scholarly journals The impact of heating, ventilation and air conditioning (HVAC) design features on the transmission of viruses, including SARS-CoV-2: an overview of reviews

2021 ◽  
Author(s):  
Gail M. Thornton ◽  
Emily Kroeker ◽  
Brian A. Fleck ◽  
Lexuan Zhong ◽  
Lisa Hartling
Keyword(s):  
Mechanical Ventilation ◽  
Relative Humidity ◽  
Air Conditioning ◽  
Virus Transmission ◽  
Sufficient Evidence ◽  
Inclusion Criteria ◽  
Design Features ◽  
Airborne Transmission ◽  
Overview Of Reviews ◽  
Ventilation Rates

Objective: Given possible airborne transmission of SARS-CoV-2, an overview of reviews was conducted to understand what is already known from the scientific literature about how virus transmission may be affected by heating, ventilation, and air-conditioning (HVAC) design features in the built environment. Methods: Ovid MEDLINE and Compendex were searched from inception to January 2021. Two reviewers independently screened titles and abstracts and full text of potentially relevant reviews, using a priori inclusion criteria. Inclusion criteria were systematic reviews examining effects of HVAC design features on virus transmission. Two reviewers independently assessed methodological quality using AMSTAR2. Results: Searching identified 361 citations, 45 were potentially relevant, and 7 were included. Reviews were published between 2007 and 2021, and included 47 virus studies. Two earlier reviews (2007, 2016) of 21 studies found sufficient evidence that mechanical ventilation (airflow patterns, ventilation rates) plays a role in airborne transmission; however, both found insufficient evidence to quantify minimum mechanical ventilation requirements. One review (2017) of 9 studies examining humidity and indoor air quality found that influenza virus survival was lowest between 40% and 80% relative humidity; authors noted that ventilation rates were a confounding variable. Two reviews (2021) examined mitigation strategies for coronavirus transmission, finding droplet transmission decreased with increasing temperature and relative humidity. One review (2020) identified 14 studies examining coronavirus transmission in air-conditioning systems, finding HVAC systems played a role in virus spread during previous coronavirus outbreaks. One review (2020) examined virus transmission interventions on public ground transportation, finding ventilation and filtration to be effective. Discussion: Seven reviews synthesizing 47 studies demonstrate a role of HVAC in mitigating airborne virus transmission. Ventilation, humidity, temperature, and filtration can play a role in viability and transmission of viruses, including coronaviruses. Recommendations for minimum standards were not possible due to few studies investigating a given HVAC parameter.

Computation of zone-level ventilation requirement based on actual occupancy, plug and lighting load information

2019 ◽  
Vol 29 (4) ◽  
pp. 558-574 ◽  
Author(s):  
Prashant Anand ◽  
David Cheong ◽  
Chandra Sekhar
Keyword(s):  
Mechanical Ventilation ◽  
Environmental Quality ◽  
Air Conditioning ◽  
Ventilation Rate ◽  
Indoor Environmental Quality ◽  
Energy Data ◽  
Variable Air Volume ◽  
Air Volume ◽  
Ventilation Rates

This paper presents a case study to compare the zone-level actual supplied ventilation rate with minimum required ventilation rate for a typical variable air volume (VAV) operation. The minimum required ventilation rate was computed using zone-level actual occupancy, plug and lighting load data. Two different algorithms were adopted to collect the actual zone-level occupancy information using camera-based technology which are (a) area-based occupancy counting and (b) row-based occupancy counting. Similarly, zone-level Plug, lighting and air-conditioning and mechanical ventilation (ACMV) system-related energy data were taken from the energy submeters and BTU meters. The median values of actual supplied ventilation rates are 0.16, 0.14, 0.14 and 0.12 m3/s for the classroom, computer room, open office and closed office, respectively. For the same zone, the computed minimum required ventilation rates are 0.10, 0.09, 0.10 and 0.08 m3/s, respectively. This case study shows that except during evening classes in classroom and computer room, the actual ventilation supplied is much more than the minimum required ventilation. These over and under ventilation scenarios have been identified as an indicator for energy wastage and poor indoor environmental quality, respectively.

