Method and apparatus for improving building energy simulations

• US 6,134,511 A
• Filed: 04/15/1998
• Issued: 10/17/2000
• Est. Priority Date: 04/15/1998
• Status: Expired due to Fees

• Current Assignee: Krishnappa Subbarao
• Original Assignee: Krishnappa Subbarao
• Inventors: Subbarao, Krishnappa
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): Knox, Lonnie A.
• Application Number:
  US09/060,734
• Time in Patent Office: 916 Days
• Field of Search: 703/1, 703/5, 703/6, 703/7, 395/500.01, 395/500.24, 395/500.27, 395/500.28
• US Class Current: 703/6
• CPC Class Codes: G06F 2111/04 Constraint-based CAD
• CPC Class Codes: G06F 2111/10 Numerical modelling
• CPC Class Codes: G06F 2113/14 Pipes
• CPC Class Codes: G06F 30/13 Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
• CPC Class Codes: G06F 30/20 Design optimisation, verification or simulation optimisation, verification or simulation of circuit designs G06F30/30

Abstract

Calibration of building energy simulations with performance data is accomplished by introducing corrective heat flows. A building is modeled on a simulator with descriptive inputs derived from a building audit. The performance predicted by the simulator under the measured driving functions is compared with the measured performance (e.g., of indoor temperatures and/or energy use). Corrective heat flows are calculated from calibration parameters and primary heat flows. The corrective heat flows are then incorporated as additional internal gains and applied to the simulator to minimize the differences between predicted and measured performances. Performance of Heating, Ventilation, and Air-Conditioning systems is included by introducing and estimating additional parameters. The calibrated simulator can be used, for example, to simulate future performance under given weather conditions and thermostatic constraints by repeating the simulation in an iterative manner, with improved values of the corrective heat flows being computed at each iteration. Additionally, the calibration parameters can also be used as a guide to modify the audit inputs to the simulation to thereby reduce the magnitude of the corrective heat flows. The calibrated simulations can be used for the commissioning, diagnosing, optimal controlling, evaluation, and identification of retrofit opportunities of buildings.

Claims

1. A computer-aided method for calibrating a building simulator with corrective flows, comprising the steps of:

providing audit inputs to said simulator, said audit inputs derived from a building system to be simulated;

providing at least one driving function input to said simulator, said at least one driving function input impacting said system;

providing at least one corrective flow input to said simulator, said at least one corrective flow input improving an accuracy of said simulator; and

performing a building simulation on said simulator using said audit inputs, said at least one driving function input, and said at least one corrective flow input, said simulation producing at least one output.

2. The method according to claim 1, wherein said step of providing at least one driving function input to said simulator further comprises the step of providing a plurality of driving function inputs to said building simulator, said plurality of driving function inputs comprising at least one of weather elements to which said building is exposed, solar radiation to which said building is exposed, and occupancy-related characteristics of said building.

3. The method according to claim 1, wherein said at least one output of said simulation comprises simulated fuel use of said building to be simulated.

4. The method according to claim 1, wherein said at least one output of said simulation comprises at least one simulated inside temperature of said building to be simulated.

5. The method according to claim 4, further comprising the steps of:

prior to said step of providing at least one corrective flow input to said simulator, performing a preliminary simulation of said building simulator to produce at least one preliminary simulated inside temperature; and

calculating at least one primary heat flow from said at least one preliminary simulated inside temperature.

6. The method according to claim 5, wherein said step of performing a simulation on said simulator comprises the step of performing a first simulation iteration on said building simulator, said first simulation iteration producing at least one first iteration simulated inside temperature.

7. The method according to claim 6, further comprising the steps of:

determining whether said first simulation iteration has reached a predetermined level of convergence based on, at least in part, said at least one first iteration simulated inside temperature; and

if not, recalculating said at least one primary heat flow from said at least one first iteration simulated inside temperature and performing a second simulation iteration on said building simulator using the recalculated at least one primary heat flow, said second simulation iteration producing at least one second iteration simulated inside temperature.

8. The method according to claim 1, further including the step of:

determining said at least one corrective flow input by, at least in part, a heat flow and an associated shell calibration parameter.

