Energy management improvement for a heating system with reduced setpoint temperature during no occupancy based upon historical sampling of room thermal response with highest power heat applied

• US 20100243231A1
• Filed: 03/26/2009
• Published: 09/30/2010
• Est. Priority Date: 03/26/2009
• Status: Active Grant

• Current Assignee: Copeland Canada Incorporated
• Original Assignee: Howard Rosen
• Inventors: Rosen, Howard
• Granted Patent: US 8,141,791 B2
• Time in Patent Office: Days
• US Class Current: 165/237
• 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 11/47 Responding to energy costs
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2120/00 Control inputs relating to users or occupants
• CPC Class Codes: F24F 2120/10 Occupancy
• CPC Class Codes: G05D 23/1904 variable in time

Abstract

A thermostat apparatus for controlling a heat pump with supplemental resistive heating as typically contained in a Packaged Terminal Air Conditioning (PTAC) unit is disclosed which provides improvements in energy management by reducing energy usage as much as possible within user guidelines when the conditioned space served by the PTAC is not occupied. A reduced setpoint temperature determination is based upon measurements of thermal response within the conditioned space to application of supplemental or resistive heat, and utilizes supplemental or resistive heat in achieving a quick recovery when people enter the conditioned space, thus enabling a more reduced setpoint temperature when the space is not occupied.

Claims

1. ) A thermostat apparatus for determining a present setpoint temperature, the thermostat apparatus for controlling a heating apparatus for heating a conditioned space, the heating apparatus including means for producing heat which includes a first heating apparatus and a second higher output heating apparatus, the second higher output heating apparatus optionally including the first heating apparatus, the second higher output heating apparatus being capable of producing more heat than the first heating apparatus alone;

the thermostat apparatus providing a first signal for normal heat intended for turning on the first heating apparatus and a second signal for high heat for turning on the second higher output heating apparatus, the thermostat apparatus also including an occupancy sensor for determining when the conditioned space is occupied and when the conditioned space is not occupied;

the thermostat apparatus including means for determining a user desired occupied setpoint temperature for use during periods the conditioned space is occupied;

the thermostat apparatus further comprising;

A) means for obtaining a value for a maximum allowed temperature recovery time, specified by the user as a parameter describing the maximum desirable period of time allowable for returning the conditioned space to a temperature approximating the user desired occupied setpoint temperature following any period of time during which the present setpoint temperature was reduced due to determining that the conditioned space was not occupied;

B) a first control means for turning on the second signal for high heat and during at least a portion of the time while high heat is applied measuring a high heat conditioned space temperature response rate;

C) means for calculating an unoccupied setpoint temperature based upon;

1) the high heat conditioned space temperature response rate; and

,

2) the maximum allowed temperature recovery time;

and,

D) means for setting the present setpoint temperature to the unoccupied setpoint temperature when the conditioned space is not occupied.

2. ) The thermostat apparatus of claim 1 further comprising:

E) means for quick recovery by utilizing the second higher output heating apparatus when it is determined that the conditioned space is occupied following a period during which the conditioned space was not occupied, the means for quick recovery intended to provide for returning the conditioned space to the user desired occupied setpoint temperature within the maximum allowed temperature recovery time.

3. ) The thermostat apparatus of claim 1) further comprising:

E) a second control means for turning on the first signal for normal heat and during at least a portion of the time while normal heat is applied measuring a normal heat conditioned space temperature response rate; and

,

F) means for quick recovery by utilizing the second higher output heating apparatus when it is determined that the conditioned space is occupied following a period during which the conditioned space was not occupied, and the measured normal heat conditioned space temperature response rate provides indication that without use of the second higher output heating apparatus that recovery of temperature cannot be achieved in less than the maximum allowed temperature recovery time; and

,

G) means for normal recovery by using the first signal for normal heat when it is determined that the conditioned space is occupied following a period during which the conditioned space was not occupied, and the measured normal heat conditioned space temperature response rate provides indication that applying heat from only the first heating apparatus will provide for recovery of temperature in less time than the maximum allowed temperature recovery time.

4. ) The thermostat apparatus of claim 1 wherein:

the measuring of the high heat conditioned space temperature response rate is repeated a number of times during any period of time while the conditioned space is not occupied.

