Building indoor air quality

Indoor air quality is becoming an ever-more important part of managing the environment of a building. When the salaries of the occupants of a building range from 10 to a 100 times the cost of operating that building, finding ways to enhance the comfort and productivity of those residents is the big picture from a facilities management perspective.

Filtration as a core element of indoor air quality

There are a number of indoor air quality parameters to consider and control within a building.

Temperature is pretty obvious for keeping occupants comfortable — and has well-understood, mature technology to provide appropriate and effective controls.

Humidity is also important; a building should be neither too dry nor too damp. With relative humidity too low, occupants become uncomfortable and building equipment, such as wooden furniture, suffers. If too high, occupants are equally unhappy, plus equipment is exposed to condensation, and micro-organisms, particularly mold, gain a more favorable environment for growth. But humidity control also is relatively easy to achieve.

The frontier that is least well-understood, and where truly effective methods for controlling the environment have been lacking, lies in the content of the air itself — particles, both living and inert. Indoor air can contain 1.5 million particles per cubic foot. And while the primary mass of those particles is large, the vast number are tiny, at a micron level and below. (Think of a bucket of rocks, with sand filling the cracks — the sand isn't heavy, but there are many more pieces.)

StrionAir reduces respirable particles

The smallest particles penetrate farthest past the defenses of the human body, reaching deep into the lungs. Emerging science suggests that the particles of one micron or smaller may simply pass across membranes in the lungs and directly into the bloodstream — an uncomfortable thought made truly disquieting when reviewing the sizes of some of the familiar offenders in the chart below.

These tiny demons come from many sources, and air filtration is the main defense against them. Under the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) Standard 52, filtration was viewed for many years as a mechanism to "catch boulders" to protect equipment. Rated by ASHRAE standard 52.1, filters were measured based on the weight of particles caught.

As science has advanced, recognition that particle size mattered led to Standard 52.2. the MERV rating emerged. In general terms, the higher the MERV rating, the more small particles are captured, measured down to the submicron level.

Hospitals have long recognized the need for fine-particle filtering for health. Most guidelines and practices require, at a minimum, a MERV 14 or higher filtration level for all patient spaces, capturing 85% or more of submicron-sized particles.

The U.S. Green Building Council, as part of the push for more productive facilities, specifies MERV 13, which captures 90% or more of particles at sizes greater than one micron. For comparison, the historical standard in most office spaces has been MERV 8 and lower in homes.

Capture and kill — Germicidal effect

Capturing fine airborne particles is part of the battle. Dealing with trapped pathogens is another. Many harmful micro-organisms, such as mold spores, are very robust, remaining alive for long periods of time. With the right level of moisture and something to eat — like the dead skin cells that constitute a large portion of interior dust — germs can thrive in a filter.

Filters with living content can "grow through," becoming active incubators to release pathogens into the airstream of a facility. And, as HVAC fans cycle on and off, filters get shaken and can "shed" trapped contents back into ductwork.

A filter that captures and kills airborne pathogens will never reintroduce any micro-organism.

See how it works

Mold — Filtration as an active part of your mold control plan

Mold problems in a building range from invisible threats to facility-closing show-stoppers.

Mold spores are, literally, everywhere. Although trying to achieve a completely zero-spore-count facility is impractical, it is still essential to exert control wherever possible. Mold control means finding manageable and effective ways to make a facility perform in the presence of manageable spore levels.

Some parts of mold control are pretty obvious, like practical management of humidity and moisture in a building. But what about such spots as air intakes, HVAC cooling coils, and ductwork? How do you keep that "dirty socks" smell from your office spaces?

Removing mold spores entrained in the airstream is an effective option. Since mold spores are some of the most long-lived and resilient micro-organisms around, filtration used to remove spores should destroy them where they're trapped — on the filter.

StrionAir filters have proven remarkably effective in helping get mold problems under control. A study at the National Geographic Society headquarters demonstrates the impact of StrionAir Systems in an environment with high outdoor mold spore counts. Mold inside the building was virtually eliminated in this case study.