9. The method according to claim 8, wherein said heat flow comprises a primary heat flow of said system to be simulated, said primary heat flow comprising at least one of a static-loss-from-a-shell-of-said-system heat flow, a discharge/charge-of-masses-due-to-inside-temperature-variations heat flow, and a solar-gains-by-an-air-node-of-said-system heat flow.

10. The method according to claim 8, further including the step of:

determining said associated shell calibration parameter after simulating said system under predetermined conditions.

11. The method according to claim 10, wherein said step of determining said associated shell calibration parameter further includes the step of determining a plurality of associated shell calibration parameters;

and

wherein said step of determining a plurality of associated shell calibration parameters includes the step of performing a best fit to energy use analysis of a sum of addends, said sum of addends including a plurality of products of each individual associated shell calibration parameter of said plurality of associated shell calibration parameters and the heat flow that is associated with said each individual associated shell calibration parameter.

12. The method according to claim 11, wherein said step of performing a best fit to energy use analysis comprises the step of performing a best fit to zero.

13. The method according to claim 10, wherein said step of determining said associated shell calibration parameter after simulating said system under predetermined conditions comprises the step of:

determining said associated shell calibration parameter through a data windowing process in which at least one data window includes a Heating/Ventilating/Air Conditioning non-operating segment.

14. The method according to claim 1, wherein said step of providing audit inputs to said simulator further comprises the step of:

providing at least one modified Heating/Ventilating/Air Conditioning parameter input.

15. The method according to claim 14, further comprising the step of:

determining said at least one modified Heating/Ventilating/Air Conditioning parameter input in a data window that includes a Heating/Ventilating/Air Conditioning operating segment.

16. An article of manufacture for improving a building simulation, comprising:

a computer-accessible storage medium;

computer programming stored on said storage medium;

wherein said computer programming is configured to be accessible from said computer-accessible storage medium by a processor and thereby cause said processor to operate so as to;

receive as input an audit shell description of a building to be simulated;

receive as input at least one measured driving function of said building to be simulated;

calculate at least one heat flow of said building based, at least in part, on said audit shell description and said at least one measured driving function;

calculate at least one corrective flow based, at least in part, on said at least one heat flow, wherein said at least one corrective flow can thereby improve an accuracy of said building simulation; and

provide said at least one corrective flow as an input to a building simulator as at least one different value of a driving function.

17. The article of manufacture of claim 16, wherein

said at least one different value of a driving function comprises at least one of a new driving function input and a modified driving function input.

18. The article of manufacture of claim 16, wherein the computer programming is further configured to cause said processor to:

determine at least one primary heat flow based on an analysis of which heat flows of said building to be simulated dominate an energy balance of said building to be simulated; and

calculate said at least one corrective flow based, at least in part, on said at least one heat flow, said at least one heat flow comprising said at least one primary heat flow.

19. The article of manufacture of claim 16, wherein the computer programming is further configured to cause said processor to:

determine at least one shell calibration parameter based on at least one output of said building simulator; and

calculate said at least one corrective flow based, at least in part, on said at least one shell calibration parameter.

20. The article of manufacture of claim 16, wherein the computer programming is further configured to cause said processor to:

receive as input an audit Heating/Ventilating/Air Conditioning description of said building to be simulated;

produce at least one Heating/Ventilating/Air Conditioning calibration parameter based, at least in part, on at least one output of said building simulator;

produce at least one modified Heating/Ventilating/Air Conditioning variable based, at least in part, on said audit Heating/Ventilating/Air Conditioning description and on said at least one Heating/Ventilating/Air Conditioning calibration parameter; and

provide said at least one modified Heating/Ventilating/Air Conditioning variable to said building simulator.

21. The article of manufacture of claim 16, wherein the computer programming is further configured to cause said processor to:

receive simulated energy use as output from said building simulator;

execute a best fit analysis of measured energy use to said simulated energy use to estimate at least one parameter.

22. The article of manufacture of claim 21, wherein the computer programming is further configured to cause said processor to:

execute said best fit analysis such that Heating/Ventilating/Air Conditioning calibration parameters are estimated in a data window in which a Heating/Ventilating/Air Conditioning system of said building is operational.