Development of Mechanical Robot for Ducting Monitoring in Mechanical Ventilation and Air Conditioning (MVAC) System

2013 ◽  
Vol 315 ◽  
pp. 1002-1006 ◽  
Author(s):  
M.D. Amir Abdullah ◽  
Abdul Mutalib Leman ◽  
K.A.A. Rahman
Keyword(s):  
Mechanical Ventilation ◽  
Data Analysis ◽  
Air Quality ◽  
Relative Humidity ◽  
Indoor Air ◽  
Air Conditioning ◽  
Maintenance Activity ◽  
Duct Cleaning

ndoor Air Quality (IAQ) problem mostly comes from improper maintenance of ducting. Monitoring of ducting were not widely practices since the awareness to maintain it will need consideration of budget. This paper examines the development of mechanical robot that can moveable across ducting to monitor ducting condition. The device expected to collect data such as Temperature (°C),, Relative Humidity (RH), gas pollutant and picture inside ducting. The result from this kind of monitoring should be a guide for proper maintenance activity. It also can predict necessary time and duration for duct cleaning. In conclusion, the mechanical robot data analysis that captured from ducting will be compared to the IAQ standard to create safe indoor air to the user or building occupants.

scholarly journals Can Air-Conditioning Systems Contribute to the Spread of SARS/MERS/COVID-19 Infection? Insights from a Rapid Review of the Literature

2020 ◽  
Vol 17 (17) ◽  
pp. 6052 ◽  
Author(s):  
Francesco Chirico ◽  
Angelo Sacco ◽  
Nicola Luigi Bragazzi ◽  
Nicola Magnavita
Keyword(s):  
Air Conditioning ◽  
Far East ◽  
Hvac Systems ◽  
Rapid Review ◽  
Sufficient Evidence ◽  
Indoor Environments ◽  
Airborne Transmission ◽  
International Agencies ◽  
Viral Particles ◽  
Air Conditioning Systems

The airborne transmission of SARS-CoV-2 is still debated. The aim of this rapid review is to evaluate the COVID-19 risk associated with the presence of air-conditioning systems. Original studies (both observational and experimental researches) written in English and with no limit on time, on the airborne transmission of SARS-CoV, MERS-CoV, and SARS-CoV-2 coronaviruses that were associated with outbreaks, were included. Searches were made on PubMed/MEDLINE, PubMed Central (PMC), Google Scholar databases, and medRxiv. A snowball strategy was adopted to extend the search. Fourteen studies reporting outbreaks of coronavirus infection associated with the air-conditioning systems were included. All studies were carried out in the Far East. In six out the seven studies on SARS, the role of Heating, Ventilation, and Air Conditioning (HVAC) in the outbreak was indirectly proven by the spatial and temporal pattern of cases, or by airflow-dynamics models. In one report on MERS, the contamination of HVAC by viral particles was demonstrated. In four out of the six studies on SARS-CoV-2, the diffusion of viral particles through HVAC was suspected or supported by computer simulation. In conclusion, there is sufficient evidence of the airborne transmission of coronaviruses in previous Asian outbreaks, and this has been taken into account in the guidelines released by organizations and international agencies for controlling the spread of SARS-CoV-2 in indoor environments. However, the technological differences in HVAC systems prevent the generalization of the results on a worldwide basis. The few COVID-19 investigations available do not provide sufficient evidence that the SARS-CoV-2 virus can be transmitted by HVAC systems.

scholarly journals The impact of heating, ventilation, and air conditioning design features on the transmission of viruses, including the 2019 novel coronavirus: a systematic review of filtration

2021 ◽  
Author(s):  
Brian A Fleck ◽  
Gail M. Thornton ◽  
Lexuan Zhong ◽  
Lisa A Hartling ◽  
Dhyey Dandnayak ◽  
...  
Keyword(s):  
Systematic Review ◽  
Air Conditioning ◽  
Virus Transmission ◽  
Infection Risk ◽  
Hvac Systems ◽  
Airborne Transmission ◽  
Virus Removal ◽  
Filter Efficiency ◽  
Novel Coronavirus ◽  
The Impact

