Wireless Sensor Grid for Spatial and Temporal Evaluation of Tracer Gas Dispersion. Sensors, 23(8), 3920.
Mapping the knowledge pattern of ultraviolet germicidal irradiation for cleaner indoor air
Due to the global outbreak of infectious diseases over the years, airborne pathogen removal from the indoor environment has become a critical issue. Ultraviolet germicidal irradiation (UVGI) has been adopted as a strategic solution, and its implementation shows the enormous potential of inactivating airborne infectious pathogens. Despite extensive research, some critical research areas or gaps remain unidentified, while at the same time, few studies highlight the knowledge trend for UVGI air disinfection research necessary to guide investigators and practitioners. The purpose of this paper is to provide a thorough and objective analysis of UVGI research areas using bibliometric analysis. The available international standard known as the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) was followed for conducting this review. A comprehensive search covering the publication year up to December 2021 using Web of Science (WoS), Scopus, and PubMed databases was conducted. Also, the selection of studies, extraction of data, and assessments of risk of bias were also carried out. The characteristics and results of selected studies in evidence graphs, pie charts, network maps, and tables were presented and discussed. A total of 210 UVGI air disinfection-related publications were identified and reviewed. Based on the keyword co-occurrence analysis, document and direct citation analysis, 112 research keywords (see Table A1), and 6 core research journals were identified. Further, the results show that 3 countries and 7 organizational collaborators are at the centre of UVGI research. Based on the clustering analysis and comprehensive analysis of the findings, the research domain was developed, which grouped UVGI research into four themes. These findings are highly important for the advancement of UVGI. This paper provides a significant contribution by showing the knowledge pattern needed to facilitate further research and applications for both academia and industry stakeholders to improve indoor air quality.
Reference:
Nunayon, S. S., Mui, K. W., & Wong, L. T. (2023). Mapping the knowledge pattern of ultraviolet germicidal irradiation for cleaner indoor air through the lens of bibliometrics. Journal of Cleaner Production, 135974.
Influences of home kitchen designs on indoor air quality
Kitchen indoor air quality (IAQ) has not been well-addressed amongst other IAQ problems at home, despite the fact that cooking is one of the major home activities that can generate high levels of respirable particles and gaseous air pollutants. This study aims at investigating the effects of home kitchen designs on the performance of various ventilation strategies in reducing exposure to IAQ pollutants. The degree of natural ventilation was found to be dependent largely on the relative position of window and door opening, and using mixed ventilation with natural cross-ventilation and mechanical ventilation did not necessarily provide better ventilation. Natural ventilation with the added fume extraction by the exhaust fan could not protect the occupants from high levels of cooking pollutants. Range hood on the other hand could quickly and locally remove particles and gaseous cooking pollutants from the source. The study recommends using a range hood alone during cooking or with single-side natural ventilation to maintain an acceptable IAQ in the home kitchen.
Reference:
Tsang, T. W., Wong, L. T., Mui, K. W., & Poon, C. Y. (2023). Influences of home kitchen designs on indoor air quality. Indoor and Built Environment, 1420326X231164290.
Ten Questions Concerning Indoor Environmental Quality (IEQ) Models
In the past two decades, with advances in data collection and in analytical techniques and tools, there has been a significant increase in research on indoor environmental quality (IEQ) assessment. To better understand the relationships between the overall IEQ performance and individual IEQ aspects, namely, indoor air quality, thermal comfort, acoustic quality, and visual quality, IEQ models have been developed by many previous studies. In this paper, the IEQ models proposed in the literature in the period from 2001 to 2022 are examined and summarized into ten questions, including but not limited to indicator selection, data collection, analysis methods, interpretation, and implication. The proposed answers aim to provide insight into current studies on IEQ models and identify gaps for future research. It has been found that the existing IEQ models differed for different building types or occupants. To compare the IEQ performance of various buildings in other countries, standardized data collection protocols are necessary, including the selection of IEQ aspects/indicators and their corresponding objective measurement strategies and standardized subjective survey methods. In addition, the data analysis approaches used to develop the IEQ models must be unified. Moreover, criteria for overall IEQ performance and the individual IEQ aspects should be provided. This study is the first comprehensive investigation of all the steps involved in IEQ model development. The answers to these ten questions can be seen as practical instructions for establishing an improved, standardized, and repeatable IEQ assessment model.