5. ) An energy efficient method of operating a thermostat apparatus, the thermostat apparatus for maintaining a present setpoint temperature in a conditioned space by controlling a heating apparatus, the heating apparatus including means for producing heat which includes a first heating apparatus and a second higher output heating apparatus, the second higher output heating apparatus optionally including the first heating apparatus, the second higher output heating apparatus being capable of producing more heat than the first heating apparatus alone;

the thermostat apparatus providing a first signal for normal heat intended for turning on the first heating apparatus and a second signal for high heat for turning on the second higher output heating apparatus, the thermostat apparatus also including an occupancy sensor for determining when the conditioned space is not occupied;

the method comprising the following steps;

A) obtaining a user specified maximum allowed temperature recovery time, this being a user specified parameter describing the maximum desirable period of time allowable for returning the conditioned space to a temperature near the user desired occupied setpoint temperature, following any period of time during which the present setpoint temperature was reduced due to determination that the conditioned space was not occupied;

B) signaling the heating apparatus to use the second higher output heating apparatus;

C) measuring a high heat conditioned space temperature response rate, during a period that the second heating apparatus is signaled for use, by measuring a rate of temperature change in the conditioned space in response to the application of heat by the second higher output heating apparatus;

D) calculating an unoccupied reduced setpoint temperature intended for use when the conditioned space is found to be not occupied, based upon

     1) the high heat conditioned space temperature response rate; and

     2) the user specified desired maximum allowed temperature recovery time;

E) when the conditioned space is not occupied, setting the present setpoint temperature to the unoccupied reduced setpoint temperature.

6. ) The method of claim 5 wherein steps B, C and D are occasionally repeated during any period of time during which the conditioned space is not occupied for purpose of providing an updated measure of the high heat conditioned space temperature response rate, and calculating again the unoccupied reduced setpoint temperature.

7. ) A thermostat apparatus for controlling a heating apparatus for heating a conditioned space, the heating apparatus including a heat pump apparatus and a resistive heating apparatus, the heat pump apparatus typically providing more efficient heating of the conditioned space with regards to energy usage than the resistive heating apparatus, the thermostat apparatus including:

a) a user input mechanism providing means for establishing a user'"'"'s normally desired setpoint temperature which may be programmed by the user to be dependent upon time, b) means for receiving input from a temperature sensor located for providing an indication of a temperature in the conditioned space, and, c) means for receiving input from an occupancy sensing apparatus located for providing an indication that the conditioned space is occupied and in the alternative that the conditioned space is unoccupied, the thermostat apparatus further including an output control signal means including a heat pump control for signaling the heat pump to provide heat to the conditioned space and a resistive heat control for signaling the resistive heating apparatus to provide heat to the conditioned space, the thermostat apparatus in normal operation maintaining the temperature in the conditioned space to be near the user'"'"'s normally desired setpoint temperature when the conditioned space is occupied, and in the alternative when the conditioned space is unoccupied maintaining the temperature in the conditioned space to be near a controlled reduced setpoint temperature;

the thermostat apparatus further comprising;

A) a coupling to a user input apparatus providing for user input establishing a maximum allowable temperature recovery time value corresponding to a user desired maximum time for temperature recovery in the conditioned space when the thermostat apparatus occupancy sensing apparatus detects a change in occupancy in the conditioned space from unoccupied to occupied;

B) a reduced temperature setpoint adjustment apparatus which;

1) measures a resistive temperature slew rate value during a slew rate measuring time interval which is at least a portion of a time when the resistive heating apparatus is providing resistive heating to the conditioned space, the resistive temperature slew rate value corresponding to a measured rate of temperature increase in the conditioned space observed during the slew rate measuring time interval; and

,

2) utilizes the resistive temperature slew rate value and the maximum allowable temperature recovery time value to establish the reduced setpoint temperature at a level lower than the user'"'"'s normally desired setpoint temperature, for conserving energy, such that at any time if resistive heating were to be signaled by the thermostat apparatus to be applied by the resistive heating apparatus, the temperature in the conditioned space would be likely to return to the user'"'"'s normally desired setpoint temperature within the maximum allowable temperature recovery time, thus enabling the controlled reduced setpoint temperature to be set lower than a value which could be used if only the heat pump apparatus were to be utilized in achieving temperature recovery; and

,

C) a recovery mechanism which turns on the resistive heat control output for at least a portion of a recovery time period, the recovery time period beginning when the conditioned space is occupied following a period in which the conditioned space was unoccupied, and the recovery time period ending when the temperature in the conditioned space reaches at least the user'"'"'s normally desired setpoint temperature.

8. ) The thermostat apparatus of claim 7 further comprising a means of performing a forced update of the resistive temperature slew rate value, even when in normal operation resistive heat is not required for heating the conditioned space, by forcing activation of the resistive heat control output for a time sufficient to allow the temperature slew rate measurement apparatus to obtain a new resistive temperature slew rate value.

9. ) The thermostat apparatus of claim 8 where the forced update of the resistive temperature slew rate value is performed only during periods when the conditioned space is unoccupied.

10. ) The thermostat apparatus of claim 7 with the measurement of the resistive temperature slew rate value being made only when the heat pump alone is not able to supply a needed amount of heat to the conditioned space.