23. The article of manufacture of claim 21, wherein the computer programming is further configured to cause said processor to:

execute said best fit analysis such that shell calibration parameters are estimated in a data window in which a Heating/Ventilating/Air Conditioning system of said building is non-operational so that said measured energy use is approximately zero.

24. The article of manufacture of claim 21, wherein the computer programming is further configured to cause said processor to:

execute said best fit analysis such that shell calibration parameters and Heating/Ventilating/Air Conditioning calibration parameters are estimated substantially simultaneously.

25. The article of manufacture of claim 16, wherein the computer programming is further configured to cause said processor to:

calculate said at least one corrective flow by determining a product of said at least one heat flow and an associated shell calibration parameter.

26. The article of manufacture of claim 16, wherein the computer programming is further configured to cause said processor to:

provide at least one modified Heating/Ventilating/Air Conditioning variable as an input to said building simulator.

27. The article of manufacture of claim 26, wherein the computer programming is further configured to cause said processor to:

receive simulated energy use as output from said building simulator for extrapolating performance of said building to be simulated.

28. The article of manufacture of claim 26, wherein the computer programming is further configured to cause said processor to:

receive at least one simulated temperature as output from said building simulator;

recalculate said at least one corrective flow based, at least in part, on said at least one simulated temperature;

provide the at least one recalculated corrective flow as an input to said building simulator; and

repeat the reception of said at least one simulated temperature, the recalculation of said at least one corrective flow, and the provision of said at least one recalculated corrective flow until a predetermined convergence is substantially attained.

29. An article of manufacture for improving a building simulation, comprising:

a computer-accessible storage medium;

computer programming stored on said storage medium;

wherein said computer programming is configured to be accessible from said computer-accessible storage medium by a processor and thereby cause said processor to operate so as to;

receive as input an audit shell description of a building to be simulated;

receive as input at least one measured driving function of said building to be simulated;

calculate at least one heat flow of said building based, at least in part, on said audit shell description and said at least one measured driving function;

calculate at least one shell calibration parameter, said at least one shell calibration parameter associated with said at least one heat flow of said building;

execute a building simulator to produce at least one simulated result based, at least in part, on at least one input to said building simulator, said at least one input responsive to said at least one heat flow and the at least one associated shell calibration parameter; and

after producing said at least one simulated result and responsive at least partly thereto, calculate at least one Heating/Ventilating/Air Conditioning calibration parameter.

30. A computer-aided method for calibrating a building simulator with corrective flows, comprising the steps of:

inputting, into the building simulator, data representative of attributes of a building to be simulated;

inputting, into the building simulator, data representative of measured driving forces that are capable of impacting the building to be simulated;

performing a simulation of the building to be simulated using the building simulator with the data representative of attributes of the building to be simulated and the data representative of measured driving forces that are capable of impacting the building to be simulated to produce at least one output;

performing an analysis to estimate at least one calibration parameter based, at least in part, on the at least one output; and

introducing a variable to the building simulator as a driving force, the variable being responsive to the at least one calibration parameter.

31. The method according to claim 30, further comprising the step of re-performing the simulation of the building to be simulated using the building simulator with the data representative of attributes of the building to be simulated and the data representative of measured driving forces that are capable of impacting the building to be simulated along with the variable to produce at least one different output.

32. The method according to claim 30, wherein the data representative of attributes of the building to be simulated comprises building audit values.

33. The method according to claim 32, wherein the building audit values comprise at least one of building shell audit values and Heating/Ventilating/Air Conditioning system audit values.

34. The method according to claim 30, wherein the data representative of measured driving forces that are capable of impacting the building to be simulated comprise at least one of weather data, solar radiation data, and occupancy-related characteristics data.

35. The method according to claim 30, wherein the at least one output comprises at least one of simulated energy use and simulated temperatures.

36. The method according to claim 30, wherein the building simulator comprises a DOE-2 based simulator.

37. The method according to claim 30, wherein said step of performing an analysis to estimate at least one calibration parameter based, at least in part, on the at least one output comprises the step of performing a best fit analysis of a sum of products to an expected value.

