Not even five years ago, engineers routinely complained about the inaccuracy of sensors and controls, especially CO2 sensors. Those devices were basically called a waste of time. Or, as one frustrated engineer called them, "a major headache."
Then "something" happened. The technology was refined, and they started becoming more reliable. Readings became more accurate, there was no longer a need to recalibrate every three to six months, and costs started coming down. Engineers discovered that CO2 sensors could, indeed, deliver on their promises to help regulate ventilation, saving energy and providing more comfort in the process.