Historically, viruses have demonstrated airborne transmission. Emerging evidence suggests the novel coronavirus (SARS-CoV-2) that causes COVID-19 may also spread by airborne transmission. This is more likely in indoor environments, particularly with poor ventilation. In the context of potential airborne transmission, a vital mitigation strategy for the built environment is heating, ventilation, and air conditioning (HVAC) systems. HVAC features could modify virus transmission potential. A systematic review following international standards was conducted to comprehensively identify and synthesize research examining the effectiveness of filters within HVAC systems in reducing virus transmission. Twenty-three relevant studies showed that: filtration was associated with decreased transmission; filters removed viruses from the air; increasing filter efficiency (efficiency of particle removal) was associated with decreased transmission, decreased infection risk, and increased viral filtration efficiency (efficiency of virus removal); increasing filter efficiency above MERV 13 was associated with limited benefit in further reduction of virus concentration and infection risk; and filters with the same efficiency rating from different companies showed variable performance. Increasing filter efficiency may mitigate virus transmission; however, improvement may be limited above MERV 13. Adapting HVAC systems to mitigate virus transmission requires a multi-factorial approach and filtration is one factor offering demonstrated potential for decreased transmission.

scholarly journals The impact of heating, ventilation, and air conditioning design features on the transmission of viruses, including the 2019 novel coronavirus: a systematic review of ultraviolet radiation

2021 ◽  
Author(s):  
Gail M. Thornton ◽  
Brian A Fleck ◽  
Natalie Fleck ◽  
Emily Kroeker ◽  
Dhyey Dandnayak ◽  
...  
Keyword(s):  
Systematic Review ◽  
Uv Radiation ◽  
Air Conditioning ◽  
Virus Transmission ◽  
International Standards ◽  
Future Research ◽  
Design Features ◽  
Survival Fraction ◽  
Uv Dose ◽  
The Impact

Respiratory viruses are capable of transmitting via an aerosol route. Emerging evidence suggests that SARS-CoV-2 which causes COVID-19 can be spread through airborne transmission, particularly in indoor environments with poor ventilation. Heating, ventilation, and air conditioning (HVAC) systems can play a role in mitigating airborne virus transmission. We conducted a systematic review of the scientific literature examining the effectiveness of HVAC design features in reducing virus transmission; here we report results for ultraviolet (UV) radiation. Following international standards for systematic reviews, we conducted a comprehensive search and synthesized findings from 32 relevant studies published between 1936 and 2020. Research demonstrates that: viruses and bacteriophages are inactivated by UV radiation; increasing UV dose is associated with decreasing survival fraction of viruses and bacteriophages; increasing relative humidity is associated with decreasing susceptibility to UV radiation; UV dose and corresponding survival fraction are affected by airflow pattern, air changes per hour, and UV device location; and UV radiation is associated with decreased transmission in both animal and human studies. This comprehensive synthesis of the scientific evidence examining the impact of UV radiation on virus transmission can be used to guide implementation of systems to mitigate airborne spread and identify priorities for future research.

scholarly journals Ventilation procedures to minimize the airborne transmission of viruses at schools

2021 ◽  
Author(s):  
L. Stabile ◽  
A. Pacitto ◽  
A. Mikszewski ◽  
L. Morawska ◽  
G. Buonanno
Keyword(s):  
Classroom Environment ◽  
Ad Hoc ◽  
Virus Transmission ◽  
Transmission Risk ◽  
Mitigation Measures ◽  
Indoor Environments ◽  
Airborne Transmission ◽  
Transmission Potential ◽  
Feedback Control Strategy ◽  
Ventilation Rates

