AU2009202085A1

AU2009202085A1 - A means of controlling air conditioning

Info

Publication number: AU2009202085A1
Application number: AU2009202085A
Authority: AU
Inventors: Stefan Reich; Andrew Rogers
Original assignee: CONNECT AIR Manufacturing Pty Ltd
Current assignee: AIR DIFFUSION AGENCIES Pty Ltd
Priority date: 2008-05-28
Filing date: 2009-05-27
Publication date: 2009-12-17
Anticipated expiration: 2029-05-27
Also published as: AU2009202085B2

Description

Regulation 3.2 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: Connect Air Manufacturing Pty Ltd Actual Inventors: Stefan Reich Andrew Rogers Address for Service: C/- MADDERNS, First Floor, 64 Hindmarsh Square, Adelaide, South Australia, Australia Invention title: A MEANS OF CONTROLLING AIR CONDITIONING Details of Associated Provisional Application No: 2008902672 dated 28 May 2008 The following statement is a full description of this invention, including the best method of perfonning it known to us.

2 FIELD OF THE INVENTION This invention relates to a means of controlling air conditioning and in particular to a system that will sense room (zone) temperatures and adjust airflow periodically to bring the temperature in each zone towards a desired temperature. 5 This invention is to be used for both heating and cooling cycles although it could be used for heating only or cooling only. BACKGROUND ART It is well known to provide heating or cooling to a number of rooms within an office building or house via duct work that leads to each room or zone from one or more central fan units. The air is first heated or 10 cooled before it is delivered into each zone. The simplest method is to deliver the required airflow into a particular room and maintain this airflow regardless of heating or cooling load. The heating or cooling requirements are determined based on various parameters such as room size, orientation to the sun, number of occupants and the like which then results in an estimated heating and cooling load. This is met by setting the airflow rate to a predetermined 15 amount. The problem with this system is that the heating or cooling requirements for a particular zone can vary both throughout the day and throughout the year. Accordingly, there are very few periods when the predetermined airflow rate results in all of the zone temperatures being at the desirable level. The majority of the time, the temperature is either side of this desired temperature or set point. 20 It is an object of this invention therefore to substantially ameliorate the above described difficulties, or to at least to provide a means for controlling air conditioning that is a useful alternative to known means or arrangements. BRIEF DESCRIPTION OF THE INVENTIONN In one aspect, the invention may be said to reside in a system for air conditioning multiple zones, the 25 system comprising airflow ducts for directing cooling or heating airflow into each zone, airflow throttle means in each duct adapted to control the rate of airflow to each zone, temperature sensors in each zone, and control means for controlling each airflow throttle means and thereby the rate of airflow supplied to a 3 zone based on the temperature of that particular zone in relation to the average temperature of some or all the zones. In a further aspect, the invention may be said to reside in a method for controlling a system for air conditioning multiple zones, the system comprising airflow ducts for directing cooling or heating airflow 5 into each zone, airflow throttle means in each duct adapted to control airflow to each zone, temperature sensors in each zone, and control means for effecting the method and controlling each airflow throttle means, the method including the steps of measuring the temperature in the zones, calculating an average temperature of some or all of the zone temperatures, and adjusting each throttle means and thereby the airflow supplied to a zone based on the temperature of that particular zone in relation to the calculated 10 average temperature. The invention as described above is designed to work regardless of there being a heating or cooling cycle. When operating as a heater, the control means calculates an average of all or some of the zone temperatures and where a temperature sensor in a given zone measures less than or equal to the average temperature, then the control means opens the corresponding throttle means. Where a temperature sensor 15 in a given zone measures greater than the average temperature, then the control means will close the corresponding throttle means. When operating as a cooler, the control means calculates an average of all or some of the zone temperatures and where a temperature sensor in a given zone measures greater than or equal to the average temperature, then the control means opens the corresponding throttle means. Where a 20 temperature sensor in a given zone measures less than the average temperature, then the control means will close the corresponding throttle means. In one form, the control means calculates an average of all or some of the zone temperatures and identifies the zone having the greatest difference from the average temperature, if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the 25 temperature in this zone to become closer to the average temperature, then the control means opens the airflow throttle means for this zone incrementally, but if that zone airflow throttle is fully opened, then the control means identifies the zone having the next greatest difference from the average temperature, if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the temperature in this zone to become closer to the average temperature, then the control means 30 opens the airflow throttle means incrementally, and so on with each of the further zones until there is no zone remaining whereupon if no airflow throttle can be opened, then the control mean identifies the zone having the greatest temperature difference compared to the average temperature, and if decreasing the 4 airflow to this zone will cause temperature in this zone to become closer to the average temperature, then the control means closes the airflow throttle means for this zone incrementally. If no adjustment can be made to the airflow throttle means for any zone that will cause the temperature in a zone to become closer to the average temperature, then no adjustment will be made. 5 This process is continued periodically at predetermined time intervals. Preferably, those time intervals may be between one and five minutes but more preferably at two minute intervals. The net result of periodically controlling airflow in the above described manner is that zones which, in the cooling mode have a high heat load, will have a greater volume of air directed to them to bring them closer to the achievable average for the given cooling capacity. Further, if there are changes throughout 10 any heating or cooling period, then the control means will act to rectify the imbalance. In a further aspect, the invention may be said to reside in a throttle means for a system for air conditioning multiple zones, the throttle means being adapted to be positioned in the path of an airflow within a duct, the throttle means including an element adapted to be moved between a closed position, in which airflow within the duct is substantially blocked, and an open position in which impediment to airflow caused 15 thereby is substantially eliminated, the throttle means being characterised in that it is adapted to hold the element at a position between fully opened and fully closed so as to control the rate of airflow thereby. In one form the throttle means is adapted to hold the element in at least two positions between fully opened and fully closed, and increment the element between the open and closed positions, and the at least two positions in between these. 20 That is, the throttle means is adapted to increase airflow thereby by incrementing the element between any of the fully closed position and a 1/3 open position, the 1/3 open position and a 2/3 open position, and the 2/3 open position and a fully open position, or indeed between any two of these positions. Similarly, the throttle means is adapted to decrease airflow thereby by incrementing the element between any of the fully open position and a 2/3 open position, the 2/3 open position and a 1/3 open position, and 25 the 1/3 open position and a fully closed position, or indeed between any two of these positions.. The throttle comprises driving means adapted to drive the throttle element between the open and closed positions, and the at least two positions in between these. The driving means are operated through a predetermined interval to move the airflow throttle to any of the plurality of positions between the open and closed positions, these positions being determined by a predetermined operating parameter, such as 30 an interval of time of operations of the driving means.

