Home > Maintaining Indoor Air Quality

Occupants in modern buildings can't simply open windows; it causes high levels of biologically active contaminants and higher air change rates, making it more uncomfortable and uneconomical. They rely on ventilation systems that allow buildings to be free of IAQ problems, thus allowing the people in them to be safer, happier, and more productive.

The three basic factors to maintain IAQ are source control, air cleaning and ventilation improvement. Source controls are source specific and are aimed at removing the source. This may not be as applicable when the source is an integral part of the zone. Air cleaners are designed only to remove suspended particulate matter.

Hence, they cannot be expected to remove pollutant gases. For IAQ maintenance, ventilation is the best solution, as it is not a pollutant specific strategy. Ventilation air serves to remove or dilute contaminants to eliminate IAQ problems. By bringing in outdoor air we can then exhaust stale air.

High levels of carbon dioxide, simply from people breathing, can cause dizziness, headaches and nausea. Outside air ducts and dampers should introduce sufficient fresh air to prevent excessive levels of carbon dioxide from accumulating.   

Good IAQ includes the following elements:

• Acceptable temperature and relative humidity
• Controlled airborne contaminants
• Adequate distribution of ventilation air

For office buildings, among the major air contamination sources are building materials and furnishings, occupants activities, and office equipment. In some cases, air contaminants generated outdoors can be brought into a building by the ventilation system. To minimize some of these sources effectively and economically, building owners should use preventive measures, such as specifying building materials and furnishings with low emission potentials, locating the outdoor-air intakes away from any known outdoor contaminated sources, and ensure that the ventilation air is delivered throughout the occupied zones.

Poor air quality leads to Sick Building Syndrome complaints, lost worker productivity, and tenant health complaints such as allergic reactions, nausea, chronic fatigue, and respiratory problems.

Habitats for microbial growth are often created by standing water in condensate pans and clogged condensate lines, by moisture blow by from fan coils into ducts, and by standing water at outside air intakes and transport to occupied areas. This will eventually contribute to foul odors and release microscopic particles which will seriously affect occupants with allergies. High efficiency filters, replaced on a regular basis and scheduled cleaning of coils, condensate pans, drains and traps will help to ensure microbes never allowed to prosper. Control of off-gassing and contaminant migration can be achieved by improving the design or maintenance of the AHU system.