Reference:
Zhang, D., Mui, K. W., & Wong, L. T. (2023). Ten Questions Concerning Indoor Environmental Quality (IEQ) Models: The Development and Applications. Applied Sciences, 13(5), 3343.
Minimizing airborne transmission in general inpatient wards through management practices
Existing infection control studies in hospitals focused on rooms with special ventilation requirements. Study on proper management practices and ventilation strategies in general inpatient wards are critical but currently lacking. To identify the simple operational practices that can limit airborne transmission within a general inpatient ward with the patient cubicle, nursing station and corridor, this study investigates the effects of infected patient locations, air change rates (ACH) and door opening angles on bioaerosol dispersion using a novel tracer gas sensor network. Experimental results show that the supply inlet and infected patient locations significantly affects the distribution and dispersion of the tracer gas within the ward. Using a higher ventilation rate to achieve a lower average airborne pathogen concentration can cause more mixing of air and a wider dispersion of airborne pathogens. Localization of bioaerosols near the source through ventilation controls, a low ACH and proper patient location near the exhaust can minimize the air turbulence and the spread and reduce the infection risks of the susceptibles. Using physical partitions or objects as shields against airborne contaminants can unpredictably influence the airflow patterns, airflow evaluations should hence be done on a case-by-case basis. The methodology established in this study puts forward an economical and fast way for evaluating airborne infection risk, and the experimental results can be useful references for building engineers and hospital facility managers to formulate proper strategies for risk assessment and infection control.
Experimental set-up simulating the infected patient (Left) and the susceptible patient (Right).
Reference:
Tsang, T. W., Wong, L. T., Mui, K. W., Satheesan, M. K., Yuen, J. W. M. (2023). Preparing for the next pandemic: Minimizing airborne transmission in general inpatient wards through management practices. Energy and Buildings, 294(1), 113214.
Numerical investigation of ventilation strategies to mitigate airborne transmission in inpatient wards
The emission of pathogens from exhalation activity, such as sneezing, by an undiagnosed infectious patient admitted to general inpatient wards, is a significant concern for infection outbreaks. The ventilation strategy for general wards needs to be better defined for infection control compared to those of operation theatres, isolation rooms and intensive care units. This research article presents a numerical study on the effect of varying air change rates (3 h-1, 6 h-1, 9 h-1, 13 h-1) and exhaust flow rates (0%, 10%, 50% of supply air quantity) on the concentration of airborne pathogens in a general inpatient ward. The findings imply that the breathing zone directly above the source patient has the highest level of pathogen exposure, followed by the breathing zones at the bedside and adjacent patients close to the source patient. The dispersion of pathogens throughout the ward over time is also apparent. However, a key difference while adopting a lower ACH (3 h-1) and a higher ACH (13 h-1) in this study was that the latter had a significantly lower number of suspended pathogens in the breathing zone than the former. In addition, combining a higher air change rate (13 h-1) with a high exhaust flow rate (50% of supply air) through a local exhaust grille dramatically reduced suspended pathogens within the breathing zone, further mitigating the risk of pathogen exposure for ward users. Therefore, this study presents a cost-effective ventilation technique to dilute and eliminate airborne infectious pathogens, minimizing their concentration and the risk of infection.
Reference:
Satheesan, M. K., Tsang, T. W., Wong, L. T., Mui, K. W. (2024). The air we breathe: Numerical investigation of ventilation strategies to mitigate airborne dispersion of MERS-CoV in inpatient wards. Heliyon. In press.
