Final Report: Ultra-low Power CO2 Sensor for Intelligent Building ControlEPA Contract Number: EPD13026
Title: Ultra-low Power CO2 Sensor for Intelligent Building Control
Investigators: Carter, Michael T.
Small Business: KWJ Engineering, Inc.
EPA Contact: Manager, SBIR Program
Project Period: May 15, 2013 through November 14, 2013
Project Amount: $80,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2013) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Green Buildings
The purpose of this Phase I SBIR program was to demonstrate that an advanced, ultralow power, microfabricated thermal conductivity detector (TCD) could be used to accurately measure carbon dioxide (CO2) in the air for the purpose of controlling room ventilation in demand-controlled ventilations systems (DCV). Demand-controlled ventilation, in which fresh air is supplied in response to occupancy and rising ambient CO2 concentration, is emerging as an energy-efficient means of controlling room comfort. Current ventilation for CO2 level is accomplished with nondispersive infrared (NDIR) sensors, which are costly to use in large numbers, such as in a large office building. The goal of Phase I was to demonstrate that a microfabricated TCD device, which can be manufactured for a small fraction of the cost of NDIR sensors, could be used to monitor CO2 accurately in the air over ranges of temperature, atmospheric pressure and relative humidity encountered in real conditions, and that CO2 could be measured at concentrations and with resolution relevant to DCV ventilation control.
The thermal conductivity sensor, in miniaturized MEMS form, is capable of extremely fast and stable CO2 measurements in air. The microsecond response time of the MEMS device allows thousands of individual measurements to be performed and signal averaged, resulting in high signal to noise, before a conventional CO2 sensor has made a single measurement. The CO2 concentration can be accurately calibrated for changes in temperature, pressure and relative humidity on a continuous basis.