Automatic variable ventilation control systems based on air quality detection.

Mechanical ventilation systems usually provide a fixed quantity of "fresh" air to a building space based upon the maximum number of people expected to occupy that particular space. When the use of a building space is below its design maximum, the amount of outside air brought into that space can be reduced, thus generally also reducing energy consumption through lower heating and cooling loads. One method of determining the necessary ventilation rate for aparticular space is to utilize an air quality detector (eg CO2 or O2) sensitive to building occupancy and activity load. The output of this detectorcan in turn be used to control ventilation rates.