5 In one form, the drive means for the throttle means is an electric motor, and throttle element is a blade pivotably mounted within the duct so as to be rotated between the open and closed positions, and the at least two positions in between these. Preferably, the predetermined operating parameter is an interval of time of operations of the driving 5 means. As an alternative, the operating parameter may be an interval of time based on the start position being either the fully opened or fully closed position or both. For example, for any given position, it will be known for how much time the driving means will be operated to take it to any of the plurality of positions between the fully opened and fully closed position or to take it back to the fully opened or fully closed position. 10 In order to drive the damper from a fully closed position to one third open position the motor is driven for a predetermined period of time. In order to achieve this, the control means knows the current position of the damper plate which in this example is fully closed and therefore knows the position that it is being driven to and the required interval for motor operation to achieve that position. In a further aspect, the invention may be said to reside in a means of controlling the air conditioning of 15 multiple zones where heating or cooling airflow is directed individually to each zone, the means comprising: airflow ducts for directing cooling or heating airflow into each zone, airflow throttle means in each duct for controlling the rate of airflow to each zone, temperature sensors in each zone, and 20 control means for controlling each said airflow throttle means in response to sensed temperatures, wherein the control means calculates an average of all or some of the zone temperatures and identifies the zone having the greatest difference from the average temperature, if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the temperature in this zone to become closer to the average temperature, then the control means opens the airtlow throttle means 25 for this zone incrementally, but if that zone airflow throttle is fully opened, then the control means identifies the zone having the next greatest difference from the average temperature, if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the temperature in this zone to become closer to the average temperature, then the control means opens the airflow throttle means incrementally, and so on with each of the further zones until there is no zone 30 remaining whereupon if no airflow throttle can be opened, then the control mean identifies the zone having the greatest temperature difference compared to the average temperature, and if decreasing the 6 airflow to this zone will cause temperature in this zone to become closer to the average temperature, then the control means closes the airflow throttle means for this zone incrementally. However, it will be realised that the invention is not to be confined or restricted to the nature of these preferred embodiments and that variations that would be apparent to a person skilled in the art will be 5 included within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of this disclosure it will now be described with respect to an exemplary embodiment which shall be described herein with the assistance of drawings wherein: Figure 1 is a schematic illustration of an exemplary arrangement for air conditioning multiple zones; and 10 Figure 2 is a table and corresponding graphs illustrating the effect that varying the throttle means has on zone temperatures. DETAILED DESCRIPTION Referring to Figure 1, where there is illustrated a system I for air conditioning multiple zones (four in this case) ZI, Z2, Z3 and Z4. 15 The system I comprises a central handling unit 2 supplying cooling or heating airflow to zones ZI, Z2, Z3 and Z4 via airflow ducts A 1, A2, A3 and A4. There is an airflow throttle means Dl, D2, D3 and D4 located in each duct A l, A2, A3 and A4 respectively, each throttle means DI, D2, D3 and D4 being adapted to control the rate of airflow released at outlets 01, 02, 03 and 04 to each zone ZI, Z2, Z3 and Z4 respectively. 20 There is a temperature sensor TI, T2, T3 and T4 in each zone Z 1, Z2, Z3 and Z4. These temperature sensors provide temperature information to a control means in the form of (for example) a programmable logic controller (PLC) or the like, which is located in a control box 4. The control means then controls each airflow throttle means Dl, D2, D3 and D4. This first embodiment will be described in relation to a cooling mode although it will work in much the 25 same manner if it were a heating mode. To initiate the system, the system 1 unit is turned on at the user interface 6 or via a remote signalling to the control box 4. The air conditioning unit at 2 may be turned on at the same time, or it may need to be 7 turned on separately The air conditioning unit at 2 will have its own thermostat which is independent of the control system according to this invention. The central handling unit 2 has heating exchange for cooling the air prior to it going to each zone via conventional duct work airflow ducts A l, A2, A3 and A4 . Prior to the final delivery of the air into each 5 zone ZI, Z2, Z3 and Z4 at outlets 01, 02, 03 and 04, each duct is provided with a throttle means, which is in this instance a damper (therefore the terms are used interchangeably hereafter), which is operable to throttle the airflow in the duct. Each damper Dl, D2, D3 and D4 comprises a disc 8 which, in the fully closed position, extends across the duct in which it is located to prevent any airflow into the zone. The disc 8 for each damper can be controlled to be driven (via an electric motor) between the fully closed and 10 fully opened position and to several positions in between. In this embodiment, each damper D1, D2, D3 and D4 can be fully closed, a third open, two thirds open and fully open. The position of the disc 8 for each of the dampers Dl, D2, D3 and D4 is controlled by the control means at 4, which knows the current position of each disc 8, and can operate each of the dampers independently to either open or close them incrementally or fully. 15 Each of the zones ZI, Z2, Z3 and Z4 has a temperature sensor Tl, T2, T3 and T4 which transmits the zone temperature to the control means in the control box 4. Upon turning the system I on, the control means is also energised. The control means may have an option, referred to as a boost option that can be selected manually. This will open fully and hold open all of the dampers Dl, D2, D3 and D4 for each zone ZI, Z2, Z3 and Z4 for a selected period of either five, ten or fifteen minutes so as to, in this 20 embodiment, cool (or heat) all of the zones Zl, Z2, Z3 and Z4 as quickly as possible. After this boost period, the control means may control each damper DI, D2, D3 and D4 so that this will act in any one of three independent ways explained hereinafter. Firstly, the control means may operate in a manual mode where the dampers DI, D2, D3 and D4 can be set to a fixed position by a user and remain in the selected position regardless of the temperature that is 25 sensed in each of the zones Z1, Z2, Z3 and Z4. This will allow for full manual control of the system or indeed only selected zones thereof. The second mode of operation will be in accordance with the method invention. In this method, the temperatures of each of the zones will be sensed by the temperature sensor Ti, T2, T3 and T4 and this data relayed to the control means where an average temperature is determined. However, it will be 30 possible for one or more of the zones to be set to a manual control as described in the first mode, in which case those zones that are being operated manually will be excluded from the temperature averaging calculation.

