Abstract:
A data center comprises a plurality of sections ( 15   a - 15   h ) assembled together to define a unitary structure ( 10 ) such that there exists at least one personnel area that spans at least two sections; wherein the sections comprise a first section with which there is associated a first service—carrying chassis ( 40, 50, 60, 70 ) and a second section with which there is associated a second service—carrying chassis  40, 50, 60, 70 ), each of the first and second service—carrying chassis comprising a frame ( 41, 51, 61, 71 ) onto which is mounted components of at least two different services ( 42 - 44, 46 ); the first and second chassis are connected to each other by means of a junction ( 47 ) between the first and second chassis; and the first and second sections each include a ceiling ( 22 ) and the first service carrying chassis is mounted on the ceiling of the first section and the second service carrying chassis is mounted on the ceiling of the second section.

Description:
FIELD OF THE INVENTION 
     The present invention concerns data centres and a method of constructing a data centre. More particularly, but not exclusively, this invention concerns data centre buildings, for example provided in sectional form. The invention also concerns a kit of parts for constructing a data centre. 
     BACKGROUND OF THE INVENTION 
     A data centre is a late 20th Century development that has grown as a response to the increasing demand for computer processing capability and a recognition of the importance of IT in the place of every business and organisation today. Whereas smaller organisations have sufficient processing power with laptops, PCs and occasionally servers, larger organisations require higher capacity centralised processing to serve a wide range of needs and applications. A few years ago this capacity was supplied by large mainframe computers, but more recently the method used has been to provide data centres comprising many networked computer servers known as blades installed in racks enabling controlled and modular expansion of capacity. The racks also typically house telecommunications equipment such as routers to handle data flow between the computer servers and data flow between the data centre and the outside world. 
     Data centres can mirror the growth and business activities of successful companies. The growth of a data centre within an expanding company may typically work as follows: 
     1. Initially the data centre may start as single rack of servers in an air conditioned room—sometimes referred to as a ‘data closet’. 
     2. As the organisation expands and along with it the number of IT racks employed, the closets become ‘Server Rooms’ or ‘IT Rooms’. 
     3. Eventually the number of racks and size of room expands, often to the point where a dedicated building or part of a building houses the IT. Whilst there is no strict definition of when the size of an IT facility becomes large, or sophisticated, enough to be termed a “data centre”, data centres are typically relatively large IT facilities providing robust and resilient IT facilities. Typically, there will be more than 50 servers (often many more) and at least some redundancy in the power supply powering the servers to ensure continuity of service. 
     4. As the company grows and/or becomes a multi-national organisation additional data centres will be built and sometimes numbers of these will be consolidated into ‘Super Data Centres’. 
     Data centre facilities can require a floor space ranging from a few hundred square feet to a million square feet. The most prevalent size for a small data centre is five to ten thousand square feet with fifty to a hundred thousand square feet being the most common floor area requirement for a large data centre. 
     Data centres will typically have the ability to deliver applications spread across an organisation and/or supply chain and/or customers in differing geographical locations. There will typically be a dedicated mechanical and electrical (M&amp;E) plant to deliver power, cooling and fire suppression with built-in redundancy with the aim of providing near continuous operation. 
     The IT industry has long recognised the criticality of central computing facilities and the need for energy efficient operations to control cost effectiveness. Current data centre technology is the summation of 30 years of innovation and engineering design thought and has come a long way in recent times. The most advanced new data centre designs tend to fall into one of two different types, each of which has advantages and disadvantages. The first, more traditional, type of data centre is a huge, custom built warehouse style building which is often located so as to be able to take advantage of local weather conditions to aid cooling of the IT equipment it houses. These data centres can be spacious, ergonomic and highly energy efficient because the structure, layout and cooling systems of each data centre are designed from scratch around its particular location and intended use. Yahoo!&#39;s “Computing Coop” data centre in New York is an example of this type of data centre. 
     The drawbacks of this type of data centre are the large cost and length of time for construction, which are necessary consequences of the bespoke design model. It is also not easy to add capacity—the data centre must be built large enough in the first place to cope with future increases in the number of servers required by its owner/occupier. These factors also make this style of data centre impractical for companies who need only a small or medium-sized data centre. A further significant drawback is the fact that only a few sites worldwide have a climate suitable for hosting such a large installation without placing undue demands on the cooling systems. The need for a large skilled construction workforce to be available at the site further limits the number of suitable locations. 
