Sensors That Make Buildings Smart!

AirTest CO2 Control Brochure
The Free AirTest CO2 Ventilation Calculator Tool
Suggested CO2 Sequence Of Operation
CO2 In School Classrooms
CO2 Reference Library
Reduce Over Ventilation And
Energy Waste with CO2
Background on CO2 for Ventilation Control
Explanation of CO2 sensor self calibration for TR9220 and TR9290
Why" Length Matters" for CO2 meansurement (TR9220, TR9290)
Technical background on CO2 DCV
Using CO2 to measure combustion fumes
Using CO2 to control smoking in hospitality venues
Assessing buildings for CO2 retrofit
CO & energy savings case studies
AirTest CO2 energy analysis software
AirTest Training Center
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CO2 Control Explained

Carbon dioxide (CO2) is one of the most plentiful gases on the planet and is clear byproduct of human activity as we all inhale oxygen and exhale CO2. It has also been recognized as a method to measure and control cfm/person ventilation rates in buildings called CO2 DCV (Demand Controlled Ventilation). The result is that building operators now have a way to measure real time outside air ventilation rate, rather than relying on a arbitrary setting of out door air intake dampers. Demand control Ventilation with CO2, can save energy in buildings in three ways:

  • 1) unnecessary over ventilation resulting from improper setting of outside air is eliminated,
  • 2) Ventilation can be modulated based on the actual number of people in a space and
  • 3) under utilized air from low occupancy areas of the building can be recirculated to provide fresh air rather than having to heat and cool incoming air.


Dual Beam And Single Beam Self Calibration

Airtest offers CO2 sensors that utilize two different approach for self calibration. Both apprach result in a maintinance free sensor that will require no calibration for the life of the sensor (typically 15 years).

The TR9220 and TR9290 transmitters use a single beam design that utilizes a background method of calibration, where the sensor calibrates iteself to the lowest level measured over a 2 to 3 week period. This will typically occur when the space is unoccupied and inside levels are equal to outside levels.
The sensor assumes this lowest level is 400 ppm. For more details on this approach to self calibration see two documents to the right specifically referencing the TR9290 and TR9220.

The EE80 and EE85 are dual beam sensors, where the sensor has an internal calibration method that does not rely on concentrations inside the building dropping to outside concentrations periodically. This sensor is ideal for applications that are operated 24/7 or that are operated in a way where the background method of self calibration may not work. There is a reference document to the right that provides further information on the dual beam approach used in the EE80 and EE85.

Please call us if after reviewing this information you have any questions or if you would like to get a highly competitive, pricing quote.


CO2 For Outside Air & Agricultural Applications

EE82 Dual Beam CO2 Sensor

AirTest CO2 (0-5V, 0-10V, 4-20mA, LonWorks®, BACnet®)

TR9290 Wall Mount
No Display
TR9290-L Wall Mount
with CO2 Display
TR9291 In-Duct or Grill Mount
TR9291 Duct Probe Mount

TR9294 Wall Mount
No Display - LonWorks® & BacNet® Versions Available
TR9294-L Wall Mount with Display - LonWorks® & BacNet® Versions Available

Dual Beam With CO2 Temperature and Humidity Option

EE80 Wall Mount
No Display
EE80 Wall Mount
With Display
EE85 Duct Probe Mount

CO2 With Temperature

TR9220 Wall Mount No Display
TR9220-L Wall Mount With Display
TR9223 Splash Resistant Case No Display
TR9223-L Splash Resistant Case With Display

Wireless CO2 Temperature & Humidity

EE245 Wireless Transmitter (CO2 Temp RH)
EE244 Wireless Industrial Transmitter (CO2 Temp RH)

Published: February 16, 2004 Last Updated: April 12, 2013