Fresh Air and Daylight: The Importance of Healthy Buildings in a Pandemic
Nicole Isle, Chief Sustainability Strategist for Tetra Tech’s High Performance Buildings Group, examines why buildings need to adopt a variety of system upgrades, operational approaches, and hygienic techniques to mitigate the spread of the COVID-19 virus.
Wellness may finally be having its day as a critical function of building design.
Over the last decade, architects and engineers have been working to educate owners and developers on the wellness impacts of sustainable building design approaches in creating healthier and more productive lives for their occupants. However, the COVID-19 pandemic has demonstrated that these wellness considerations are no longer a mere value-add to a building, but rather a necessary element in allowing larger groups to safely reoccupy a space. Before we can go back to work, each building owner and operations team is going to have to consider what wellness integrations need to be put in place before tenants can return.
Buildings already designed to LEED, WELL, or Fitwel requirements have a leg up in this area. Designing for environmental health and lower carbon impacts have long been key selling points of these rating systems, but each feature criteria works to mitigate the spread of COVID-19 and help occupants adjust safely to a new normal. What follows is a look at what some of these design integrations are, and what occupant benefits they might provide in the context of COVID-19.
While it’s important to note that none of the criteria we review here can wholly prevent the spread of the virus, these strategies, coupled with social distancing, can help make spaces safer.
The windows in some spaces at the First Tech Credit Union Headquarters in Hillsboro, Oregon, can be removed to offer better views to nature, and more importantly, increase natural ventilation, bringing more fresh air into the space. Image courtesy of Joel B. Sanders Agency.
One easy way to limit the buildup of viruses and bacteria within indoor air is to get rid of them! Mechanical air handling systems are meant to supply fresh oxygenated air to indoor spaces and exhaust carbon dioxide, particulate matter, formaldehyde, carbon monoxide, and a host of harmful compounds like volatile organic compounds (VOCs) from the air. In the process, virus particles are exhausted too, but if the building’s ventilation and air change rates are insufficient, a higher concentration of virus particles may remain in the breathing space. It is well known that COVID-19 is spread when an infected person sneezes or coughs expelling droplets containing millions of little microbes. They then can become aerosolized in the breathing space or land on touchable surfaces.
WELL Air Precondition 3 and LEED v4.1 O+M (Indoor Environmental Quality [EQ] Prerequisite 1) require ventilation systems to be tested and balanced every five years and maintained to ASHRAE 62.1 air supply rates. This best practice should be adopted by building operators to ready their buildings for reopening as air supply rates can, and often do, drop below adequate levels as changes are made to system operations, building space use, and as equipment ages.
With well-designed ventilation systems and periodic maintenance, building operators can minimize the spread of the virus. More so, increasing air supply by 30 percent over ASHRAE 62.1 (recommended by WELL Air Optimization 6 and LEED v4.1 BD+C EQ Credit 1) serves to provide additional fresh air that can help dilute the concentration of the virus in the breathing space. A higher air supply rate is standard practice in the healthcare industry, and given the risk of COVID-19, it’s a good time to adopt this practice and tune/retrofit existing building equipment to bring in additional fresh air. Sensors added to the air supply systems can tie to the Building Management System, providing regular air supply and air quality monitoring (WELL Air Optimization 8).
It is also great practice to open windows and doors, if possible, to increase air flow through buildings. WELL and LEED promote operable windows (WELL Air Optimization 7; LEED v4.1 BD+C EQ Prerequisite 1) and openings.
All of these air quality measures can be documented in an Indoor Air Quality Policy for the building, and Fitwel Indoor Environment strategy 6.3 provides framework for its development.
Beyond good engineering and maintenance practices to reduce the virus’ spread, a secondary benefit that may ease the discomfort and concerns around returning to work are integrating practices that improve occupant satisfaction. People sense they are in a healthy building when there is great daylight and the air smells fresh and not stagnant. That healthy feeling can be enhanced by open windows or doors and help occupants feel energized from sunlight and clear views to nature. The ability to easily access the outdoors via terraces and balconies further supports the health benefits. Occupants feel safer and more comfortable when their environment supports their health. By coupling good design and operations practice with connections to nature and biophilia (WELL Mind Precondition 2 and Fitwel Workspaces strategies 7.1-7.2), health conditions can be improved, resulting in less stress returning to work.
It's common practice that outdoor air supply systems include some level of filtration to remove particulates, dust, and debris from entering the indoor environment. However, the level of filtration and filter maintenance is important to deliver fresh, healthy air to occupants. And, given the heightened concerns employees have for returning to the office, we can expect more questions and scrutiny of the air they’re breathing. That makes now a good time to establish filter replacement protocols that meet manufacturer recommendations and to evaluate whether the building’s air supply equipment can accommodate higher levels of filtration.
WELL Air Optimization 12 requires replacement records and establishes filter type by outdoor air conditions. Dense urban areas, hot and dry inland areas, as well as locations near transportation hubs and major highways likely have greater levels of particulate matter necessitating greater filtration. LEED (LEED v4.1 BD+C IEQ Credit 1) recommends a minimum MERV 13 filter and WELL Air Optimization 12 recommends up to MERV 16, with MERV 8 prefilters based on a review of outdoor air quality and particulate matter (called PM2.5 and PM10) levels. PM2.5 are the smallest air particulates that enter the lungs and blood stream causing heart disease and other cardiovascular complications.
MERV 13 is a superior filter and it can capture up to 75 percent of PM2.5 and bacteria and viruses. MERV 16 can capture up to 95 percent and could be of special consideration if the building recirculates indoor air. Above and beyond, LEED and WELL credit would be the use of MERV 17 or higher-grade filters classified as HEPA.
