4  FM quick reads on IAQ

1. Data To Measure IAQ Is Complex Proposition


Today's tip is to understand that measuring IAQ is more complicated than a metric such as energy use. Measuring indoor air quality means amalgamating several different metrics to give a holistic IAQ picture.

"There is not just one measurement that can assess the dynamic relationship between the presence of air contaminants and the ventilation to effectively dilute and remove them," says David Bearg, president of Life Energy Associates. "Instead, assessing the healthfulness of an indoor environment is more a matter of measuring key parameters" such as effective ventilation rates, contaminant levels, absolute humidity, and even occupant satisfaction.

"The most important thing is measuring and maintaining airflow rates and exhaust," says John McFarland, director of operations, Working Buildings, Inc. Luckily, air flow is also the easiest IAQ-related metric to measure and benchmark, says McFarland, who is also the vice chair of the ASHRAE 62.1 committee.

ASHRAE 62.1 is generally thought of as a design standard, but facility managers can use its recommended ventilation rates toward IAQ. Determine the cubic feet per minute (CFM) of airflow per person, then use 62.1 to determine if the current airflow rates meet the minimum requirements for the space occupancy, especially if space functions have changed.

Also, a high percentage of completed preventive maintenance bodes well for good IAQ. It means you're regularly checking filters, examining dampers to make sure they're opening and closing properly, and making sure drain pans aren't full of water. Essentially, you're continuously commissioning your systems to make sure they're behaving as they should.

ASHRAE 62.1 also provides a standard for relative humidity (maximum of 65 percent in the 2007 edition), which is another part of the IAQ whole. "Extremes of moisture, either too dry or too humid, can adversely impact IAQ," Bearg says. If the air is too wet, mold can form. But air that is too dry (especially in the winter), makes occupants uncomfortable, says Bearg. So measuring the dew point temperature and humidity, and benchmarking that data, is one of the more important, yet overlooked, parts of getting a holistic IAQ view.

Chemical toxins can hurt IAQ

Today's tip is to be aware of chemical toxins in a building's air supply. The sustainability movement among facilities addresses these issues head-on by encouraging building materials with few or no volatile organic compounds, proper procedures during construction and retrofits to protect indoor air quality, and the elimination of chemical products.

While the EPA is supposed to track the toxicity of materials, it wasn't founded until the 1970s, and many buildings are older than that. Also, we introduce almost 2,000 new synthetic chemicals each year, far more than the EPA can test.

What can you do? Bring in an expert to conduct a thorough materials audit. Make decisions about the chemicals you allow in your facilities. Many excellent websites provide free information on alternative building products for sustainable buildings, so get educated.

During a retrofit, how often do you review building-materials sources and toxicity tests? Manufacturers often perform material-safety tests in controlled laboratory settings. Dig a little deeper into materials' contents to be sure you are protecting occupants and visitors from chemical exposure.

Also, are workers who perform retrofits sealing HVAC systems to prevent toxic substances from infiltrating the occupied space? The Leadership in Energy and Environmental Design (LEED) rating system offers one point for this critical, long-term health measure, but it is not a prerequisite. Take the initiative, and stay involved to ensure the work gets done.

Simply paying attention to a product's durability isn't necessarily the best route, either. New materials are usually durable because they contain more adhesives and chemically complex bonds. They are less likely to disintegrate or degrade over time, but maybe it's better to wear out and be replaced than to allow the harmful chemicals to remain in the building longer. Modular components can address this issue, allowing workers to replace just a small, worn-out portion of a larger system.

In federal buildings, 50 incidents of blindness, second-degree burns, and severe respiratory diseases occur every year due to mishandling chemicals. Do you have a risk-management plan that anticipates and tries to prevent such situations?

If mold is an issue, avoid it by providing proper heating and sufficient airflow, as well as sealing leaks, rather than using harsh remediating procedures after the fact.

Air Filter Improvements Help Efficiency Efforts

Today's tip is to be aware of changes in the air-filtration industry. Manufacturers have created new products that not only have improved indoor air quality but also have reduced the cost of installing and operating air-filtration equipment.

As maintenance and engineering managers continue to focus on IAQ and its impact on their facilities and occupants, manufacturers are providing them with more efficient HVAC systems and components, including air filters. This technology reduces pressure drops and improves filter efficiency.

ASHRAE has been promoting the minimum efficiency reporting value system to standardize definitions. MERV measures a filter's arrestance (ability to remove large airborne particles from the air) and dust-spot efficiency (ability to remove small airborne particles). Common commercial HVAC systems include:

Fiberglass filter. This throwaway air filter is the most common type. Layered fiberglass fibers form the filter media and typically are reinforced with a metal grating that supports the fiberglass.

Polyester and pleated filters. These filters are similar to fiberglass filters but typically have a higher resistance to airflow and a superior dust-stopping ability.

High efficiency particulate arrestance (HEPA) filters. These units filter the air passing through them at a very fine scale. The U.S. Department of Energy and its contractors use HEPA filters that meet DOE standard STD-3020-97 to filter 99.97 percent of all particles 0.3 microns or larger.

Washable air filters. These products are not as common and rely on the build-up of dust along the cloth to improve the efficiency of the filter. Industrial processes involving high volumes of coarse dust are typical applications.

All filters cause some pressure loss as air flows across them. The longer a filter has been in use, the greater the pressure loss because build-up reduces airflow; and energy demand increases as fans work harder.

The situation has improved in recent years, however. The most important design improvements involve placing more folds in the filter media and creating valleys to increase surface area. Also, the filter can be rotated so it is not perpendicular to the airstream, which may require minor changes to the filter bay.

Facility Policy Practices for Good IAQ

Sometimes a facility's HVAC system has remained largely untouched since it was installed 30 years ago. To help ensure the quality of the facility's indoor air, newer mechanicals might be a big help. But there's a lot you can do by making sure vintage mechanicals are not being operated under equally vintage policies.

First, review current energy conservation programs. Many energy conservation programs were started before concern over IAQ arose. One practice, indiscriminately closing outside air dampers, should be discontinued immediately.

In addition, the benefits garnered from energy-saving measures such as duty cycling, load shedding, raising chilled water temperatures and reducing hot water temperatures, should be evaluated in light of their effects on the indoor air environment.

Continuously document the operation of the HVAC system. Because the HVAC system acts as the lungs of the building, it is important to verify and document its operation periodically. Often HVAC system and component technology can assist in accomplishing this goal. For example, with air flow monitoring technology, it is possible to track the amount of outdoor air delivered down to each zone.

Also, develop an ongoing training program for building personnel. System operators and building managers need to be kept up to date on proper IAQ and their IAQ responsibilities. Trade journals, books, seminars and consultation with IAQ professionals are good starting points.

And last, don't be afraid to publicize proactive IAQ efforts to building occupants and potential tenants. A building's good IAQ is a market asset. Creating a newsletter, tweeting or updating the department's Facebook page to inform occupants and potential tenants on the latest IAQ developments and your building's IAQ program are some ways to capitalize on this asset.


IAQ , data , airflow rate , preventive maintenance , relative humidity

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