     The second type of data centre is the modular data centre, which is constructed from several factory-built modules. The modules are typically built and sometimes even fitted out at a central facility and then shipped to the location of the data centre, where they are connected together and to the local utilities. U.S. Pat. No. 7,738,251 (Google), for example, describes a modular data centre in which each module is formed by an ISO shipping container. This second type of data centre addresses some of the problems with the first type, but has several disadvantages of its own. In particular, it is necessary for easy transport of the modules that they conform to the dimensions of ISO shipping containers; however this significantly limits the space available inside each module for IT equipment, cooling systems and human access. If actual shipping containers are used as the basic modules, then this also places severe constraints on how the modules can be linked up into a single data centre. These features also mean that this style of data centre is generally not as energy efficient as the first type. 
     Some of the disadvantages of containerised data centres are overcome by the modular data centres described in WO 2010/139921 (Bripco) and WO 2011/051655 (Colt Technology Services). The data centres of WO 2010/139921 and WO 2011/051655 both consist of several modules which connect to form a building having internal spaces that span several modules. This allows for many more layout options than is possible with a containerised design. 
     The data centres of WO 2010/139921 and WO 2011/051655 still suffer from the disadvantage that, because the modules are assembled away from the site of the data centre, each module must be transported as a volumetric unit (where the volume of the unit when operational is the same as the volume of the unit when being transported). This necessarily involves significant costs due to the size of the modules, much of which volume comprises empty space inside the modules. This feature of prior art modular and/or containerised data centres places a limit on how energy efficient and cost-effective they can be, when the entire supply and construction process is taken into account. 
     The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved data centre and an improved method of constructing a data centre. 
     SUMMARY OF THE INVENTION 
     The present invention provides, according to a first aspect, a data centre comprising a plurality of sections assembled together to define a unitary structure such that there exists at least one personnel area that spans at least two sections; wherein the sections comprise a first section with which there is associated a first service-carrying chassis and a second section with which there is associated a second service-carrying chassis, each of the first and second service-carrying chassis comprising a frame onto which is mounted components of at least two different services; the first and second chassis are connected to each other by means of a junction between the first and second chassis; and the first and second sections each include a ceiling and the first service carrying chassis is mounted on the ceiling of the first section and the second service carrying chassis is mounted on the ceiling of the second section. 
     It will be appreciated that the personnel area may be any area within a data centre which it is possible for a person to enter, i.e. any room or corridor. For example the personnel area may be a rack room. The personnel area may be a cold aisle. The personnel area may be a cold corridor. Alternatively the personnel area may be a hot aisle. The personnel area may be a hot corridor. The data centre may comprise several such personnel areas. 
     The first and second sections each include a ceiling. The first service carrying chassis is mounted on the ceiling of the first section. The second service carrying chassis is mounted on the ceiling of the second section. Substantially all of the services in the first and second sections may be carried by the first and second service carrying chassis. There may be no services provided in the first and second sections other than the services carried by the first and second service carrying chassis. The services may include mechanical and electrical apparatus. 
     Thus, in an embodiment of the invention there may be no key mechanical and electrical apparatus (i.e. critical to the installation and operation of the data centre) mounted on the walls or floor of the majority of, if not all of, the data centre (e.g. such that no walls or floors are used in the data centre as supporting structure for the provision of trunk-like services to the areas in the data centre accommodating the IT racks). The advantages of mounting (substantially) all of the mechanical and electrical (M&amp;E) apparatus in chassis on the ceiling in most areas of the data centre are several. Firstly, this allows the data centre structure to be broken down into a kit comprising a minimum number of component types, which in turn reduces the cost of constructing the data centre and allows it to be economically shipped to a site remote from where the kit is manufactured. Secondly, it means that the services, including the mechanical and electrical apparatus required by the data centre, can be fully installed and tested before the kit is assembled into a data centre, which makes assembly of the kit very quick and simple. Thirdly, the use of a single chassis to provide multiple services is a compact and efficient solution which speeds assembly on site, compared to prior art construction techniques in which installation of M&amp;E services would be time-consuming. Further benefits and advantages will become apparent to the reader from the description that follows. 