8 Periodically then, the control means will determine an average of each of the zones sensed. The controller will then compare this average temperature against the actual temperature in each of the zones sensed as measured by temperature sensors in the zones sensed. Where a temperature sensor, say TI, in a given zone ZI measures a temperatures that is greater than or 5 equal to the average temperature Tavg (i.e. the zone ZI is hotter than Tavg), then the control means will cause the corresponding throttle means DI to increase airflow thereby by opening an increment (i.e. from 1/3 open to 2/3 open). Where a temperature sensor, again say TI, in a given zone ZI measures a temperatures that is less than the average temperature Tavg (i.e. the zone ZI is cooler than Tavg), then the control means will cause the 10 corresponding throttle means Dl to decrease airflow thereby by closing an increment (i.e. from 2/3 open to 1.3 open). The control means will look for the zone having the greatest difference in temperature when compared with the calculated average temperature Tavg. If the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the temperature in this zone to become 15 closer to the average temperature, then the control means will open the airflow throttle means for this zone incrementally. If however the airflow throttle in this zone is already fully opened, then the control means will then identify the zone having the next greatest difference from the average temperature, determine if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will 20 cause the temperature in this zone to become closer to the average temperature, in which case the control means opens the airflow throttle means incrementally, and so on with each of the further zones until there is no zone remaining whereupon the airflow throttle means can be opened. At this point the control means then identifies the zone having the greatest temperature difference compared to the average temperature, and determines if decreasing the airflow to this zone will cause 25 temperature in this zone to become closer to the average temperature, in which case the control means closes the airflow throttle means for this zone incrementally. Only one adjustment is made at a time, until two minutes time when the controller operates again to sense the temperatures and adjust the dampers. This is illustrated in the table and graphs at Figure 2, where it can be seen that the rate of airflow 30 delivered to Zone 1 was decreased by moving the disc 8 of damper DI from fully open to 2/3 open and then to 1/3 open in turn, for the purpose of equalising the temperature in these two zones. When the 9 temperature in Zone 2 dropped below that of Zone I at time interval 6, the rate of airflow delivered to Zone 2 was decreased by moving the disc 8 of damper D2 from fully open to 2/3 open, in order to rectify this. In this manner, cooling air is preferentially directed to zones that are not cooling as quickly by 5 comparison to other zones. In this mode of operation (i.e. automatic), the control means allows the setting of comfort level offsets which allow a person to manually adjust the temperature in a particular zone (via the user interface 6) to a warmer or cooler level by comparison to the calculated average temperature Tavg. These comfort level offsets may be in increments of half a degree within a range of plus or minus three 10 degrees either side of the average temperature, and comfort level offsets within the range described above may be set for all or any of the zones being controlled by the control means. The required temperature will be set by requesting a target temperature, the control means will read the temperature in the zone and store this temperature as the target temperature for this zone only. The user may then adjust this temperature by setting a comfort level offset of+ or - 3 degrees. The target 15 temperature and offset temperature for a zone will not change irrespective of temperature changes in other zones. The control means may average the zone temperatures from zones with the least amount of comfort level offset. In other words, the average temperature should be derived only from zones without a comfort level offset. If no such zones exist, then it should be derived from zones having half a degree comfort level 20 offset and if there are none of those, then the average should be derived from zones having a one degree comfort level offset. If the average is derived from zones with a comfort level offset then this offset should be deducted from the resulting average to obtain the average temperature. Zones that are operating in the manual mode or fixed temperature mode should not be used to calculate the average temperature. Finally, a third mode of operation is where it will be possible to set and maintain a fixed temperature in a 25 zone. The required temperature will be set by a user requesting the fixed temperature mode in a particular zone using user interface 6, whereupon the control means will read the temperature in the zone and store this temperature as the target temperature for this zone only. In this mode of operation, the control means also permits the setting of comfort level offsets, so that a user may manually adjust the target temperature in a particular zone (via the user interface 6) to a warmer or cooler level by comparison to the stored 30 target temperature. This target temperature will not change irrespective of temperature changes throughout other zones.

