Multipoint air sampling system having common sensors to provide blended air quality parameter information for monitoring and building control

1. A system for monitoring air quality conditions and controlling air flow in an environment that includes an airflow control device that controls at least one airflow volume, the system comprising:

a multipoint air sampling system comprising one or more sensors that detect one or more of air comfort parameters or air contaminants, the sensors generating output signals indicative of the level of the detected air comfort parameters or air contaminants, wherein at least one of the sensors is a shared sensor that senses contaminants in the air that has been collected from a plurality of separate locations, the separate locations including an at least partially enclosed area and at least one location containing outside air or supply air;

a signal processing controller that receives the sensor output signals and in response generates one or more blended air quality parameter signals and provides one or more of such blended air quality parameter signals to the airflow control device, to control at least the supply airflow volume provided to the at least partially enclosed area, wherein at least one of the blended air quality parameter signals comprises a differential air quality parameter signal that represents the magnitude of the difference between the sensed value of at least one air contaminant in the at least partially enclosed area and the sensed value of the same air contaminant in one of the outside air or the supply air, the signal processing controller comprising one or more demultiplexers that develop separate signals representing each sensed air contaminant in each of the separate locations;

wherein the signal processing controller generates signals that cause the airflow control device to increase the supply air volume when the differential air quality parameter signal is greater than a threshold signal value or exhibits a predetermined signal pattern comprising a rapid increase in the sensed air contaminant.

2. The system of claim 1 wherein one or more of the sensors is selected from a group of sensors consisting of electrochemical, optical, infrared absorption, photo-acoustic, polymer, variable conductivity, flame ionization, photo-ionization, solid state, mixed metal oxide, ion mobility, surface acoustic wave, and fiber optic.

3. The system of claim 1 wherein the air contaminants comprise one or more contaminants selected from a group consisting of: chemical, biological, and radiological composition elements; particles having a diameter between about 0.01 microns to about 100 microns; carbon monoxide; smoke; aerosols; formaldehyde; NOX; SOX; hydrogen sulfide; chlorine; methane; hydrocarbons; ammonia; refrigerant gases; radon; ozone; radiation; biological terrorist agents; chemical terrorist agents; toxic gases; mold; and bacteria.

4. The system of claim 1 wherein the air comfort parameters comprise one or more parameters selected from a group consisting of: temperature, humidity, relative humidity, dewpoint temperature, absolute humidity, wet bulb temperature, and enthalpy.

5. The system of claim 1 further comprising a local sensor that senses temperature, and wherein at least one of the shared sensors senses one of a group of parameters including absolute humidity and dewpoint temperature and senses in the area where the local temperature sensor is located, and wherein at least one blended air quality parameter signal represents either the relative humidity, wet bulb temperature or enthalpy value of the area sensed.

6. The system of claim 5 further comprising:

an air handling unit where a percentage of the return air from the at least partially enclosed area is mixed with a percentage of outside air to create the supply air to be provided to the at least partially enclosed area; and

wherein the signal processing controller uses the local temperature sensors to sense both return and outside air temperature of said air handling unit and also uses one of the shared sensors to generate a differential enthalpy signal equal to the blended air quality parameter signal represented by the difference between the enthalpy values of the air handler's return air and outside air.

7. The system of claim 6 further comprising:

an economizer controller for the air handling unit that uses the differential enthalpy signal to at least partially increase outside airflow when the enthalpy value of outside air is less than the enthalpy value of the return air; and

wherein the airflow control device comprises an outside airflow controller that is used to override the operation of the economizer controller when the value of at least one sensed air contaminant in the outside air is greater than a threshold signal value or exhibits a predetermined signal pattern.

8. The system of claim 7 wherein the outside airflow controller is also used to increase the amount of outside air when the value of the differential enthalpy signal is greater than a threshold signal value or exhibits a predetermined signal pattern.

9. The system of claim 1 wherein the signal processing controller generates signals that cause the airflow control device to at least partially decrease the outside air volume into the at least partially enclosed area when the value of at least one sensed air contaminant in the outside air is greater than a threshold signal value or exhibits a predetermined signal pattern.

10. The system of claim 1 wherein the signal processing controller creates a dilution ventilation command signal.

11. The system of claim 1 further comprising a local occupancy sensor.

12. The system of claim 1 wherein the signal processing controller generates signals that cause the airflow control device to at least partially decrease the supply air volume when the level of at least one sensed air contaminant in the supply air is greater than a threshold value or exhibits a predetermined signal pattern.

13. The system of claim 1 wherein the signal processing controller is used to at least partially control the outside air into a building and at least partially increase the outside air volume into the building, when the differential air quality parameter signal is greater than the threshold signal value or exhibits the predetermined signal pattern.

14. The system of claim 13 further comprising:

an air handling unit where a percentage of the return air from an at least partially enclosed area down to and including 0% is mixed with a percentage up to and including 100% of outside air into the building to create the supply air to be provided to the at least partially enclosed area; and

wherein the signal processing controller generates signals that cause the airflow control device to at least partially increase the outside air volume into the building through the air handling unit, when the differential air quality parameter signal is greater than the threshold signal value or exhibits the predetermined signal pattern.

15. The system of claim 13 wherein the value of the output signal of a local or shared sensor is used to at least partially change the threshold signal value or the predetermined signal pattern.

16. The system of claim 1 wherein the signal processing controller scales the air quality parameter signals so that they are on the same relative scale.

17. The system of claim 1 wherein at least one of the sensors senses carbon dioxide and at least one of the sensors senses a different air contaminant, and wherein the output signals from such sensors are used by the signal processing controller to create at least one blended air quality parameter signal, and wherein the signal processing controller uses the blended air quality parameter signal to create a dilution ventilation command signal that is communicated to the airflow control device to at least partially control the at least one airflow volume.

18. The system of claim 1 wherein the value of the output signal of the shared sensor is used to at least partially change the threshold signal value or the predetermined signal pattern.