     The services carried by the chassis may be in the form of utility-type services of the kind that require a conduit, for example, a pipe or cable or the like, to allow flow of fluids, power, signals, or the like from one location to another. The services may provide electrical power, data transfer and a fluid, for example. 
     The at least two different services may include at least one busbar. The at least two different services may include at least two busbars. One of these busbars may, but need not, be a backup busbar. The at least two different services may include at least one conduit for transporting fire suppressant gas. The at least two different services may include a cable tray. The at least two different services may include a length of network cable. 
     The at least two different services may include one or more connectors, for example for connecting adjacent sections of a busbar together. The junction between the two adjacent chassis may be formed by a plurality of separate connections. The junction may be formed by one or more separate junction connectors that link the services at one end of the chassis with the corresponding services at one end of the adjacent chassis. Preferably, there is provided a single junction connector for joining the services of adjacent chassis. 
     The at least two different services may include a lighting system. It will be appreciated that in an embodiment of the invention in which the lighting system is substantially entirely mounted on the ceiling, having light switches mounted on the walls (as is common practice for data centres and indeed all buildings) is precluded. The lighting system may include one or more sensors for detecting when a first area of the data centre is occupied. The lighting system may be arranged such that the lights in the first area of the data centre are on when that area is occupied and are off when that area is not occupied. Advantageously, this arrangement removes the requirement for manually operated light switches and also improves the energy efficiency of the data centre. 
     The data centre may be arranged such that at least one of the ceilings includes at least one track for mounting a service carrying chassis on. The track may be in the form of a rail. At least one of the service carrying chassis may be mounted on the at least one track. At least one of the service carrying chassis may include at least one engagement member arranged to engage with the track. The at least one engagement member may be arranged to slidably engage with the track. Advantageously, in an embodiment of the invention in which at least one of the service carrying chassis slidably engages with the track, that service carrying chassis may be easily moved from one position on the track to another. At least one of the service carrying chassis and/or the track may include at least one sliding prevention member arranged to controllably prevent sliding between the track and the at least one service carrying chassis. The sliding prevention member may be a bolt. The sliding prevention member may be a clamp. At least one of the first and second service carrying chassis may be arranged so as to connect to at least one other service carrying chassis. 
     Each of the first and second service carrying chassis may comprise a frame, onto which is mounted at least one item of mechanical and electrical apparatus. The at least one item of mechanical and electrical apparatus may comprise a busbar section. The at least one item of mechanical and electrical apparatus may comprise a length of network cable. The at least one item of mechanical and electrical apparatus may comprise a cable tray. Alternatively or additionally the at least one item of mechanical and electrical apparatus may comprise a length of fire suppressant gas conduit. 
     If each of the first and second service carrying chassis comprises a frame, the frame may include engagement members for engaging with the track. The engagement members, if present, may slidably engage with the track. 
     Embodiments of the invention in which the services required for running the data centre are carried by one or more service carrying chassis benefit from the advantages that installing the services, including the mechanical and electrical apparatus, into the data centre is a simple task of arranging the chassis adjacent to each other and connecting them together. This requires little or no specialist expertise. The design of the chassis may be optimised so that they are simple to manufacture and convenient to transport, which allows the possibility of outsourcing the manufacture of the chassis whilst maintaining high quality standards. It also allows the possibility of forward manufacturing chassis and keeping them in stock for when they are required. Separating the manufacture of the services from the construction of the building structure in this manner also significantly compresses the manufacture and build time of the data centre. The data centre may include three or more chassis, connected in series, for carrying at least two different services. Each chassis may have a length of greater than 1 m. Each chassis may have a length of less than 10 m. Each chassis may have a width of greater than 0.1 m. Each chassis may have a width of less than 2 m. 
     The data centre may be a modular data centre. The first and second sections may, but need not, be first and second modules of a modular data centre. It will be appreciated that the present invention is particularly advantageous when applied to embodiments in which the data centre is modular, since modular data centres are generally shipped from a manufacture location to a remote final assembly location. Usually each module is a pre-fabricated volumetric unit and must be transported as such; however the present invention allows the possibility of shipping each module as a compact kit of parts. Clearly this is highly advantageous with regards to the cost and energy efficiency of the modular data centre. 
