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Control and prevention of biofouling was the goal at a Florida university and affiliated elementary school, where specific air-handling system choices were a critical part of a $50 million campus expansion project. Two new 70,000- to 80,000-square-foot buildings were recently equipped with air-handling systems that had to meet stringent standards for IAQ. Perhaps surprising to some, this feat was accomplished with 17,000 square feet of fiberglass duct board, specifically Owens Corning QuietR®, which has been certified by the GreenGuard Environmental Institute’s Children & SchoolsSM Program.
Nova Southeastern University (NSU) is adding two buildings to its 300-acre campus in Davie, Fla., as part of a project to expand its University School, a leading private school serving grades Pre-K through 12, located on 40 acres of the main campus. One building is a 70,800-square-foot University School Fine and Performing Arts Center; the other is an 82,200-square-foot University School Lower School building, where teachers provide personalized education for students in Pre-K through fifth grade.
Yes, it’s big. NSU has more than 26,000 students and is said to be the largest fully accredited independent institution of higher education in the Southeastern United States.
EFFECTS ON CHILDRENNSU selected Hill York as its air conditioning contractor. Hill York chose Owens Corning for the air-handling systems. One reason for that selection is the fact that the duct board is certified by the GreenGuard Environmental Institute (GEI). The institute developed the Children & Schools Certification Program in response to rising concerns over respiratory illnesses associated with IAQ (like asthma). The U.S. Environmental Protection Agency (EPA) estimates that one-half of U.S. schools have IAQ problems, which are blamed for reducing student performance on tasks requiring concentration, calculation, and memory.
According to GEI, children are more at risk than adults for problems resulting from environmental toxins. Children have higher inhalation rates per pound of body weight than adults, which means they are more susceptible to pollutants in the environment, and those pollutants can be more damaging to their health.
To account for inhalation exposure to young children, GEI applied a body burden correction factor to current allowable emission levels from indoor materials and furnishings. The exposure to individual chemicals was also adjusted to allow no greater than 1/100 of currently published Threshold Limit Values, or no greater than one-half of California’s Chronic Reference Exposure Levels, whichever is lower.
“As a provider of optimized green solutions, we are pleased to install air-handling products that are certified for use with young children,” said Jeff Phillabaum, president, Hill York. The company specializes in commercial and institutional projects including educational, governmental, health care, recreational, and religious facilities, and green building solutions.
“Our customers count on Hill York for cost-effective, energy-efficient, and performance-managed cooling solutions that make life more comfortable,” said Phillabaum. “We have been installing Owens Corning ducts with confidence for many years, but it is wonderful to also have independent third-party verification of the product’s contribution to IAQ.”
Dr. Marilyn Black, founder of GEI, said, “The institute applauds Owens Corning in its continued commitment to furthering our mission of improving IAQ for children in schools.”
Weston Gunnarson, project manager for Hill York, said one unusual aspect of the project is placement of the return-air ducts in the music building. “For ultra-quiet operating performance, the return openings are down near the bottom of the walls to get them as far away from the cooling equipment as possible.”
A challenge for construction in humid South Florida is avoiding mold growth before the building is closed in and conditioned. “We have never had a problem with Owens Corning duct board,” said Gunnarson.
UV SCHOOL REPORTA 2006 consultant report from the California Energy Commission (CEC) provides guidance on the use of ultraviolet radiation in the “C” wavelength range (UVC) systems in schools - specifically, what kinds of UVC systems can be used; the importance of IAQ; maintenance issues related to UVC; how UVC can save energy; safety issues; cost; field experiences with UVC for coil cleaning; the current CEC study of IAQ in schools; the importance of coil fouling; how UVC systems should be sized, located, and operated; situations that could benefit from use of UVC for coil cleaning; climate and environmental issues; facility/HVAC issues; equipment selection; and UVC manufacturers, lamps, ballasts, and recommendations.
