A
system for monitoring and modifying the quality and temperature of air within a conditioned space includes a blower unit, a
damper unit for selectively admitting outside air into the conditioned space, a temperature moderating unit and a
control unit. The
control unit includes a
thermostat and conventional
temperature control apparatus for selectively activating the temperature moderating unit to maintain the desired temperature in the conditioned space. The
control unit also incorporates CO2 concentration measuring and control apparatus which includes a small CO2 sensor. The CO2 sensor includes a
cathode, an
anode and a
solid electrolyte disposed intermediate and electrically in contact with each of the
cathode and the
anode to effect a primary electrical
cell. A heater and a heater
thermostat serve to maintain the temperature of the
cell at about 250° C. The
cathode and
anode materials and the
chemical composition of the
electrolyte are further selected such that the
voltage generated across the heated
cell varies in accordance with the CO2 concentration. CO2 concentration modifying apparatus is responsive to sensing a first predetermined CO2 concentration for turning on the blower unit and to sensing a second, higher, predetermined CO2 concentration for actuating the
damper unit to admit outside air.