FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
1. Title of the invention:
AIR CONDITIONING ENERGY CONSUMPTION DETERMINATION SYSTEM
2. Applicants)

NATIONALITY

ADDRESS

TATA CONSULTANCY SERVICES LIMITED

Indian

Nirmal Building, 9th Floor, Nariman Point, Mumbai-400021, Maharashtra, India

3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
The present subject matter, in general, relates to air conditioning systems, and
in particular, to determination of energy consumption of the air conditioning systems.
BACKGROUND
Buildings may have offices, shops, residences, hospitals, etc., spread across
different floors. Different departments within an office may be located on different floors of the building. Typically, such offices share centralized air conditioning systems, for example, Heating-Ventilating-Air Conditioning (HVAC) systems, installed in the building. The energy consumed by the offices and departments to, say cool the office spaces, is computed in terms of air conditioning (AC) energy.
The AC energy consumed by different offices and departments within the
office may vary. In one conventional method, the AC energy consumed by a particular department of an office can be monitored on the basis of energy meter readings corresponding to that department. However, exclusive metering is not possible if a department is intermingled with other departments. Also, the installation of energy meters is both cost-ineffective and complex as locations for installing the energy meters may be inaccessible or unavailable.
Another method of determining the AC energy consumed by a particular
department located on a given floor of a building is to divide the total AC energy consumption of the entire floor by the area occupied by the department. However, such a scheme is generally erroneous in case different departments share floor space with one another or differ in operational pattern.
SUMMARY
The subject matter described herein relates to a system and a method for
determining an air conditioning energy consumption of a particular section within a building. In one implementation, a particular section is selected out of a number of sections in a building. On the basis of selected section, a number of air conditioning devices serving the selected section are identified by an identification module. Based upon the identified devices,

an energy consumption data and a number of refrigeration tonnage ratings are received from an HVAC metering device. A determination module determines an energy consumption of the selected section by apportioning the energy consumption data to the selected section based on the number of refrigeration tonnage ratings.
These and other features, aspects, and advantages of the present subject matter
will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
BRIEF DESCRIPTION OF DRAWINGS
The detailed description is described with reference to the accompanying
figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components. For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale.
Fig. 1 illustrates a block diagram representation of an air conditioning energy
consumption determination system, according to an embodiment of the present subject matter.
Fig. 2 illustrates a computing device implementing the air conditioning energy
consumption determination system as described in Fig.l, according to an embodiment of the present subject matter.
Fig. 3 illustrates a method for determining the air conditioning energy
consumption, according to an embodiment of the present subject matter.
DETAILED DESCRIPTION
Centralized air conditioning systems, like HVAC systems in particular, are one
of the largest power consumers in a building. In hospitals, manufacturing plants, offices, etc., air conditioning (AC) energy consumption accounts for more than half of the total energy consumption. In case of an office occupying various floors of a building, the AC energy

consumption of a department of the office can be determined by distributing the total AC energy consumption among various departments in that office. Further, such a determination may be utilized to levy monitory charges based on the AC energy consumption of each department. However, the determination may become complex when there are multiple departments on each floor and each department shares a common floor area with another department.
Conventionally, the air conditioning energy consumed by a department is
determined on the basis of readings from energy meters installed for the department or by multiplying the total area of the department with the energy consumed per unit area of the building. The second approach is followed where there are a large number of departments in an office. However, this approach pre-supposes that a smaller department in terms of floor area has proportionately lower energy consumption. Accordingly, such an assumption may not always be valid, and a floor area alone may not be the best metric for efficient determination of the AC energy consumption.
In addition, if the departments are cross-functional, such an area-based
approach often results in erroneous determination of the AC energy consumption by any department, thereby levying incorrect charges on the departments. To avoid such inaccurate -determination of charges, another conventional technique is to consider the trend of the AC energy consumption followed by the departments over a span of time. Based on this, an average may then be appropriately computed to predict the AC energy consumed by a particular department. However, as the manpower and resources allocated to the departments often undergo variations, such an average-based approach may prove to be less accurate in the long run.
To this end, a system and a method for determining air conditioning (AC)
energy consumed by various sections of a building are disclosed. Such sections may be separated from each other either physically, say by walls, boundaries, floors or logically. The logical partitioning may be done for a section which shares floor space with other sections.

