Methods and systems for controlling an hvac system to identify energy usage under different control strategies

Patent metadata

Field	Value
Publication number	US-2025067452-A1
Application number	US-202318455318-A
Country	US
Kind code	A1
Filing date	Aug 24, 2023
Priority date	Aug 24, 2023
Publication date	Feb 27, 2025
Grant date	—

Abstract

A method for determining a measure of thermal energy delivered via a VAV box includes receiving an AHU supply air temperature, a VAV discharge air temperature, a space air temperature, and a VAV discharge flow rate. The measure of thermal energy delivered by the VAV box to the space during the first period of time is determined based at least in part on three or more of the received parameters. The determined measure of thermal energy delivered by the VAV box and a determined measure of thermal energy delivered by each of a plurality of other VAV boxes of the facility are aggregated over the first period of time, resulting in an aggregated measure of thermal energy. This may be used to adjust one or more control parameters to achieve a desired balance of energy consumption versus comfort, energy and/or health.

First claim

What is claimed is:

1 . A method for determining a measure of thermal energy delivered via a Variable Air Volume (VAV) box to a space of a facility, the VAV box receiving a supply air from an Air Handler Unit (AHU) of a Heating, Ventilating and/or Air Conditioning (HVAC) system of the facility and providing a VAV discharge air flow to the space of the facility, the method comprising:
receiving an AHU supply air temperature (TAHU SAT ) that is representative of the temperature of the supply air that is received from the AHU by the VAV box; receiving a VAV discharge air temperature (T DAT ) that is representative of the temperature of the VAV discharge air flow provided to the space by the VAV box; receiving a space air temperature (T SPACE ) that is representative of the temperature of the air in the space; receiving a VAV discharge flow rate (VAV FLOWRATE ) that is representative of a flow rate of the VAV discharge air flow provided to the space by the VAV box; controlling the HVAC system of the facility using first control parameters over a first period of time; determining the measure of thermal energy delivered by the VAV box to the space during the first period of time based at least in part on three or more of the VAV discharge flow rate (VAV FLOWRATE ), the VAV discharge air temperature (T DAT ), the space air temperature (T SPACE ) and the AHU supply air temperature (TAHU SAT ); aggregating the determined measure of thermal energy delivered by the VAV box and a determined measure of thermal energy delivered by each of a plurality of other VAV boxes of the facility over the first period of time, resulting in a first aggregated measure of thermal energy; controlling the HVAC system of the facility using second control parameters over a second period of time; determining the measure of thermal energy delivered by the VAV box to the space during the second period of time based at least in part on three or more of the VAV discharge flow rate (VAV FLOWRATE ), the VAV discharge air temperature (T DAT ), the space air temperature (T SPACE ) and the AHU supply air temperature (TAHU SAT ); aggregating the determined measure of thermal energy delivered by the VAV box and the determined measure of thermal energy delivered by each of the plurality of other VAV boxes of the facility over the second period of time, resulting in a second aggregated measure of thermal energy; and displaying the first aggregated measure of thermal energy and the second aggregated measure of thermal energy on a display to help identify the effectiveness in controlling the HVAC system using the first control parameters relative to the second control parameters.

2 . The method of claim 1 , further comprising:
changing one or more of control parameters of the HVAC system of the facility based at least in part on the first aggregated measure of thermal energy and the second aggregated measure of thermal energy.

3 . The method of claim 1 , further comprising:
controlling the HVAC system of the facility using the first control parameters under each of a plurality of different operating conditions; aggregating the determined measure of thermal energy delivered by the VAV box and the determined measure of thermal energy delivered by each of the plurality of other VAV boxes of the facility while controlling the HVAC system of the facility using the first control parameters under each of the plurality of different operating conditions; refining a baseline thermal energy consumption model of the facility based at least in part on the aggregated determined measure of thermal energy delivered by the VAV box and the determined measure of thermal energy delivered by each of the plurality of other VAV boxes of the facility while controlling the HVAC system of the facility using the first control parameters under each of the plurality of different operating conditions; controlling the HVAC system of the facility using second control parameters under a particular operating condition; aggregating the determined measure of thermal energy delivered by the VAV box and the determined measure of thermal energy delivered by each of the plurality of other VAV boxes of the facility while controlling the HVAC system of the facility using the second control parameters under the particular operating condition; comparing the aggregated determined measure of thermal energy delivered by the VAV box and the determined measure of thermal energy delivered by each of the plurality of other VAV boxes of the facility while controlling the HVAC system of the facility using the second control parameters under the particular operating condition with a baseline aggregated measure of thermal energy generated using the baseline thermal energy consumption model; and based at least in part on the comparison, determining a relative performance of controlling the HVAC system of the facility using the second control parameters versus controlling the HVAC system of the facility using the first control parameters.

4 . The method of claim 1 , wherein the measure of thermal energy delivered by the VAV box to the space when the HVAC system is heating the space is determined by:
when the VAV discharge air temperature (T DAT ) is greater than the space air temperature (T SPACE ):

Thermal
⁢

Energy
⁢

Delivered

=

VAV
FLOWRATE

*
Cp
*

(

T
DAT

-

TAHU

SAT

)

where, Cp is the specific heat capacity of air; and

when the VAV discharge air temperature (T DAT ) is less than or equal to the space air temperature (T SPACE ):

Thermal
⁢

Energy
⁢

Delivered
⁢

=

0
.

5 . The method of claim 1 , wherein the VAV box includes a VAV heater that when activated adds sensible heat to the VAV discharge air flow to elevate the VAV discharge air temperature (T DAT ).

6 . The method of claim 5 , wherein the measure of thermal energy delivered by the VAV box to the space when the HVAC system is cooling the space is determined by:
when the VAV heater is not activated:

Thermal
⁢

Energy
⁢

Delivered

=

VAV

F
⁢
L
⁢
O
⁢
W
⁢
R
⁢
A
⁢

Assignees

• Honeywell Int Inc

Inventors

• Aggarwal Kanchan
• Kamath Madhav
• Lingan Magesh
• Ranjan Prabhat

Classifications

• F24F11/52 Primary

  Indication arrangements, e.g. displays · CPC title

• F24F11/74

  for controlling air flow rate or air velocity · CPC title

• F24F3/0442

  with volume control at a constant temperature · CPC title

• F24F11/63

  Electronic processing · CPC title

• F24F11/47

  Responding to energy costs · CPC title