Thermostat incorporating a carbon dioxide sensor suitable for reading using potentiostat techniques, and environmental control system incorporating such thermostat

A system for monitoring and modifying the quality and temperature of air within a conditioned space and including a damper unit for selectively admitting outside air into the conditioned space, a temperature moderating unit and a control unit, said control unit comprising:

• A) a thermostat including temperature set point establishment means and temperature control means for selectively activating said temperature moderating unit when the temperature of the conditioned space deviates by a predetermined amount from the established temperature set point;
• and
• B) CO2 concentration measuring and control apparatus for the conditioned space, said CO2 concentration measuring and control apparatus comprising:
• 1) a CO2 sensor comprising:
• a) a reference electrode source of oxygen anions;
• b) a lower electrical reference electrode coupled to said reference electrode source of anions;
• c) a solid electrolyte coupled to said lower reference electrode;
• d) a buffer layer;
• and
• e) an upper electrode coupled to said buffer layer;
• 2) CO2 concentration measuring apparatus in which:
• a) an electrical voltage is applied between said lower electrical reference electrode and said upper electrical electrode, said electrical voltage having a cyclic waveform and instantaneous values between a predetermined negative voltage and a predetermined positive voltage;
• and
• b) the current through said electrolyte measured, at a predetermined voltage intermediate said predetermined negative voltage and said predetermined positive voltage, is representative of the CO2 concentration;
• and
• 3) CO2 concentration modifying apparatus responsive to the measurement of at least a first predetermined CO2 concentration for actuating said damper unit to admit outside air into the conditioned space.

A system for monitoring and modifying the quality and temperature of air within a conditioned space and including a blower unit, a damper unit for selectively admitting outside air into the conditioned space, a temperature moderating unit and a control unit, said control unit comprising:

• A) a thermostat including temperature set point establishment means and temperature control means for selectively activating said temperature moderating unit when the temperature of the conditioned space deviates by a predetermined amount from the established temperature set point;
• and
• B) CO2 concentration measuring and control apparatus for the conditioned space, said CO2 concentration measuring and control apparatus comprising:
• 1) a CO2 sensor comprising:
• a) a reference electrode source of oxygen anions;
• b) a lower electrical reference electrode coupled to said reference electrode source of anions;
• c) a solid electrolyte coupled to said lower reference electrode;
• d) a buffer layer;
• and
• e) an upper electrode coupled to said buffer layer;
• 2) CO2 concentration measuring apparatus in which:
• a) an electrical voltage is applied between said lower electrical reference electrode and said upper electrical electrode, said electrical voltage being a cyclic waveform and instantaneous values between a predetermined negative voltage and a predetermined positive voltage;
• and
• b) the current through said electrolyte, measured at a predetermined voltage intermediate said predetermined negative voltage and said predetermined positive voltage, is representative of the CO2 concentration;
• and
• 3) CO2 concentration modifying apparatus:
• a) being responsive to the measurement of at least a first predetermined CO2 concentration for turning on said blower unit;
• and
• b) being responsive to the measurement of at least a second predetermined CO2 concentration, higher than said first predetermined CO2 concentration, for actuating said damper unit to admit outside air into the conditioned space.