In one implementation, the method to determine the AC energy consumption
by a section in a building includes selecting a section out of multiple sections of the building, such as different departments in an office. Further, based upon the selected section, a number of HVAC devices of an HVAC system, for example, air handling units (AHUs), chillers, pumps serving the selected section are identified. The HVAC system serves as a centralized air conditioner for the entire building. If the building is multi-storied, the selected section may be located on a first floor, a second floor, etc. Else, if the building is single storied, the selected section may be located in any direction on, say north-west, south-east etc., within the single storey building. Individual energy meter reading of these HVAC devices are obtained from at least one energy meter dedicated to each of the HVAC devices. Based upon the energy meter readings and types of energy metric associated with the identified HVAC devices and the selected section, the AC energy consumption specific to the selected section is determined. Such types of energy metric include a refrigeration tonnage rating, operating hours of the selected section and amount of heat generated within the selected section.
In one embodiment, an AC energy consumption determination system may be
implemented for an office having a number of sections spread across different floors of a building. In another implementation, the AC energy consumption determination system may be implemented in various other commercial hubs such as malls, restaurants, and residential buildings. Still further, the AC energy consumption determination system may be implemented in any enclosed space which does not have any physical or logical boundaries, but served by the air conditioning devices.
The AC energy consumption determination system may be any computing
device connected to a network, and may interact with an office management system over the network to obtain a list of the HVAC devices in the various sections and their respective meter readings. The AC energy consumption determination system identifies a number of AHUs serving a selected section from the obtained list of identified HVAC devices. As an example, if sections A and B occupy the same floor of the building, then both could share some of the AHUs serving that floor while some of the AHUs could be exclusive to each one of them. Based upon the identified AHUs, a number of additional HVAC devices connected

to the AHUs are further identified. These additional devices may include chillers, chiller pumps, heat exchanger units, and cooling water towers.
Further, individual energy meter readings of all of these additionally identified
HVAC devices are obtained. In one implementation, based upon refrigeration tonnage ratings of. the identified AHUs as an energy metric, the AC energy consumption of the chillers, the chiller pumps, the heat exchangers and the cooling water towers is determined from the energy meter readings. This determined energy consumption of the additional HVAC devices together with the energy meter readings of the AHUs constitutes the AC energy consumption of the section.
In case a section shares a floor area with another section(s) on a floor, a ratio of
operating time of the section and the total operating time of all sections present on the floor is taken as an additional energy metric, apart from the refrigeration tonnage. Likewise there can be other types of energy metric as well, which relate to presence of heat sources (like number of computers, number of employees, coffee machines) within each section. Accordingly, the energy consumption of the AHUs may also be determined from' the energy meter readings based on the operating time, number of heat sources etc., as relevant types of energy metric associated. Moreover, these types of energy metric are also employed, in addition to the refrigeration tonnage rating, for determination of energy consumption in terms of the additional HVAC devices connected to the AHUs.
In one embodiment, the air conditioning energy determination system provides
an interactive interface by providing section-wise energy consumption comparisons by way of bar graphs, pie charts etc., thereby providing a user an ease of judging the highest energy consumer. In addition, the AC expenditure apportioning system may work in tandem with an energy management system, thereby providing the user a way of discovering causes of variations in energy consumption incurred at, say, sectional level.
Further, the system as described in the present subject matter facilitates
administrators to identify major air conditioning energy consumers in the building and initiate appropriate energy conservation measures customized for those consumers. In addition, the

administrators can claim charges for energy consumption from each section in a fair and justified manner.
While aspects of described systems and methods for the AC energy
consumption determination systems can be implemented in any number of different computing systems, environments, and/or configurations, the embodiments are described in the context of the following exemplary system(s).
Fig. 1 illustrates a block diagram representation of an energy consumption
determination system 100 to determine an AC energy consumption of a section out of various sections housed within a single building served by an HVAC system, according to an embodiment of the present subject matter. The AC energy consumption determination system 100 may be hereinafter referred to as a determination system 100. In addition, examples of the sections include departments of an office, rooms, halls, shops, warehouses, and other types of similar enclosed spaces within the building.
The determination system 100 includes a metering system 102, and is
communicatively linked to an AC energy consumption apportioning system 108, hereinafter referred to as an apportioning system 108. The metering system 102 includes various HVAC devices 104, hereinafter referred to as air conditioning (AC) devices 104, which constitute the HVAC system of the building. Examples of such devices include, but are not limited to, air handling units (AHU) 104-1, chillers 104-2, chiller pumps 104-3, heat exchangers 104-4, and cooling water towers 104-5. An HVAC metering device 106 measures the individual energy consumption of these AC devices 104 in British Thermal Units (BTU). The HVAC metering device 106 then communicates the energy meter readings to the apportioning system 108 to determine the AC energy consumption of the selected section of the building.
In one embodiment, the apportioning system 108 includes an identification
module 110, and a determination module 112. In said embodiment, the identification module 110 is configured to select at least one section out of a number of sections of the building. The building, in the present context, is a multi-storied office. Likewise, a particular section of the

