You would expect the members of the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) to point out the general inaccuracy of when the new millennium has been perceived to start. The recent Summer Meeting also featured a look back and look ahead at indoor air quality (IAQ).
According to speakers at a forum on “IAQ for the New Millenium,” we know that particulate, odors, and microbials all contribute to poor IAQ. Particle control is achieved to varying degrees through low-efficiency air filtration (“bug catchers”), ASHRAE-grade filters, and HEPA and ULPA filters. Odors are controlled through adsorption and chem-isorption methods.
However, the big IAQ focus these days, and probably into the near future, is the control and remediation of molds and fungi. “Mold is going to be the asbestos of the future,” stated an attendee.
Some aspects of system maintenance, like coil cleaning, are being pointed to as solutions to rising health concerns. And this is where service/maintenance contractors can have a huge impact.
Without proper design and maintenance, “We’re growing life downstream of the cooling coil.”
Is there a connection between IAQ and the increased use of vav systems over the last 20 years? “It only kicks on when cooling is needed, and the coil doesn’t get a chance to dry out,” pointed out an attendee. If the coil is also dirty, it serves as food for microbial growth.
“Duty cycling is a probable culprit in increased mold growth and resulting IAQ complaints, such as asthma,” responded an engineer. More air conditioning systems tend to be shut off on the weekends, when many buildings (like offices and schools) are not in use. Again, the coil does not dry off.
“If you design and install and service the system correctly, you won’t have mold,” pointed out one attendee. “You can design out 90% to 95% of the mold growth.” For instance, “Don’t put duct insulation within 6 feet of the coil. And clean the coil.”
There are design considerations that affect maintenance accessibility. “If you have an AHU with no access doors, how do you maintain the coils?”
And here’s another factor: Due to energy-conservation measures, “We’re not recycling as much outdoor air.”
System operation may need to be addressed in an IAQ standard. “I think we underestimate the importance of maintenance,” said an attendee. “We must address operational standards. Why are there design standards, but none for operations and maintenance?”
Water and high humidity were acknowledged to be culprits in mold growth and the resulting poor IAQ. Even when mold is dead, it’s an allergen. The trick is not to grow it in the first place.
Some 20 years ago, hvac maintenance was done weekly. Now it gets done three or four times a year, if it’s planned. And, more often than not, it’s a breakdown call that gets a service/maintenance contractor in to see the equipment.
To get owners interested, you must equate IAQ to comfort and productivity, stated forum attendees. “It’s amazing how many conservation measures promote microbial growth.” That in itself means that maintenance should be performed more often, not less, than before.
And owners just can’t ignore the fact that clean coils would save them a considerable amount of money.