11. ) A method for maximizing the energy efficiency while heating a conditioned space using a thermostat apparatus for coupling to and control of a heating apparatus, the heating apparatus including a heat pump apparatus and a resistive heating apparatus, the heat pump apparatus typically providing more efficient heating of the conditioned space in terms of energy usage than the resistive heating apparatus, the thermostat apparatus receiving inputs from a temperature sensor located for providing an indication of temperature in the conditioned space, and from an occupancy sensing apparatus located for providing an indication that the conditioned space is occupied and in the alternative that the conditioned space is unoccupied, the thermostat apparatus including means for providing control outputs including a heat pump control output for signaling the heat pump to provide heat to the conditioned space and a resistive heat control output for signaling the resistive heating apparatus to provide heat to the conditioned space, the method comprising the steps of:

A) operating the thermostat apparatus to maintain the temperature in the conditioned space to be near a user'"'"'s normally desired setpoint temperature when the conditioned space is occupied, and when the conditioned space is unoccupied operating the thermostat apparatus to maintain the temperature in the conditioned space to be near a controlled reduced setpoint temperature, the controlled reduced setpoint temperature being set lower than the user'"'"'s normally desired setpoint temperature for conserving energy;

B) applying first user input to the thermostat apparatus to establish a normal setpoint temperature for use while the conditioned space is occupied as sensed by the occupancy sensing apparatus;

C) applying second user input to establish a maximum allowable temperature recovery time value corresponding to a user desired maximum time for temperature recovery in the conditioned space when the thermostat apparatus occupancy sensing apparatus detects a change in occupancy in the conditioned space from unoccupied to occupied;

D) causing the thermostat apparatus to measure a resistive temperature slew rate value during a measuring time interval which is at least a portion of a time when the resistive heating apparatus is providing resistive heating to the conditioned space, the resistive temperature slew rate value corresponding to a measured rate of temperature increase in the conditioned space observed during the measuring time interval; and

,

E) the thermostat apparatus establishing the controlled reduced setpoint temperature utilizing the resistive temperature slew rate value and the maximum allowable temperature recovery time value to be set at a level such that if resistive heating were to be applied by the resistive heating apparatus, the temperature in the conditioned space would be likely to reach the user'"'"'s normally desired setpoint temperature within the maximum allowable temperature recovery time, thus enabling the controlled reduced setpoint temperature to be set lower than a temperature value which could be used if only the heat pump apparatus were to be utilized in achieving temperature recovery.

12. ) A thermostat apparatus for controlling a heating system for heating a conditioned space, the heating system including a first heating apparatus supplying a normal heat and a second heating apparatus supplying an alternative heat, the first heating apparatus typically providing more efficient heating of the conditioned space in terms of energy usage than the second heating apparatus, the thermostat apparatus including means for receiving input from a temperature sensor located for providing an indication of a temperature in the conditioned space and also means for receiving input from an occupancy sensing apparatus located for providing an indication that the conditioned space is occupied and in the alternative that the conditioned space is unoccupied, the thermostat apparatus further including output control signal means including a first heating apparatus control output for signaling the first heating apparatus to provide heat to the conditioned space and a second heating apparatus control output for signaling the second heating apparatus to provide heat to the conditioned space, the thermostat apparatus in normal operation maintaining the temperature in the conditioned space to be near an established user'"'"'s normally desired setpoint temperature when the conditioned space is occupied, and in the alternative when the conditioned space is unoccupied maintaining the temperature in the conditioned space to be near a controlled reduced setpoint temperature;

the thermostat apparatus further comprising;

A) a coupling to a user input apparatus providing for user input establishing a maximum allowable temperature recovery time value corresponding to a user desired maximum time for temperature recovery in the conditioned space when the thermostat apparatus occupancy sensing apparatus detects a change in occupancy in the conditioned space from unoccupied to occupied;

B) a reduced temperature setpoint adjustment apparatus which;

1) measures a high energy temperature slew rate value during a slew rate measuring time interval which is at least a portion of a time when the second heating apparatus is providing heating to the conditioned space, the high energy temperature slew rate value corresponding to a measured rate of temperature increase in the conditioned space observed during the slew rate measuring time interval; and

,

2) utilizes the high energy temperature slew rate value and the maximum allowable temperature recovery time value to establish the controlled reduced setpoint temperature at a level lower than the user'"'"'s normally desired setpoint temperature, for conserving energy, such that at any time if the second heating apparatus is signaled by the thermostat apparatus to apply alternative heat, the temperature in the conditioned space would be likely to return to the user'"'"'s normally desired setpoint temperature within the maximum allowable temperature recovery time, thus enabling the controlled reduced setpoint temperature to be set to a value lower than a value which could be used if only the first heating apparatus were to be utilized in achieving temperature recovery; and

,

C) a recovery mechanism which turns on the second heating apparatus control output for at least a portion of a recovery time period, the recovery time period beginning when the conditioned space is occupied following a period in which the conditioned space was unoccupied, and the recovery time period ending when the temperature in the conditioned space reaches at least the user'"'"'s normally desired setpoint temperature.