office may occupy an entire storey or share floor space with another section on the same storey. The section may also be distributed across a number of stories.
As per one implementation, the identification module 110 interacts with an
office management system (not shown in the figure) to identify a location of the selected section within the office. The location may be a whole storey or a particular portion of the storey. Based upon the identified location, the identification module 110 further retrieves a list of other sections specific to this location, if any. If there are other sections present on the identified location, then the identification module 110 additionally retrieves an operating time of the selected section and all the other sections sharing space with the selected section. In one embodiment, the operating time includes man-hours, which denotes a product of the number of employees of the section with number of operating hours of the section,
Furthermore, the identification module 110 identifies a number of AC devices
104 specific to the identified location. In one example, for the specific location, the AC devices 104 include the air handling units (AHUs) 104-1, chillers 104-2, chiller pumps 104-3, heat exchange units 104-4 and cooling water towers 104-5. Accordingly, the identification module 110 further retrieves a list of energy consumption readings of the identified AC devices 104 from the HVAC metering device 106 of the metering system 102. In addition, the identification module 110 receives an energy metric, for example a refrigeration tonnage rating of each of the identified AHUs, from the metering device 106. Specifically, the refrigeration tonnage rating denotes an air conditioning capacity of any AHU. In addition, the energy metric may include man-hours, number of computing machines, coffee machines, and other types of similar machines of certain sections. Specifically, the number of computing machines, coffee machines etc. act as an indicator of heat generated within the selected section. All these types of energy metrics help in determining the AC energy consumption of the identified devices, thereby facilitating determination of the AC energy consumption specific to the selected section.
In an implementation, the determination module 112 interacts with the
identification module 110 to determine an equivalent energy consumption of the identified AC devices 104 corresponding to the selected section, on the basis of the received types of

energy metric. Such determined energy consumption corresponding to the selected section refers to apportioned energy consumption corresponding to the selected section. Alternatively, determining the equivalent energy consumption in context of the selected section is analogous to apportioning the total energy consumption to the selected section.
In an implementation, based on the AC energy consumption of the selected
section, the determination module 112 determines the share of the selected section in the overall air conditioning energy consumption. Accordingly, the AC energy consumption values for every section within the office may be collected and recorded within a database of the apportioning system 108 on a periodic basis.
Fig. 2 illustrates components of the apportioning system 108, according to an
embodiment of the present subject matter. In said embodiment, the apportioning system 108 includes one or more processor(s) 202, interface(s) 204, and a memory 206. The processor(s) 202 may include one or more processing units. The processor(s) 202 can be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuitries, or any devices that manipulate signals based on operational instructions. Among other capabilities, the processor(s) 202 are configured to fetch and execute computer-readable instructions and data stored in the memory 206.
The interface(s) 204 may include a variety of software and hardware
interfaces, for example, interfaces for peripheral device(s), such as a keyboard, a mouse, an external memory, a printer. Further, the interface(s) 204 may enable the apportioning system 108 to communicate with other computing devices, such as web servers and external databases. The interface(s) 204 may facilitate multiple communications within a wide variety of protocols and networks, including wired networks, e.g., LAN, cable, etc., and wireless networks, e.g., WLAN, cellular, satellite, etc. For the purpose, the interface(s) 204 may include one or more ports for connecting to a number of computing devices.
The memory 206 can be implemented using any computer-readable medium
including, for example, volatile memory (e.g., RAM) and/or non-volatile memory (e.g., flash,