Experimental studies on airborne transmission in hospitals
Experimental studies provide understanding, knowledge, and real-case empirical evidence on the effects of building ventilation and environmental factors on airborne transmission in hospitals. Information obtained from existing studies gives insight into formulating engineering solutions and management practices to combat nosocomial airborne infections. A systemic review was conducted to summarize the experimental methods, research interests, useful results and limitations. With a steady but slow trend of increasing interest, experimental studies focused mainly on the effects of ventilation systems, strategies and configurations on airborne transmission. The dispersion of bioaerosols under the combined effects of environmental factors, emission scenarios and human movement was investigated. Localized ventilation, air purifiers and disinfection technologies were also examined. The experimental techniques and some useful insights on optimal ventilation strategies and management practices were summarized and highlighted. Limitations of the empirical studies included sampling difficulties, limited scale and number of testing scenarios, uncontrolled/ unconsidered influencing factors and the mediums for experimentations. Using IoT-based sampling devices for experiments and real-time monitoring of bioaerosols or their surrogates, field surveys on a case-by-case basis in hospitals and interdisciplinary studies and collaborations could help overcome the research challenges and provide practical and effective solutions to minimize airborne transmission in hospitals.
Reference:
Tsang, T. W., Wong, L. T., Mui, K. W. (2023). Experimental studies on airborne transmission in hospitals: A systematic review. Indoor and Built Environment. Online first.
CFD simulations using a genetic algorithm
Optimising ventilation strategy for an indoor environment necessitates systematically evaluating the influence of a diverse combination of physical and operational parameters in the design space. This study proposes a methodology that couples an evolutionary algorithm (genetic algorithm) with an evaluation mechanism (Computational Fluid Dynamics) to determine the optimal ventilation strategy for an inpatient ward. The traditional approach would exhaustively simulate numerous scenarios to identify the optimal combination of parameters meeting the design objective. The proposed methodology would iteratively evaluate diverse design solutions with fewer CFD simulations than the traditional approach. The results of design space exploration suggest that design parameters, namely, location of the infected patient; air change rate; flow rate through local exhaust grille; number, location, and size of supply air diffuser and local air exhaust grille are critical in minimising the risk of cross-infection caused through contact transmission in a ward.
Satheesan, M. K., Tsang, T. W., Mui, K. W., Wong, L. T. (2023). Optimal ventilation strategy for multi-bed hospital inpatient wards: CFD simulations using a genetic algorithm. Indoor and Built Environment. Online first.
Macro Environment
Mesoscale
In the mesoscale CFD, we generally look into how the natural terrain and urban landcover and/or landuse affect the flows and turbulence over urban areas. The mesoscale Weather Research and Forecasting (WRF) model is used. Local climate zone (LCZ) and building categories (LCZBCs) are integrated into WRF for the first time, handling landcover/landuse and building configuration. The urban morphology parameters (UMPs) in LCZ are clustered into three groups: urban structure, vegetation fraction, impervious surface thermal properties, to contrast the influence from landcover/landuse. Our results show that urban structure induces an elevated nighttime temperatures that modifies the flows. The difference in urban-rural building/street structure is the key factor in compact (LCZ1) and open (LCZ4) high-rise areas, especially commercial-dominant ones, in which the temperatures (and air-conditioning load) are increased. Besides, greenery is found to be most effective to mitigate the elevated urban temperatures and lessen air-conditioning demand in middle-rise (LCZ2&5) and low-rise (LCZ3&6&8&10) areas. Its benefit is most prominent for residential-dominant areas that could reduce the temperatures and air-conditioning load. In contrast to rural pavement, urban impervious surfaces induce negligible increases in temperature and air-conditioning load.
