Indoor Air Quality (IAQ)

Proper ventilation control is perhaps the single most important contributor to the quality of air in enclosed spaces. Some common approaches to ventilation control lead to excessive outdoor air intake and result in a massive energy waste

Digital Air Volume (DAV) Systems can easily be configured to accommodate a more dynamic ventilation method, one which automatically adapts to the movement of occupants within a building. This ventilation method, known as Zoned CO2 Control, offers a viable strategy for achieving the goal of indoor air quality, and is one of several approaches referenced in ASHRAE std. 62-1989.

Zoned CO2 Control - Carrier offers Zoned CO2 Control as an integrated system which includes the Terminal Control Unit, a microprocessor-based controller for air terminals, and Carrier air handlers with integrated electronic controls (via the PIC or Comfort Controller). Zoned air quality control is provided by modulating the terminal airflow in response to both temperature and indoor air CO2 levels in conjunction with the Air handling equipment's outdoor air damper.

Carrier's Zoned CO2 Control system can be configured to provide the minimum, maximum and calculated average CO2 sensor values for each zone location. The air handler control then uses the average or maximum value to adjust outside air intake.

As zone CO2 levels increase, the terminal airflow to the space is increased until the zone temperature is adversely affected. At that point, the air handler increases its outside air intake. Over time, the system automatically adjusts to the point at which the terminal airflow maintains the zone temperature, and the air handler's mixed-air damper maintains the zone CO2 setpoint. A return duct-mounted VOC or CO2 sensor may be added to insure the air quality.

How It Works - A unique feature of Carrier's Zoned CO2 Control system is its ability to respond to the zone with the highest CO2 value. Particularly in zones with large, variable occupancy densities, Zoned CO2 Control effectively enhances indoor environmental quality while reducing operating costs. Through the use of Relative Humidity (RH) sensors, a similar type of zoned RH control system can be configured.