etc.). The memory 206 includes program module(s) 208 and program data 209. The program module 208 includes routines, programs, objects, components, data structure, etc., which perform particular task or implement particular abstract data types. In one implementation, the program module 208 includes the identification module 110, the determination module 112, and other module(s) 210. Other module(s) 210 includes programs that supplement applications implemented by the apportioning system 108.
The program data 209 may include section data 216, HVAC system data 218,
apportioned energy consumption data 220, and other data 222. The other data 222 may include data that is generated as a result of the execution of one or more modules in the other modules 210.
As mentioned before, a building may house several offices and each of such
offices may have various sections across several floors of the building. The building is served
by at least one HVAC system and the AC energy expended by the HVAC system is consumed
by each of the sections. To compute the AC energy consumed by at least one section of the
office, the apportioning system 108 is implemented within the determination system 100. As
per one implementation, the apportioning system 108 includes the identification module 110
to select a particular section out of a list of sections or sections stored in the section data 216.
In case of an organization, an operator of the determination system 100 may request the
apportioning system 108 to access the list of sections within the organization.
In another implementation, the apportioning system 108 may automatically
display the list of sections to the operator, say when the operator logs into the determination system 100. Accordingly, the operator selects any of the section. The identification module 110 accesses the section data 216 to identify, for example, a location of the section within the office, based upon the selected section. In addition, the identification module 110 identifies a list of sections that share the identified location and retrieves the operating time of all such sections present over the identified location, from the section data 216.
Further, the identification module 110 accesses the HVAC system data 218 to
identify a list of the AC devices 104 specific to the identified location and accordingly obtain energy consumption readings of the identified AC devices 104. As explained in the

description of Fig. 1, the determination module 112 interacts with the identification module 110 to determine the AC energy consumption of every identified device specific to the selected section, on the basis of various types of energy metric.
In an example, such determination of the AC energy consumption of every
identified device by the determination module 112 includes calculation of the energy consumption for every identified device based on the various types of energy metric. Without limiting the scope of the present subject matter, the determination may also be extended to cover appropriating, proportionately assigning, proportionately allocating, etc. the energy consumption of the identified devices to the selected section based on the various types of energy metric. For clarity purposes, the forthcoming expression depicts the determination performed by the determination module 112 by way of calculation.
In one implementation, the determination module 112 classifies a number of
air handling units (AHUs) 104-1 into Al and A2. The AHUs 104-1 may also include precision air handling units (PAHUs), which are an improvised version of a normal AHU. In an example, the set Al includes all those AHUs 104-1, which exclusively serve the selected section and the set A2 includes all those AHUs 104-1, which serve the selected section as well as the other sections corresponding to the identified location.
From the energy meter readings of the identified AC device, the energy
consumed by all the AHUs 104-1 in set Al is added to calculate a total apportioned energy SI, as shown in the following equation (1):
Sl = Σ AHUA1 (k) (1)
where AHUA1 denotes an energy consumption meter reading of any AHU in the set A1, k is any number from 1 to N, if there are N number of AHUs 104-1 in the set A1. From equation (1), it is clear that S1 is the sum of all energy meter readings of N number of AHUs 104-1 in the set Al, as calculated by the determination module 112.
In order to determine the apportioned energy consumed by the chillers 104-2
corresponding to the set Al, any of the AHUs 104-1 in the set Al may be considered. Any AHU in the set Al may be represented by a symbol AHUi. The identified set of chillers 104-2 that serve AHUi may be denoted by C(i). Any chiller in C(i) may also serve AHUs 104-1 other than AHUi. Accordingly, the apportioned energy consumed by any chiller is calculated

