Adaptive environment control system

• US 4,897,798 A
• Filed: 12/08/1986
• Issued: 01/30/1990
• Est. Priority Date: 12/08/1986
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.), AT&T Information Systems Inc. (AT&T, Inc.)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.), AT&T Information Systems Inc. (AT&T, Inc.)
• Inventors: Cler, Lawrence J.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Mattson, Brian M.
• Application Number:
  US06/939,372
• Time in Patent Office: 1,149 Days
• Field of Search: 364/505, 364/506, 364/512, 364/550, 364/551, 364/148, 364/557, 374/11, 374/182, 374/189, 374/197, 374/198, 165/13, 165/14, 165/22, 165/26, 165/48 R, 236/46 R, 236/46 A, 237/2 R, 237/2 A
• US Class Current: 700/276
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/46 Improving electric energy efficiency or saving
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays
• CPC Class Codes: F24F 11/61 using timers
• CPC Class Codes: F24F 11/64 using pre-stored data
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: G05D 23/1917 using digital means

Abstract

This adaptive environment control system provides an HVAC control system that adapts to the continually-changing thermal characteristics of the building in which it operates. The adaptive environment control system periodically estimates the thermal characteristics of the building and uses these estimates to control the operation of the HVAC system. The adaptive environment control system also periodically measures the performance characteristics of the HVAC system to obtain data with which to update these thermal characteristic estimates. These thermal characteristic estimates enable the adaptive environment control system to determine both the length of time it takes the building to heat up and cool down when the HVAC system idles, as well as the amount of time it takes the HVAC system to heat or cool the building. These measurements and estimates are taken on a dynamic basis so that the adaptive environment control system responds to any changes in the environment, either within or without the building, including degradation of the operation of the HVAC system. The adaptive environment control system can calculate, through the estimates and measurements, the thermal performance of both the building and the HVAC system, so that the HVAC system is operational sufficiently early to maintain the building interior temperature within a predetermined range of the set-point threshold level of the thermostat.

Claims

1. An adaptive environment control system for dynamically modifying operation of an HVAC system to control interior temperature of a building as a function of thermal properties of the building, comprising:

means for repeatedly determining the interior temperature and temperature outside of said building;

means connected to said determining means for repeatedly estimating, from said determined temperatures, values of said thermal properties;

means connected to said estimating means and responsive to said estimated values of said thermal properties for controlling the operation of said HVAC system based on said estimated values to bring the interior temperature of said building to a pre-set temperature at a predetermined time;

means connected to said estimating means for repeatedly predicting future values of said thermal properties from said estimated values; and

means connected to said estimating means and said predicting means for generating an alarm indication if values predicted for a given time differ from values estimated for said given time by more than a predetermined amount.

2. The system of claim 1 further comprising:

means for measuring performance characteristics of said HVAC system; and

wherein said estimating means is connected to said measuring means and responsive to said measured performance characteristics for revising said estimated values of said thermal properties.

3. The system of claims 1 or 2 wherein said controlling means includes:

p1 means connected to said estimating means and said determining means and responsive to said estimated values of said thermal properties and said determined interior temperature for calculating a period of time required for said HVAC system to bring said building interior temperature to said pre-set temperature; and

means connected to said calculating means and responsive to the calculated time period for initiating the operation of said HVAC system at said required time period prior to said predetermined time to bring the interior temperature of said building to said pre-set temperature at said predetermined time.

4. The system of claim 2 wherein the controlling means includes:

means connected to said measuring means and responsive to said measured performance characteristics for generating an alarm indication when said measured performance characteristics deviate from nominal performance characteristics by more than a predetermined amount.

5. The system of claim 3 wherein said controlling means further includes:

means for predicting the interior temperature of said building for a length of time equal to said time period required to bring said interior temperature to said pre-set temperature; and

means connected to said predicting means and responsive to said predicted temperature for activating said HVAC system if said predicted temperature deviates from said pre-set temperature by more than a predefined amount.

6. The system of claims 1 or 2 wherein said generating means includes:

means connected to said estimating means and responsive to said estimated values of said thermal properties for generating an alarm indication when said estimated values of said thermal properties of said building deviate from nominal values of said thermal properties of said building by more than a predetermined amount.

