New Approaches to Indoor Air Quality
Good indoor air quality (IAQ) can mean a number of things. Here are some factors to consider when evaluating the safety of your air environment.
- By Andy Olson
- Oct 01, 2020
Like the terms beauty, vacation or humor, “indoor air quality” can have a distinctive meaning for different people. In almost all cases, the first aspect of IAQ to consider is temperature. Buildings that are uncomfortably hot or cold can drive customers away and create ill-will among employees. In fact, studies have repeatedly shown a connection between worker comfort and productivity, with excess heat having a particularly negative effect. Extreme heat can do more than just slow down work, however; it can be outright dangerous, causing a range of ailments from heat stress to heat stroke.
Airborne particulates like smoke or dust are another safety and quality control concern—and not just for laboratory and industrial facility managers. Schools, public buildings and commercial facilities across the country are evaluating their air filtration, ventilation and exhaust systems right now in response to the ongoing COVID-19 pandemic.
Stagnant air can also cause mold- and condensation-related problems, impacting both products and people (as it can cause sick building syndrome and sweating slab syndrome). This is of particular concern for food processing plants and grow facilities. On the opposite side of the spectrum, turbulent air is another concern for these types of facilities, especially meat processing facilities. According to a University of Nebraska study, turbulent air can lead to the spread of airborne disease.
Clearly, IAQ is a multi-faceted problem. While HVAC (heating, ventilation and air conditioning) systems with metal ductwork have traditionally been the primary solution for IAQ control, a number of newer and alternative technologies are now emerging that can supplement or even replace that. We will examine several of them here, including fabric ductwork/air diffusers, HVLS fans and how industrial curtain walls can improve the effectiveness of both.
HVAC and Ductwork
Most buildings with traditional heating and cooling systems have some type of duct system to distribute airflow throughout a building. Ductwork systems encompass airflow that is mixed with fresh, filtered and conditioned air (heated, cooled, humidified, dehumidified) and introduced back into the space. Fresh air requirements are more critical, as ASHRAE 62.1 identified the amount of fresh air required based on the type of environment. Similar to urgency for temperature, mixing this “fresh air” into the space is important to ensure healthier environments.
There are many types of ductwork systems. They may use oval, round or rectangular shapes and can be made from a wide range of materials including flexible plastics, fiberglass or—most commonly—metal. Recently, fabric ductwork has been gaining widespread acceptance, and for good reason.
The Benefits of Fabric Ductwork
Fabric ductwork/diffuser systems have a number of benefits over traditional metal systems, most of which stem from the fabric itself.
Since these fabrics have continuous linear dispersion, they diffuse air evenly across the entire length of the ductwork system. This full-length diffusion eliminates the hot and cold spots created by localized diffusers in traditional systems, which may be placed many feet apart. Conventional metal systems with high-volume diffusers also suffer significant performance differences from heating to cooling and fresh air dispersion, due to buoyancy and volume of changes.
Fabric duct systems are particularly useful in industries that require strict temperature and humidity control, such as growing facilities, other food and beverage facilities and data centers. Minimizing harmful turbulent air, which can spread illness, is possible with fabric systems that produce soft moving air by way of more exchanges. Fabric options are also becoming popular in gymnasiums and pools, where moisture may cause metal ductwork to degrade. In a worst-case scenario, this degradation creates “rust rain.”
The light weight of their fabric also makes fabric duct systems less expensive and easier to ship than metal ductwork, as well as significantly less time-intensive to install.
Unlike metal, fabric ductwork systems are immune to scratches and dents, and since they do not have resonating properties like metal, they are quieter than their traditional counterparts. They are also easier to clean; while they may have fittings similar to traditional ductwork, they are designed with zippered sections for easy removal. These sections can then be vacuumed or laundered and are sized to fit into most industrial washing machines. Optional fabrics are available with anti-microbial agents to inhibit bacteria growth.
Fabric diffusers are an ideal fit for spaces where air distribution is necessary, but fabric ductwork is not feasible. In applications that require low velocity airflow, a directional displacement diffuser is an option. Engineered to create optimal airflow patterns, the 360 degrees of even air dispersion is designed to not disturb particulates that may reside on surfaces, such as allergens or chemicals that cannot mix with other inventory or spaces.
Kitchen and restaurant spaces commonly implement fabric diffusers. Industrial kitchens are filled with essential equipment, which limits the space for ceiling mounted fabric ducts. Instead, the fabric diffuser is designed for applications with fume hoods or other airflow-sensitive environments. Air passes through specialized fabric panels, resulting in uniform, low-velocity, radially diverging air patterns with little—if any—turbulence. Complete with a snap frame attachment for easy removal and cleaning, kitchen applications are able to stay compliant and efficient with their airflow.
