HVAC & Environmental Systems Division
Contaminants like carbon dioxide can affect students and teachers, making the challenge of teaching even more demanding and preventing students from reaching their potential. Poor indoor air quality (IAQ) can lead to a range of problems, from undesirable odors to sick building syndrome.
Why not just bring in more outside air? Unfortunately, that's easier said than done – particularly in schools with limited funding. In many climates, fresh outdoor air is loaded with heat and humidity – two conditions that are costly to control. Good indoor air quality requires a delicate balance between comfort and efficiency.
Federal statistics show about 20 percent of schools in the nation report air-quality problems. Selecting the most appropriate HVAC system for a school does more than just help improve the health and comfort of the faculty and students; it also plays an important role in cost efficiency.
Children, because of their size, may be more susceptible to the pollutants and contaminates than adults. One out of 13 school-aged children suffers from asthma, a chronic respiratory disease (Kennedy, 2001). According to the U.S. Environmental Protection Agency, asthma results in more than 10 million absentee days in schools annually. It is believed that the allergens and irritants that contribute to asthma and other illnesses can be reduced in schools with an effective air quality program.
IAQ is affected by emittance of various sources and air movement dynamics. Indoor air pollutants can be natural and anthropogenic materials. These indoor pollutants are being circulated throughout buildings by the HVAC system and can cause occupants to become ill. In high people density spaces such as schools and convention centers there are naturally higher levels of pollutants thus exposing more people to poor indoor air quality.
Natural pollutants are carbon dioxide, pollens, spores, microorganisms, dust, and radon. Some indoor sources of these pollutants are small pools of water in the heating/ventilation/air-conditioning (HVAC) system, stacks of books and papers that have accumulated dust, and people. Outdoor sources are landscape materials and airborne particles brought in by the wind or ventilation system.
Anthropogenic air pollutants are volatile compounds (VOCs), semi-volatile organic compounds (SVOCs), carbonyl compounds, carbon monoxide, oxides of nitrogen, and particulate matter. Some indoor sources of these pollutants are small pools of water in the heating/ventilation/air-conditioning system, paint, carpets, furnishing, and glues. Outside sources are automobiles, waste management, industrial processes, and fuel storage.
Air pollution has been an environmental concern for many years. Long streams of smoke can be seen emitting from factory smokestacks. Sometimes, the smoke can be seen coalescing into clouds. Occasionally, these clouds are pink in color. When the clouds converge and become oversaturated, rain falls to the earth. The vegetation that is watered by the precipitation sometimes shows signs of surface burning. This burning is caused by pollutants in the rain (“acid raid”). Animals, including humans, eat the vegetation; illness occurs. The air pollution caused by the factories invades the environment first through the water cycle. Secondly, the acid permeates ecosystems and food chains. This pollution is clearly visible. It is seen outdoors. Hence, it is termed outdoor air pollution. Conversely, indoor air pollution occurs indoors and is harder to visually detect.
Since indoor air pollution is generally invisible, most people have not concerned themselves with it. Odors are detected infrequently. However, people are becoming ill by breathing air inside of buildings. Children are becoming sick in the schools they attend. Some of the illnesses are being attributed to the air quality within the schools. The air quality in schools is becoming a primary concern.
One of the most effective and energy-efficient solutions to the air quality and energy challenge is the Exhaust Air Energy Recovery System (EA-ERS). An EA-ERS, with the help of an energy recovery wheel, transfers heat and humidity from incoming outside air to the exhaust air in summer, increasing the overall efficiency of the system. It does the opposite in winter, pre-heating outside air and adding moisture.
Cooling is achieved by moving energy out of incoming fresh air into outgoing exhaust air. Instead of using refrigerant or water, a chemical desiccant is used to recycle cooling from the exhaust air into incoming ventilation air. The energy recovery wheel slowly rotates, absorbing energy from the incoming fresh air into the desiccant, and then releasing water vapor into the exhaust air stream. It reduces the temperature and humidity difference between outdoor and return air while also bringing in sufficient fresh air to improve IAQ.
Reducing the Equipment and Operation Cost
Heating and cooling systems that utilize with Exhaust Air Energy Recovery System (EA-ERS). An EA-ERS drastically reduce the design load on an air conditioning system by 10-50 percent. Buildings that incorporate EA-ERS operate with higher energy efficiency resulting in lower building energy consumption thus ensuring lower operating cost to maintain required air quality. The annual energy cost for an average school facility's HVAC system totals $20,000. Units with an ERS save 30-50 percent of that cost – an estimated $10,000 annual savings.