Determination of thermal resistance using infrared thermography

• US 8,186,873 B1
• Filed: 10/08/2008
• Issued: 05/29/2012
• Est. Priority Date: 10/08/2008
• Status: Active Grant

• Current Assignee: Teledyne FLIR LLC (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: Madding, Robert P.
• Primary Examiner(s): Johnson, Amy Cohen
• Application Number:
  US12/247,751
• Time in Patent Office: 1,329 Days
• Field of Search: 374/43, 374/44, 374/120, 374/121, 374/124, 374/133, 374/135, 374/110, 374/112, 374/115, 374/29, 374/30, 374/4, 374/57, 374/137, 324/557, 324/559
• US Class Current: 374/43
• CPC Class Codes: G01N 25/18 by investigating thermal conductivity by calorimetry G01N25/20; by measuring change of resistance of an electrically-heated body G01N27/18
• CPC Class Codes: G01N 25/72 Investigating presence of flaws

Abstract

Various techniques are provided for determining thermal resistance values of building materials through the use of infrared cameras. In one example, an infrared camera may be used to capture one or more infrared images of a wall. Using temperatures obtained from the images, a thermal resistance value such as an R-Value associated with the wall may be determined. Potential cost savings associated with adjusting the thermal resistance value may also be determined.

Claims

1. A method of determining thermal resistance associated with a wall, the method comprising:

capturing an infrared image comprising a surface of the wall and a surface of at least one target using an infrared camera, wherein the wall surface and the target are in a first environment on a first side of the wall, and wherein the target surface is a substantially reflective surface;

determining a temperature of the wall surface from the infrared image;

determining a temperature of the target surface from the infrared image, wherein the target surface temperature corresponds to a reflected apparent temperature of the first environment;

determining a temperature of a second environment on a second side of the wall; and

calculating a thermal resistance value of the wall based on the wall surface temperature, the target surface temperature, and the temperature of the second environment.

2. The method of claim 1, wherein the target is at approximately thermal equilibrium with the first environment during the capturing.

3. The method of claim 1, wherein the target is a first target, wherein the infrared image further comprises a surface of a second target in the first environment, the method further comprising determining a temperature of the second target surface from the infrared image, wherein the second target surface is a substantially non-reflective surface, wherein the temperature of the second target surface corresponds to a temperature of air of the first environment, wherein the calculated thermal resistance value is further based on the second target surface temperature.

4. The method of claim 1, wherein the infrared image is a first infrared image, the method further comprising capturing a second infrared image in the second environment, wherein the second environment temperature is determined from the second infrared image.

5. The method of claim 1, wherein the determining and calculating steps are performed by the infrared camera.

6. The method of claim 1, wherein the determining and calculating steps are performed by a computing device.

7. The method of claim 1, further comprising:

calculating energy costs associated with the calculated thermal resistance value and an adjusted thermal resistance value; and

calculating a cost savings based on the calculated energy costs.

8. The method of claim 1, further comprising repeating the method to determine a plurality of thermal resistance values.

9. The method of claim 1, wherein the thermal resistance value is associated with radiative and convective heat flow through the wall.

10. The method of claim 1, wherein the thermal resistance value corresponds to an approximately steady state heat flow through the wall.

11. The method of claim 1, wherein the thermal resistance value associated with the wall is attributable to a combination of the wall, a first air film adjacent to the first side of the wall, and a second air film adjacent to the second side of the wall.

12. The method of claim 1, wherein the thermal resistance value associated with the wall is attributable to only the wall itself.

13. The method of claim 1, wherein the thermal resistance value is an R-Value.

14. A system for determining thermal resistance associated with a wall, the system comprising:

an infrared camera adapted to;

capture an infrared image comprising a surface of the wall and a surface of at least one target, wherein the wall surface and the target are in a first environment on a first side of the wall, and wherein the target surface is a substantially reflective surface,

determine a temperature of the wall surface from the infrared image, and

determine a temperature of the target surface from the infrared image, wherein the target surface temperature corresponds to a reflected apparent temperature of the first environment; and

a processor configured to calculate a thermal resistance value of the wall based on the wall surface temperature, the target surface temperature, and a temperature of a second environment on a second side of the wall.