     The volume of the kits of parts for a plurality of such modules when transported in such a compact manner may be significantly less (for example less than half) of the sum volume of the modules once assembled from such kits of parts. The invention also allows transportation of kits from a location remote from the intended site of the data centre to a local factory that is relatively near to the data centre site. The kits may be assembled into modules at the factory and then transported to the data centre site. 
     The modularity of the data centre is preferably provided by means of the data centre being divided into discrete sections that when assembled together form a unitary data centre structure. Thus, the various modules that form the data centre may perform different functions and need not be identically configured. There may for example be several IT room modules in the data centre. There may be a cooling air supply module for providing cooling air to the IT equipment in the data centre. 
     The sections may each comprise a wall. The sections may each define a volume. The volume may be greater than 10 m 3  and is preferably greater than 20 m 3 . The volume may be less than 250 m 3 . It will be appreciated that the volume defined by each section need not be physically bounded on all sides. Thus two adjacent sections may each have a partially or fully open face on their adjacent sides; the division between adjacent sections would nonetheless still be clear as a result of connections, joins or abutting surfaces at the boundary between the adjacent sections. Such a feature provides considerably more design freedom since the components need not be assembled to make individual and self-contained modules, but can instead be used to construct something more akin to a custom-built data centre, for example with two or more modules defining a connected open space, with the consequent improvements to energy efficiency and working environment that this brings. 
     The data centre so constructed may be of a type that utilises a hot aisle/cold aisle configuration. There may be a plurality of hot aisles interleaved between a plurality of cold aisles. The data centre may utilise an above-floor cooling regime. The cooling regime may provide cooling air via a personnel corridor, as opposed to using dedicated cooling air ducts. 
     The data centre may be housed within a larger building. The floor of the data centre (or the floor of the ground floor of the data centre if there is more than one storey to the data centre) may for example be formed by the floor of the large building. 
     The present invention also provides, according to a second aspect, a service carrying chassis for use in a data centre. The data centre may be one which comprises a plurality of sections, each with a ceiling, assembled together to define a unitary structure such that there exists at least one personnel area that spans at least two sections. The data centre may for example be a data centre according to the first aspect of the invention described herein. The service carrying chassis preferably comprises a frame, onto which is mounted components of at least two different services; and a mounting system for attaching the chassis to one of the ceilings of the data centre. 
     The components may include a busbar section. The components may include a plurality of busbar sections. The plurality of busbar sections may be arranged parallel to each other. The components may include a cable tray. The components may include a length of network cable. The components may include a light fitting. 
     The mounting system may comprise one or more engagement members arranged to engage with at least one of the ceilings. The engagement members may be arranged so as to be suitable for engaging with a track. The engagement members may be arranged so as to be suitable for slidably engaging with a track. 
     The present invention also provides, according to a third embodiment, a method of constructing a data centre comprising the steps of providing at least one ceiling portion; providing a plurality of supporting members; mounting services on the at least one ceiling portion; arranging the at least one ceiling portion and the plurality of supporting members into a first volume; transporting the ceiling portion and supporting members so arranged; and assembling the ceiling portion and supporting members to form a section of a data centre, the section so formed having a second volume; wherein the first volume is smaller than the second volume. 
     The first volume may be less than three-quarters of the second volume. Preferably the first volume is less than half of the second volume. The services may include at least two different services. The method may be performed such that the data centre is a modular data centre. If the data centre is a modular data centre, the first volume may be less than the volume of any one of the modules of the data centre in assembled form. If the data centre is a modular data centre, the first volume may be less than half of the volume of any one of the modules of the data centre in assembled form. The step of mounting services on the at least one ceiling portion may include the step of providing a first service carrying chassis comprising first components of at least two different services. The step of mounting services on the at least one ceiling portion may include the step of attaching the first service carrying chassis to the at least one ceiling portion. The ceiling portion may comprise one or more ceiling portions. 
     The method may additionally include the steps of providing at least one further ceiling portion; providing a second service carrying chassis comprising second components of at least two different services; attaching the second service carrying chassis to the at least one further ceiling portion; and connecting the first components to the second components. The method may be performed such that the second components are substantially identical to the first components. 
     The step of mounting services on the at least one ceiling portion may include the steps of providing at least one track on the ceiling portion, and slidably attaching the first service carrying chassis to the at least one track. 