10 These comfort level offsets may be in increments of half a degree within a range of plus or minus three degrees either side of the target temperature, and comfort level offsets within the range described above may be set for all or any of the zones being controlled by the control means. In the second embodiment, the control means will work in a similar manner to the above described 5 embodiment. It will have a boost option which will hold dampers fully open for a selected period to heat or cool zones as quickly as possible. However, in this embodiment, after the boost period, the control means will act in one of two ways depending on the option selected. The first option will be a manual mode in which individual dampers can be set to a fixed position and they will remain in this position regardless of temperatures within each zone. 10 In a second mode, the user can designate a "strong zone". This strong zone is a zone within a house that has the best temperature i.e. being the temperature closest to that being desirable. This zone then gets priority when the average temperature is calculated (across all zones that are set to this mode) and the strong zone gets higher priority over and above the other zones so as to produce a weighted average. In other words, the average temperature will be closer to the temperature in the strong zone. All zones will 15 aim towards this target temperature but it will be possible to set comfort levels in each zone at plus or minus three degrees in half degree increments resulting in a zone being warmer by the amount of the comfort level program for this particular zone. The comfort level offsets will be taken into account when calculating the target temperature. If the sensor in zone one ZI reads 22 degrees but the offset is set to minus 2 degrees, this means that the target temperature for that zone is 20 degrees. 20 Having derived the average temperature from all of the zones ZI, Z2, Z3 and Z4, the control means will read the temperatures measured by sensors TI, T2, T3 and T4 every ten seconds and adjust airflow using throttle means Dl, D2, D3 and D4 every two minutes. The control means then works in the same manner as described above. The systems described in both of the abovementioned embodiments will not require the control to have 25 any regard to the air conditioner thermostat temperature. The control means will regulate the airflow to zones based on the temperature of a particular zone in relation to the average temperature of the other zones. According to this aspect of the invention, there is a convenient means provided to operate dampers pertaining to a number of predetermined positions between a fully open and fully closed position. 30 Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures can be made within the scope of the invention, l1 which is not to be limited to the details described herein but is to be accorded the full scope of the appended claims so as to embrace any and all equivalent devices and apparatus.

