Ensuring good indoor air quality (IAQ) in buildings is an important task for facility managers, due to the significant impact it has on the sustainability of a building as well as the health of its occupants. Based on research done over the years, several national health and environmental organizations such as the U.S. Environmental Protection Agency (EPA), American Lung Association (ALA) and the American College of Allergy, Asthma and Immunology (ACAAI), view indoor air pollution as one of the greatest risks to human health. One study commissioned by the ACAAI revealed that 50 percent of all respiratory illnesses are either caused or aggravated by poor IAQ.
Fortunately, IAQ problems can largely be avoided through periodic preventative maintenance and smart choices of building materials, finishes, furnishings and cleaning products. First, though, it’s important to understand common sources of indoor air pollution.
There are several IAQ threats found in the average building, arising from a variety of sources. When it comes to walls, ceilings, and HVAC systems, however, the two most serious potential pollutants are mold and volatile organic compounds (VOCs).
Mold forms when tiny mold spores make contact with surfaces made from organic materials such as wood or paper. The surface often becomes damp as a result of roof or plumbing leaks or uncontrolled condensation. When there is an outbreak of mold in a building, occupants may begin to report odors and a variety of health problems, such as headaches, breathing difficulties, skin irritation, allergic reactions and aggravation of asthma symptoms.
Mold can also grow inside uninsulated HVAC sheet metal ductwork if it’s not sufficiently sealed or maintained over time. During the summer, warm, uninsulated ducts located in unconditioned areas of buildings tend to sweat as cold air travels through them. Conversely, during winter, low temperatures can cause condensation as heat travels through cold ducts. Unfortunately, this condensed moisture sometimes mixes with dust or dirt present in ducts to eventually spawn mold growth. Since the HVAC system distributes air throughout the building, this can create a serious IAQ problem if left unattended.
VOCs are gases or vapors, such as formaldehyde, that can negatively affect the health of building occupants. They are omitted from various solids and liquids, such as paints and lacquers, paint strippers, building materials, furnishings, cleaning supplies and pesticides that somehow incorporate organic chemicals into their manufacturing process. All products manufactured with organic chemicals have the potential for releasing VOCs while in use.
Now that we’ve gone over the sources of poor IAQ, we can look at the various ways of eliminating them.
In addition to repairing plumbing and roof leaks as they arise there are two key periodic maintenance tasks that will help keep the interior mold free.
Seal and Insulate Ductwork
Most HVAC system specs for commercial buildings include well sealed, insulated ducts-made sufficiently airtight- to minimize the amount of heat loss in the winter and cool air leakage in the summer. Leaks in supply ducts reduce the delivered volumes of air at diffusers and registers, leading building occupants to increase the total amount of supply air to compensate for the losses, requiring more energy to use than designed.
Leaks in return ducts, however, not only reduce the system’s thermal efficiency, but they can draw pollutants into the ductwork, which will carry them into the interior air supply. Sealing and insulating ducts help ensure optimal efficiency and shielding from air pollutants, maintains the constant temperature needed to prevent the duct condensation that can spawn mold and microbe growth.
If a building’s ductwork is uninsulated, fiberglass duct wrap can be installed over the ducts to plug any potential leaks and allow excellent thermal performance and occupant comfort. At the very minimum, make sure that the ductwork is wrapped in all unconditioned areas. Quality fiberglass duct insulation and joint caulking will only get you so far, however. To keep the flow of conditioned air clean periodic HVAC system maintenance is recommended.
HVAC System Maintenance
To ensure ductwork stays mold free, it is wise to schedule periodic inspections to verify that the HVAC system is clean and in working order. High-efficiency air filters of correct size and quality are key components of a well-maintained HVAC system and should be changed every two to three months. Ducts, too, should be regularly inspected for the detection of dust and other debris, as well as mold and other contaminants.
If mold growth is found in sheet metal ductwork, the surface must be cleaned in compliance with the National Air Duct Cleaning Association (NADCA) ACR 2013 Standard. ACR 2013 requires the use of mechanical agitation methods to remove particulate, debris, nutrient sources and surface contamination. Avoid using any liquid or spray cleaners, including biocides.
The most effective method for cleaning ductwork is air sweeping, which introduces compressed air into the duct through a hose capped with a skipper nozzle. The compressed air propels the nozzle through the ductwork, dislodging dirt, dust and debris along the way. The dislodged particles are drawn downstream through the duct and out of the system. For a download of NADCA ACR 2013 go to http://pages.optify.net/ACR2013.
These days, there are several opportunities to significantly reduce the level of VOCs in indoor air by making the right choices of buildings materials during new construction and renovation projects, as well as paints, finishes, carpeting and furniture. For best results, make sure all are certified “Low-VOC” products, which have little or no VOC content.
In addition, building maintenance and housekeeping staff should use only low VOC cleaning supplies, pesticides and air fresheners inside the building. Most manufacturers have worked hard in recent years to reduce the VOC emissions of their products to very low levels. However, it is still important to check individual product data to be certain. Certification from GREENGUARD Environmental Institute is one resource for determining if a product’s VOC content is within acceptable limits.
One of the newest innovations for reducing the VOC content of interior air with building products is the concept of VOC sequestration. This concept involves patented technology incorporated into the manufacturers’ interior wall products, such as CertainTeed’s AirRenew IAQ gypsum board and Saint Gobain’s Novelio Clean Air fiberglass wall covering. These products capture VOCs – especially formaldehyde – as they circulate thorough interior air and convert them into inert compounds that remain within the wall, unable to be released back into the air. The products will also remove any additional VOC content introduced into the interior spaces over time by a new carpeting, furniture and finishes.
Indoor air pollution is a threat to the health of building occupants, as well as the building’s sustainability. If acceptable IAQ levels are maintained in buildings the result will be a comfortable, healthy, interior environment for many years to come. Being proactive as a facility manager and preventing any threats to the IAQ of an existing facility truly benefits all parties involved.
Lucas Hamilton is the manager of building science applications for CertainTeed Corporation.
By Lucas Hamilton
Building Services Management October 2013
Volume 13 Issue 10