SYSTEMS AND METHODS FOR SENSING DEW POINT IN A BUILDING SPACE

• US 20140129044A1
• Filed: 11/02/2012
• Published: 05/08/2014
• Est. Priority Date: 11/02/2012
• Status: Active Grant

• Current Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Wenzel, Michael J.
• Granted Patent: US 9,188,993 B2
• Time in Patent Office: Days
• US Class Current: 700/300
• CPC Class Codes: G05B 13/021 in which a variable is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 2219/2642 Domotique, domestic, home control, automation, smart house
• CPC Class Codes: G05D 23/19 characterised by the use of electric means G05D23/1393 takes precedence

Abstract

A method of maintaining a temperature of a surface in a building space to be above a dew point of the building space includes calculating a dew point based on a temperature measurement and a relative humidity measurement. The method further includes estimating a safety margin associated with the dew point calculation, determining a minimum temperature of the surface, wherein the minimum temperature is a function of the dew point and the safety margin, and commanding a first component of a building automation system to adjust a current temperature of the surface to be greater than the minimum temperature.

Claims

1. A computerized method of maintaining a temperature of a surface in a building space above a dew point of the building space, the method comprising:

calculating a dew point based on a temperature measurement and a relative humidity measurement;

estimating a safety margin associated with the dew point calculation;

determining a minimum temperature of the surface, wherein the minimum temperature is a function of the dew point and the safety margin; and

commanding a first component of a building automation system to adjust a current temperature of the surface to be greater than the minimum temperature.

2. The method of claim 1, wherein the first component of the building automation system comprises a chilled beam system, and wherein the surface in the building space comprises a surface of the chilled beam system.

3. The method of claim 1, further comprising:

calculating a temperature threshold, wherein the temperature threshold describes a difference between the current temperature of the surface and the dew point; and

determining if the temperature threshold is greater than the safety margin.

4. The method of claim 3, further comprising:

commanding, when the temperature threshold is not greater than the safety margin, a second component of the building automation system to decrease at least one of the temperature and relative humidity of the building space.

5. The method of claim 1, wherein the safety margin comprises a function of at least one of:

(a) a mathematical uncertainty associated with a measurement of at least one of the temperature of the building space and the humidity, (b) a mathematical uncertainty associated with a rate of change of the measurement of at least one of the temperature of the building space and the humidity, and (c) a mathematical uncertainty associated with a location of the measurement of at least one of the temperature of the building space and the humidity.

6. A computerized method of maintaining a temperature of a surface in a building space above a dew point of the building space, the method comprising:

receiving a temperature of the building space;

receiving a relative humidity of the building space;

receiving at least one mathematical error associated with the temperature of the building space and at least one mathematical error associated with the relative humidity;

calculating the dew point using the temperature of the building space and the relative humidity;

calculating a mathematical uncertainty using the at least one mathematical error associated with the temperature of the building space and the at least one mathematical error associated with the relative humidity;

determining a minimum temperature of the surface in the building space, wherein the minimum temperature is a function of the dew point and the mathematical uncertainty;

receiving a current temperature of the surface in the building space;

commanding, when the current temperature is greater than the minimum temperature, a first component of a building automation system to maintain the current temperature; and

commanding, when the current temperature is less than the minimum temperature, a first component of the building automation system to increase the current temperature.

7. The method of claim 6, wherein the first component of the building automation system comprises a chilled beam system, and wherein the surface in the building space comprises a surface of the chilled beam system.

8. The method of claim 6, further comprising:

calculating a temperature threshold, wherein the temperature threshold describes a difference between the current temperature of the surface and the dew point; and

determining if the temperature threshold is greater than the mathematical uncertainty.

9. The method of claim 8, further comprising:

commanding, when the temperature threshold is not greater than the mathematical uncertainty, a second component of the building automation system to decrease at least one of the temperature and relative humidity of the building space.

10. The method of claim 6, wherein the mathematical uncertainty comprises a function of at least one of (a) an uncertainty associated with a measurement of at least one of the temperature of the building space and the humidity, (b) an uncertainty associated with a rate of change of the measurement of at least one of the temperature of the building space and the humidity, and (c) an uncertainty associated with a location of the measurement of at least one of the temperature of the building space and the humidity.

11. A controller for maintaining a temperature of a surface in a building space above a dew point of the building space, the controller comprising:

a processing circuit configured to receive a temperature of the building space;

wherein the processing circuit is further configured to receive a relative humidity of the building space;

wherein the processing circuit is further configured to receive at least one mathematical error associated with the temperature of the building space and at least one mathematical error associated with the relative humidity;

wherein the processing circuit is further configured to calculate the dew point using the temperature of the building space and the relative humidity;

wherein the processing circuit is further configured to calculate a mathematical uncertainty using the at least one mathematical error associated with the temperature of the building space and the at least one mathematical error associated with the relative humidity;

wherein the processing circuit is further configured to determine a minimum temperature of the surface in the building space, the minimum temperature being a function of the dew point and the mathematical uncertainty;

wherein the processing circuit is further configured to receive a current temperature of the surface in the building space;

wherein the processing circuit is further configured to command, when the current temperature is greater than the minimum temperature, a first component of a building automation system to maintain the current temperature; and

wherein the processing circuit is further configured to command, when the current temperature is less than the minimum temperature, a first component of the building automation system to increase the current temperature.

