6 minute read
Living with COVID-19 through engineering strategies
by Chong Wai Yen, Managing Director, Commercial HVAC, Carrier Singapore
Air-conditioning and mechanical ventilation systems can play an important role.
Mr Chong Wai Yen
Healthcare professionals and scientists are on the frontlines in the fight against COVID-19. During these crucial times, what can other professionals, including engineers, do? Fortunately, building owners, engineers and facility managers can respond effectively to these challenges. By reimagining buildings as barriers to contamination, we can work together to enhance the built environment in ways that will have a meaningful impact on the health and well-being of occupants and visitors.
Optimising HVAC systems to combat COVID-19
Buildings have become a first line of defence in reducing the transmission of an unseen but lethal viral threat. HVAC (Heating, Ventilation, and Air Conditioning) systems play a critical role in this defence. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) says that “ventilation and filtration provided by heating, ventilating, and air-conditioning systems can reduce the airborne concentration of SARS-CoV-2 and thus the risk of transmission through the air” [1]. The Centers for Disease Control and Prevention (CDC) of the US has made similar findings, and says that employers can decrease the spread of COVID-19 by maintaining a healthy work environment. “Consider improving the engineering controls using the building ventilation system”, the CDC suggests. These improvements may include increased ventilation rates and increased percentage of outdoor air circulating through the system [2]. Building owners and engineers have the opportunity to optimise the HVAC systems through the adoption of specific air filtration solutions to reduce the risk of pathogen transmission.
The concept of Healthy Buildings
Well before the outbreak of COVID-19, the Healthy Building Movement had begun, to measure and improve air quality in the built environment, in order to improve productivity and health. Creating a healthy building through HVAC systems and engineering controls is a key component of combatting
COVID-19. It is part of a strategy that balances the overall effectiveness with the financial impact it can have on a business. HVAC systems can play an important role in preventing the spread of viruses. To ensure the proper indoor air quality (IAQ), an effective HVAC system should include some or all of the following: • Ventilation: When outside air is not provided via separate devices, the HVAC system should provide outside air, based on the size/use of the space. This can be achieved with simple tweaks in setting adjustments, adding new or retrofit equipment, or bringing in more, fresh, outside air to replace indoor air and help reduce airborne pathogens and other contaminants. • Enhanced Filtration: Filters are rated on their ability to capture and retain particles of different sizes. The industry standard is a Minimum Efficiency Reporting
Value (MERV) rating. Filters with MERV >13 have a significant ability to capture particulate matter (PM) and smaller particles. HEPA (High Efficiency Particulate Air) filters are even more efficient and can capture bacteria and viruses. • Other IAQ Devices: Numerous technologies are available to reduce the presence of contaminants. Ultraviolet irradiation, ultraviolet photocatalytic oxidation, ionisation, plasma treatment, electrostatic precipitation, activated carbon adsorption and other techniques can be adopted to specifically target volatile organic compounds (VOCs), bacteria and viruses. Some of these options can be made available as integral parts of the HVAC system.
Healthy Buildings and improved productivity
While the current urgency around healthy indoor environments in buildings revolves largely around stopping the spread of COVID-19, research has shown the potential impact of healthy environments to be much greater. Carrier funded a series of studies, in collaboration with researchers from the Harvard T.H. Chan School of Public Health’s Centre for Health and the Global Environment, also called the COGfx Studies. The first study found that improved indoor environmental quality doubled occupants’ cognitive functioning. It is also worth noting that occupants in high-performing, green-certified buildings had higher cognitive function (improved response time and performance) scores than occupants in similarly high-performing buildings that were, however, not green-certified. The second COGfx study revealed the impact of ventilation on cognitive functioning and evaluated the economic and environmental costs against the health and productivity benefits of enhanced ventilation in office buildings. The findings of studies done across seven US cities were astounding. Improved productivity per person per year was observed to be USD 6,500. The increased productivity of an employee is said to be 150 times more than the resulting energy costs. The third and most recent study was conducted in six different countries and revealed that the cognitive function in office workers declines as the levels of fine particulate matter (PM2.5) and carbon dioxide (CO2) increase. Higher CO2 can be an indicator of poor ventilation in buildings. Mechanical ventilation, such as an HVAC system with efficient filtration, can help to protect building occupants from the negative cognitive effects of PM2.5 and CO2. This further supports the conclusion that IAQ is not only good for people's health and safety, it is also good for the bottom line - through increased productivity, fewer days of sick leave and better cognitive functioning.
Prioritising re-occupancy strategies
Building owners, engineers and HVAC consultants, seeking to prepare facilities for re-occupancy, may wish to prioritise IAQ and proper ventilation. Building assessments are an excellent starting point, and once complete, there are a range of solutions available for optimising IAQ. Healthy indoor environments are not about a moment - they are part of a movement!
References
[1] ‘Pandemic COVID-19 and Airborne Transmission’, ASHRAE Environmental Health Committee, USA, approved 4/17/20, Web, 23 April 2020. https://www.ashrae.org/file%20library/technical%20 resources/covid-19/eiband-airbornetransmission.pdf. [2] ‘Guidance for Businesses and Employers Responding to Coronavirus Disease 2019 (COVID-19)’, Centers for Disease Control and Prevention, USA, Web, 8 March 2021. https://www. cdc.gov/coronavirus/2019-ncov/community/guidance-business-response.html.
Figure 3: The COGfx Study on 24 study participants demonstrated that improved indoor environmental quality doubled cognitive function test scores.
To meet the need for precise, reliable automated control in the most demanding HVAC zone applications, Carrier has released a new line of TruVu Dual IP Advanced Application Controllers for the i-Vu building automation system. These controllers were designed to ease installation and enhance system control and monitoring. Designed for robust networking in single equipment and advanced zone control applications, the five new native Building Automation and Control Network (BACnet) controllers feature faster processors, dual IP high-speed communications ports and highercapacity memory. All support the full line of Carrier’s communicating and non-communicating sensors and actuators, and feature an expansion port designed to accommodate future communication cards. Options include basic control, BACnet or MODBUS integration, on-board air flow sensors and future support for Input/Output (I/O) point expanders. The new BACnet controllers also support sophisticated network redundancy via high-speed IP communication. “By combining and connecting advanced hardware and software technologies in innovative ways, we wanted to create a new line of controllers and accessories with the connectivity, power, memory and flexibility needed for the most demanding control applications in the industry. The overriding goal was to make those HVAC systems more energyefficient and cost-effective to operate. But we also wanted them to make life easier for everyone - from system designers and equipment installers to facilities managers and building owners - on a practical day-to-day basis”, said Mark Jones, Business Manager, Commercial Controls, Carrier. Built-in, fail-safe dual Ethernet ports support daisy chain topologies to make installation easier, and support for IP network Ring topology using Rapid Spanning Tree Protocol (RSTP) facilitates network redundancy. All programs and historical data are stored in non-volatile memory, eliminating the need for batteries, while a capacitor-backed real-time clock keeps time for up to three days during power failures and network interruptions. USB ports provide local access for system start-up and troubleshooting. All of the new models are fully compatible with Carrier’s pre-engineered application libraries and support custom control sequences using the Snap graphical programming tool. The new TruVu Dual IP Advanced Application Controllers and accessories are available for order through Carrier sales offices worldwide.
Carrier’s TruVu controllers for the i-Vu building automation system help provide comfort, control, and energy savings.
