Insights

Museums Emerging from the Pandemic: Building Systems

HGA Arts & Culture experts weigh in on the future of museums in this ongoing series, Museums Emerging from the Pandemic.
HGA’s design for the Tennessee State Museum (above) received the first place 2020 ASHRAE Technology Award. Learn more about the project here.

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 still many questions about how a building’s HVAC system can also be a tool to help address occupant safety and mitigate the spread of the virus. This post will help museum operators make decisions about leveraging building mechanical systems to combat COVID-19 and increase visitor and employee confidence in returning to their facilities.

Our engineering team has pooled our internal expertise with industry resources, outside experts, our experience in healthcare environments, and successful installations to provide the following detailed information for how museum occupants, facility operators, and decision-makers can understand current building mechanical systems. This information can help inform immediate and longer-term actions to improve these spaces in the new-normal for operation.

The following 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 the benefits and challenges for each action. The strategies are organized into categories that will help you understand which actions can/should be implemented immediately, followed by lower-cost items that can be implemented when practical, and finally, actions that have significant benefit but higher up-front costs.

Please note that while the following information provides multiple methods for improving the ability of a museum’s HVAC system to disinfect the 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 system helps to identify any potential areas of concern. Where ventilation systems are compliant, staff and visitors can be confident that there is industry support in mechanical systems for returning to museum facilities.

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 or higher 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 replace 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 diseases 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 separate from any efforts related to touchless-restrooms and 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, a concern arises with maintaining proper temperature and humidity control for sensitive collection areas. 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 areas 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, 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 systems serving 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 settles 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, don’t require as much additional energy. BPI systems have been proven effective in disinfection and removal of past viral outbreaks, and recent studies released this summer have shown similar results with COVID-19 virus. 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.

Contributors

Leighton Deer, PE; James Shields, FAIA; Joan Soranno, FAIA; Marc L’italien, FAIA; Nancy Blankfard, AIA

Read Part One: Visitor Experience in the Museums Emerging from the Pandemic series and look for Part Three soon. If you have questions or comments about this piece, please contact Amy Braford Whittey, National Business Developer for the Arts.

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.