Indoor Air Quality (IAQ) Overview
- IAQ is crucial since people spend significant time indoors.
- Four key factors enhance IAQ: filtration, humidification, ultraviolet light, and fresh outdoor air.
Filtration
- Filtration captures and retains airborne particles from the air stream.
- Systems range from basic fiberglass filters for homes to advanced filters for hospital clean rooms.
- Filters are typically located on the return side of the ductwork.
- Residential options include:
- Basic fiberglass filters (disposable, last ~1 month).
- Media filters (2-4 inches thick, last 3-6 months).
- Electronic air cleaners (permanent, require seasonal cleaning).
- A dirty filter restricts airflow, reduces system capacity, and increases electrical consumption.
Humidification
- Humidification introduces water vapor into the airstream, improving IAQ.
- Required humidity levels vary by climate; common during heating seasons or in dry areas.
- Ideal indoor humidity is 50%; levels above 60% can lead to mold, and below 40% can cause discomfort.
- Two types of humidifiers:
- Steam humidifiers (introduce warm steam).
- Bypass humidifiers (add moisture through a wet media filter).
Ultraviolet (UV) Light
- UV light kills airborne and surface contaminants, commonly used in hospitals.
- Typically installed facing the evaporator coil to kill mold, viruses, and bacteria.
- More effective on surface contaminants than airborne ones; slower air streams increase effectiveness.
Fresh Outdoor Air
- Introducing fresh air helps expel stale indoor air and remove built-up contaminants like mold.
- Fresh outdoor air is generally cleaner and replenishes the indoor environment.
- Building codes mandate fresh air intake to maintain a healthy indoor environment.
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