Microscale
In the microscale CFD, we generally look into how buildings and urban morphology affect the flows and turbulence. The large-eddy simulation (LES) was used to calculate the flows around/over explicitly resolved buildings. Winds are the basic forces for atmospheric transport such as pollutant removal and pedestrian thermal comfort. The transport capability is commonly measured in terms of length and velocity scale. In this connection, the flows in the atmospheric surface layer (ASL) over the Kowloon Peninsula, Hong Kong are scrutinized by LES to characterize the motion scales over real urban morphology. Apart from statistical analysis, the streamwise fluctuating velocity u’’ is examined by both wavelet and energy spectrum in which a primary peak is consistently shown at streamwise wavelength 70 m ≤ λx ≤ 300 m. A secondary peak at a longer wavelength 800 m ≤ λx ≤ 3,000 m, however, is unveiled by wavelet only. It denotes the existence of intermittent turbulence structures whose sizes are much longer than those of buildings. Further wavelet analysis reveals that major energy-carrying eddies are enlarging (tens to hundreds of meters) from the roughness sublayer (RSL) to the inertial sublayer (ISL). Analogous to its smooth-wall and schematic rough-wall counterparts, the turbulence kinetic energy (TKE) over urban areas is peaked in the ISL which is carried by eddies of size 50 m ≤ λx ≤ 1,000 m. The (horizontal) spatial distribution of energy-carrying eddies is further visualized to contrast the (dissimilar) motion scales in the RSL and ISL. Finally, conditional sampling is used to demystify the contribution to vertical momentum flix u’’w’’ in terms of streamwise wavelength and quadrants. The results advance our fundamental understanding of ASL transport processes, fostering sustainable environmental policy.
Reference:
Du, R., Liu, C. H., & Liu, Y. (2023). High-frequency fluctuation of air temperature during a heatwave event in urban environment and the physical mechanism behind. Building and Environment, 245, 110824.
Liu, Y., Liu, C. H., Brasseur, G. P., & Chao, C. Y. (2023). Empirical mode decomposition of the atmospheric flows and pollutant transport over real urban morphology. Environmental Pollution, 331, 121858.
Du, R., Liu, C. H., Li, X. X., & Lin, C. Y. (2023). Effect of local climate zone (LCZ) and building category (BC) classification on the simulation of urban climate and air-conditioning load in Hong Kong. Energy, 271, 127004.
Liu, Y., Liu, C. H., Brasseur, G. P., & Chao, C. Y. (2023). Amplitude modulation of velocity fluctuations in the atmospheric flows over real urban morphology. Physics of Fluids, 35(2).
Liu, Y., Liu, C. H., Brasseur, G. P., & Chao, C. Y. (2023). Proper orthogonal decomposition of large-eddy simulation data over real urban morphology. Sustainable Cities and Society, 89, 104324.
Liu, Y., Liu, C. H., Brasseur, G. P., & Chao, C. Y. (2023). Wavelet analysis of the atmospheric flows over real urban morphology. Science of The Total Environment, 859, 160209.
Drainage System
Development of a full-scale, 3-floor mock-up toilet experimental research facility
To establish a testing ground for CFD model validation and identify the potential transmission pathways and the influences of the environmental factors in promoting airborne transmissions through drainage systems and within the toilet environment, a full-scale, 3-floor mock-up toilet experimental research facility was constructed at The Hong Kong Polytechnic University. The facility consists of two fully functioning toilets built according to the layout and dimensions of the toilet of a single-person public housing flat. The toilets are equipped with an operable plumbing and drainage system with the drainage-ventilating pipe extended 1 m above the roof, an electrical system, an openable window, an exhaust fan, and a sliding door. This facility will later be used for experimental works for validating the CFD models for dynamic water and airflow in the drainage system.
(left) Schematic diagram; (right) Photo of the mock-up toilet
Reference:
Mui, K. W., Tsang, T. W., Wong, L. T., Lee, W. M. (2022). A full-scale 3-floor mock-up toilet experimental research facility, presented at the 47th CIBW062 International Symposium of Water Supply and Drainage for Buildings, on 23-26 October 2022.
Measurement of air pressure in a ventilation section of a 150-mm diameter stack during a branch pipe discharge
The instantaneous air pressures in an upstream ventilation section of a laboratory-scale test rig which consisted of a drainage stack of 2.5-m long, 150 mm-diameter during a downstream connected branch pipe discharging were measured at a flow rate of 1-4 L/s. The stack upstream ventilation section is open to the atmosphere via an orifice with a diameter of 5-20 mm. The average air pressure was recorded during the discharge. The results could help to generate data for CFD validation.