7. The system of claim 1 wherein said estimating means includes:

means for obtaining measurements of an environment of said building; and

means connected to said obtaining means and responsive to said measurements for estimating said values of said thermal properties of said building.

8. The system of claim 7 wherein said estimating means includes:

means connected to said obtaining means and responsive to said measurements for estimating parameters indicative of ratios of said values of said thermal properties of said building.

9. The system of claim 7 further comprising:

means for comparing said estimated values of said properties against predefined limits; and

means connected to said comparing means for resetting said estimated values of said thermal properties to nominal values of said thermal properties within said predefined limits when said estimated values of said thermal properties exceed said predefined limits.

10. The system of claim 1 wherein the generating means comprises:

means for generating an alarm indication if a sum of differences between predicted and estimated values for different given times exceeds a predetermined amount.

11. The system of claim 1 wherein:

said thermal properties represent time-rate-of-change of heat gain or loss of thermal mass of said building, rate of heat transfer of said building to a surrounding environment, and thermal input to said building provided by said HVAC system.

12. The system of claim 11 wherein the means for estimating the values of the thermal properties comprise:

means for estimating from said determined temperatures a ratio of (a) said thermal input to said building by said HVAC system and (b) said rate of heat transfer of said building to said surrounding environment multiplied by a difference of said determined interior and outside temperatures; and

means for estimating from said determined temperatures a ratio of (a) said rate of heat transfer of building to said surrounding environment multiplied by said difference of said determined interior and outside temperatures and (b) said time-rate-of-change of heat gain or loss of said thermal mass of said building multiplied by a rate-of-change of said determined interior temperature.

13. An adaptive environment control system for controlling operation of an HVAC system to bring interior temperature of a building to a pre-set temperature, comprising:

means for storing a set of building characteristic data;

means for repeatedly determining the interior temperature and temperature outside of said building;

means connected to said storing means and to said temperature-determining means and responsive to said building characteristic data and said determined temperatures for repeatedly estimating values of thermal properties of said building;

means connected to said estimating means and responsive to said estimated thermal properties for controlling the operation of said HVAC system based on said estimated thermal properties to bring the interior temperature of said building to said pre-set temperature at a predetermined time;

means connected to said estimating means for repeatedly predicting future values of said thermal properties from said estimated values; and

means connected to said estimating means and said predicting means for generating an alarm indication if values predicted for a given time differ from values estimated for said given time by more than a predetermined amount.

14. The system of claim 13 further comprising:

means for measuring performance characteristics of said HVAC system; and

means connected to said measuring means and said storing means and responsive to said measured performance characteristics for updating said building characteristic data in said storing means.

15. The system of claims 13 or 14 wherein said controlling means includes:

means connected to said estimating means and said determining means and responsive to said estimated values of said thermal properties and said determined interior temperature for calculating a period of time required for said HVAC system to bring said building interior temperature to said pre-set temperature; and

means connected to said calculating means and responsive to the calculated time period for initiating the operation of said HVAC system at said required time period prior to said predetermined time to bring the interior temperature of said building to said pre-set temperature at said predetermined time.

16. The system of claim 15 wherein said controlling means further includes:

means for predicting the interior temperature of said building for a length of time equal to said time period required to bring said interior temperature to said pre-set temperature; and

means connected to said predicting means and responsive to said predicted temperature for activating said HVAC system when said predicted temperature deviates from said pre-set temperature by a predefined amount.

17. The system of claim 14 wherein said controlling means includes:

means connected to said measuring means and responsive to said measured performance characteristics for generating an alarm indication when said measured performance characteristics deviate from nominal performance characteristics by more than a predetermined amount.

18. The system of claim 14 wherein said generating means includes:

means connected to said measuring means and responsive to said estimated values of said thermal properties for generating an alarm indication when said estimated values of said thermal properties deviate from nominal values of said thermal properties by more than a predetermined amount.

19. The system of claim 13 wherein the generating means comprises:

means for generating an alarm indication if a sum of differences between predicted and estimated values for different given times exceeds a predetermined amount.

20. The system of claim 13 wherein:

said thermal properties represent time-rate-of-change of heat gain or loss of thermal mass of said building, rate of heat transfer of said building to a surrounding environment, and thermal input to said building provided by said HVAC system.

