[Editor's note: This article is the third installment in a four-part series that examines poor indoor air quality (IAQ) in schools and what the HVACR trade can do to help stem the crisis. Here,The Newsdetails the options available to schools facing problems with high levels of humidity.]

At the beginning and end of the school year, oppressive heat in school buildings can be a common problem in many parts of the country. In older schools without comfort cooling systems, indoor temperatures can soar well into the 90s. Students and teachers in school buildings with older, overworked, or poorly maintained air conditioning systems can face the same problems in the event of an unexpected equipment failure.

The result can be oppressive heat and an atmosphere that makes learning almost impossible.

It's not only the high temperatures that can make students and teachers uncomfortable; high humidity levels often contribute to IAQ problems. The News spoke with several manufacturers to explore some of the causes of humidity problems and some possible dehumidification solutions for institutional settings.

IAQ Problems, Solutions

"School IAQ has become more visible as the HVAC industry and the general public realize the measurable benefit of good air quality and the sometimes alarming consequences of allowing workplaces and educational institutions to operate with poor air quality," said Anne Shubert, marketing coordinator for Stulz Air Technology Systems Inc., Frederick, Md. "It is an issue that demands attention for the most obvious reason - to protect the health of our children.

"Schools should be held to the same strict OSHA [Occupational Safety and Health Administration] and industrial hygiene standards as enlightened workplaces."

Spencer Gorland, president of Rotor Source Inc., Baton Rouge, La., pointed to American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) standards as a good starting point when it comes to addressing poor school IAQ.

"It's a problem because we need healthy environments to produce healthy minds," he said. "Poor IAQ detracts from the learning process and purpose of the educatory process. To provide a healthier environment, we need enforcement of design principles in accordance with ASHRAE 62-1989. We need to budget retrofits to existing schools as well."

Keith Coursin, president of Desert Aire, Milwaukee, noted, "School IAQ is becoming a recognized problem not only within the HVAC industry, but also with the general public. Parents are now more aware of how a school can affect their children's health. In particular, they are conscious of the air quality that their children are breathing during the day.

"Even if one disregards the rarity of stachybotrys, there are hundreds of lesser mold strains that can still have negative effects on our children. Allergies, asthma, infection, and even suppression of the immune system are all known side effects caused by mold and fungi. Fortunately, mold growth can be easily prevented with the right combination of HVAC equipment. The solution and technology are in our hands."

Coursin noted that depending on fresh outdoor air can cause problems. "Ironically, though, while ASHRAE 62 is becoming commonly adopted as the IAQ standard of choice by school systems, we are all forgetting that simply introducing fresh air into classrooms does not ensure good health for our children," he said. "Only dehumidified fresh air helps eliminate the conditions that promote mold growth.

"Therefore, the primary step that I believe needs to be taken to promote healthier learning environments for our children is to educate school boards, construction engineers, architects, and contractors about the necessity to introduce dry, dehumidified, 100-percent outdoor air into school facilities. We must teach them that to effectively condition entering air, it must be conditioned based upon wet-bulb temperature, not dry-bulb temperature. The ideal piece of equipment that is qualified to do this task is a dehumidifier."

"School IAQ is important for several reasons," said Brian Monk, vice president of sales and marketing for Circul-Aire/Dectron Internationale, Montreal.

"Exposure to contaminants is measured by concentration versus time. As a result, a child in a school environment who may be exposed to environmental pollution at a low level can still be adversely affected, since that child is in the school for eight to 10 hours a day.

"Moreover, children are not as resilient to industrial pollutants as adults are, and who would want to expose any child to any contaminant if it can be avoided. Today's technology, properly applied and installed, can minimize our children's exposure to harmful pollutants that are chemical or biological in nature."

A cutaway view of the Desert Aire VerticalAire dehumidifier.

Sidebar: Manufacturers Offer Dehumidification Options

Stulz Air Technology Systems Inc.(www.stulz-ats.com) manufactures CeilAirâ„¢ ceiling-mounted supplemental air conditioners, which are used in school buildings throughout the United States. "CeilAir units provide precision temperature and humidity control," said Anne Shubert, marketing coordinator for Stulz Air Technology Systems Inc., Frederick, Md.

"Primary school applications include static control environments, such as computer labs, telecommunications closets, and local area network (LAN) rooms to provide 24/7 protection to sensitive electronic equipment. CeilAir units are available with high-efficiency air filtration and are a low-cost option to provide close temperature and humidity control for critical areas that require continuous environmental air conditioning during night setback periods.

"In addition, as a primary product for indoor air quality (IAQ) applications, the Stulz-ATS Ultrasonicâ„¢ humidifier line is well suited for a variety of school uses. They are of a unitary design and provide clean, low-cost humidification control. ... Many benefits are realized by occupants, as well as stored materials, when humidifiers are used for classrooms, libraries, rare document storage, music rooms, electronic equipment, and science labs."

Rotor Source Inc. (www.rotorsource.com) manufactures energy recovery wheels and desiccant dehumidification wheels.

"Energy recovery makes ventilation cost efficient," said Spencer Gorland, president of Rotor Source Inc., Baton Rouge, La. "Desiccant dehumidification allows for moisture reduction of incoming air in humid climates to minimize indoor air relative humidity and prevent mold growth."

Desert Aire (www.desert-aire.com) manufactures two refrigeration-based, IAQ dehumidifiers - Total Aireâ„¢ and VerticalAireâ„¢ - that are regularly installed in school buildings, according to Keith Coursin, president of Desert Aire, Milwaukee.

"The primary benefit of using our dehumidifiers in a school building is to supply required levels of fresh, 100-percent outdoor air to students as specified by ASHRAE Standard 62, without introducing added moisture to the facility," said Coursin.

"By eliminating moisture from the outdoor air, Desert Aire's units prevent the conditions that promote the growth of harmful mold, mildew and fungi - organisms that have been linked to causing asthma and other respiratory problems.

"An important standard feature offered on both our units is their ability to provide exact leaving air temperatures (LAT). The temperature of incoming air is significantly lowered to purge it of its moisture.

"However, the resulting air is often too cold to introduce into the school without making students and occupants uncomfortable. With our units, supply air is conditioned and delivered at a precise preset temperature."

Coursin said 4-inch pleated filters are standard on all units. "Desert Aire realizes that 100-percent outdoor air can introduce many airborne particles to a school," he said.

"To ensure that as many contaminants are captured as possible, we insisted on using a thicker 4-inch filter rather than a common 1- or 2-inch filter in our IAQ units. The thicker filter also takes longer to become saturated with pollutants, and, as an added benefit, must be replaced less frequently. In addition, our TotalAire dehumidifiers can be built with an optional desiccant enthalpy wheel. On humid days, this added wheel can significantly lower the humidity of the entering air. Not only does this eliminate unwanted moisture, but it also reduces the load on the unit's refrigeration coil, therefore saving greater energy for the facility."

Circul-Aire/Dectron Internationale (www.circul-aire.com) manufactures air filtration and dehumidification systems for school buildings. Brian Monk, vice president of sales and marketing for Circul-Aire/Dectron Internationale, Montreal, noted that classrooms and auditoriums often require filtration to protect their respective environments from outdoor air contamination due to vehicular traffic, whereas indoor pools require humidity control to provide a healthy environment for the students.

"The Dectron Air Purification Systems (APS Series) provide a multiple staged filtration incorporating high-efficiency gas and particle filtration, as well as UV irradiation," said Monk.

- John R. Hall

Publication date: 08/09/2004