     The at least one ceiling portion may be constructed from a plurality of corner elements and a plurality of horizontal support members. The horizontal support members are preferably joined to the corner elements to form a rectangular structure. 
     The plurality of supporting members preferably includes a plurality of vertical support members. The plurality of vertical support members may include a plurality of corner posts. The plurality of vertical support members may include intermediate posts. The vertical support members are preferably not joined to the ceiling portion during transportation. Preferably, the vertical support members are laid flat (and horizontal) during transportation. The corner elements have a height that is no more than 25% different from, and preferably substantially the same as, half the height of the first volume (of the parts when transported). Preferably the corner elements have a height of less than 1 m. Preferably the corner elements are arranged vertically when transported. Preferably the corner elements and the vertical support members are so arranged that in the assembled data centre, a vertical member extends vertically from each corner element. One of the corner element and the vertical support member includes a socket in which the other of the corner element and the vertical support member is received, in the assembled data centre. In the assembled data centre, the section of the data centre formed by the ceiling portion and the supporting members may form part of a roof of the data centre. The section of the data centre formed by the ceiling portion and the supporting members may form part of the floor of a second of higher storey of the data centre. Advantageously, the ceiling portion and the supporting members may be so configured that they may form, at the choice of the user/installer, part of a roof of a data centre or part of a floor of a second or higher storey of a data centre. The ceiling portion and the supporting members may thus be transported together with one or more roof portions. Having one set of components (e.g. ceiling portion and associated supporting members) that can be used selectively in each of (a) a single storey data centre, (b) as a lower level in a multi-storey data centre, or (c) as the uppermost level in a multi-storey data centre, allows for streamlining of manufacture and minimising the number of different components or systems required for multiple data centre builds. 
     It will be appreciated that the modules or sections of the data centre may be assembled before being joined to each other. Alternatively, part-assembled modules or sections of the data centre may be joined before each section or module is fully assembled. In either case, fit-out of the data centre will typically follow once the building of the data centre has been completed and the mechanical and electrical services installed. Installation of servers and networking IT equipment will typically be conducted when fitting-out, and/or possibly after (so that fit-out does not extend to putting servers in racks in the data centre building). 
     The method may be performed such that the first service carrying chassis is a service carrying chassis as described above. 
     Thus, in an embodiment of the invention the components of a data centre may be manufactured remotely from the site where the data centre is to be located, and furthermore, substantially all of the services (including the necessary mechanical and electrical apparatus) required for the operation of the data centre may be installed onto the ceiling portion and tested at this stage. There is no need to assemble the data centre components into a data centre in the factory, which clearly allows for a highly streamlined production line. The data centre components, with the services already fitted, can then be packaged into a volume small enough that several packages can be fitted into a standard ISO shipping container. 
     Clearly this has significant cost and environmental advantages as compared to shipping each data centre module in volumetric form, as is required by current modular data centre designs. The present invention also provides, according to a fourth aspect, a kit of parts for constructing a section of a data centre, the kit comprising at least one ceiling portion; a plurality of supporting members; and at least one service carrying chassis comprising components of at least two different services; wherein the at least one service carrying chassis is arranged to be mounted to the at least one ceiling portion. 
     The ceiling portion may be arranged to also function as a roof portion. The ceiling portion may be arranged to also function as a floor portion, for example if the kit is for constructing a section of a multi-storey data centre. The kit may additionally comprise at least one floor portion. The kit may be supplied such that the at least one service carrying chassis is mounted on the at least one ceiling portion at the time of supply. The at least one service carrying chassis may be integral with the at least one ceiling portion. 
     The kit may be arrangeable in a first configuration for facilitating transport of the kit and in a second configuration corresponding to the assembled configuration of the kit, wherein the volume of the first configuration is less than half the volume of the second configuration. The first configuration may have dimensions such that it fits inside an ISO shipping container. The first configuration may have dimensions such that at least two kits arranged in the first configuration fit inside a single ISO shipping container. Preferably the first configuration has dimensions such that at least three kits arranged in the first configuration fit inside a single ISO shipping container. The kit of parts may be arranged such that the data centre is a data centre as described above. 