The document is being referenced throughout the state to help school districts utilize ways to improve both IAQ and energy consumption in public school buildings. “These guidelines provide a primer on ultraviolet lighting systems for coil cleaning for school facility decision-makers, equipment specifiers, and manufacturers,” the document states. “Information is also provided that might help manufacturers see how their product offerings might be viewed by other market participants.”
The guideline acknowledges that UVC has been used to irradiate dirty air-handling system components, to deactivate microorganisms on the coils and drain pans of these systems. “The UVC is designed to rapidly clean the surfaces and to subsequently penetrate between the coil fins to clean within the coils.” Removing the microbiological coil contamination is meant to reduce the pressure drop and enhance air-side heat transfer, improving efficiency. Another benefit is improved IAQ due to reduced entrainment of microbes into air passing over the coil before it enters the room.
The report claims that benefits of UV lighting for coil cleaning, in a retrofit situation, are achieved by returning coil performance to the as-built condition; or in a new building situation, by maintaining the coil in a continuously clean condition.
According to the report, three main types of UVC systems are generally used in buildings: in-duct, upper-room, and air-handler systems. In-duct systems provide enough UV radiation to kill microorganisms in the air flowing past the lamps. Upper-room units are installed in occupied rooms above the heads of the occupants, shielded from their view, and relying upon movement and heat sources to create currents that cause air to flow through the units. Air handler systems are placed near the cooling coil and drain pan in the delivery plenum; the UV radiation deactivates microorganisms that would otherwise foul the surfaces of the air-handling unit, providing irradiation of stationary surfaces.
For the most effective microbial control, UVC devices should be installed on the supply side of the system downstream from the cooling coil and above the drain pan, said Robert Scheir, Ph.D. and president of Steril-Aire Inc. “This location provides more effective control than in-duct UVC installations because it attacks both categories of contaminants - airborne (viruses and bacteria) and surface (biofilm/mold). By keeping coils and drain pans in a constantly clean state, it also reduces maintenance and energy costs. It’s a win-win proposition because schools can reduce absenteeism, improve operational efficiency, and minimize the chance of closures due to infectious diseases or mold proliferation.”
The report also states: “Evidence strongly suggests that poor environments in schools, primarily due to the effects of indoor pollutants, adversely influence the health, performance, and attendance of students and teachers. This evidence links high concentrations of several air pollutants to reduced school attendance.” The report also cites information linking microbial pollution with asthma and respiratory illness, and suggests that UVC light may reduce both energy consumption and help deliver air with improved quality, by cleaning both coil and drain pan surfaces, and progressively penetrate between the coil rows and fins with time.
The report points out that “an effective traditional coil cleaning program cleans the coils three to four times per year. Use of UVC lamps can eliminate the need for these costly, tedious cleaning treatments that create system downtime and use chemicals, biocides, or pressure washing.” The UVC lamps themselves should be inspected on a regular basis, the report states.
“The frequency of cleaning of the UVC lamps depends on the level of filtration and whether the lamps are upstream or downstream of the filter. Some practitioners suggest that if lamps are installed downstream of an effective filter, the lamps will not need to be cleaned at all before they need to be replaced.”
The initial cost of lamps, and related control equipment, plus periodic replacement costs of the lamps themselves, “should be compared to the maintenance costs that will otherwise result from regular chemical, biocidal, or pressure cleaning” - or costs related to deferred maintenance, such as catastrophic failures and closures. The value of reduced absenteeism and improved learning performance also need to be factored into the benefits of using UVC systems, says the report.
In another study sponsored by the CEC, UVC lamp systems were installed in 36 packaged air conditioning units in three school districts across California. Their performance was compared to 18 control units in those school districts over a six-week period starting in August 2005. “Both packaged rooftop and wall-mount-type air conditioning units were included in the study. Units that were less than four years old were excluded from the study.”
