The first rule of HVAC maintenance in a healthcare setting might be taken from a page in medicine: “primum non nocere,” or “First do no harm.” The reason is that indoor air quality is a real issue in healthcare. Not only can common airborne bacteria and other organisms compromise sick patients, but serious, drug-resistant pathogens can prove deadly.
It's why the Centers for Disease Control launched a campaign targeting hospital-acquired infections. According to the CDC, nearly two million patients in this country acquire an infection in the hospital every year. About 90,000 of them die…more than 30,000 of pneumonia.
HVAC systems get some of the blame. HVAC systems can act as a source of contaminants by providing a hospitable environment for the growth of microorganisms and by then distributing biologically contaminated air within the building, according to a report by the U.S. Environmental Protection Agency.
An independent panel of medical and engineering experts in microbiology, medicine, epidemiology, indoor air quality and building ventilation evaluated 40 original studies and concluded, “There is strong and sufficient evidence to demonstrate the association between ventilation, air movements in buildings and the transmission/spread of infectious diseases such as measles, tuberculosis, chickenpox, influenza, smallpox and SARS.”
Standards issued by the Joint Commission on the Accreditation of Healthcare Organizations require healthcare facilities to design, install and maintain ventilation equipment for airborne contaminant control facilities, and document their maintenance. JCAHO also calls for assessing and controlling risks associated with HVAC and other utility systems, and inspecting, testing, and maintaining those systems regularly.
Even the U.S. Environmental Protection Agency has weighed in on the issue. It reported that preventive maintenance will:
* Improve indoor environmental quality.
* Reduce energy consumption by removing contaminant sources and ensuring proper calibration and efficient operation of mechanical components.
* Well-implemented maintenance plans are tried and true, of course, but not all facilities are well maintained. That makes it worthwhile to visit practices, policies and procedures that have stood the test of time.
According to the American Council for an Energy Efficient Economy, maintenance ought to include regular filter changes. Operation of fan belts, compressors and dampers need to be checked yearly. Fans, cooling and condenser coils and condensate drains should be cleaned. Controls should be calibrated and refrigerant levels checked. The U.S. EPA published guidelines shown in Table 1.
HVAC maintenance plan
Source: “Building Air Quality, a guide for building owners and facility managers” published by the U.S. Environmental Protection Agency |
General elements of a maintenance plan include:
Critical HVAC system components that require maintenance in order to maintain comfort and deliver adequate ventilation air include:
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Hardware isn't the only thing that should be maintained, however. Having proper documentation is important to ensure lifecycle efficiency. Specification data and operating instructions on each piece of equipment should be handy as should electrical wiring diagrams, spare parts lists and control sequences. Too often, maintaining documentation gets short shrift.
Although well-intentioned, even solid maintenance programs can come up short. A common problem is lack of easy access to, and clearance around, filters. If filters are not easily accessible, they may be ignored.
That's bad because, depending on the filter type and amount of particulates in the air, changeouts could be required quarterly.
Engineering cleaner air
Missing changeouts can be a growing problem, literally. As filters load, they can become breeding grounds for captured mold, bacteria, viruses and other pathogens that can thrive on dust, dead skin cells and other captured matter. As colonies grow, pathogens may reentrain into the air stream as would their waste products. Also, mold or other fungi growing on a filter can produce high spore count. Spores also can move throughout the building and be inhaled by inhabitants.
Contaminated filter media are a threat to maintenance personnel who could be exposed to dangerous microbes during routine inspection, maintenance and disposal.
Unfortunately, HVAC systems based solely on mechanical filtration are not designed to inactivate microbes in the air stream. Electrically enhancing mechanical filter technology, however, kills the causes of infectious diseases in healthcare facilities.
A battery of independent, third-party tests conducted by the University of Colorado, LMS Technologies, Southwest Foundation for Biomedical Research, and others shows the technology destroys a range of bacteria, fungi, viruses and endotoxins in a matter of hours, rather than days or weeks.
It minimizes the causes of a long list of diseases, including the common cold, human flu, pneumonia, SARS, avian flu, anthrax, tuberculosis, smallpox and nosocomial infections. Importantly, the technology inactivates the cells, eliminating their ability to replicate. Spent filters are not a biohazard and require no special handling or disposal.
What makes the technology tick? An electrical power supply, ionization array, electrical field generating array and a low airflow-resistance disposable filter media, all enclosed in a two-foot square, 12- to 15-inch deep frame shown in Figure 1.
shows an electrically enhanced mechanical air filtration technology can be configured to fit most air handlers in both new construction and retrofit air handlers
The ionization array imparts a negative electrical charge to organic and inorganic particulates in the air stream. Dust, allergens, pollen, dander and even pathogens take on the charge.