by taking into account all AHUs 104-1 served by that particular chiller. The apportioned energy consumed by a particular chiller in the set C(i) is calculated as per following equation:
(2)
where, Chi denotes the meter reading of any chiller in the set C(i); TRAHui denotes refrigeration tonnage of AHUi; £TRAHU (k) denotes sum of refrigeration tonnage of all AHUs 104-1 connected to C(i); k is any number froml to N, if there are N number of AHUs 104-1 connected to Chi; and Chi(a) denotes an apportioned energy consumption with respect to Chi. Let, TRAHIH / ZTRAHu (k) may be denoted by a factor Fl for use in further equations.
[00041] In the aforementioned manner, the apportioned energy consumption for every
chiller in the set C(i) is calculated by the determination module 112. The addition of all such apportioned energy consumption values gives the total energy consumption of the chillers 104-2 corresponding to AHUi, which may be represented by the following equation (3):
(3)
where, AHUi (C(i)) denotes sum of all apportioned chiller energies in the set
C(i); Chi(a)(k) denotes apportioned energy consumption of any chiller in the set C(i); k is any
number from 1 to N, if there are N number of chillers 104-2 in the set C(i).
[00042] Likewise, the apportioned energy consumed by the chillers 104-2 to condition
the given section corresponding to the AHUs 104-1 in the set Al is calculated by the determination module 112. Further, the determination module 112 adds all these apportioned energy consumption values to produce the total apportioned energy consumption by the chillers 104-2 corresponding to the AHUs 104-1 in the set AI. This sum may be referred to as S2, which can be represented by the following equation (4):
S2 = £ AHUi(C(i))(k) (4)
where, AHUi (C(i))(k) denotes sum of apportioned energies for a set of chillers 104-2 connected to any AHU of the set Al, and k is any number froml to N, if there are N number of AHUs 104-1 within the set A1.
[00043] Further, the apportioned energy consumed by the chiller pumps 104-3 towards
conditioning the space occupied by the selected section through the AHUs 104-1 in the set Al

is determined in a way similar to the determination of the apportioned energy consumption of the chillers 104-2. This calculated sum may be represented as S3, by the following equation:
53 = £ AHUi(CP(i))(k) (5)
where AHUi(CP(i)) (k) denotes sum of apportioned energies for any set of chiller pumps 104-3, say CP (i), connected to any AHUi of the set Al, and k is any number froml toN, if there are N number of AHUs 104-1 within the set Al.
[00044] Further, the apportioned energy consumed by the each AHU in the set A2 is
calculated. Any AHU/PAHU is the set A2 may be represented by a symbol AHUj. The apportioned energy consumed by AHUj, is calculated by multiplying the energy meter readings of AHUj with the ratio of the selected section's operating time over the sum total of the operating time of all the sections served by AHUj. In one implementation, the operating time of all sections refers to man hours of the section. Using this methodology, the energy consumed by each of the AHUs 104-1, specific to the selected section, in the set A2 is calculated by the determination module 112. The following equation illustrates the same:
(6)
where, AHUjA2 denotes energy meter readings of any AHU in A2; AHUjA2(a) denotes apportioned energy consumption corresponding to AHUj; MHSD denotes man-hours (operating time) of the selected section; and £MHD denotes total man-hours all sections associated with AHUj. Let the ratio, MHSD/ £ MHD, be denoted by F2. The sum of all such apportioned energy consumption values of AHUs 104-1 in the set A2 can be referred by S4, which may be represented by the following equation:
54 = £ AHUjA2(a)(k) (7)
where AHUjA2(a)(k) denotes the apportioned energy consumption of any AHU in the set A2 and k is any number froml to N, if there are N number of AHUs 104-1 in the set A2.
[00045] Further, the set of the identified chillers 104-2 serving AHUj may be
represented by C(j). The apportioned energy consumption of any of the identified chillers 104-2 in the set C(j), say Chj, is calculated by multiplying the energy meter readings of the chiller with the refrigeration ratio and F2. The refrigeration ratio in the present context

denotes the ratio of refrigeration tonnage rating supplied by AHUj over the total refrigeration tonnage supplied by all the AHUs 104-1 served by the chiller. As mentioned in the Equation (6), the factor F2 is the ratio of the selected section's operating time over the sum total of the operating time of all the sections served by AHUj. Using this methodology, the apportioned energy consumed by each chiller in the set C(j) is calculated by the determination module 112. The same may be represented by following equation;
(8)
where, Chj denotes the meter reading of any chiller in the set C(j); TRAHUJ denotes refrigeration tonnage of AHUj; £TR.AHu(k) denotes sum of refrigeration tonnage of all AHUs 104-1 served by the chiller in the set C(j); Chj(a) denotes the apportioned energy consumption with respect to Chj; and k denotes any number from 1 to N, if there are N number of AHUs 104-1 connected to Chj.
The determination module 112 adds all values of the apportioned energy
consumption of every chiller in the set C(j) to produce the total apportioned chiller energy consumption required for exclusively serving AHUj, Such calculation may be represented by the following equation:
AHUj(CG)) = Σ Chj(a)(k) (9)
where, AHUj (C(j)) denotes sum of all apportioned chiller energy consumption values in the set C(j) corresponding to AHUj; Chj(a)(k) denotes the apportioned energy consumption of any chiller in the set C(j); and k is any number from! to N, if there are N number of chillers 104-2 within the set C(j).
In a similar fashion, the total apportioned chiller energy consumption required
to exclusively serve rest of the AHUs 104-1 in the set A2 can be calculated. Adding all these values gives the total apportioned chiller energy consumption required to serve the selected section through the AHUs 104-1 in the set A2. Such sum may be denoted as S5 by the following equation:
S5 = Σ AHUj(CG)Xk) (10)