38. The method according to claim 37, wherein the expected value comprises at least one of measured energy use and measured temperatures.

39. The method according to claim 30, wherein the variable comprises a product, the product having the at least one calibration parameter and a heat flow as multiplicands thereof.

40. The method according to claim 39, wherein the heat flow comprises a primary heat flow, the primary heat flow dominating an energy balance equation of the building to be simulated.

41. The method according to claim 30, wherein the at least one calibration parameter comprises at least one shell calibration parameter.

42. The method according to claim 30, wherein said step of introducing a variable to the building simulator as a driving force comprises at least one of the steps of adding a new driving function as a driving force input and modifying a driving force that was previously input in said step of inputting data representative of measured driving forces.

43. The method according to claim 30, wherein the variable comprises a corrective heat flow.

44. The method according to claim 43, wherein the corrective heat flow comprises at least one of a corrective static-loss-from-the-building-shell heat flow, a corrective discharge/charge-of-masses-due-to-inside-temperature-variations heat flow, and a corrective solar-gains-by-an-air-node-of-the-building heat flow.

45. The method according to claim 30, further comprising the step of:

performing a different analysis to determine at least one heat flow based, at least in part, on the at least one output;

wherein the variable comprises the at least one calibration parameter and the at least one heat flow; and

still further comprising the steps of;

re-performing the simulation of the building to be simulated using the building simulator with the data representative of attributes of the building to be simulated and the data representative of measured driving forces that are capable of impacting the building to be simulated along with the variable to produce at least one intermediate output;

re-performing the different analysis to re-determine the at least one heat flow based, at least in part, on the at least one intermediate output; and

iteratively repeating said steps of re-performing the simulation and re-performing the different analysis until a selected convergence is substantially attained to produce at least one calibrated output.

46. A data processing apparatus for calibrating a building simulator with corrective flows, comprising:

means for inputting, into the building simulator, data representative of attributes of a building to be simulated;

means for inputting, into the building simulator, data representative of measured driving forces that are capable of impacting the building to be simulated;

means for performing a simulation of the building to be simulated using the building simulator with the data representative of attributes of the building to be simulated and the data representative of measured driving forces that are capable of impacting the building to be simulated, said means for performing a simulation producing at least one output;

means for performing an analysis to estimate at least one calibration parameter based, at least in part, on the at least one output; and

means for introducing a variable to the building simulator as a driving force, the variable being responsive to the at least one calibration parameter.

47. A computer-aided method for calibrating a building simulator with corrective flows, comprising the steps of:

performing a simulation of a building to produce at least one first output;

estimating at least one calibration parameter and determining at least one first heat flow based, at least in part, on the at least one first output;

re-performing the simulation of the building using a product comprised of the at least one calibration parameter and the at least one first heat flow to produce at least one second output;

determining at least one second heat flow based, at least in part, on the at least one second output; and

re-performing the simulation of the building using another product comprised of the at least one calibration parameter and the at least one second heat flow to produce at least one third output.

48. The method according to claim 47, further comprising the steps of:

repeatedly determining at least one another heat flow based on at least one previous output of the simulation of the building; and

repeatedly re-performing the simulation of the building using a product comprised of the at least one calibration parameter and the at least one another heat flow until at least one subsequent output indicates that a selected convergence level has been substantially attained.

49. The method according to claim 47, wherein (i) the product and the another product comprise a corrective heat flow and another corrective heat flow, respectively, (ii) the at least one calibration parameter comprises a shell calibration parameter, and (iii) the at least one first, second, and third outputs each comprise at least one of at least one simulated temperature and at least one simulated energy use.