12. The controller of claim 11, wherein the first component of the building automation system comprises a chilled beam system, and wherein the surface in the building space comprises a surface of the chilled beam system.

13. The controller of claim 11, wherein the processing circuit is further configured to:

calculate a temperature threshold, the temperature threshold describing a difference between the current temperature of the surface and the dew point; and

determine if the temperature threshold is greater than the mathematical uncertainty.

14. The controller of claim 13, wherein the processing circuit is further configured to:

command, when the temperature threshold is not greater than the mathematical uncertainty, a second component of the building automation system to decrease at least one of the temperature and relative humidity of the building space.

15. The controller of claim 11, wherein the mathematical uncertainty comprises a function of at least one of (a) an uncertainty associated with a measurement of at least one of the temperature of the building space and the humidity, (b) an uncertainty associated with a rate of change of the measurement of at least one of the temperature of the building space and the humidity, and (c) an uncertainty associated with a location of the measurement of at least one of the temperature of the building space and the humidity.

16. A computerized method of maintaining a dew point of a building space below a temperature of a surface in the building space, the method comprising:

receiving a temperature of the building space;

receiving a relative humidity of the building space;

receiving at least one mathematical error associated with the temperature of the building space and at least one mathematical error associated with the relative humidity;

calculating the dew point using the temperature of the building space and the relative humidity;

calculating a mathematical uncertainty using the at least one mathematical error associated with the temperature of the building space and the at least one mathematical error associated with the relative humidity;

determining a maximum dew point, wherein the maximum dew point is a function of a current temperature of the surface and the mathematical uncertainty;

commanding, when the dew point is less than the maximum dew point, a second component of a building automation system to maintain at least one of the temperature and the relative humidity of the building space; and

commanding, when the dew point is greater than the maximum dew point, the second component of the building automation system to decrease at least one of the temperature and the relative humidity of the building space.

17. The method of claim 16, wherein the second component of the building automation system comprises a heating, ventilation, and air conditioning (HVAC) system.

18. The method of claim 16, further comprising:

calculating a temperature threshold, wherein the temperature threshold describes a difference between the current temperature of the surface and the dew point; and

determining if the temperature threshold is greater than the mathematical uncertainty.

19. The method of claim 18, further comprising:

commanding, when the temperature threshold is not greater than the mathematical uncertainty, a first component of the building automation system to increase the temperature of the surface in the building space.

20. The method of claim 16, wherein the mathematical uncertainty comprises a function of at least one of (a) an uncertainty associated with a measurement of at least one of the temperature of the building space and the humidity, (b) an uncertainty associated with a rate of change of the measurement of at least one of the temperature of the building space and the humidity, and (c) an uncertainty associated with a location of the measurement of at least one of the temperature of the building space and the humidity.

21. A controller for maintaining a dew point of a building space below a temperature of a surface in the building space, the controller comprising:

a processing circuit configured to receive a temperature of the building space;

wherein the processing circuit is further configured to receive a relative humidity of the building space;

wherein the processing circuit is further configured to receive at least one mathematical error associated with the temperature of the building space and at least one mathematical error associated with the relative humidity;

wherein the processing circuit is further configured to calculate the dew point using the temperature of the building space and the relative humidity;

wherein the processing circuit is further configured to calculate a mathematical uncertainty using the at least one mathematical error associated with the temperature of the building space and the at least one mathematical error associated with the relative humidity;

wherein the processing circuit is further configured to determine a maximum dew point, the maximum dew point being a function of a current temperature of the surface and the mathematical uncertainty;

wherein the processing circuit is further configured to command, when the dew point is less than the maximum dew point, a second component of a building automation system to maintain at least one of the temperature and the relative humidity of the building space; and

wherein the processing circuit is further configured to command, when the dew point is greater than the maximum dew point, the second component of the building automation system to decrease at least one of the temperature and the relative humidity of the building space.

22. The controller of claim 21, wherein the second component of the building automation system comprises a heating, ventilation, and air conditioning (HVAC) system.

23. The controller of claim 21, wherein the processing circuit is further configured to:

calculate a temperature threshold, the temperature threshold describing a difference between the current temperature of the surface and the dew point; and

determine if the temperature threshold is greater than the mathematical uncertainty.

24. The controller of claim 23, wherein the processing circuit is further configured to:

command, when the temperature threshold is not greater than the mathematical uncertainty, a first component of the building automation system to increase the temperature of the surface in the building space.

25. The controller of claim 21, wherein the mathematical uncertainty comprises a function of at least one of (a) an uncertainty associated with a measurement of at least one of the temperature of the building space and the humidity, (b) an uncertainty associated with a rate of change of the measurement of at least one of the temperature of the building space and the humidity, and (c) an uncertainty associated with a location of the of the measurement of at least one of the temperature of the building space and the humidity.