Three years ago engineers and architects of Geary Community Hospital's $34 million expansion promised their cutting-edge HVAC design would reduce maintenance costs, increase energy efficiency and provide unprecedented indoor air quality (IAQ).
The predictions have proved true based on recent reviews by Steve Rippert, CHFM, GCH's director of maintenance. More importantly, the project MEP consulting firm, Henderson Engineers, in Lenexa, Kan., and architect Hoefer Wysocki Architects, in Kansas City, Mo., delivered a hospital addition with state-of-the-art HVAC technology and performance that's comparable to any large metropolitan healthcare group.
"It's incredible that a small town with only 25,000 people like Junction City, Kansas, now has the same technology you would typically expect only in large cities," says Rippert.
One example of reduced maintenance is the 95,000-square-foot expansion's four air handlers and dedicated dehumidifiers, which haven't needed coil cleaning during three years of monthly checks. This saves the hospital a minimum of $1,500 in annual cleaning costs, according to Rippert. Although no efficiency tests have been performed, clean coils are more efficient and free from unhealthy microbial contamination.
This adds to unprecedented IAQ in the expansion's critical environments, such as the 15,000-square-foot surgery suite and several of its design strategies:
- Ultra-violet germicidal irradiation (UVGI) lamps disinfect air conditioning coils, positively-sloped condensate drain pans, interior HVAC unit surfaces and the supply air from microbial contaminants.
- Improved heat transfer from the perpetually clean HVAC equipment provides optimum energy efficiency.
- Operating room (OR) surgeons have adjustable, pinpoint accuracy of any temperature/humidity setting they deem necessary for an ensuing operation or procedure.
- Each OR's positive pressure ventilation systems envelope the patient and staff during surgeries with a protective air barrier.
Henderson Engineers, which is a full service national MEP firm with branch offices in Nevada, Arkansas, Texas, Florida, Arizona and New York, created a design team for the project led by Shane Lutz, P.E., LEED AP, BD+C, CHFM, principal; and Jared Wagner, P.E., LEED AP, BD+C, mechanical engineer. Although the HVAC system was anchored with a conventional four-pipe chiller and boiler loop concept, the IAQ technology is some of the most cutting edge healthcare strategies available today. In particular, the design surpassed guidelines for healthcare mechanical engineering design by the Facility Guidelines Institute (FGI), Dallas; and Standard 170--"Ventilation of Health Care Facilities"--of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), Atlanta.
The UVGI systems are from the Fresh-Aire UV Commercial Series, manufactured in Jupiter Fla., by Triatomic Environmental Inc. They use 32-inch-long UV lamps in modular racks affixed to the supply side of every coil. All the UV systems were field-installed into five air handlers by project mechanical contractor, Central Mechanical Construction, Manhattan, Kan.
Besides maintenance cost savings, UVGI also weighs heavily into each HVAC unit's energy efficiency. Industry studies reveal that coils void of biological growth have unrestricted static pressure, reduced blower electric load and optimum heat transfer. For example, a thin growth of bio-film on coil surfaces can reduce the free area and increase air velocity up to nine-percent. Cleaner coils also deliver up to a 30-percent increase in cooling capacity when compared to dirty coils, according to Michael Wixson, principal of Associated Air Products in Lenexa, Kan., a manufacturer's representative that assisted with the UVGI specification.
"We've seen the effects of no UV lights in older HVAC systems," says Lutz, "and there's a tendency for coil microorganism growth that you definitely wouldn't want distributed throughout a critical environment such as OR or any other healthcare environment."
UVGI alters the DNA and disables the reproductive capabilities of any microbe passing through its UV field in the air handler. Microbes later become entrapped in each unit's High Efficiency Particulate Arrestor (HEPA) filters manufactured by Camfil Farr, Jonesboro, Ark. Combined with each air handler's 30-percent pre-filter and 65-percent filter, the HEPA filters' 99.9-percent particle-free filtration delivers optimum IAQ.
What separates the expansion's design from older healthcare designs, which typically use conventional air conditioning package units, is a dedicated outdoor air dehumidifier by Munters, Selma, Texas. The 100-ton unit cools and heats, but most importantly dehumidifies the surgery suite air to the surgeons' requirements, which is typically in the 30 to 50-percent relative humidity (RH) range. Each OR has a stand-alone steam humidifier supplied by the central plant boilers to boost RH, if needed.
"Typically 72°F and 50-percent RH is fine for most hospital areas, however surgeons wear gowns and it's a high-stress area where perspiration isn't acceptable, says Wagner. "Therefore we specified a dedicated dehumidification unit for the surgery suite that surgeons can easily set for temperatures and RH such as 65°F and a 30-percent RH, which most conventional air-conditioners would struggle to achieve."
The mechanical design team also worked closely to appropriate adequate space for the outdoor air dehumidifier's location in a mechanical room in close and efficient proximity to the surgery suite. While more cost effective than a rooftop system, this equipment placement created challenges such as noise suppression, adequately sized outdoor air intakes and other issues the Henderson Engineers team solved.
Also integral to the OR's IAQ are tight tolerances on pressurization, the prevention of untreated air infiltration into surgery areas and 30 air changes/hr., the latter which surpasses healthcare standards by 100 percent. Air terminal units with multi-point sensors on both supply and return ductwork allow the return airflow to track the supply airflow to maintain positive pressure in the rooms. Linear stainless steel ceiling Hospital Operating Room Diffusers (HORD) systems manufactured by Price Industries, Atlanta, have two components--laminar diffusers that broadcast a gentle 25-fpm, non-turbulent airflow over the patient, and a perimeter linear curtain that encircles the OR's staff and patient area with a protective air curtain barrier. Low return air grilles located symmetrically in the OR remove contaminated air and any heavier than air gases safely and effectively from the space. All totaled, the system assures only disinfected and HEPA filtered air around the surgery area with minimal airborne contaminant infiltration.
The expansion's Metasys building automation system (BAS) manufactured by Johnson Controls, Milwaukee, Wis., monitors the suite's environment as well as the as a new intensive care unit, expanded radiology and other departments. "The combination of all these technologies provides the most sterile environment possible around the patient," says Lutz.
The remainder of the addition uses three 350-ton YK model chillers by York--division of Johnson Controls; three cooling towers by Marley--div. SPX Cooling Technologies, Overland Park, Kan., two 200-hp Unilux Advanced Manufacturing LLC, Schenectady, N.Y., and one steam-fired, 200-hp boiler by Superior Boiler Co., Hutchinson, Kan.
In future HVAC designs, Lutz said Henderson Engineering is moving toward more accurate return air controlling devices along with new recently-developed UV light systems that also include carbon filtering for volatile organic compounds (VOC) and photo-catalytic oxidation (PCO) all in one unit. This type of disinfection and air purification will have a positive impact on critical healthcare environments such as OR's, in-vitro fertilization clinics, but also other facilities requiring improved IAQ.
Whereas healthcare HVAC designs 10 years ago with the UVGI, HEPA and the other optimum IAQ safeguards that Henderson Engineers builds into its HVAC systems might have prompted questions from healthcare administrators 10 years ago. But today Lutz says these technologies are more well-known as irreplaceable specifications for the health and safety of patients and staff.
Source: Triatomic Environmental Inc.