Two electrostatic arrays, a negatively charged one in front of the filter media and a grounded one behind it, polarize filter fibers. Fibers take on a positive polarity on the upstream side and a negative polarity on the downstream side. The arrays also polarize any particulates that may not have been ionized, enhancing their attraction to polarized filter fibers.
Another problem caused by not changing filters frequently enough is filter overload. Overloading increases pressure drop beyond the filter's designed end-of-life limit, which requires motors to work harder to move air through the system. Not exactly energy efficient, or conducive to extending the lifecycle of expensive equipment.
Clogged filters past their changeout date also can blow out, exposing coils to particulates that can accumulate on coil surfaces, hinder air flow and require still more energy and extra work from equipment. Particulates can build up in ducts, become contaminated with mold, and may require cleaning, an expensive proposition.
Bridging the gap
Electrically enhanced filtration technology bridges that gap, providing both high filter efficiency with low pressure drop.
Its filtration efficiency varies, based on filter design. Chart 1 compares filtration efficiency of a given filter media with and without an electrical charge. At MERV 15 to 16 levels, the electrically charged filters can achieve in excess of 95 percent filtration efficiency (particle capture) at the submicron level (ASHRAE 52.2, E1).
compares filtration efficiency of a given filter media with and without an electrical charge. The electrically charged filter achieves up to a 95 percent filtration efficiency at the submicron level (ASHRAE 52.2, E1) at an initial pressure drop as low as 0.2” w.g. at 500 FPM
At those high efficiencies, you might think that pressure drop would be hefty. It's not. The MERV 13-rated filter, for example, has initial and ending pressure drops of 0.2” w.g. to 1.0” w.g. at 500 fpm, respectively. That's half the pressure drop of the newest “green” filtration technologies and a third of that of traditional filters.
The technology's effectiveness allows maintenance personnel to stretch times between changeouts to up to as much as 24 months as shown in Chart 2.
shows that electrically enhanced mechanical air filtration technology effectively filters for up to 18 months before requiring filter replacement. Traditional filter technologies typically would require three changeouts in that span
Vancouver vets ventilation
And that's just what Vancouver General Hospital in British Columbia, Canada, required.
Managers at Vancouver General knew their ventilation system needed help when they learned of the impending demolition of two buildings and subsequent new construction adjacent to the hospital's Surgical Day Care Centre.
In general, construction and renovation projects in and outside of healthcare facilities can charge air with a variety of particulates, none of them good for patients. It's essential that a facilities' ventilation system steps up to the plate and continues to maintain healthful IAQ. Oftentimes, however, the system can't. It wasn't designed for it, or it hasn't been well maintained.
In Vancouver's case, hospital officials insisted on maintaining the centre's air quality, regardless of outside conditions. One of the first orders of business was selecting a filtration system that would efficiently cleanse particulate-laden air while minimizing ending pressure drop and maintenance.
Desmond Pattrick, project manager for Stantec Consulting of Vancouver, the hospital's engineering services consultant, specified electrically enhanced filtration technology. The hospital approved installation of a custom-fabricated, roof-mounted fresh air supply bank with 18 of the filtration units. The bank provides fresh air to three air handling units with capacities of 3000, 5250 and 8100 cfm.
During demolition and construction, indoor air quality specialists Theodor Sterling Associates of Vancouver, monitored particulate concentrations (a.k.a. respirable suspended particulates) in the filtration chamber and inside and outside the centre.
Filter chamber measurements showed the incidence of particulates dropped 89 percent, compared to outside air. Optical particle counter readings taken from the facility's rooftop and in the filtration chamber were 17 ug/m3 and 2 ug/m3, respectively.
The high filtration efficiency and low pressure drop that helped Vancouver General maintain air quality also translate into lower HVAC energy consumption. In fact, the filtration technology reduces required fan energy by more than 10 percent, compared to other technologies. A four-week test of an air handling unit at another facility proved the point.
The test measured the AHU's operating costs before and after installation of electrically enhanced air filtration technology. The test tracked kilowatt-hours, energy costs and air volume for two weeks prior to installation and two weeks after installation. Relative humidity and average temperature also were measured throughout the test.
The electrically enhanced filtration technology saved an average of 615 kWh per day. Multiplying that savings by 260 days of operation in a year produced a total savings that, even with relatively low electric utility rates of $0.073 a kWh yielded a payback of 3.3 years.
Controlling operating and maintenance costs, and helping ensure good indoor air quality sometimes requires more than proven procedures. New technology can be an effective ally in helping maintenance personnel keep equipment operating efficiently and supporting a healthful environment. HBI
Aaron Ayer is vice president of marketing for StrionAir. He can be reached at aayer@strionair.com. Healthcare Building Ideas 2008 August-September;4(6):40-42