     According to a further aspect of the invention, there is provided a data centre comprising a plurality of sections assembled together to define a unitary structure such that there exists at least one personnel area that spans at least two sections; wherein 
     the sections comprise a first section with which there is associated a first service-carrying chassis and a second section with which there is associated a second service-carrying chassis; 
     the first and second chassis are connected to each other by means of a junction between the first and second chassis; and 
     the first and second chassis each carry at least two different services. 
     It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: 
         FIG. 1  shows a plan view of a data centre according to a first embodiment of the invention; 
         FIG. 2 a    shows a perspective view of a section of the data centre of  FIG. 1 ; 
         FIG. 2 b    shows an exploded view of the components of a section of the data centre of  FIG. 1 ; 
         FIG. 3  shows a partial perspective view of the data centre of  FIG. 1 ; 
         FIG. 4  shows a perspective view of a service carrying chassis according to the first embodiment; 
         FIG. 5  shows a perspective view of a different service carrying chassis according to the first embodiment; 
         FIG. 6  shows a perspective view of a further different service carrying chassis according to the first embodiment; 
         FIG. 7  shows a perspective view of yet another different service carrying chassis according to the first embodiment; 
         FIG. 8  shows a perspective view from above of a ceiling portion and supports according to the first embodiment; 
         FIG. 9  shows a perspective view from below of a ceiling portion, service carrying chassis and supports according to the first embodiment; 
         FIG. 10  shows a perspective view of a floor portion and other components of a data centre section according to the first embodiment; 
         FIG. 11  shows a perspective view of components of a data centre section according to the first embodiment; 
         FIG. 12  shows a perspective view of packaged components of three data centre sections according to the first embodiment; 
         FIGS. 13 a  and  b    show perspective views of a DX module and an air optimiser module respectively according to the first embodiment; 
         FIG. 14  shows a perspective view of a partially assembled section of the data centre of  FIG. 1 ; 
         FIG. 15 a    shows a perspective view of all of the sections of the data centre of  FIG. 1 ; 
         FIG. 15 b    shows a perspective view of the data centre of  FIG. 1 ; 
         FIG. 16 a    shows a perspective view of part of a two-storey data centre according to a second embodiment; 
         FIG. 16 b    shows an exploded perspective view of parts of the data centre shown in  FIG. 16 a   ; and 
         FIG. 17  is a composite illustration showing on the right-hand side a perspective cut-away view of the two-storey data centre of the second embodiment and on the left hand side schematic representations of the construction of the ceiling of each storey. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows the layout of a data centre building  10  according to a first embodiment of the invention. At either end of the building  10  there is an entrance  11 . At the front of the building there is a fire exit  12 . Also at the front of the building are two ambient air intake holes  13 . Each ambient air intake  13  contains a set of controllable louvres which enable the amount of ambient air that is allowed into the building to be controlled. Ambient air entering the building is denoted by the white arrows. Between the two ambient air intakes  13  there are two holes defining a pair of exhaust air outlets  14 . Exhaust air outlets  14  also each contain a set of controllable louvres. Exhaust air exiting the building is denoted by the black arrows. 
     The data centre building  10  is made up of eight sections  15   a - h , with the joins between adjacent sections shown by dotted lines. The short ends of the rectangular sections form the front and back external side walls of the building. The left-hand side of section  15   a  and the right-hand side of section  15   h  form the left and right external side walls respectively of the building. All of the sections  15   a - h  have the same dimensions and basic construction, differing only in the provision and arrangement of internal and external doors and walls and air inlets and outlets. 
       FIG. 2 a    shows section  15   e  (internal walls have been omitted for the sake of clarity) in isolation.  FIG. 2 b    shows an exploded view of the components of section  15   e  (with internal walls, but omitting external wall panels). All of the sections  15  consist of a floor portion  21 , a ceiling portion  22 , four corner support posts  23 , four intermediate support posts  24 , and six external wall panels  25  (only the three front external wall panels are shown in  FIG. 2 a   ). Section  15   e  additionally includes a fire door in the front end wall, and sections  15   d  and  15   f  each additionally include an exhaust air outlet  14  in the front end wall. The external wall panels of these sections are shaped appropriately to accommodate these features. The external wall panels  25  are formed from highly insulated aluminium panels, with a fire resistance of at least one hour. 