AbstractReducing the transmission of SARS-CoV-2 through indoor air is the key challenge of the COVID-19 pandemic. Crowded indoor environments, such as schools, represent possible hotspots for virus transmission since the basic non-pharmaceutical mitigation measures applied so far (e.g. social distancing) do not eliminate the airborne transmission mode. There is widespread consensus that improved ventilation is needed to minimize the transmission potential of airborne viruses in schools, whether through mechanical systems or ad-hoc manual airing procedures in naturally ventilated buildings. However, there remains significant uncertainty surrounding exactly what ventilation rates are required, and how to best achieve these targets with limited time and resources. This paper uses a mass balance approach to quantify the ability of both mechanical ventilation and ad-hoc airing procedures to mitigate airborne transmission risk in the classroom environment. For naturally-ventilated classrooms, we propose a novel feedback control strategy using CO2 concentrations to continuously monitor and adjust the airing procedure. Our case studies show how such procedures can be applied in the real world to support the reopening of schools during the pandemic. Our results also show the inadequacy of relying on absolute CO2 concentration thresholds as the sole indicator of airborne transmission risk.

scholarly journals Canadian Recommendations for Clinical Trials of Pharmacologic Interventions in Rheumatoid Arthritis: Inclusion Criteria and Study Design: Table 1.

2011 ◽  
Vol 38 (10) ◽  
pp. 2095-2104 ◽  
Author(s):  
JACOB KARSH ◽  
EDWARD C. KEYSTONE ◽  
BOULOS HARAOUI ◽  
J. CARTER THORNE ◽  
JANET E. POPE ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Clinical Trial ◽  
Clinical Trials ◽  
Disease Activity ◽  
Study Design ◽  
New Drugs ◽  
Nominal Group ◽  
Consensus Method ◽  
Inclusion Criteria ◽  
Design Features

Objective.Current clinical trial designs for pharmacologic interventions in rheumatoid arthritis (RA) do not reflect the innovations in RA diagnosis, treatment, and care in countries where new drugs are most often used. The objective of this project was to recommend revised entry criteria and other study design features for RA clinical trials.Methods.Recommendations were developed using a modified nominal group consensus method. Canadian Rheumatology Research Consortium (CRRC) members were polled to rank the greatest challenges to clinical trial recruitment in their practices. Initial recommendations were developed by an expert panel of rheumatology trialists and other experts. A scoping study methodology was then used to examine the evidence available to support or refute each initial recommendation. The potential influence of CRRC recommendations on primary outcomes in future trials was examined. Recommendations were finalized using a consensus process.Results.Recommendations for clinical trial inclusion criteria addressed measures of disease activity [Disease Activity Score 28 using erythrocyte sedimentation rate (DAS28-ESR) > 3.2 PLUS ≥ 3 tender joints using 28-joint count (TJC28) PLUS ≥ 3 swollen joint (SJC28) OR C-reactive protein (CRP) or ESR > upper limit of normal PLUS ≥ 3 TJC28 PLUS ≥ 3 SJC28], functional classification, disease classification and duration, and concomitant RA treatments. Additional recommendations regarding study design addressed rescue strategies and longterm extension.Conclusion.There is an urgent need to modify clinical trial inclusion criteria and other study design features to better reflect the current characteristics of people living with RA in the countries where the new drugs will be used.

scholarly journals Study on IBS Cooling Panel Wall System with Difference Types of Cooling Mediums

2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Eny Nor Syahira Mohamad Hashim ◽  
◽  
Norhafizah Salleh ◽  
Noor Azlina Abdul Hamid ◽  
◽  
...  
Keyword(s):  
Relative Humidity ◽  
Air Conditioning ◽  
Ventilation System ◽  
Target Strength ◽  
Outdoor Temperature ◽  
Design Concepts ◽  
Building Ventilation ◽  
American Society ◽  
Wall System ◽  
Indoor And Outdoor

This paper proposes a cooling house system that can promote thermal comfort in buildings without air-conditioning. The cooling panel wall forms a part of an Integrated Building System (IBS), and is essentially made of tubes filled with either water or glycerin as the coolant. Target strength for the panel wall was designed based on the Malaysian Standard (MS) while the building ventilation system followed the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) standard. The results are reported based on indoor and outdoor temperature difference together with relative humidity to identify the best performing house model and also coolant. The outcome of this research is expected to add value to design concepts with a better promotion of air flow and circulation in the building, without over-usage of natural resources and higher building cost to achieve the same objective.

Sign in / Sign up

Export Citation Format

Share Document