Source: NASA “Submicron and Nanoparticulate Matter Removal by HEPA-Rated Media Filters and Packed Beds of Granular Materials” by J.L. Perry.
The COVID-19 virus is tiny—about 30 nanometers in diameter (for context, the diameter of an average hair follicle is about 80,000 nanometers). So small it alone will pass through most air filters on its own. However, it often catches a ride on particulate matter like PM2.5, coagulating into a piece of larger matter. Therefore, it is important that a minimum of MERV 13 filtration is used to filter out these particles, if not higher levels of filtration if the ventilation system can accommodate. These higher levels of filtration are powerful enough to mitigate (though, again, not prevent) the virus’ spread. For this reason, we are not recommending the installation of HEPA filters in commercial spaces. These filter types should be reserved for healthcare and critical facilities.
If systems cannot accommodate these larger filter sizes and associated pressure drop, electronic systems could be employed such as bio-polar ionization to kill bacteria and viruses. WELL offers credit for UV treatment to treat mold and mildew spores on the cooling coils and drain pans of forced-air cooling systems (WELL Air Optimization 14). While this strategy works well in this instance, it will be ineffective in treating the virus because as it is traveling through the HVAC system, there is simply not enough residence time for the UV to do its work. The air simply passes through too quickly. Alternatively, standalone UV systems or UV lights can be used in spaces after hours to sterilize air and surfaces as part of a regular cleaning protocol.
LEED, WELL, and Fitwel also offer credit for testing indoor air quality. While standard ASHRAE 62.1 air quality test protocols don’t cover the detection of viruses, its implementation can help to demonstrate to occupants that the best practices you’ve implemented in the building are working and are thereby likely to protect against the spread of the virus (LEED v4.1 O+M EQ Prerequisite 4, WELL Air Precondition 1 and Optimization 5, and Fitwel Indoor Environment strategy 6.4).
Certain humidity levels can enable viruses to survive longer and even grow in number, making it harder to control their spread. High humidity may promote the accumulation and growth of microbes and low relative humidity has also been associated with longer survival (slower inactivation) rates.
The solution is for buildings in climates with broad humidity ranges to maintain relative humidity levels by adding or removing moisture from the air. The practice inhibits and improves air quality and thermal comfort. WELL Comfort Optimization 7 recommends that the mechanical systems in all projects (except spaces designed for high humidity such as natatoriums and greenhouses) have the ability to maintain relative humidity (RH) between 30 and 60 percent at all times. The modeled RH levels in the space must also remain within this range for at least 98 percent of all business hours of the year. Recent data on indoor humidity and the spread of the virus recommends maintaining an RH range of between 40 and 60 percent. The recommended range serves to maintain larger droplets that contain viral particles, thus causing them to deposit onto room surfaces more quickly instead of remaining aerosolized in the breathing space. It also is thought that there is higher likelihood for the membranes to be disrupted and inactivated. And below this range, low ambient humidity hurts the ability of the immune system to fight respiratory viral infections.
Cleaning Products and Protocol
This is a great time to evaluate building janitorial cleaning practices.
LEED offers credit for green cleaning practices (LEED v4.1 O+M EQ Prerequisite 3 and EQ Credit 6-7), but WELL Materials Optimization 9 and Fitwel Shared Spaces strategies 8.1-8.2 and 8.4 go beyond the types of cleaning products used and offer additional rigor for training and protocols that could be especially helpful in mitigating the spread of the COVID-19 virus.
Clean hands and surfaces remain a key tool in combating the virus in interior spaces.
The WELL guidance could help building operations teams to develop more comprehensive cleaning programs. WELL covers training on the sequence of cleaning steps and the use of personal protective equipment. And the standard covers cleaning protocols, specifically the extent and frequency of cleaning such as dated cleaning logs as well as protocols for disinfection, including the identification and maintenance of a list of high-touch surfaces and their limitations to disinfection. WELL Water Optimization 8 further supports cleanliness by offering building occupant guidance for proper handwashing, specifically for sink and faucet design, soap dispensers, and hand drying.
In comparison, Fitwel delineates its guidance by higher risk locations, specifically protocols for bathroom cleaning (strategy 8.1) and break areas (strategy 8.4), and also provides signage guidance for proper hand washing (strategy 8.2).
Confidence in Your Strategy
There is no catchall approach to remove the risk of COVID-19 from your building. There are too many variables when moving people in an out of a space. What’s key to mitigating its spread—along with proper social distancing—is discovering which approaches will be most effective given the uniqueness of your space. We’re offering a comprehensive presentation that illustrates the variety of system upgrades, operational approaches, and hygienic techniques that can help create safer, healthier work environments. If you are interested in a digital presentation, please send an inquiry to email@example.com.
UPDATES TO WELL AND LEED THE WEEK OF MAY 28, 2020:
To help bring focus to strategies from the WELL Building Standard to support in the fight against COVID-19, the International WELL Building Institute just launched a PDF resource that brings focus the strategies described here and more to include company risk management planning and mental and community resilience and recovery.
The US Green Building Council (USGBC) announced plans to release new LEED pilot credits for COVID-19 health and safety strategies for buildings. Pilot credits can be swapped into your project scorecard for credit under the LEED Innovation in Design credit category. USGBC also announced upgrades to LEED v4.1 to prioritize health and a report or certificate for spaces well prepared for building reentry.Rendering Luman building in West LA courtesy of Gensler