scope:

INTRODUCTION

This is part two of a four-part series of papers reporting on the test and evaluation of typical CO₂ sensors used in building HVAC systems. In this study, fifteen models of NDIR (nondispersive infrared) HVAC-grade CO₂ sensors were tested and evaluated. In all, 45 sensors (three from each model) were evaluated to determine the sensor accuracy, linearity, repeatability, and hysteresis. The results are compared with the manufacturers' specifications. The experimental procedure used to test and evaluate the sensors was described in Part 1 (Shrestha and Maxwell 2009) of this paper. Among the 15 models tested, eight models have a single-lamp, singlewavelength configuration, four models have a dual-lamp, single-wavelength configuration, and three models have a single-lamp, dual-wavelength configuration. All single-lamp, single-wavelength sensors and one single-lamp, dualwavelength sensor incorporate an "automatic baseline adjustment" algorithm in the sensor's electronics package.

This paper presents an overview of the past studies performed by researchers to evaluate the performance of CO₂ sensors used in HVAC application. Further, a brief discussion on CO₂ sensor specifications and experimental test procedures (detailed in Part 1 of this paper) is provided. In addition, the paper presents test and evaluation results, including a comparison of the performance of various CO₂ sensors.