50. A computer-aided method for calibrating a building simulator with corrective flows, comprising the steps of:

inputting, into the building simulator, data representative of attributes of a building to be simulated;

inputting, into the building simulator, data representative of measured driving forces that are capable of impacting the building to be simulated;

performing a simulation of the building to be simulated using the building simulator with the data representative of attributes of the building to be simulated and the data representative of measured driving forces that are capable of impacting the building to be simulated to produce at least one output;

performing an analysis to estimate at least one calibration parameter based, at least in part, on the at least one output;

performing a different analysis to determine at least one heat flow based, at least in part, on the at least one output;

introducing a variable to the building simulator as a driving force, the variable being responsive to the at least one calibration parameter and the at least one heat flow;

re-performing the simulation of the building to be simulated using the building simulator with the data representative of attributes of the building to be simulated and the data representative of measured driving forces that are capable of impacting the building to be simulated along with the variable to produce at least one intermediate output;

re-performing the different analysis to re-determine the at least one heat flow based, at least in part, on the at least one intermediate output; and

iteratively repeating said steps of re-performing the simulation and re-performing the different analysis until a selected convergence is attained to produce at least one calibrated output.

51. An article of manufacture for improving a building simulation, comprising:

a computer-accessible storage medium;

computer programming stored on said storage medium;

wherein said computer programming is configured to be accessible from said computer-accessible storage medium by a processor and thereby cause said processor to operate so as to;

receive as input audit values of a building to be simulated, said audit values comprising at least shell audit values and Heating/Ventilating/Air Conditioning system audit values;

receive as input driving functions, said driving functions impacting the building to be simulated;

perform said building simulation using said audit values and said driving functions to produce a plurality of outputs;

determine a plurality of primary heat flows based, at least in part, on said plurality of outputs;

estimate a plurality of shell calibration parameters based, at least in part, on said plurality of outputs and said plurality of primary heat flows by a executing a best fit analysis;

calculate a plurality of corrective heat flows responsive to said plurality of primary heat flows and said plurality of shell calibration parameters;

introduce said plurality of corrective heat flows into at least one input of said building simulation; and

re-perform said building simulation using said audit values and said driving functions, along with said plurality of corrective heat flows, to produce a different plurality of outputs.

52. A computer-aided method for calibrating a building simulator with shell calibration parameters, comprising the steps of:

inputting, into the building simulator, data representative of attributes of a building to be simulated;

inputting, into the building simulator, data representative of measured driving forces that are capable of impacting the building to be simulated;

performing a simulation of the building to be simulated using the building simulator with the data representative of attributes of the building to be simulated and the data representative of measured driving forces that are capable of impacting the building to be simulated to produce at least one first output;

performing a first best fit analysis to estimate at least one first shell calibration parameter based, at least in part, on the at least one first output and an expected value thereof;

modifying at least a portion of the data representative of attributes of the building to be simulated responsive to the at least one first shell calibration parameter to produce once-modified data representative of attributes of the building to be simulated; and

re-performing the simulation of the building to be simulated using the building simulator with the once-modified data representative of attributes of the building to be simulated and the data representative of measured driving forces that are capable of impacting the building to be simulated to produce at least one second output.

53. The method according to claim 52, further comprising the steps of:

performing a second best fit analysis to estimate at least one second shell calibration parameter based, at least in part, on the at least one second output and the expected value thereof;

modifying at least a portion of the once-modified data representative of attributes of the building to be simulated responsive to the at least one second shell calibration parameter to produce twice-modified data representative of attributes of the building to be simulated; and

re-performing the simulation of the building to be simulated using the building simulator with the twice-modified data representative of attributes of the building to be simulated and the data representative of measured driving forces that are capable of impacting the building to be simulated to produce at least one third output.

54. The method according to claim 53, further comprising the step of:

repeating the steps of performing best fit analyses, modifying the data representative of attributes of the building to be simulated responsive thereto, and re-performing the simulation until at least one produced output of the simulation meets at least one selected closeness criterion when compared to the expected value thereof.

55. The method according to claim 52, wherein the first, second, third, and produced outputs, as well as the expected value thereof, comprise at least one of energy use and inside temperature of the building to be simulated.

56. The method according to claim 52, wherein said step of performing a first best fit analysis to estimate at least one first shell calibration parameter based, at least in part, on the at least one first output and an expected value thereof comprises the step of performing the first best fit analysis to estimate the at least one first shell calibration parameter using, at least partly, a primary heat flow of the building to be simulated that is associated with the at least one first shell calibration parameter.