15. The system of claim 14, wherein the processor is part of the infrared camera.

16. The system of claim 14, wherein the processor is part of a computing system.

17. The system of claim 14, wherein the system further comprises a measuring device adapted to be positioned in the second environment to measure the second environment temperature.

18. The system of claim 14, wherein the infrared image is a first infrared image, wherein the infrared camera is adapted to capture a second infrared image in the second environment and determine the second environment temperature from the second infrared image.

19. The system of claim 14, wherein the processor is adapted to:

calculate energy costs associated with the calculated thermal resistance value and an adjusted thermal resistance value; and

calculate a cost savings based on the calculated energy costs.

20. The system of claim 14, wherein the infrared camera is adapted to provide a user interface to instruct a user to position the target and initiate the capture of the thermal image.

21. The system of claim 14, wherein the infrared camera is adapted to capture a plurality of infrared images comprising the wall surface and the target surface and determine temperatures of the wall surface and the target surface from the infrared images, wherein the processor is configured to calculate a plurality of thermal resistance values based on the wall surface temperatures, the target surface temperatures, and the temperature of the second environment.

22. The system of claim 14, wherein the thermal resistance value is associated with radiative and convective heat flow through the wall.

23. The system of claim 14, wherein the thermal resistance value corresponds to an approximately steady state heat flow through the wall.

24. The system of claim 14, wherein the infrared camera comprises a range finder adapted to determine a distance from the infrared camera to the wall surface, wherein the thermal resistance value is further based on the distance determined by the range finder.

25. The system of claim 14, wherein the thermal resistance value associated with the wall is attributable to a combination of the wall, a first air film adjacent to the first side of the wall, and a second air film adjacent to the second side of the wall.

26. The system of claim 14, wherein the thermal resistance value associated with the wall is attributable to only the wall itself.

27. The system of claim 14, wherein the thermal resistance value is an R-Value.

28. A non-transitory machine-readable medium comprising a plurality of machine-readable instructions which when executed by a device are adapted to cause the device to perform a method of determining thermal resistance associated with a wall, the method comprising:

instructing a user to operate an infrared camera to capture an infrared image comprising a surface of the wall and a surface of at least one target, wherein the wall surface and the target are in a first environment on a first side of the wall, and wherein the target surface is a substantially reflective surface;

instructing a user to measure a temperature of a second environment on a second side of the wall;

determining a temperature of the wall surface from the infrared image;

determining a temperature of the target surface from the infrared image, wherein the target surface temperature corresponds to a reflected apparent temperature of the first environment; and

calculating a thermal resistance value of the wall based on the wall surface temperature, the target surface temperature, and the temperature of the second environment.

29. The non-transitory machine-readable medium of claim 28, wherein the device is the infrared camera.

30. The non-transitory machine-readable medium of claim 28, wherein the device is a computing device.

31. The non-transitory machine-readable medium of claim 28, wherein the infrared image is a first infrared image, wherein the instructing a user to measure a temperature of a second environment comprises instructing the user to capture a second infrared image in the second environment, wherein the method further comprises determining the temperature of the second environment from the second infrared image.

32. The non-transitory machine-readable medium of claim 28, wherein the method further comprises:

receiving an adjusted thermal resistance value;

calculating energy costs associated with the calculated thermal resistance value and the adjusted thermal resistance value; and

calculating a cost savings based on the calculated energy costs.

33. The non-transitory machine-readable medium of claim 28, wherein the method further comprises repeating the method to determine a plurality of thermal resistance values.

34. The non-transitory machine-readable medium of claim 28, wherein the thermal resistance value is associated with radiative and convective heat flow through the wall.

35. The non-transitory machine-readable medium of claim 28, wherein the thermal resistance value corresponds to an approximately steady state heat flow through the wall.

36. The non-transitory machine-readable medium of claim 28, wherein the thermal resistance value associated with the wall is attributable to a combination of the wall, a first air film adjacent to the first side of the wall, and a second air film adjacent to the second side of the wall.

37. The non-transitory machine-readable medium of claim 28, wherein the thermal resistance value associated with the wall is attributable to only the wall itself.

38. The non-transitory machine-readable medium of claim 28, wherein the thermal resistance value is an R-Value.