HEALTHFUL SCHOOL ENVIRONMENTS
- By ROBBIN RITTNER-HEIR
- October 1st, 2004
What does it take to create that perfect learning environment? You know, that’s the place where teachers — speaking, not shouting — instruct students who sit quietly and comfortably in their chairs, intent on the subject at hand, tuned in, turned on and ready to learn. There’s no one coughing or sniveling in a corner; no background drone, hum or other noisy distractions.Oh, your schools’ classrooms don’t match that description? Well, perfection may be a bit too much to ask for, but improved indoor environmental quality is attainable with work and planning.
Since many districts are in the process of renovating and/or replacing their brick-and-mortar assets, it’s an excellent time to take stock and make choices that promote improved IEQ. All you have to do is work from the ceiling down.
Fluorescent lighting became the illuminator of choice in schools during the 1930s and 1940s, replacing incandescent bulbs and fixtures. They gave off more light, generated less heat, lasted longer and cost approximately one-fourth as much as their predecessors to operate. There was, however, one drawback — they buzzed and hummed.
More precisely, it was the magnetic ballast that furnished the mercury arc used to vaporize the gases which make the fluorescent tubes function, that created the constant noise, says Mark Lien, manager of Specification Marketing for Cooper Lighting . Without any other disturbances in a classroom, the hum from the magnetic ballasts alone exceeds the currently recommended standard .35-decibel noise limit.
Additionally, the old-style fluorescents are very prone to flickering because they cycle at too low a megahertz rate, Lien says. The resulting flickering has been shown to cause headaches, nausea, eyestrain, fatigue and, in some instances, can trigger epileptic seizures.
According to Lien, the advent of electronic ballasts and the T-8 fluorescent tube eliminated a lot of the noise.The electronic ballast is almost inaudible and will pass any noise level standard, he says. It also cycles at a faster rate, which eliminates the flickering and resulting side effects. Lien adds that magnetic ballasts will no longer be sold for new commercial installations after April 2006 and will only be available as replacements for existing fixtures through 2010. The electronic ballast lights are the standard for new construction and are an inexpensive retrofit for older buildings, with the units paying for themselves in as little as a year.
With recent trends toward incorporating more natural daylight, Lien says that schools can opt for installation of daylighting controls. These controls employ sensors that pick up the amount of natural light and automatically turn lights on and off as needed. These controls are most cost effective when included in new construction and can pay for themselves within two to four years.
An option Lien doesn’t recommend is the use of full-spectrum lighting, which is considered to most closely mimic sunlight. A study done in the Soviet Union, in which lights in a factory were replaced with full-spectrum bulbs, showed that, after an initial four-hour boost, productivity fell off dramatically because of lethargy similar to that caused by prolonged sun exposure, he explains. T-8 tubes produce a higher color rendering than the old fluorescents, but don’t reach the level of full spectrum, he explains, thereby offering an excellent compromise.
That’s one noise source down. But, there’s still the matter of that deafening rumble in your classrooms. It’s your heating and air conditioning systems.
The Big Boom
Ventilation is based on the number of people in a prescribed space, and schools present a unique indoor environment because of population densities, says Gary Luepke, senior application engineer for Trane Commercial Systems .
Schools generally have a higher density of people than the average office setting. The concentration of people in small and special-use spaces require ventilation systems that have to work harder than those systems in other buildings. Also, with school buildings having fewer operable windows to draw in fresh air, mechanical systems are forced to handle more of the load.
Old-style HVAC units — those located under the windows in a classroom — are self-contained units. The fans, condensers and coils are internal to each room, making it difficult to impossible to meet noise level standards, Luepke says.
The noise fix for HVAC units is remote placement, outside of the classroom, Luepke says. Locating the system in a more central location, with heat and air conditioning delivery through ductwork into the classroom, substantially reduces noise levels.
In most cases, remote unit placement usually is relegated to new construction because older buildings generally don’t have the necessary clearances for installation of ductwork, he adds. For those buildings, there are replacements for the individual classroom units that have more sound-deadening insulation and/or may vent to the outside to reduce classroom noise. They also are better equipped to handle changes in temperature and humidity, as well as being more energy efficient, Luepke says.
Another issue with school ventilation systems is the transmission of airborne contaminants — thosegifts that keep on giving. They range from the latest virus going around, to the formation of toxic mold on air conditioning coils. The latter has been responsible for the closure of any number of schools across the country.
However, one method for killing contaminants is the use of ultraviolet lights, installed at the air conditioning cooling coils and in ventilation units, says Roger Stamper, vice president of Sales and Marketing for Steril-Aire . The lights are designed to curtail the spread of flu, retard the growth of toxic mold and lessen bacteria-related odors.
Stamper says the lights are at the C-band wavelength, the shortest of the UV bands. Unlike chemically-based decontaminants, organisms can’t become immune to the UV light, Stamper explains. The light offers line-of-sight killing of mold in HVAC systems.
According to Stamper, the ultraviolet light system is safer than most chemical decontaminants, as well. The only potential drawback is short-term eye dryness and irritation that can only be caused by being in close proximity to the lights, such as when doing maintenance on them.
If you already have ductwork for HVAC coming into your classrooms, it’s important to make sure that the duct liners, which also serve to muffle ventilation system sounds, aren’t going to contribute to potential health problems.
Scott Tonkinson, director of Marketing and Advertising for Bonded Logic , says that fiberglass has been used as a duct liner for about 90 to 95 percent of the ductwork produced. Fiberglass, he remarks, if it cracks or breaks, can allow for air leakage and energy loss. It also gives off particles that can end up being carried through the ventilation stream and, when inhaled, can lodge in the lungs, increasing the chance for any number of respiratory issues. In addition, he says fiberglass can promote the growth of toxic mold. Tonkinson recommends the use of IAQ-friendly duct liners, made of
nondetrimental, sustainable materials.
According to Tonkinson, good IEQ begins with your building materials, adding that new protocols are being established for indoor air emissions testing. One of the most stringent guidelines is the Collaborative for High Performance Schools (CHPS, section 1350) enacted in California, which includes special environmental, sustainable and ‘green’ building practices related to energy conservation and efficiency, indoor air quality and resource efficiency.
Using products made of sustainable materials tends to eliminate a lot of the potential product interaction problems, he says. Knowing the properties of all the materials being used in your classrooms — from the paint and furnishings to the carpeting or flooring —is essential.
Know the products and know their off-gassing potential, Tonkinson admonishes. He recommends checking the Material Safety Data Sheets for all the products to be used to make sure that any gasses or other by-products released will not interact toxically with each other.
Taming the Noise
Making sure that windows are properly insulated and doors fit snugly are a few more steps toward muffling sounds, keeping the climate in the rooms comfortable and achieving IEQ. However, you also need to contain noise within the classroom itself.
Ceiling insulation and acoustical panels can serve two purposes — to maintain heating and cooling levels, and to create a better acoustical environment for sound. And if the walls are many-times-painted cinder block, there may still be too much echoing. In that case, acoustical panels on the walls can help to reduce the reverberation rate. A side benefit is that it also can add to the visual aesthetics of the classroom.
Tonkinson feels the key to IEQ-friendly classrooms is to use sustainable materials wherever possible. Then everyone can comfortably sit back and breathe easier when class is in session.