Despite worldwide efforts to mitigate the spread of the COVID-19 pandemic with mask mandates, social distancing and lockdowns, a wealth of studies have shown that the most critical factor to avoid the spread of pathogens is indoor air quality. The connection between health and the indoor environment is clear: the SARS-CoV-2 virus is spread mainly by inhaling fine aerosol particles suspended in the air in poorly ventilated and crowded indoor settings. As various industries adapt to the post-pandemic era, how is the construction industry incorporating demands for more effective air filtration to protect individuals inside public spaces?
Focusing on air filtration solutions and strategies to capture hazardous particles is one way to improve indoor air quality and reduce the spread of harmful viruses. In this scenario, effective infection control requires innovative solutions in design building and air filtration. The best outcomes are achieved when indoor air quality is a priority from the start – in other words, when infection prevention is introduced in the building design stage as opposed to being one of the final steps of the construction stage.
“Commercial buildings get the ideal air quality and the most cost-efficient solution when the engineering and architecture teams are dedicated to designing an air quality-centered building,” said Gregory Scott Newsome, CFO and Board Director of Dexwet Air Filters, an air filtration technology company making innovative air filters that capture nanoparticles. “Indoor air quality and infection prevention are increasingly becoming a health and wellness priority worldwide. What we have seen is that new buildings offer superior indoor air quality and more cost-efficient filtration when builders bring air filtration to the forefront of the design process.”
When that happens, the next step is focusing on cartridge filtration as the final layer to capturing hazardous particles. Today, manufacturers are adopting innovative air filtration techniques that focus on capturing particles.
Commercial buildings have been designed following the same air filtration and air flow strategy since 1950s. In essence, once the construction phase is completed, the ventilation contractor comes to determine the air flow with proper duct sizing and air balance. In the commercial construction sector, this is determined by a commercial HVAC load calculation, which is used to right-size the HVAC system according to the business’ needs. A load calculation, determined by the Air Conditioning Contractors of America (ACCA), indicates how many heating and cooling British thermal units (BTUs) are needed, and a right-sized commercial HVAC system will match the capacity of the building.
“The HVAC load calculation measures the amount of air exchange the HVAC system must exchange from the indoor air to maintain a comfortable room temperature,” said Anthony Perera, President of Air Pros USA, an HVAC repair and service company that services markets in Florida, Colorado, Georgia, Texas, and Washington. “An accurate estimate of air flow, BTU, heating, and cooling helps decrease utility bills, extends the life of the HVAC unit, and ensures appropriate temperatures throughout a large building through all seasons.”
However, effective air filtration does not stop there. Since commercial spaces must accommodate larger crowds, commercial buildings usually have several filtration systems along the way. This reduces air flow, increases energy costs, and burdens the HVAC unit. “Higher efficiency filters may have a higher resistance to airflow – also known as pressure drop – and fans may have to be changed to accommodate the pressure drop,” said Perera. “But in crowded spaces, we can’t expect the HVAC filtration system alone to improve overall indoor air quality.”
High-Efficiency Emerging Technologies
With traditional dry air filters, the effective filtration of smaller particles can greatly reduce airflow. Dry air filters can reduce air flow by up to 60%. In other words, better filtration can result in higher airflow resistance, higher energy costs, and shorter equipment lifecycle. The challenge for air filter technology companies is to improve the effectiveness of filtration of the smallest of particles with minimal reduction to airflow. But what if air filtration technology companies could eliminate this conventional trade-off?
Dexwet’s filters feature staggered, perforated filter rods coated in a sticky medical-grade silicone oil. Unlike fiber filters, this configuration allows air to pass through with minimal airflow resistance at less than 6%. In a recent independent study conducted by IBO Interior Analysis O.G., scientists analyzed over two million data points collected in a populated classroom over a three-week period. The results showed that Dexwet Pure Air Radiator Filters captured 99.9% of nanoparticles, including pollen, viruses, and nano dust.
“Conventional dry filters diffuse fine dust particles already after 20% of their lifetime in a billiard-ball-effect as larger particles press through smaller ones,” said Dexwet’s Gregory Scott Newsome. “A wet filtration surface, however, permanently absorbs particles. The sticky oil which coats Dexwet Pure Air Filters’ rods envelope the smaller living pathogens, such as bacteria or viruses, and cuts the oxygen supply, killing the living pathogen.”
Austrian air quality expert Peter Tappler led the study and concluded that Dexwet filters represent a significant step toward infection prevention as it provides higher efficiency with negligible increase in pressure drop. Air filters are essential for a healthy indoor climate, but also have a big impact on the energy performance of buildings. Another positive aspect of Dexwet’s filter technology is that they do not require energy. This is particularly relevant as energy efficiency and green building technologies are increasingly important for new commercial construction projects in several markets.
A crucial aspect to air quality is air cycles. Air quality is typically measured by the number of air cycles through a room during an hour. Brandan Dodds is an experienced environmental, health and safety (EHS) professional with YellowBird, an online gig economy platform matching credentialed, experienced, and vetted EHS professionals with businesses nationwide. During the pandemic, Dodds has assessed the air quality in commercial buildings to help them prepare to safely reopen to the public. He advises that one of the most important safety measures to prevent the spread of viruses indoors is to conduct air flow analysis and ventilation testing.
“According to the Center for Disease Control guidelines, an example of recommended air changes per hour for a commercial building setting is 8-12x an hour (about every 5-7.5 minutes the air should be changed completely with fresh outside air),” said Dodds. “This minimizes the exposure time of particles in the air for occupants.”
As the public becomes more aware of indoor air quality, facility managers should consider having a certified EHS expert perform air assessments and provide recommendations. With services on-demand, YellowBird can help them ensure buildings stay compliant with CDC guidelines and improve indoor air quality with unbiased EHS professionals.
Rethinking Air Circulation and Ventilation for Commercial Buildings
Although recirculating air has been the default in commercial buildings for decades, experts say ventilating with new, outdoor air is vital to diluting hazardous airborne particles. Simply circulating air with fans isn’t enough, which is why some scientists recommend opening windows regularly to bring in fresh air. However, in many public spaces, including hotels, malls, and office buildings, windows don’t open. In those places, the HVAC system is the only way to dump pathogen-saturated air and bring in fresh air.
A safe indoor environment relies on making public health a priority for commercial construction, and strategies include hiring professionals who understand the complexities of ventilation, designing buildings that provide proper ventilation, and incorporating innovative technologies that effectively capture viruses and purify the air.