Energy usage estimation for climate control system

• US 20050194455A1
• Filed: 01/04/2005
• Published: 09/08/2005
• Est. Priority Date: 03/21/2003
• Status: Active Grant

• Current Assignee: Emme E2MS, LLC
• Original Assignee: Home Comfort Zones Incorporated
• Inventors: Alles, Harold Gene
• Granted Patent: US 7,392,661 B2
• Time in Patent Office: Days
• US Class Current: 236/1.00B
• CPC Class Codes: F24F 13/10 movable, e.g. dampers
• CPC Class Codes: F24F 2013/087 using inflatable bellows
• CPC Class Codes: F24F 3/0442 with volume control at a constant temperature

Abstract

An HVAC system controller which estimates the energy cost or savings incurred due to a user-instigated change in a climate control schedule. The HVAC system controller is adapted to operate a multi-zone climate control system in a building, and is especially adapted to operate a retrofit zone climate control system in a residence. The HVAC controller displays the estimated cost or savings to the homeowner, enabling him to make an informed decision about whether to keep the change in the climate control schedule.

Claims

1. A method whereby an HVAC controller estimates a change in energy usage by an HVAC system controlled by the HVAC controller, the method comprising:

maintaining a baseline energy usage for a current HVAC system setting;

changing the HVAC system setting in response to input from a user of the HVAC controller;

estimating a new energy usage for the changed HVAC system setting; and

displaying the estimated energy usage to the user.

2. The method of claim 1 further comprising:

using the estimated energy usage as the maintained baseline energy usage for use in subsequent estimations.

3. The method of claim 1 further comprising:

maintaining a schedule of HVAC system settings;

wherein the changing of the HVAC system setting comprises changing the maintained schedule.

4. The method of claim 1 wherein:

the method further includes,

maintaining tables of degree-hours beyond which a local climate will exceed each of a plurality of temperatures;

the HVAC system setting comprises a condition-to temperature; and

the estimating of the new energy usage includes,

looking up the condition-to temperature in the tables of degree-hours to determine a number of degree-hours of conditioning which the HVAC system will operate to maintain the condition-to temperature,

calculating a cost of operating the HVAC system that many degree-hours, and

determining a difference between the calculated cost and a previously stored cost.

5. The method of claim 4 wherein the tables of degree-hours comprise:

an annual high temperature degree-hours above for cooling table;

an annual low temperature degree-hours above for cooling table;

an annual high temperature degree-hours below for heating table; and

an annual low temperature degree-hours below for heating table.

6. The method of claim 5 further comprising:

maintaining a cooling season daily local climate pattern table;

maintaining a heating season daily local climate pattern table; and

using the pattern tables, interpolating hours of the day which are not directly represented in the tables of degree-hours.

7. An HVAC controller for operating at least one of a furnace, an air conditioner, and a heat pump of a building located in a local climate, the HVAC controller comprising:

means for maintaining a schedule;

means whereby a user can make a change to the schedule;

means for operating the at least one of the furnace, air conditioner, and heat pump, in response to the schedule;

means, responsive to the change being made to the schedule, for estimating an energy cost/savings associated with the change; and

means for displaying the estimated energy cost/savings to the user.

8. The HVAC controller of claim 7 wherein the means for estimating comprises:

means for maintaining a thermal model of the building; and

means for maintaining a model of the local climate.

9. The HVAC controller of claim 8 wherein the model of the local climate comprises:

a table, indexable by temperature over a temperature range, storing data each indicating an annual total of degree-seconds that the local climate will be above each temperature in the range.

10. The HVAC controller of claim 8 wherein the change comprises:

an alteration to an individual setting in the schedule.

11. The HVAC controller of claim 10 wherein the alteration comprises one of:

a change to a temperature setting and a change to a time setting.

12. The HVAC controller of claim 8 wherein the change comprises one of:

a switch between a normal mode and a setback mode of thermostat operation;

a comparison of the schedule to a fixed previous setting.

13. The HVAC controller of claim 8 wherein the schedule comprises one of:

a single daily schedule;

a schedule having different settings for at least two days during a week.

14. The HVAC controller of claim 8 wherein the means for estimating further comprises:

means for applying a first climate model for estimating cooling costs and a second climate model for estimating heating costs.

15. The HVAC controller of claim 8 further comprising:

means for selecting the model of the local climate from a plurality of predefined climate models.

16. The HVAC controller of claim 15 wherein:

each of the plurality of predefined climate models includes,

a first table indicating, for each of a plurality of months, probabilities that an average daily high temperature during that month will exceed each of a plurality of temperatures in a first range;

a second table indicating, for each of a plurality of months, probabilities that an average daily low temperature during that month will exceed each of a plurality of temperatures in a second range; and

a third table indicating, for each of a plurality of months, an average daily high temperature and an average daily low temperature.

17. The HVAC controller of claim 8 further comprising:

means for improving over time an accuracy of the means for estimating, in response to data gathered from operation of the HVAC controller.

18. A method whereby an HVAC controller estimates energy usage of a building'"'"'s HVAC system under its control, the method comprising:

maintaining a schedule of target temperature ranges;

operating the HVAC system to keep the building'"'"'s temperature within a current one of the target temperature ranges;

making a change to the schedule in response to user input;

estimating an energy cost/savings caused by the change; and

displaying the estimated energy cost/savings to the user.

19. The method of claim 18 further comprising:

maintaining a thermal model of the building; and

wherein estimating the energy cost/savings includes utilizing the thermal model.

20. The method of claim 18 further comprising:

maintaining a local climate model; and

wherein estimating the energy cost/savings includes utilizing the local climate model.

21. The method of claim 20 further comprising:

maintaining a thermal model of the building; and

wherein estimating the energy cost/savings further includes utilizing the thermal model.

22. The method of claim 21 wherein estimating the energy cost/savings further includes:

accounting for local climatic differences between heating season and cooling season.

23. The method of claim 21 wherein maintaining the local climate model includes:

maintaining a plurality of tables of degree-hours, each indexable by temperature to determine a value of degree-hours that the local climate is likely to be above the indexing temperature.

24. A method of estimating an energy usage cost/savings resulting from a change in a original schedule in an HVAC controller, the HVAC controller operating an HVAC system in a building having a plurality of rooms, the method comprising:

for each day in the schedule,

for each hour of that day in the schedule,

for each of the rooms,

accumulating energy usage by that room at that hour on that day;

comparing the accumulated energy usage to an energy usage that would have resulted from the original schedule to identify the energy usage cost/savings; and

displaying the energy usage cost/savings for a user of the HVAC controller.

25. The method of claim 24 further comprising:

maintaining a first table (Table

     18) of data identifying, for each temperature in a high temperature range, a number of degree-hours that daily high temperatures are likely to be above that temperature;

maintaining a second table (Table

     19) of data identifying, for each temperature in the high temperature range, a number of degree-hours that daily low temperatures are likely to be above that temperature;

maintaining a third table (Table

     20) of data identifying, for each temperature in a low temperature range, a number of degree-hours that daily high temperatures are likely to be above that temperature;

maintaining a fourth table (Table

     21) of data identifying, for each temperature in the low temperature range, a number of degree-hours that daily low temperatures are likely to be above that temperature;

using the first and second tables in estimating cooling costs; and

using the third and fourth tables in estimating heating costs.

26. The method of claim 25 further comprising:

maintaining a fifth table (Table

     6) of data identifying a cooling season daily outside temperature pattern;

maintaining a sixth table (Table

     7) of data identifying a heating season daily outside temperature pattern;

further using the fifth table in estimating cooling costs; and

further using the sixth table in estimating heating costs.