Claims

1. A system for air conditioning multiple zones, the system comprising airflow ducts for directing cooling or heating airflow into each zone, airflow throttle means in each duct adapted to control the rate of airflow to each zone, temperature sensors in each zone, and control means for 5 controlling each airflow throttle means and thereby the rate of airflow supplied to a zone based on the temperature of that particular zone in relation to the average temperature of some or all of the zones.

2. The system for air conditioning as in claim 1, wherein the throttle means comprises a throttle element adapted to be moved between a closed position, in which airflow within the duct is 10 substantially blocked, and an open position in which impediment to airflow caused thereby is substantially eliminated, the throttle means being characterised in that it is adapted to hold the throttle element at a position between fully opened and fully closed, thereby controlling the rate of airflow thereby.

3. The system for air conditioning as in claim 2, wherein the throttle means is adapted to hold the 15 throttle element in at least two positions between fully opened and fully closed.

4. The system for air conditioning as in claim 3, wherein the throttle means is adapted to increment the throttle element between the open and closed positions, and the at least two positions in between these.

5. The system for air conditioning as in claim 4, wherein the throttle means is adapted to increase 20 airflow thereby by incrementing the throttle element between any of the fully closed position and a 1/3 open position, the 1/3 open position and a 2/3 open position, and the 2/3 open position and a fully open position, or indeed between any two of these positions.