where, AHUj (C(j))(k) denotes sum of all apportioned chiller energy consumption values in the set C(j) connected to AHUj and k is any number froml to N, if there are N number of AHUs 104-1 within the set A2.
Further, the apportioned energy consumption by the chiller water pumps to
condition the space occupied by the selected section through the AHUs 104-1 in the set A2 can be determined in a way similar to that of determining the chiller energy corresponding to the set A2. The calculated sum may be referred to as S6, and represented by the following equation:
S6 = X AHUj(CP(j))(k) (11)
where, AHUj (CP(j))(k) denotes sum of apportioned energy consumption values for a set of chiller pumps 104-3, say CP(j), connected to any AHUj and k is any number froml to N, if there are N number of AHUs 104-1 within the set A2.
Further, the heat exchangers 104-4 identified by the identification module 110
as related to the selected section are classified by the determination module 112 into sets Dl and D2. The set Dl includes all those heat exchange units that exclusively serve the selected section. The set D2 includes all those heat exchange units which serve more than one section, including the selected section.
The energy consumption readings of all the heat exchangers 104-4
corresponding to the set Dl are added. The sum may be referred to as S7, which can represented by the following equation:
S7 = £ HED1(k) (12)
where, HEDi denotes the meter reading of any heat exchanger within the set Dl
and k denotes a value from 1 to N if there are N number of heat exchangers 104-4 within Dl.
The apportioned energy consumption by any heat exchanger in the set D2,
having the meter reading, say HED2h, is calculated in a way similar to the calculation of the apportioned energy consumption of AHUs 104-1 in the set A2. The same may be represented by the following equation:
(13)

where, HEo2h(a) denotes the apportioned energy consumption corresponding to HEo2h; MHSD denotes man-hours (operating time) of the selected section; and £MHD denotes total man-hours of all sections associated with HED2h.
The addition of the apportioned energy consumption by all the heat exchangers
104-4 in the set D2 is referred to as S8, which may be represented by the following equation:
S8 = ]T HED2h(a)(k) (14)
where, HEo2h(a)(k) denotes the apportioned energy consumption of any heat exchanger within the set D2 and k denotes a value from 1 to N, if there are N number of heat exchangers 104-4 within D2.
[00052] Furthermore, the determination module 112 calculates the apportioned energy
consumption of all cooling towers 104-5, which serve the identified chillers 104-2. For this purpose, the meter reading, say TOWm, of a particular water tower, is multiplied with the ratio of the sum of the apportioned energy consumption of all the identified chillers 104-2 to a sum of the energy meter readings of all the chillers 104-2 connected to the cooling water towers 104-5. The following equation illustrates the calculation for any cooling water tower:
(14)
where, TOWm denotes the meter reading of any cooling tower serving the chillers 104-2 in the set C(i) and C(j); £Ci(a) denotes the sum of apportioned energy consumption of all chillers 104-2 corresponding to the AHUs 104-1 in the set Al and being served by the cooling tower; £QKa) denotes the sum of apportioned energy consumption of all chillers 104-2 corresponding to the AHUs 104-1 in the set A2 and being served by the cooling tower; £Chi denotes the sum of energy meter readings of all chillers 104-2 corresponding to the AHUs 104-1 in the set Al and being served by the cooling tower; XChj denotes the sum of energy meter readings of all chillers 104-2 corresponding to the AHUs 104-1 in the set A2 and being served by the cooling tower; £Ce denotes the sum of energy meter readings of all chillers 104-2 not corresponding to the AHUs 104-1 in the set Al and A2, but being served by the cooling tower; and TOWm(a) denotes the apportioned energy consumption of any cooling tower in the building.