21. The system of claim 20 wherein the means for estimating the values of the thermal properties comprise:

means for estimating from said determined temperatures a ratio of (a) said thermal input to said building provided by said HVAC system and (b) said rate of heat transfer of said building to said surrounding environment multiplied by a difference of said determined interior and outside temperatures; and

means for estimating from said determined temperatures a ratio of (a) said rate of heat transfer of said building to said surrounding environment multiplied by said difference of said determined interior and outside temperatures and (b) said time-rate-of-change of heat gain or loss of said thermal mass of said building multiplied by a rate-of-change of said determined interior temperature.

22. A method of controlling operation of an HVAC system to regulate interior temperature of a building as a function of thermal properties of the building, comprising the steps of:

repeatedly determining the interior temperature and temperature outside of said building;

repeatedly estimating, from said determined temperatures, values of said thermal properties;

controlling the operation of said HVAC system using estimated thermal properties to bring the interior temperature of said building to said pre-set temperature at a predetermined time;

repeatedly predicting future values of said thermal properties from said estimated values; and

generating an alarm indication if values predicted for a given time differ from values estimated for said given time by more than a predetermined amount.

23. The method of claim 22 further including the steps of:

measuring performance characteristics of said HVAC system; and

revising said estimated values of said thermal properties on a basis of said measured performance characteristics.

24. The method of claims 22 or 23 wherein the step of controlling includes the steps of:

calculating a period of time required for said HVAC system to bring said building interior temperature to said pre-set temperature; and

effecting the operation of said HVAC system at said required time period prior to said predetermined time to bring the interior temperature of said building to said pre-set temperature at said predetermined time.

25. The method of claim 24 wherein said step of controlling further includes the steps of:

predicting the interior temperature of said building for a length of time equal to said time period required to bring said interior temperature to said pre-set temperature; and

activating said HVAC system if said predicted temperature deviates from said pre-set temperature by more than a predetermined amount.

26. The method of claim 23 wherein said step of generating includes the steps of:

generating an alarm indication when said measured performance characteristics deviate from nominal performance characteristics by more than a predetermined amount.

27. The method of claims 22 or 23 wherein the step of generating includes the step of:

generating an alarm indication when said estimated values of said thermal properties deviate from nominal values of said thermal properties by more than a predetermined amount.

28. The method of claim 22 wherein said step of estimating includes the steps of:

obtaining measurements of an environment of said building; and

estimating said values of said thermal properties of said building based on said obtained measurements.

29. The method of claim 28 wherein said step of estimating includes the step of:

estimating parameters indicative of ratios of said values of said thermal properties of said building.

30. The method of claim 28 further comprising the steps of:

comparing said estimated values of said thermal properties against predefined limits; and

resetting said estimated values of said thermal properties to nominal values of said thermal properties within said predefined limits when said estimated values of said thermal properties exceed said predefined limits.

31. The method of claim 23 wherein the step of generating comprises the step of:

generating an alarm indication if a sum of differences between predicted and estimated values for different given times exceeds a predetermined amount.

32. The method of claim 22 wherein the step of repeatedly estimating comprises the step of:

estimating values of said thermal properties representing time-rate-of-change of heat gain or loss of thermal mass of said building, rate of heat transfer of said building to a surrounding environment, and thermal input to said building provided by said HVAC system.

33. The method of claim 32 wherein the step of estimating comprises the steps of:

estimating from said determined temperatures a ratio of (a) said thermal input to said building provided by said HVAC system and (b) said rate of heat transfer of said building to said surrounding environment multiplied by a difference of said determined interior and outside temperatures; and

estimating from said determined temperatures a ratio of (a) said rate of heat transfer of said building to said surrounding environment multiplied by said difference of said determined interior and outside temperatures and (b) said time-rate-of-change of heat gain or loss of said thermal mass of said building multiplied by a rate-of-change of said determined interior temperature.

34. A method of controlling operation of an HVAC system to bring interior temperature of a building to a pre-set temperature, comprising the steps of:

storing a set of building characteristic data;

repeatedly determining the interior temperature and temperature outside of said building;

repeatedly estimating values of thermal performance properties of said building using said building characteristic data and said determined temperatures;

controlling the operation of said HVAC system using said thermal performance properties to bring the interior temperature of said building to said pre-set temperature at a predetermined time;

repeatedly predicting future values of said thermal properties from said estimated values; and

generating an alarm indication if values predicted for a given time differ from values estimated for said given time by more than a predetermined amount.