Microbial samples were taken and analyzed from the surfaces of the cooling coils for each of the units prior to the installation and operation of the UVC lamp systems, and at the end of the test period. “Results showed that the UVC lamps notably reduced the levels of microbial counts in the evaporator coils in the air conditioning units.” Airflow and efficiency measurements showed a positive trend in reducing pressure drop and improving airflow.
The report states that lamps operate most effectively in still air at 25°C (77°F). Lamps are most effective when they are new and clean; they lose efficacy with age and reduced cleanliness. “Humidity has little effect on lamp output, but germicidal efficacy appears to decrease with increasing relative humidity.”
Because lamps lose their efficacy with age, and operating conditions often are not optimal, the report advises that “lamps need to be oversized so they can provide effective performance for a reasonable duration in a real-world environment of dust, humidity, and cooling airflow.”
Ultimately, the report recommends that the school decision-makers talk to several manufacturers of UVC lights for product application, cost, installation, and product information.
SCHOOL AND H1N1Public interest most likely will peak again regarding flu and the latest strain of swine flu when flu season kicks back into high gear this autumn. Manufacturers like Sanyo North America Corp.’s Biomedical, Environmental, HVAC, and Food Divisions have been developing products and services specific to the market.
Its commercial-use Virus Washer air purification systems have been donated to various institutions to help improve their situations and offer a solution. “The new electrolyzed technology used in the Virus Washer effectively suppresses viruses and bacteria,” said Deepak Mistry, strategic development and marketing manager, Environmental Division leader. “It was designed for large commercial areas where people gather, including schools, hospitals, and other public institutions.”
This electrolyzed water technology has proven to be effective in suppressing airborne viruses, bacteria, odors, allergens, and mold through global third-party certification institutions, said Mistry. The technology has also been proven effective in suppressing a number of influenza strains, including avian flu and the seasonal flu, he said.
In addition, electrolyzed water has been shown to be effective in significantly reducing the level of viable airborne viruses, according to an independent research institution in the United States, Mistry said, which used accepted methods to imitate the aerosol-related physical characteristics of human viruses. “Independent testing in Japan and other countries has also demonstrated that electrolyzed water has the unique ability to inactivate human viruses,” he said.
The technology is said to inactivate more than 99 percent of airborne viruses and bacteria from treated air through electrolyzed water. Specialized electrolyzed water technology utilizes no harmful chemicals, Mistry said; tap water is used. The washer is said to reduce pollen, mold, and dust allergens such as chalk and smoke. The washer has been shown to be effective against major types of odors (smoke, bathroom, pet, sulfides).
According to Scheir of Steril-Aire, “H1N1 opens the door for contractors to call on schools to offer preventive control strategies that will bring long-term benefits.
“We don’t know how long H1N1 will remain a threat, or how severe a threat it may become, but we do know that infectious diseases and allergens will always be a problem for schools, so why not defend against the longer-term threat? H1N1 has caused school officials to be concerned and proactive, so contractors should find a receptive audience.”
The use of high-output germicidal UVC in HVAC systems, he said, offers effective long-term control because it will destroy a range of airborne infectious disease organisms including viruses and bacteria.
“Also, another huge source of school IAQ trouble comes from biofilm, a gluey matrix of fungi, bacteria, debris, and other microorganisms that grow in the presence of moisture,” Scheir said. “Biofilm is widely prevalent in HVAC systems and triggers allergy/asthma symptoms and operational problems that are sometimes mistakenly attributed solely to mold.”
The manufacturer has recently introduced two updated products to address IAQ in schools. The UVC Kit for Unitary Air Conditioners is designed for easy installation in unitary systems of less than 5 tons, such as those used in dormitories. The UVC Kit for Air Handlers is designed for use with fan coil units, unit ventilator systems, and indoor air handlers with coils up to 84 inches with dual access. School applications include classrooms and office areas.
For more information, visit www.greenguard.org, www.hillyork.com, www.owenscorning.com/comminsul/, www.sanyobiomedical.com/certification, and www.sterilaire.com.
Publication date: 08/03/2009