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Clearing the air with HVAC systems.

Towering above city streets or nestled in a suburban landscape, the monolithic presence of modern office buildings exudes a quiet invincibility: Here is where the work of Corporate America gets done. However, with increasing concern for the airborne contaminants within these structures, they are being viewed less as commercial signature pieces and more as million square foot Petri dishes - hosting sundry bacteria, viruses, equipment emissions, and adhesive gasses that can proliferate and adversely affect employee health and productivity. Even more ghastly, in the event of a fire, these buildings may become inescapable; ironically, the cladded windows installed to save energy might prove instrumental in the loss of life.

The magnitude of the indoor air quality and fire safety problems cannot be disputed, but the manner by which to address them is by no means straightforward. To raze the structures and start anew is patently wasteful and prohibitively costly; on the other hand, to disregard the hazard posed to workers within these buildings is callous, bordering on immoral. It is, in large measure, the heating, ventilating, and air conditioning (HVAC) industry that has been thrust into this breach.

To be sure, the cause of "sick building syndrome" or potentially impaired fire survivability is not, in very large measure, traceable to the operation of the HVAC system; but as both problems involve contaminated air - bacteria, et al. and smoke, respectively - use of HVAC equipment is naturally seen as a front-line response.

Hold your fire

Of most pressing import, of course, is the manner in which HVAC equipment and control systems can reduce or eliminate the threat posed by fire. By accurate sensing, quick activation, and effective use of available HVAC devices, a conflagration need not become a calamity.

The catalyst for proper equipment response in the event of fire is the fire control system, which interfaces with HVAC equipment to ensure appropriate measures are taken in timely sequence. Fire control systems are distinct and separate from comfort control systems often packaged controls installed directly by a HVAC manufacturer onto its equipment - and for good reason. As explained by Wade Smith, vice president and general manager of La Crosse, WI-based The Trane Company's Building Automation Systems Division, the requirements for fire controls are necessarily strict and adherence is potentially expensive. "We do not see the sensing and annunciation of fire as part of the comfort control system. [Fire control systems] are covered by stringent UL requirements that leave the [HVAC equipment] supplier very little flexibility in terms of adopting new technology or taking advantage of cost-saving ideas. It is useful to separate the two systems so the comfort control system is not burdened with the due diligence and high cost necessary in fire/life safety systems."

In effectively separating fire control systems from their comfort control counterparts, the role of controls companies and their installing contractors becomes decidedly more critical. The responsibility of placing sensors, calibrating management software, and coordinating the operation of HVAC equipment in a fire crisis situation devolves to them; however, they do not undertake this task alone.

According to Michael Lynch, senior product manager for Milwaukee-based Johnson Controls, Inc., the importance of ensuring effective system operation requires input from several interested parties. "A consulting engineer, in conjunction with the authority having jurisdiction (usually the fire chief or, in larger cities, a fire inspector), is in charge of defining what they want to happen functionally; that is, if a fire alarm is detected [in a specific location], what needs to happen with the air handling equipment?" Once the proper response is specified, it becomes the task of the installing contractor to translate those requirements into a computer algorithm that can be incorporated within the fire control system's software.

Fanning the flames

Having further discharged responsibility by ensuring a proper interface between the fire control system and in-place HVAC equipment, the installing controls contractor will be assured the HVAC system will act as an ally in case of fire. As outlined by Joseph Lechtanski, vice president and general manager of Air Systems Products for Syracuse, NY-based Carrier Corporation, the specific functions that might be performed by HVAC devices in response to a fire signal can be quite complex. "When the life/safety system senses a fire or smoke condition, it will send a signal to the HVAC equipment to alert it to the fact there is a fire and then direct the equipment to go into a 'smoke purge' mode.

"At that point the equipment, having received the signal, begins [its highest priority] software routine that, among other things, will pressurize spaces especially stairwells needed for evacuation - to prevent smoke infiltration. It places the space under positive pressure, thereby preventing smoke infiltration into areas not yet affected by the fire.

"Under certain situations, areas in the fire zone are shut down so as not to draw smoke into other areas. Certain fans will be shut down so smoke [is not drawn] and distributed throughout the building. Other fans will be directed, depending on their location and that of the fire, to go into a pressurization mode to maintain positive pressure in the space. Fans drawing from an area [sensed to be] smoke-contaminated would normally receive a signal to either shut down or, if there are fire dampers that could close off certain contaminated areas, they would be instructed to close."

Breathing a little easier

Though radically less severe than fire-related stress or fatality, the health price paid by exposure to indoor air pollutants is no less real. In a recent edition of HVACare, a newsletter published by York, PA-based York Corporation, several maladies directly caused by office contaminants were cited. Among those listed were Legionnaire's disease, a flu-like illness traced to bacteria breeding in cooling towers and humidifiers, and somewhat related to "humidifier fever"; allergic reactions to mold spores, environmental tobacco smoke (ETS), and insect parts; and nuisance reactions to ETS and volatile organic compounds (VOC) out-gassed from construction materials, furnishings, and carpeting.

As noted in the newsletter, such afflictions are serious concerns for both employees and management. These illnesses and reactions mean lost workdays for affected employers. For a humidifier fever outbreak, where three-fourths of a building's occupants can be affected, a business could be temporarily shut down. In addition, chronic pulmonary diseases such as asthma and bronchitis can be aggravated enough that a disability claim may be filed."

HVAC operations can address this problem in several ways. The first measure involves the use of air handling equipment to "flush" stale interior air with fresh outside air. In an attempt to encourage such a procedure, the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE), Atlanta, recently adopted a new standard (ASHRAE 62-1989) requiring a minimum of 15 cfm of outside air per person be circulated within a building - triple the level previously stipulated. Although this recommendation underscores the current belief that circulating fresh air is a partial cure for sick buildings, the simple and continuous introduction of outside air is not a panacea.

