Zonal demand control ventilation for a building

Patent metadata

Field	Value
Publication number	US-10309668-B2
Application number	US-201514940194-A
Country	US
Kind code	B2
Filing date	Nov 13, 2015
Priority date	Nov 13, 2015
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

A method for operating an air handling unit of an HVAC system. The method includes opening an outside air flow control device to enable breathing air flow during a high outdoor air time period to a first zone having a first number of occupants and a second zone having a second number of occupants that is less than the first number of occupants. The outside air flow control device is then closed to enable conditioning air flow during a low outdoor air time period to the first and second zones. Further, a variable air volume (VAV) air flow control device provides desired amounts of breathing air to the first and second zones suitable for the first and second number of occupants, respectively. A VAV air temperature control device then provides conditioning air to the first and second zones having a suitable temperature for the first and second number of occupants.

First claim

What is claimed is:

1. A method for operating an air handling apparatus of a heating, ventilation, and air conditioning system associated with first and second thermal zones of an enclosed space having a plurality of zones, wherein the air handling apparatus includes an air handling unit (AHU) or a rooftop unit (RTU) each including an outside air flow actuator and a variable air volume (VAV) device associated with the first and second zones wherein each VAV device includes a VAV air flow actuator and a VAV air temperature control actuator, comprising:
operating the outside air flow actuator to enable breathing air flow in a supply duct during a high outdoor air time period wherein the supply duct conveys breathing air to the first and second zones and wherein the first zone includes a first number of occupants and the second zone includes a second number of occupants that is less than the first number of occupants;
operating the outside air flow actuator to enable conditioning air flow into the supply duct during a low outdoor air time period wherein the supply duct conveys conditioning air to the first and second zones;
operating the AHU or RTU and VAV air flow actuators to provide a desired amount of breathing air from the supply duct to the first zone suitable for the first number of occupants and breathing air to the second zone suitable for the second number of occupants, wherein the AHU or RTU and VAV air flow actuators are operated during the high and low outdoor air time periods; and
operating the VAV air temperature control actuator to condition breathing air received from the supply duct to provide conditioning air to the first zone having a suitable temperature for the first number of occupants and conditioning air to the second zone having a suitable temperature for the second number of occupants, wherein the VAV air temperature control actuator is operated during the high and low outdoor air time periods and wherein the outside airflow, VAV air flow and VAV air temperature control actuators are controlled using pulse width modulated signals according to a duty ratio during the high and low outdoor air time periods, wherein the duty ratio is controlled for minimizing outside air introduction to the supply duct while maintaining a carbon dioxide (CO2) level for each of the first zone and the second zone below the maximum allowable CO2 level.

2. The method according to claim 1 , further including calculating a carbon dioxide (CO2) level for an associated zone based on a combined CO2 level measurement within the return duct for the first and second zones and tea number of occupants scheduled to be within the associated zone.

3. The method according to claim 2 , wherein the number of occupants in a first zone and the number of occupants in a second zone is determined by accessing a personal calendaring application or a web portal.

4. The method according to claim 1 , wherein the duty ratio for controlling the outside air flow actuator to maintain a carbon dioxide (CO2) level in a zone is dependent on the number of occupants in the zone.

5. The method according to claim 1 , wherein a damper in the AHU or RTU and a damper in the VAV device associated with the first zone is opened wider during the high outdoor air time period than during the low outdoor air time period.

6. The method according to claim 1 , wherein the VAV air temperature control actuator associated with the first zone is set at a low occupancy set point.

7. The method according to claim 1 , wherein the high and low outdoor air time periods are adjustable in accordance with the occupancy of an individual zone.

8. The method according to claim 1 , wherein the VAV air temperature control actuator operates a cooling and/or heating coil valve for controlling temperature.

9. A system for heating, ventilation, and air conditioning associated with first and second thermal zones of an enclosed space having a plurality of zones, the system comprising:
an air handling unit (AHU) or a rooftop unit (RTU) comprising:
an outside air flow actuator and a variable air volume (VAV) device associated with the first and second zones wherein each VAV device includes a VAV air flow actuator and a VAV air temperature control actuator;
a controller configured to operate the outside air flow actuator to enable breathing air flow in a supply duct during a high outdoor air time period wherein the supply duct conveys breathing air to the first and second zones and wherein the first zone includes a first number of occupants and the second zone includes a second number of occupants that is less than the first number of occupants;
and to enable conditioning air flow into the supply duct during a low outdoor air time period wherein the supply duct conveys conditioning air to the first and second zones;
the controller further configured to operate the AHU or RTU and VAV air flow actuators to provide a desired amount of breathing air from the supply duct to the first zone suitable for the first number of occupants and breathing air to the second zone suitable for the second number of occupants, wherein the AHU or RTU and VAV air flow actuators are operated during the high and low outdoor air time periods;
the controller further configured to operate the VAV air temperature control actuator to condition breathing air received from the supply duct to provide conditioning air to the first zone having a suitable temperature for the first number of occupants and conditioning air to the second zone having a temperature suitable for the second number of occupants;
a carbon dioxide (CO2) sensor in a return air duct of the AHU, wherein the CO2 sensor detects a combined CO2 level generated by the occupants in the first and second zones; and
wherein the controller is configured to calculate a maximum allowable CO2 level for an associated zone based on a combined CO2 level measurement within the return duct for the first and second zones and the number of occupants in the associated zone, and responsive to the detected combined CO2 level, generate a pulse width modulated control signal for the outside air flow actuator, wherein the duty ratio is controlled for minimizing outside air introduction to the supply duct while maintaining a carbon dioxide (CO2) level for each of the first zone and the second zone below the maximum allowable CO2 level.

10. The system according to claim 9 , wherein the high and low outdoor air time periods are adjustable in accordance with the occupancy of an individual zone.

11. The system according to claim 9 , wherein a damper in the AHU or RTU and a damper in the VAV device associated with the first zone is opened wider during the high outdoor air time period than during the low outdoor air period.

12. The system according to claim 9 , wherein the VAV air temperature control actuator associated with first zone is set to a low occupancy set point.

13. The system according to claim 9 , wherein the method is implemented as part of a building control system.

Assignees

• Siemens Ag
• Siemens Industry Inc

Inventors

• Song Zhen
• Srivastava Sanjeev
• Okunev Dmitriy
• Wang Lingyun

Classifications

• F24F11/0001 Primary

  for ventilation (F24F11/30 takes precedence) · CPC title

• F24F3/0442

  with volume control at a constant temperature · CPC title

• F24F3/00

  Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems (room units F24F1/00) · CPC title

• F24F11/62

  characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values · CPC title

• F24F11/46

  Improving electric energy efficiency or saving · CPC title