ft is understood that some chillers 104-2, as represented by Ce, connected to
the cooling water tower are not connected to the identified AHUs 104-1 to serve the selected section. Accordingly, the apportioned energy consumption of such chillers 104-2 towards the selected section is null. In one implementation, the determination of such type of chillers 104-2 may be made by the identification module 110.
Accordingly, the apportioned energy consumption of every cooling water
tower in conditioning the space of the selected section is calculated by the determination module 112. Adding all these values give the total energy consumption by all the cooling water towers 104-5 for conditioning the selected section. The sum as a result of such addition may be represented by S9 and by the following equation:
S9 = Σ TOWm(a)(k) (15)
where, TOWm(a) denotes the apportioned energy consumption of any cooling tower in the building and k denotes any value from 1 to N, if there are N number of cooling towers 104-5 in the building.
Therefore, the total energy consumption in conditioning the building space
occupied by the selected section is determined by the determination module 112 and may be
represented as: S1 + S2 + S3 + S4 + S5 + S6 + S7 + S8 + S9. This total energy consumed by
the selected section refers to the apportioned AC energy consumption, which is then stored in
the apportioned energy consumption data 220 by the determination module 112.
In one implementation, an analysis module (not shown in the figure) may be
linked to both the identification module 110 and the determination module 112 to analyze the power consumption of the selected section, thereby acting as an energy management system. The analysis module may accordingly help the office or any organization to plan optimization of power consumption, thereby decreasing the carbon footprint of the organization. Fig. 3 illustrates an exemplary method 300 to determine the air conditioning energy consumption of a specific section of a building, according to an embodiment of the present subject matter. The method 300 may be described in the general context of computer executable instructions. The method 300 may be a computer implementable method. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, functions, and the like that perform

particular functions or implement particular abstract data types. The method 300 may also be practiced in a distributed computing environment where functions are performed by remote processing devices that are linked through a communication network. In a distributed computing environment, computer executable instructions may be located in both local and remote computer storage media, including memory storage devices.
The order in which the method is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method, or an alternate method. Additionally, individual blocks may be deleted from the method without departing from the spirit and scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof. The method 300 described herein is in the context of the determination system 100, however, the method 300 can be implemented in other systems as will be understood by a person skilled in the art.
At block 302, a particular section in a building is selected. For example, the identification module 110 of the apportioning system 108 selects a section. Such a selection may be user defined. In one embodiment, the identification module 110 selects any section from a list of sections.
Further, at block 304, the identification module 110 identifies a location of the selected section within the building. For example, the identification module 110 identifies that the selected section is present on the fourth floor of the building. In addition, the identification module 110 identifies a certain number of air conditioning devices 104 involved in providing air conditioning to the selected section. Based on the location of the selected section, the identification module 110 identifies these air conditioning devices 104. In one implementation, the air conditioning devices 104 include AHU/PAHUs 104-1, chillers 104-2, chiller pumps 104-3, heat exchangers 104-4, and cooling water towers 104-5. At block 306, the determination module 112 apportions the energy consumption of each identified air conditioning device to the selected section, based on the energy meter readings and various types of energy metric, for example refrigeration tonnage of the identified AHU devices 104-1. In one implementation, the determination module 112 interacts

with the identification module 110 to receive the energy meter readings and the refrigeration tonnage rating from the metering device 106 of the metering system 102. Further, if the identified location houses other sections or sections apart from the selected section, then operating time of all sections may be taken into consideration as additional energy metric. In one embodiment, the operating time includes man-hours of sections. However, without limiting the scope of the present subject matter, other parameters which indicate heat generated within the selected section, such as a number of computing machines, coffee machines etc. may also be taken into consideration as the other types of energy metric.
Finally, at block 308, the determination module 112 determines an AC energy consumption of the selected section based on the apportioned energy consumption of the identified AC devices 104. In an implementation, the apportioned energy consumption of all identified AC devices in combination represents the energy consumption of the selected section. Accordingly, the energy consumption determined for different sections is displayed to the user say in the form of pie charts, bar graphs etc. This information may be used to make informed decisions on energy consumption and may also be used as input to energy management systems.
The determination system 100 described in the present subject matter facilitates accurate determination of the air conditioning energy consumption per section in a reasonable manner on the basis of refrigeration tonnage of the corresponding air conditioning devices 104 as well as the heat generated due to various sources within the section. Accordingly, building administrators can identify the sections consuming significant cooling energy and initiate appropriate energy conservation measures customized for such sections. In addition, the administrators recover the building's energy charges from each section in a fair manner by instituting a 'charge-back mechanism', which can be a function of the actual air conditioning energy consumption of the section.
Although embodiments for the determination system 100 have been described in language specific to structural features and/or methods, it is to be understood that the invention is not necessarily limited to the specific features or methods described. Rather, the

specific features and methods are disclosed as exemplary implementations for the determination system 100.

