Automatic calibration of a demand control ventilation system

1. A Demand Control Ventilation (DCV) system for a building, comprising:

a first temperature sensor positioned to sense an outside air temperature;

a second temperature sensor positioned to sense a return air temperature;

one or more dampers, each of the one or more dampers for controlling a flow of air into or out of the building;

a controller, the controller configured to control a position of the one or more dampers;

wherein the controller is further configured to automatically determine one or more calibrated damper position settings at which a flow rate of outside air drawn through the damper and into the building matches a corresponding predetermined ventilation setting, the controller using one or more flow rates that are based on measurements of one or more sensors to determine the one or more calibrated damper position settings, the controller automatically determining from time to time the one or more calibrated damper position settings when one or more predetermined environmental conditions are detected;

wherein the controller is programmed to use the one or more calibrated damper position settings to achieve a desired ventilation rate; and

wherein the one or more predetermined environmental conditions comprise at least a predetermined temperature differential between the return air temperature and the outside air temperature.

2. The Demand Control Ventilation (DCV) system of claim 1 , wherein during automatic calibration, the controller is configured to adjust the one or more dampers such that a predetermined flow of outside air is drawn through the damper and into the building at each of one or more calibration damper positions.

3. The Demand Control Ventilation (DCV) system of claim 1 , wherein the one or more sensors comprise one or more of the first temperature sensor and the second temperature sensor.

4. A Demand Control Ventilation (DCV) system for a building, comprising:

a first temperature sensor positioned to sense an outside air temperature;

a second temperature sensor positioned to sense a return air temperature;

one or more dampers, each of the one or more dampers for controlling a flow of air into or out of the building;

a controller, the controller configured to control a position of the one or more dampers;

wherein the controller is further configured to automatically determine one or more calibrated damper position settings, the controller using one or more flow rates that are based on measurements of one or more sensors to determine the one or more calibrated damper position settings, the controller automatically determining from time to time the one or more calibrated damper position settings when one or more predetermined environmental conditions are detected, wherein the one or more predetermined environmental conditions comprise at least a predetermined temperature differential between the return air temperature and the outside air temperature; and

wherein the controller is programmed to use the one or more calibrated damper position settings to achieve a desired ventilation rate.

5. The Demand Control Ventilation (DCV) system of claim 4 , wherein during automatic calibration, the controller is configured to adjust the one or more dampers such that a predetermined flow of outside air is drawn through the damper and into the building at each of the one or more calibrated damper position settings.

6. The Demand Control Ventilation (DCV) system of claim 4 , wherein the controller is programmed with desired environmental conditions for calibration, and wherein the controller is configured to determine if current environmental conditions are closer to the desired environmental conditions than during a previous calibration, and if so, automatically determine one or more calibrated damper position settings.

7. The Demand Control Ventilation (DCV) system of claim 4 , wherein the controller is configured to allow a user to initiate calibration of the one or more calibrated damper position settings.

8. The Demand Control Ventilation (DCV) system of claim 4 , wherein the controller is configured to allow a user to input one or more calibration parameters to be used in determining the one or more calibrated damper position settings.

9. A Demand Control Ventilation (DCV) system for a building, comprising:

one or more dampers, each of the one or more dampers for controlling a flow of air into or out of the building;

a controller, the controller configured to control a position of the one or more dampers;

wherein the controller is further configured to automatically determine one or more calibrated damper position settings, the controller using one or more flow rates that are detected using one or more sensors to determine the one or more calibrated damper position settings, the controller automatically determining from time to time the one or more calibrated damper position settings when one or more predetermined environmental conditions are detected, wherein the one or more predetermined environmental conditions comprise at least a predetermined temperature differential between an inside air temperature inside of the building and an outside air temperature;

wherein the controller is programmed to use the one or more calibrated damper position settings to achieve a desired ventilation rate;

wherein the controller automatically enters a calibration mode from a normal operation mode from time to time and executes a calibration algorithm to determine the one or more calibrated damper position settings;

wherein the controller is programmed with settings indicative of desired environmental conditions for the calibration mode; and

wherein the controller is configured to monitor environmental conditions, and when current environmental conditions are closer to the desired environmental conditions than during a previous calibration, the controller runs the calibration algorithm.

10. The Demand Control Ventilation (DCV) system of claim 9 , wherein during automatic calibration, the controller is configured to adjust the one or more dampers such that a predetermined flow of outside air is drawn through the damper and into the building at each of one or more calibrated damper positions.

11. The Demand Control Ventilation (DCV) system of claim 9 , wherein the one or more sensors comprise one or more temperature sensors.

12. The Demand Control Ventilation (DCV) system of claim 9 , wherein the controller is configured to allow a user to initiate calibration of the one or more calibrated damper position settings.

13. The Demand Control Ventilation (DCV) system of claim 9 , wherein the controller is configured to allow a user to input one or more calibration parameters to be used in determining the one or more calibrated damper position settings.