6. The system for air conditioning as in either of claims 4 or 5, wherein the throttle means is adapted to decrease airflow thereby by incrementing the throttle element between any of the fully open 25 position and a 2/3 open position, the 2/3 open position and a 1/3 open position, and the 1/3 open position and a fully closed position, or indeed between any two of these positions.

7. The system as in any one of the preceding claims, wherein the control means is adapted, when the system is operating as a heater, to calculate an average of all or some of the zone temperatures and where a temperature sensor in a given zone measures less than or equal to the average 30 temperature, cause the corresponding throttle means to increase airflow thereby. 13

8. The system as in any one of the preceding claims, wherein the control means is adapted, when the system is operating as a heater, to calculate an average of all or some of the zone temperatures and where a temperature sensor in a given zone measures greater than the average temperature, cause the corresponding throttle means to decrease airflow thereby. 5

9. The system as in any one of the preceding claims, wherein the control means is adapted, when the system is operating as a cooler, to calculate an average of all or some of the zone temperatures and where a temperature sensor in a given zone measures greater than or equal to the average temperature, cause the corresponding throttle means to increase airflow thereby.

10. The system as in any one of the preceding claims, wherein the control means is adapted, when the 10 system is operating as a cooler, to calculate an average of all or some of the zone temperatures and where a temperature sensor in a given zone measures less than the average temperature, cause the corresponding throttle means to decrease airflow thereby. Il.

The system as in any one of the preceding claims, wherein, having calculated an average of all or some of the zone temperatures, the control means is adapted to identify the zone having the 15 greatest difference from the average temperature, if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the temperature in this zone to become closer to the average temperature, then the control means opens the airflow throttle means for this zone incrementally, but if that zone airflow throttle is fully opened, then the control means identifies the zone having the next greatest difference from the average 20 temperature, if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the temperature in this zone to become closer to the average temperature, then the control means opens the airflow throttle means incrementally, and so on with each of the further zones until there is no zone remaining whereupon if no airflow throttle can be opened, then the control mean identifies the zone having the greatest temperature 25 difference compared to the average temperature, and if decreasing the airflow to this zone will cause temperature in this zone to become closer to the average temperature, then the control means closes the airflow throttle means for this zone incrementally.

12. The system as in any one of the preceding claims, wherein the system further comprises a user interface, via which a user may interface with the control means. 30

13. The system as in any one of the preceding claims, wherein the control means is adapted to operate in a manual mode where the throttle means can be set to a fixed position by a user and remain in the selected position regardless of the temperature that is sensed in each of the zones. 14

14. The system as in any one of the preceding claims, wherein the control means allows the setting of comfort level offsets which allow a user to manually adjust the temperature in a particular zone to a warmer or cooler level by comparison to the calculated average temperature.

15. A method for controlling a system for air conditioning multiple zones, the system comprising 5 airflow ducts for directing cooling or heating airflow into each zone, airflow throttle means in each duct adapted to control airflow to each zone, temperature sensors in each zone, and control means for effecting the method and controlling each airflow throttle means, the method including the steps of measuring the temperature in the zones, calculating an average temperature of some or all of the zone temperatures, and adjusting each throttle means and thereby the airflow 10 supplied to a zone based on the temperature of that particular zone in relation to the calculated average temperature.

16. The method of claim 15, further including the step of, when the system is operating as a heater, comparing the calculated average temperature to a temperature in a given zone, and where the temperature is this given zone measures less than or equal to the average temperature, cause the 15 corresponding throttle means to increase airflow thereby.

17. The method as in any one of the preceding method claims, further including the step of, when the system is operating as a heater, comparing the calculated average temperature to a temperature in a given zone, and where the temperature in this given zone measures greater than the average temperature, cause the corresponding throttle means to decrease airflow thereby. 20

18. The method as in any one of the preceding method claims, further including the step of, when the system is operating as a cooler, comparing the calculated average temperature to a temperature in a given zone, and where the temperature is this given zone measures greater than or equal to the average temperature, cause the corresponding throttle means to increase airflow thereby.

19. The method as in any one of the preceding method claims, further including the step of, when the 25 system is operating as a cooler, comparing the calculated average temperature to a temperature in a given zone, and where the temperature is this given zone measures less than the average temperature, cause the corresponding throttle means to decrease airflow thereby.

