HGA Arts & Culture experts weigh in on the future of museums in this ongoing series, Museums Emerging from the Pandemic.
As we continue to navigate the evolving COVID-19 pandemic, some museums and cultural facilities are taking steps toward re-opening their facilities to the public. Many institutions are implementing physical distancing protocols, timed ticketing strategies, and cleaning procedures to mitigate the spread of the virus. However, there are many questions about how a building’s HVAC system can also be a tool to help address occupant health and mitigate the spread of the virus. The below will help museum operators make decisions about leveraging building mechanical systems to combat the spread of COVID-19 and increase visitor and employee confidence in returning to their facilities.
The following detailed information from our engineering team—experts in museum system design—is augmented by insights from industry resources and specialists, our experience in healthcare design, and successful past installations. These guidelines outline how museum occupants, facility operators, and decision-makers can assess current building mechanical systems. This information can help inform immediate and longer-term actions to improve these spaces for the new normal of operation.
The outlined strategies provide multiple methods for improving the ability of a typical museum’s HVAC system to disinfect indoor air. Each strategy includes a brief description of benefits and challenges. The strategies are organized into categories: those that can/should be implemented immediately, followed by lower-cost items that can be implemented when practical, and finally, by actions that have significant benefit but higher up-front costs.
Please note that while the following information provides methods for improving the ability of a museum’s HVAC system to disinfect indoor air, these all occur “after the fact.” Improvements to the HVAC system will not prevent a virus from being deposited on a surface if an infected person coughs or sneezes, nor will it prevent the transmission of a virus from that surface to a person’s hands and then to their face. Improvements to an HVAC system will not eliminate the threat of viral contamination.
No- and Low-Cost Strategies: Implement Now
Ensure and Document that HVAC and Outdoor Air Systems Meet Industry and Code Minimum Requirements
In order to protect the health and safety of building occupants, ensure that your museum’s mechanical systems are meeting outdoor air ventilation regulatory requirements from building codes and industry standards, such as ASHRAE 62. Documenting the design and operational compliance of building ventilation systems helps to identify any potential areas of concern. Where ventilation systems are compliant, staff and visitors returning to museum facilities can be confident that industry standards are being met in the mechanical systems.
Ensure Filtration Systems are MERV 13 or Better
MERV 13 (Minimum Efficiency Reporting Value) filters are the minimum filtration levels needed to begin capturing and filtering respiratory droplets containing airborne viruses such as COVID-19. They are approximately 50% effective on the first pass through the air handling units. As such, museums should ensure that air handling units have MERV 13 filters or better and are sealed to prevent bypass air around the filters. Most museum facilities already have high-efficiency filtration systems to protect collections, so it may be likely that minimum effective filter systems are in place. MERV 13 filters come in multiple sizes and are available with low pressure drops that can be easily installed in most air handling systems. Facility teams will require protocol and training for managing and replacing filter systems of MERV 13 or better that may contain the COVID-19 virus.
Maintain, Flush or Clean Water Systems
To minimize the risk of Legionnaires’ disease and other illnesses associated with water, take steps to ensure that all water systems and features (e.g. sink faucets, drinking fountains, decorative fountains, etc.) are safe to use after any prolonged facility shutdown. This includes basic steps to ensure that no components of building water systems have stagnant areas and is in addition to efforts related to creating touchless-restrooms and other touchless shared public facilities.
Lower Cost Strategies: Implement Where Practical
Increase Outdoor Air and Circulation Air
Increasing the amount of clean outdoor airflow above industry minimums promotes dilution of indoor air and reduces the recirculation of potentially contaminated room air. Increased air circulation also allows for more time to dilute air and allow filter systems to remove contaminants. This can easily be accomplished when outdoor air conditions are suitably mild through existing air handling systems that have economizer modes of operation. However, maintaining proper temperature and humidity control for sensitive collection areas becomes a concern. Increasing outdoor air conditions may not be practically achievable as increased peak heating, cooling, and humidification control capacity will be required, as well as increased energy consumption to condition the air to acceptable temperature and humidity ranges. In short, increasing outdoor air and circulation air is effective in staff and public areas, but not recommended where sensitive collections are present.
