Posted on

ASHRAE Standard 62.1 Addendum ab Establishes CO2 Maximums in Occupied Spaces

ASHRAE Standard 62.1 has long been the “go to” for specifying minimum ventilation rates and establishing guidelines for indoor air quality in Commercial HVAC applications.

As demand control ventilation applications (DCV) become ubiquitous in the Commercial HVAC market, so has real-time CO2 monitoring. Real-time CO2 monitoring is a known way to determine, not only fresh air rates in a space, but also occupancy within a space. The main challenge with AHSRAE 62.1-2022 is that there was no standardization or guidelines for Engineers, Design Professionals or Building Owners to follow when determining how to deploy real-time CO2 monitoring for DCV.

Addendum ab to ASHRAE 62.1-2022 addresses this challenge through the addition of standard differential CO2 concentration limits above ambient (400ppm) specifically for use with CO2 DCV systems specific to the type of Occupancy Category.

Table 6.1 (Page 5) establishes this maximum CO2 threshold above ambient for specific Occupancy Categories. For example, a classroom with students aged 5-8 would have a maximum CO2 threshold of 1000ppm (400ppm ambient + 600ppm CO2 above ambient).

Addendum ab Compliant NDIR CO2 Sensors

Addendum ab also establishes accuracy requirements for CO2 sensors used in DCV applications.

Section states that CO2 sensors shall be certified by the manufacturer to be accurate within +/-75ppm at concentrations of 600, 1000, and 2500ppm when measured at seal level at 77 degrees Fahrenheit (25 degrees Celsius).

Innovaer Technologies is the market leader in CO2 measurement applications. Our portfolio of single-channel and dual-channel NDIR sensors ensure our OEM Partners are complaint with Addendum ab.

Single-Channel CM1106HA-NS

Dual-Channel CM1107NA


  • In-House Photodetector Manufacturing
  • Enhanced Light Source
  • In-House Product Aging
  • 20 Point Matrix Temperature & RH Calibration
  • 100% Reliability Testing
  • Full Manufacturing System Traceability
  • Enhanced Product Packaging

CM1106HA-NS Single-Channel NDIR CO2 sensor and the CM1107NA Dual-Channel NDIR CO2 are also compliant with:

  • California Title 24
  • WELL
  • RESET Grade A

Sensor Stock is Available!

Inventory of both the single-channel and dual-channel NDIR CO2 is available now. Reach out to the team at Innovaer Technologies to purchase samples.