We Claim:
1. A method comprising:
identifying a plurality of air conditioning devices (104) serving a section by an identification module (110), wherein the section is selected out of a plurality of sections in a building;
receiving an energy consumption data and a plurality of refrigeration tonnage ratings of the identified air conditioning devices (104) from an HVAC metering device (106) associated with the plurality of air conditioning devices (104); and
determining an energy consumption of the section by a determination module (112), wherein the determination module (112) apportions the received energy consumption data to the section based at least, in part, on the plurality of refrigeration tonnage ratings.
2. The method as claimed in claim 1, wherein the identifying the plurality of air conditioning devices (104) comprises identifying a plurality of air handling units (104-1), chillers (104-2), chiller pumps (104-3), heat exchangers (104-4), and cooling water towers (104-5) serving the section.
3. The method as claimed in claim 1, wherein the receiving further comprises receiving an operating time of the section and an amount of heat generated within the section from the HVAC metering device (106).
4. The method as claimed in claim 2, wherein the determining comprises apportioning the received energy consumption data of the plurality of air handling units (104-1) and heat exchangers (104-4) to the section based at least on an operating time of the section and an amount of heat generated within the section.
5. The method as claimed in claim 2, wherein the determining comprises apportioning the received energy consumption data of the plurality of chillers (104-2) and chiller pumps (104-3) to the section based at least in part on the plurality of refrigeration tonnage ratings of the plurality of air handling units (104-1).
6. The method as claimed in claim 2, wherein the determining comprises apportioning the received energy consumption data of the plurality of chillers (104-2) and chiller

pumps (104-3) to the section based at least in part on an operating time of the section and an amount of heat generated within the section.
7. The method as claimed in claim 2, wherein the determining comprises apportioning the received energy consumption data of the plurality of cooling water towers (104-5) to the section based on an energy consumption of the plurality of chillers (104-2).
8. An air conditioning energy determination system for an organization, the system comprising a method as claimed in preceding claims to determine air conditioning expenditure for a plurality of departments in the organization.
9. An air conditioning energy consumption determination system (100) comprising:
a metering system (102) to provide a plurality of energy meter readings and refrigeration tonnage ratings of a plurality of air conditioning devices (104); and
an energy consumption apportioning system (108) comprising:
an identification module (110) to identify the plurality of air conditioning devices (104) serving a section selected from a plurality of sections in the building; wherein the identification module (110) receives the plurality of energy meter readings and refrigeration tonnage ratings of the identified air conditioning devices (104) from the metering system (102); and
a determination module (112) to determine an energy consumption of the section according to the plurality of energy meter readings and refrigeration tonnage ratings of the identified air conditioning devices (104),
10. The system (100) as claimed in claim 9, wherein the plurality of identified air conditioning devices (104) comprise a plurality of air handling units (104-1), chillers (104-2), chiller pumps (104-3), heat exchangers (104-4), and cooling water towers (104-5).
11. The system (100) as claimed in claim 10, wherein the determination module (112) determines an energy consumption of the plurality of air handling units (104-1) and

the heat exchangers (104-5) based at least in part on the plurality of energy meter readings.
12. The system (100) as claimed in claim 10, wherein the determination module (112)
determines an energy consumption of the plurality of air handling units (104-1) and
the heat exchangers (104-5) based at least in part on an operating time of the section
and an amount of heat generated within the section.
13. The system (100) as claimed in claim 10, wherein the determination module (112) determines an energy consumption of the plurality of chillers (104-2) and chiller pumps (104-3) based at least in part on the plurality of energy meter readings and the refrigeration tonnage ratings,
14. The system (100) as claimed in claim 10, wherein the determination module (112) determines an energy consumption of the plurality of chillers (104-2) and chiller pumps (104-3) based at least in part on an operating time of the section and heat generated within the section.
15. The system (100) as claimed in claim 10, wherein the determination module (112) determines an energy consumption of the plurality of cooling water towers (104-5) based on an energy consumption of the plurality of chillers (104-2).