Flushing with outside air is not a viable solution if the quality of that air is also suspect. Trane's Smith says, "A lot of the documented cases of sick building syndrome are caused by problems with the outside air. [Outside] air being brought in may, on a temporary basis, be inadequately pure in nature. Indoor air quality levels may have deteriorated, but the introduction of polluted outside air [can make them worse]."

Even if outside air is sufficiently clean, uncomfortable temperatures require conditioning prior to circulation within the building - an additional expense. "It is far less expensive, from an energy consumption standpoint, to recirculate existing air," says Lechtanski. "So common design practice [prior to the new ASHRAE standard] was to try and limit fresh air introduction to 10 percent or less."

The drawbacks to using outside air are not insoluble, though. According to Todd McKinney, national sales manager for the Commercial Products Division of Farr Company, a Los Angeles-based manufacturer of filtration equipment and systems, using a combination of particulate filters and activated carbon absorbers within the HVAC system can cleanse outside air while allowing increased use of recirculated air. "If both [types of filters] are used, building owners then have an option to be in conformity with ASHRAE 62-1989 and get the equivalent of 20 cfm in offices using reduced amounts of outdoor air [thus saving the trouble and expense of having to condition greater volumes of air]."

Owner, heal thyself

Notwithstanding the capacity of HVAC equipment to move air and purge contaminants, a more pro-active approach to sick building syndrome requires that building owners and managers ensure their HVAC systems are clean and well-maintained. According to Daniel Daly, project coordinator for Portland, OR-based Environmental Remediation Systems Corporation, HVAC machinery and ductwork, if ignored, can become a very hospitable abode for virulent pollutants. "There are microbiological build-ups [in HVAC devices], especially in the changing of seasons when certain systems are shut down while others are activated. Moisture in those systems can generate all types of molds and bacteria that, when the system is again turned on, become distributed throughout the building."

Daly says one solution to a fouled HVAC system is to inspect it, draw samples from it, and have a laboratory analysis determine the specific nature of the contamination. If tests indicate a harmful substance is present, an appropriate decontamination should be designed, budgeted, and implemented. To avoid costly future occurrences, says Daly, periodic re-inspections should be scheduled.

Not only does improperly attended HVAC equipment allow harmful residue to form, a degraded system can further contribute to indoor air pollution through its inability to effectively ventilate a space - irrespective of the quality of air it is handling. However, according to Lechtanski, this problem is at least partially addressed by the diagnostic technology now included in the packaged controls generally available on most manufacturers' equipment. "Some of the worst indoor air quality situations have occurred during a period of time following the failure of a major piece of HVAC equipment. It was not uncommon for a major piece to be out of commission for several days during which all ventilation could be lost to a space. Imbedded diagnostics now allow avoidance of such an adverse situation."

At a time when American productivity and resourcefulness are being put to the test, both domestically and abroad, the health and safety of one invaluable resource - employees - must be placed at a premium. Corporate tenants will, and should, insist upon the finest conditions possible for their workers. Astute building professionals and facilities managers anticipating this demand will find reliance upon well-maintained, clean, and operationally sound HVAC systems one of the straightest arrows in their quiver.

HVAC industry Announces New Efforts to Address Ozone Depletion

If the consequences of atmospheric ozone depletion - to which the escape of CFC refrigerants has been linked - are as dire as many learned researchers claim, then the activities of HVAC manufacturers and suppliers have an adverse environmental impact transcending just indoor air quality. Not surprisingly, examination of alternatives to the villainous CFCs was a dominant theme at the Annual Meeting of the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) this past January in New York City.

Faced with a series of refrigerant phase-outs during the coming decades as mandated by the Montreal Protocols of 1988 and 1990 - several exhibitors in attendance independently announced significant strides designed to ease the transition to alternative, ozone-friendly refrigerants:

* Carrier Corporation has developed three new chillers capable of operating with HCFC-22 and another chiller compatible with HFC-134a. In addition, Carrier revealed it will be providing innovative gas-fired and steam-fired absorption chillers, utilizing technology the company says allows less reliance upon CFCs.

* In order to meet the prospective demand for alternative refrigerants, DuPont announced production start-up for the manufacture of a family of environmentally acceptable refrigerants. To be marketed under the trade name "SUVA" (SUVA-Centri-LP for HCFC-123; SUVA Cold-MP for HFC-134a, SUVA Chill-LP for HCFC-124; and SUVA Freez-HP for HFC-125), DuPont's announcement constitutes a commitment to produce acceptable refrigerants in commercially required quantities.

* Recognizing the need to conserve existing supplies of refrigerants that will otherwise be depleted by phase-outs, and committed to protecting the atmosphere from unintended discharges, The Trane Company presented two highly effective refrigerant recovery devices. The first was a light-weight, portable refrigerant recovery machine that can be used by a single technician to remove 99.9 percent of the refrigerant from a chiller; the second was The Trane Purifier Purge, a system designed to reduce CFC emissions from chillers by up to 90 percent during normal purge operation.

* York Corporation displayed its CodeKit (TM) drivelines which can replace a worn-out centrifugal driveline, or one not compatible with HCFC-123. The new device, in nearly all cases, can be connected to existing heat-exchanger shells and can be fit to York, Carrier, Trane, and other companies' centrifugal chillers.
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Title Annotation:includes related article; heating, ventilating, and air conditioning equipment
Author:Stepanek, Steven
Publication:Buildings
Date:Apr 1, 1991
Words:2141
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