Reference:
Wong, L. T., Mui, K. W., Cheng, C. L., & Leung, P. H. (2021). Time-Variant Positive Air Pressure in Drainage Stacks as a Pathogen Transmission Pathway of COVID-19. International journal of environmental research and public health, 18(11), 6068.
Wong, L. T., Mui, K. W., Cheng, C. L. (2021). Measurement of positive air pressure in a ventilation section of a 150-mm diameter stack during a branch pipe discharge, presented at the 46th CIBW062 International Symposium of Water Supply and Drainage for Buildings, on 26-27 October 2021.
Energy
A Hybrid Simulation Model to Predict the Cooling Energy Consumption for Residential Housing in Hong Kong
In Hong Kong, buildings consume 90% of the electricity generated and over 60% of the city’s carbon emissions are attributable to generating power for buildings. In 2018, Hong Kong residential sector consumed 41,965 TJ (26%) of total electricity generated, with private housing accounting for 52% and public housing taking in 26%, making them the two major contributors of greenhouse gas emissions. Furthermore, air conditioning was the major source consuming 38% of the electricity generated for the residential building segment. Strategizing building energy efficiency measures to reduce the cooling energy consumption of the residential building sector can thus have far-reaching benefits. This study proposes a hybrid simulation strategy that integrates artificial intelligence techniques with a building energy simulation tool (EnergyPlus™) to predict the annual cooling energy consumption of residential buildings in Hong Kong. The proposed method predicts long-term thermal energy demand (annual cooling energy consumption) based on short-term (hourly) simulated data. The hybrid simulation model can analyze the impacts of building materials, construction solutions, and indoor–outdoor temperature variations on the cooling energy consumed in apartments. The results indicate that using low thermal conductivity building materials for windows and external walls can reduce the annual cooling energy consumption by 8.19%, and decreasing the window-to-wall ratio from 80% to 40% can give annual cooling energy savings of up to 18%. Moreover, significant net annual cooling energy savings of 13.65% can be achieved by changing the indoor set-point temperature from 24 °C to 26 °C. The proposed model will serve as a reference for building energy efficiency practitioners to identify key relationships between building physical characteristics and operational strategies to minimize cooling energy demand at a minimal time in comparison to traditional energy estimation methods.
Reference:
Mui, K. W., Wong, L. T., Satheesan, M. K., & Balachandran, A. (2021). A Hybrid Simulation Model to Predict the Cooling Energy Consumption for Residential Housing in Hong Kong. Energies, 14(16), 4850.
Building Cooling Energy Consumption Prediction with a Hybrid Simulation Approach
Greenhouse gas emissions associated with energy consumption in buildings contribute significantly to climate change. In subtropical regions, a well-designed building envelope can effectively reduce the energy demand for space cooling. This study proposes a hybrid simulation approach that can be applied to diverse building types to estimate the annual cooling energy consumption. The proposed model, which is based on Bayesian regularization, demonstrates good generalization ability to predict energy consumption for residential as well as healthcare buildings. In the study, a genetic algorithm was employed to optimize the model parameters for obtaining the minimum or maximum envelope heat gain. It is recommended through this study that by adopting a combination, namely, (i) design parameters resulting in minimum envelope heat gain, (ii) coupling of an air change rate of 9 h-1 and recirculation ratio of 50%, (iii) lowering lighting power density from 13 W/m2 to 7.3 W/m2, would prove to be an efficient strategy that balances energy and infection control for a general inpatient ward. The proposed generalized hybrid simulation approach can be a helpful tool for building systems engineers to formulate design guidelines or renovation plans to reduce energy consumption and thus greenhouse gas emissions.
Reference:
Mui, K. W., Satheesan, M. K., & Wong, L. T. (2022). Building Cooling Energy Consumption Prediction with a Hybrid Simulation Approach: Generalization Beyond the Training Range. Energy and Buildings, 276, 112502.
Satheesan, M. K., Mui, K. W., & Wong, L. T. (2021) Role of occupancy and indoor temperature on energy efficiency of tiny housing, presented at Indoor Air 2022 – the 17th International Conference of the International Society of Indoor Air Quality & Climate, on 12–16 June 2022.