35. The method of claim 34 including the steps of:

measuring operational characteristics of said HVAC system;

calculating a new set of building characteristic data from said measured operational characteristics; and

updating said stored set of building characteristic data using said new set of building characteristic data.

36. The method of claims 34 or 35 wherein the step of controlling includes the steps of:

calculating a period of time required for said HVAC system to bring said building interior temperature to said pre-set temperature; and

initiating the operation of said HVAC system at said required time period prior to said determined time to bring the interior temperature of said building to said pre-set temperature at said predetermined time.

37. The method of claims 34 or 35 wherein the step of generating further includes the step of:

generating an alarm indication when said estimated values of said thermal properties deviate from nominal values of said thermal properties by more than a predetermined amount.

38. The method of claim 36 wherein the step of controlling includes the steps of:

predicting the interior temperature of said building for a length of time equal to said time period required to bring said interior temperature to said pre-set temperature; and

activating said HVAC system when said predicted temperature deviates from said pre-set temperature by more than a predetermined amount.

39. The method of claim 35 wherein the step of generating further includes the step of:

generating an alarm indication when said measured operational characteristics deviate from nominal operational characteristics by more than a predetermined amount.

40. The method of claim 34 wherein the step of generating comprises the step of:

generating an alarm indication if a sum of differences between predicted and estimated values for different given times exceeds a predetermined amount.

41. The method of claim 34 wherein the step of repeatedly estimating comprises the step of:

estimating values of thermal performance properties representing time-rate-of-change of heat gain or loss of thermal mass of said building, rate of heat transfer of said building to a surrounding environment, and thermal input to said building provided by said HVAC system.

42. The method of claim 41 wherein the step of estimating comprises the steps of:

estimating from said determined temperatures a ratio of (a) said thermal input to said building provided by said HVAC system and (b) said rate of heat transfer of said building to said surrounding environment multiplied by a difference of said determined interior and outside temperatures; and

estimating from said determined temperatures a ratio of (a) said rate of heat transfer of said building to said surrounding environment multiplied by said difference of said determined interior and outside temperatures and (b) said time-rate-of-change of heat gain or loss of said thermal mass of said building multiplied by a rate-of-change of said determined interior temperature.

43. A method of controlling operation of a building HVAC system comprising the iteratively-performed steps of:

storing a set of building characteristic data;

determining temperature inside of said building;

determining temperature outside of said building;

estimating values of thermal performance properties of said building using said building characteristic data and said determined inside and outside temperatures;

controlling the operation of said HVAC system using said thermal performance properties to bring the interior temperature of said building to a pre-set temperature at a predetermined time;

measuring operational characteristics of said HVAC system;

calculating a new set of building characteristic data from said measured operational characteristics for storage in place of the previously-stored set of building characteristic data;

predicting future values of said thermal performance properties from said estimated values; and

generating an alarm indication if values predicted for a given time differ from values estimated for said given time by more than a predetermined amount.

44. The method of claim 43 wherein the step of generating comprises the step of:

generating an alarm indication if a sum of differences between predicted and estimated values for different given times exceeds a predetermined amount.

45. The method of claim 43 wherein the step of estimating comprises the step of:

estimating values of thermal performance properties representing time-rate-of-change of heat gain or loss of thermal mass of said building, rate of heat transfer of said building to a surrounding environment, and thermal input to said building provided by said HVAC system.

46. The method of claim 45 wherein the step of estimating comprises the steps of:

estimating from said determined temperatures a ratio of (a) said thermal input to said building provided by said HVAC system and (b) said rate of heat transfer of said building to said surrounding environment multiplied by a difference of said determined interior and outside temperatures; and

estimating from said determined temperatures a ratio of (a) said rate of heat transfer of said building to said surrounding environment multiplied by said difference of said determined interior and outside temperatures and (b) said time-rate-of-change of heat gain or loss of said thermal mass of said building multiplied by a rate-of-change of said determined interior temperature.