MERV 14 and Higher or HEPA Filtration Systems
MERV 14 filters (or better) are approximately 75% or more effective at removing particles and viruses such as COVID-19 on the first pass through the air handling units. HEPA (High Efficiency Particulate Air) filters are over 99% effective. Many museum facilities already have high-efficiency filtration systems in place to protect collections, so it may be likely that enhanced filter systems are in already place. If so, these systems are effective in eliminating most airborne, respiratory COVID-19 particles on a single-pass through the building air handling systems. If current mechanical systems do not have these filtration systems in place, the improved filter efficiency must be carefully balanced with the increased size of filters, the higher pressure drop required (which increases fan energy use), and more expensive filters. Again, facility teams will require protocol and training for managing and replacing filter systems that may contain COVID-19.
Maintain Relative Humidity Levels of 40-60% if Possible
Because viruses thrive in low- and high-humidity environments, maintaining indoor space conditions between 40% and 60% limits virus growth and propagation and creates the ideal humidity ranges for collections protection and human health and wellness. For many museums, and especially sensitive collections areas, maintaining humidity levels below 60% relative humidity should not be a challenge based on industry expectations. Likewise, providing a minimum of 40% relative humidity year-round is likely possible for properly-designed mechanical systems in museums with the appropriate building construction. However, if the current building mechanical systems and enclosures are not designed for 40% minimum relative humidity, there may be significant practical challenges for new humidifiers in dryer and colder climates, which may necessitate wall and glazing improvements to prevent condensation at the envelope. In short, maintain a 40% minimum relative humidity year-round when your facilities are designed to support it.
Costlier Strategies: Implement for Disinfection
Room-Level Ultraviolet Germicidal Irradiation (UVGI)
Ultraviolet germicidal irradiation (UVGI) uses short-wave ultraviolet energy for air stream and surface disinfection. Studies have shown that room-level or upper-room level locations are the most effective disinfection location of UV systems, as they treat all surfaces exposed to the light. Room-level installations place UV fixtures above occupants and are typically directed towards the ceiling to minimize occupant exposure, as UV light damages organic materials. Room-level UV systems are easier to retrofit, but they come at a higher first cost per area served and higher operating and replacement cost per area served when compared to centralized disinfection sources. However, sensitive museum collections must never be exposed to UV light. In a museum setting, upper-room UVGI may be most appropriate in high-traffic areas such as main entrances and rooms with high occupant density, as long as collections can be removed from the space.
Ultraviolet Germicidal Irradiation (UVGI) in HVAC Systems
While UV light has limited room-level application, UV systems can be placed in building air distribution systems to disinfect air streams. The location and configuration of UV systems in air streams requires careful attention. Inactivation rates of 90% or higher for bacterial, fungal, and virus disinfection (such as COVID-19) can be achieved using a UV system in properly-designed air handling systems. UV systems in central air distribution systems can more cost-effectively disinfect large areas of buildings compared to room-level systems and are safe for areas where collections are present, as the collections are not directly exposed to the UV light. UV systems use low-pressure mercury lamps which need to be replaced approximately annually and do increase annual energy usage and operational costs.
Bi-Polar Ionization (BPI) in HVAC Systems
Bi-polar ionization (BPI) generators create positively and negatively charged oxygen ions that bind to contaminants in the air, which are then captured in a filter or settle out of the air stream. These systems are easy to install in central air handling systems and when compared to UV systems or enhanced filtration systems, do not require as much additional energy. BPI systems have been proven effective in elimination of past viral outbreaks, and recent studies released this summer have shown similar results with COVID-19. However, they have not been as extensively researched or tested as UV systems. Some older types of Bi-Polar ionization have the potential to create small amounts of ozone, which in larger amounts are harmful to sensitive collections.
As museums and cultural facilities begin re-opening to the public, building mechanical systems are an important strategy to help ensure the health of occupants and mitigate the spread of COVID-19. Proper ventilation and minimum filtration are simple and effective methods to minimize the spread of the virus. Adjustments to building operations including circulating additional amounts of indoor and outdoor air, and using enhanced filtration systems further reduce contamination risks, while upgraded mechanical systems with properly-designed disinfection technologies such as UV light and Bi-Polar Ionization can be used to actively neutralize the COVID-19 virus and create a healthier museum experience for occupants and the collections.
HGA has created a hub for our insights and reactions to the COVID-19 pandemic as architects, engineers, interior designers, and problem solvers. Follow the conversation here.