Breathing is our biggest interaction with the environment; we inhale 15,000 liters of air a day. The quality of that air is critical. In recent decades, the evolution of the built environment has been driven by two things: increasing requirements and expectations for Indoor Air Quality and the need to minimize energy consumption and environmental impacts. On the IAQ side, not that long ago, buildings allowed smoking, had minimal filtration, had little consideration for off-gassing from furnishing and materials, and were primarily designed for thermal comfort using prescriptive codes. With the increasing awareness that poor air quality impacts health and productivity, that has changed to buildings with effective air cleaning, low emitting materials, and designed with performance-based IAQ parameters. Recent events, such as the Pandemic and frequent wildfires, heightened the awareness that “air can hurt you too” and with that the demand for improved and verified IAQ.
At Dynamic, the focus has always been on developing ground-breaking technology to provide superior IAQ, as well as, energy and operational savings. Since over 90% of the cost of providing IAQ is energy and maintenance, our systems help meet de-carbonization goals. While in some ways the market has come to us, we have continually broadened and refined our range of products to meet ever more specific demands.
IAQ is a function of the outdoor air quality, the types and generation rates of the contaminants inside the building, and the effectiveness of the HVAC system in removing contaminants and supplying clean air. There are three major categories of contaminants of concern, particle, biological, and gas phase. To provide consistent IAQ, an air cleaning system must be able to address all three.
Particles have a myriad of indoor and outdoor sources. By weight and volume, 97% of particles are bigger than 1 um (1 micron is 1/25,000th of an inch), by count 98% of the particles are smaller than 0.5 um. While in the past most filters targeted the larger particles (>3um) that affect coils and equipment, it has become increasingly clear that from a health standpoint, the fine (<2.5um) and ultrafine (<0.1um) particles in the air are the most critical. These can be inhaled deeply into the lungs and carry with them a range of problems. Ultrafines are particularly an issue, as they have “high pulmonary deposition efficiency, …UFP’s surface can carry large amounts of adsorbed toxic air pollutants (oxidant gases, organic compounds, transition metals)” (Oberdörster 2001).
In non-industrial buildings (especially in an urban setting), the primary source of fine and ultrafine particles inside is typically outdoor air. Combustion processes (vehicles, powerplants, wildfires, etc.), atmospheric dust, condensation, and coagulation of gas phase compounds as they react with Ozone are a few of the constant generators of fine and ultrafine particles outside. Further, while indoor contaminant levels tend to vary with occupancy, the outdoor levels of small particles can vary by order of magnitude from day to day.
Airborne biological contaminants have certainly been front of mind for the last few years. Biologicals are a subset of particles and include molds, bacteria, and viruses. While there are plenty of biologicals in outdoor air, from a health standpoint, the primary sources of concern are generally indoors: people are number one, followed by chronically wet/damp surfaces and animals. Mold spores tend to be > 2mm; bacteria range from .1mm to >3.5mm; and viruses can be as small as .02mm. Importantly, airborne viruses and bacteria are carried by exhaled droplet nuclei mostly in the 1-3mm range. Biologicals can have a wide range of short and long-term effects, that vary considerably from person to person (allergies are an obvious example). Biological control has always been targeted and dealt with in critical applications such as hospitals, labs, food processing, etc. Since it is difficult to monitor specific biologicals in real-time, controls have focused on filtration efficiencies, airflow patterns, and air change rates. One of the legacies of the Pandemic is that owners, designers, and occupants of commercial and residential spaces want HVAC and air cleaning systems that can control the movement and capture airborne biological contamination.
There are thousands of gas-phase chemicals and compounds, with a wide array of sources both indoors and outside. In typical outdoor air, more than 99% of the compounds are either harmless or essential: oxygen, nitrogen, and argon. The ~0.05% that’s left and the micro-environments in a building are what we are concerned about. Some of the more prevalent compounds indoor air are:
Volatile Organic Compounds (VOCs): This is a very large, ubiquitous family of compounds with a number of sources both natural and man-made. They can range from benign to toxic and include things like isoprene (benign) from plants, toluene, and benzene (carcinogenic) from fuels and solvents, and aldehydes paints and furnishings.
Acid Gases: SOX, NOX, H2S, etc. These are generally from outdoor air: the first two come primarily from combustion sources and are on the National Ambient Air Quality Standards (NAAQS) list of compounds for acceptable outdoor air. (NAAQS target levels determine whether a given area is an “attainment” or “non-attainment” zone due to the quality of its outdoor air.) H2S has a number of potential sources: agriculture, water treatment, salt marshes, paper mills, and industrial processes.
Base Gases: The main compounds of concern here would be ammonia and amine compounds. The latter are associated with many foul-smelling odors.
Ozone: is a powerful oxidant also on the NAAQS non-attainment list. It has a number of sources, but high levels in outdoor air are generally from combustion and industrial sources. Ozone is an irritant that reacts with lung and nasal tissue. It also interacts with VOCs to create ultrafine particles.
Historically, gas phase compounds (other than CO2) were only considered in specialized environments: non-attainment zones, industrial settings, museums, water treatment plants, chip fabs, etc. But as the effects of gas phase contaminants on occupants has become better understood, so have the expectations and requirement for controlling them in the Indoor air. For the first time in its history, ASHRAE Standard 62.1 has included a list of gas phase “Design Compounds” and “Design Limits” in the 2022 addition.
To provide and maintain IAQ, the air cleaning and HVAC system must be able to effectively control indoor contaminant levels regardless of their source. Historically, outdoor air was often the primary means of controlling indoor contaminant levels: dilution is the solution to pollution. However, as indoor contaminant sources have been eliminated (e.g. smoking), the relationship between indoor and outdoor air is not always so clear-cut. Further, increasing ventilation can be at odds with decarbonization goals as outdoor air must be heated, cooled, cleaned, and de/humidified. Air cleaning can be the most effective and cost-effective strategy for ensuring IAQ while minimizing operational costs. Ventilation is an important part of the equation but, it is more effective to clean all the air rather than dilute some of it.
Particle/Biological/Gas Phase: Polarized Media Air Cleaners
The V8 Air Cleaning System (with MERV 13 and 14 versions), outperforms anything in the market in terms of contaminant control and cost of ownership. The V8 agglomerates and captures even the smallest particles and biologicals. In so doing, it also can significantly reduce adsorbed odors.
Panel and V-Bank Air Cleaners use different media but the same principles and are used typically in smaller equipment. They may also be coupled with our UVC systems.
Biological: Sterile Sweep Germicidal UVC Systems
From the scanning beam of the Sterile Sweep to the flexibility of our Remote UVC Systems, we have been using 254nm to inactivate captured and airborne biologicals for over a quarter of a century. We have been using critical and sensitive projects, such as the Anthrax Clean-up at the Post Office and field hospitals during the Pandemic.
Gas Phase: EDGE Panels Activated Carbon Blends
EDGE Carbon Panels are a true revolution in gas phase removal. They put the proven power of activated carbon in a flexible, low-pressure drop, format with targeted blends for various applications.