20. The method as in either of claims 16 or 18 further including the step of, having calculated an average of all or some of the zone temperatures, identifying the zone having the greatest 30 difference from the average temperature, if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the temperature in this zone to become closer to the average temperature, then opening the airflow throttle means for this zone 15 incrementally, but if that zone airflow throttle is fully opened, then identifying the zone having the next greatest difference from the average temperature, if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the temperature in this zone to become closer to the average temperature, then opening the airflow throttle means 5 incrementally, and so on with each of the further zones until there is no zone remaining whereupon if no airflow throttle can be opened, then identifying the zone having the greatest temperature difference compared to the average temperature, and if decreasing the airflow to this zone will cause temperature in this zone to become closer to the average temperature, then closing the airflow throttle means for this zone incrementally. 10

21. The method as in any one of the preceding method claims, further including the step of repeating the method at regular intervals.

22. A throttle means for a system for air conditioning multiple zones, the throttle means being adapted to be positioned in the path of an airflow within a duct, the throttle means including an element adapted to be moved between a closed position, in which airflow within the duct is 15 substantially blocked, and an open position in which impediment to airflow caused thereby is substantially eliminated, the throttle means being characterised in that it is adapted to hold the element at a position between fully opened and fully closed so as to control the rate of airflow thereby.

23. The throttle means as in claim 22, wherein the throttle means is adapted to hold the element in at 20 least two positions between fully opened and fully closed.

24. The throttle means as in claim 23, wherein the throttle means is adapted to increment the element between the open and closed positions, and the at least two positions in between these.

25. The throttle means as in claim 24, wherein the throttle means is adapted to increase airflow thereby by incrementing the element between any of the fully closed position and a 1/3 open 25 position, the 1/3 open position and a 2/3 open position, and the 2/3 open position and a fully open position.

26. The throttle means as in either of claims 24 or 25, wherein the throttle means is adapted to decrease airflow thereby by incrementing the element between any of the fully open position and a 2/3 open position, the 2/3 open position and a 1/3 open position, and the 1/3 open position and a 30 fully closed position. IL U

27. The throttle means as in any one of claims 24 to 26, wherein the throttle means comprises driving means adapted to drive the throttle element between the open and closed positions, and the at least two positions in between these.

28. The throttle means as in claim 27, wherein the driving means is operated through a predetermined 5 interval to move the airflow throttle to any of the plurality of positions between the open and closed positions, these positions being determined by a predetermined operating parameter.

29. The throttle means as in claim 28, wherein the predetermined operating parameter is an interval of time of operations of the driving means.

30. The throttle means as in either of claims 28 or 29, wherein the drive means for the throttle means 10 is an electric motor.

31. The throttle means as in any one of the preceding claims to a throttle means, wherein the throttle element is a blade pivotably mounted within the duct so as to be rotated between the open and closed positions, and at least two positions in between these.

32. A means of controlling the air conditioning of multiple zones where heating or cooling airflow is 15 directed individually to each zone, the means comprising: airflow ducts for directing cooling or heating airflow into each zone, airflow throttle means in each duct for controlling the rate of airflow to each zone, temperature sensors in each zone, and control means for controlling each said airflow throttle means in response to sensed 20 temperatures, wherein the control means calculates an average of all or some of the zone temperatures and identifies the zone having the greatest difference from the average temperature, if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the temperature in this zone to become closer to the average temperature, then the control means opens the airflow throttle means for this zone incrementally, but if that 25 zone airflow throttle is fully opened, then the control means identifies the zone having the next greatest difference from the average temperature, if the airflow throttle means for this zone is closed or partly closed, and if increasing airflow to this zone will cause the temperature in this zone to become closer to the average temperature, then the control means opens the airflow throttle means incrementally, and so on with each of the further zones until there is no zone 17 remaining whereupon if no airflow throttle can be opened, then the control mean identifies the zone having the greatest temperature difference compared to the average temperature, and if decreasing the airflow to this zone will cause temperature in this zone to become closer to the average temperature, then the control means closes the airflow throttle means for this zone 5 incrementally.