Food processing facilities are also switching to ceiling mounted diffusers with 360-degrees of air-porous openings. Compared to metal, the round fabric diffuser brings the occupied space to temperature 22 percent faster while offering a lower ceiling load. A diffuser like this presents facility managers who are struggling with budget or space limitations the same level of food-grade sanitation and airflow benefits of fabric ductwork. They also eliminate drip pans that are often used with metal diffusers to prevent condensation leaking into production areas.
HVLS Fans Help Even Out Temperatures
While traditional HVAC systems can heat and cool air, they do not optimize airflow. Since air temperature rises one-half to one degree Fahrenheit for every foot in height, there can be a 20-degree difference between the floor and ceiling in tall facilities during the heating season. An HVAC system must work hard for extended periods to maintain the floor-level temperature, wasting precious energy and dollars.
By gently mixing the layers of conditioned air, HVLS fans can help HVAC systems work more efficiently and economically. In air-conditioned facilities, the breeze from an HVLS fan typically allows up to a five degrees Fahrenheit increase in the HVAC system’s thermostat setting with no change in comfort. Since electric costs are reduced approximately four percent with each degree the setting is raised, this can mean an annual savings of 20 percent can be achieved in warm-weather climates.
HVLS fans are also beneficial to facilities without HVAC systems, helping to guard against heat stroke, heat exhaustion and other related maladies by providing workers with an evaporative cooling sensation. Just a two to three mph breeze can reduce the effective temperature by seven to 11 degrees Fahrenheit, making employees safer, more productive and less prone to quality-compromising errors.
HVLS fans’ benefits are equally pronounced during the winter months. By gently circulating warm air from the ceiling back toward employees at the floor level, they de-stratify the layers of heated air that would otherwise accumulate and mitigate the rising heat effect. Thus, facilities equipped with HVLS fans reduce the burden on their heating system and are able to reduce energy consumption and save money. As an additional benefit, air movement created by HVLS fans helps eliminate moisture on floors and walls.
Fan Networking and BMS Integration
Facilities such as big-box stores, warehouses and convention centers may sprawl over tens (or even hundreds) of thousands of square feet, with different areas of the building facing different temperature and humidity challenges. Therefore, multiple fan networks may need to be used, with fans operating independently of each other.
To coordinate these networks, fan control systems have been developed that can control as many as 24 HVLS fans through a single device. That controller allows for independent speed adjustments, scheduled start/stop times and the ability to start/stop based on preset temperature settings—a feature that can be very important in food operations, such as produce, cheese or wine storage. It also ensures that fans are only running when they need to run, reducing energy use and creating desirable IAQ settings for workers and product.
The most advanced HVLS network control systems can be accessed remotely, via an Ethernet port. Additionally, HVLS fan networks can be programmed into a building management system (BMS) and connected to other infrastructure equipment such as exhaust fans.
Divide and Conquer: Segmenting Space with Industrial Curtain Walls
As one might expect, the smaller the space that needs to be heated, cooled or exhausted, the smaller the energy cost needed to efficiently run an HVAC, HVLS fan or exhaust system in that space. While room segmentation can be done with permanent walls, they are often not the best option in buildings where layouts regularly change.
Facility managers are increasingly turning to industrial curtain walls to segment ambient air spaces from those requiring conditioned air. Thanks to flexible, easy-to-install fabric curtain walls, facility managers now have an adaptable solution to effectively separate ambient from conditioned air areas. If and when the layout of the facility changes, curtain walls can easily be reconfigured to fit the newest space footprint.
Temperature control is not the only segmentation benefit; curtain walls and HVLS fans can also help in addressing IAQ issues such as dust, smoke and other airborne particulates.
At best, dust on equipment, furniture, office equipment, windows, and floors can cause a constant drain on cleaning and maintenance resources. At worst, however, uncontrolled particulate matter can spoil or degrade products.
Curtain walls can be single-layer fabric or multi-layer insulated and can easily be fitted with clear vision panels for visual communication between spaces. Additionally, they are now available with antimicrobial interior batting. The inclusion of standalone, high-speed roll-up doors in the curtain wall allows for efficient thoroughfare, while minimizing time the interior is open to the processing area. Infiltration could be further reduced by positively pressurizing the clean space.
While indoor air quality has always been a concern for facility managers, it is now more important than ever. Fortunately, there are a range of new technologies and tools available to address IAQ in a flexible, site-specific manner. Facilities that invest in these technologies are likely to see across-the-board benefits, from an improved in-store customer experience to happier and more productive employees to improved product quality, an ROI that is universally beautiful.
This article originally appeared in the October 2020 issue of Occupational Health & Safety.