     Floor portion  21  and ceiling portion  22  are both based on a framework consisting of two long side steel beams  26 , two short end steel beams  27 , and four steel corner elements  28 , which are designed to connect with the corner posts  23 . The beams and corner elements are welded together in a rectangular shape. Steel joists (not visible) extending between the side beams are provided at regular intervals. The steel beams may, if desired, be provided with weakened sections which allow them to flex, so that the data centre building will be more resilient in the event of an earthquake. 
     Floor portion  21  additionally has a plywood floor deck supported on the joists, and a sheet of waterproof liner material fixed to the bottom of the joists. Ceiling portion  22  additionally has insulating material fixed above and below the joists, and a steel panel roofing system (such as Kingspan) including falls to both sides of the roof and external drainage collection, fixed over the top layer of insulating material. The lower surface (not visible) of the ceiling portion  22  is made from steel plate with a plastic coating finish. 
     Inside the section  15   e  there is an internal wall consisting of three internal wall panels  29  (one of which includes a glass viewing pane) and a vented door assembly  19 . Two further internal wall panels  29  are also provided at the opposite end of section  15   e . These serve to seal off the end of a cold aisle in the data centre  10 . The internal and external wall and ceiling portions may, if desired, be constructed with magnetic shielding, RF or X-ray protection. The internal finish of the walls and ceiling is a plastic coated galvanised steel finish. 
     Data centre  10  comprises eight sections  15  arranged adjacent to each other and bolted together. Sections  15   a  and  15   h , which will henceforth be referred to as air optimiser sections, each contain a region  16  which is designed to accommodate air treatment equipment such as adiabatic coolers, DX coolers, filters and fans. Sections  15   a  and  15   h  also each include an ambient air intake  13  through which ambient air can enter the data centre building  10 , a controllable return air vent  17  through which warm air exhausted by IT equipment in the data centre can be returned to the air treatment equipment, and an air mixing box  18  for mixing the air from return air vent  17  and ambient air intake  13 . Sections  15   a  and  15   h  additionally each have an internal wall running along most of the length of one side of the section. These walls include the return air vents  17  and several doors which provide access to the air treatment equipment. 
     Sections  15   b - g , which will henceforth be referred to as IT sections, are designed to accommodate IT equipment housed in standard server racks of up to 1200 mm depth. Each section  15   b - g  contains elongate rectangular rack storage areas (sections  15   b - f  each have two such rack storage areas whilst section  15   g  has just one, to allow for access to the adjacent air treatment region  16 ). Each rack storage area is effectively defined by a single row of racks  20  running lengthways along the section, i.e. widthways across the building. 
     In each section  15   b - g  at the rear end of the rack storage area(s) there is an internal wall running across the entire width of the section. A vented door  19  having controllable louvres is provided in the wall to allow personnel access and the passage of cooling air into the space between the racks, which is therefore a cold aisle. An additional, smaller internal wall is provided at the opposite end of the rack storage areas, spanning the gap between the racks. This internal wall is designed to close off the cold aisle at the front end. At the top of both rows of racks  20  are over-rack blanking plates (not shown) designed to stop cold air passing between the top of the racks  20  and the ceiling of the section. Hence, air can only leave the cold aisle through the racks  20 . 
     When the sections are connected together a corridor running along and in between the rear external wall of the building and the rear internal walls is defined. This corridor runs along the entire length of the data centre building  10 , terminating at each end in a wider area directly behind each air treatment region  16 . The air treatment equipment supplies cooling air directly into this corridor at each end, hence it is a cold corridor. From this cold corridor, the cooling air passes through the vented doors  19  into the cold aisles. 
     The spaces that are defined between the rear sides of adjacent rows of racks when the sections  15   a - h  are connected together receive warm air exhausted by IT equipment in the racks, and are therefore hot aisles. The hot aisles are directly connected to a larger hot corridor which runs adjacent to the front external wall of the building, between the two return air vents  17 . Hot air can exit the hot corridor through exhaust air outlets  14  and/or return air vents  17 . 
     The data centre building  10  includes various services including lighting, smoke detection and fire suppression, power distribution, and controlling the air treatment equipment. As far as possible the mechanical and electrical apparatus is mounted on the ceiling of the data centre building  10 . The arrangement of the mechanical and electrical apparatus in data centre building  10  will now be described with reference to  FIGS. 3-7 . 
     The space behind the air treatment region  16  in section  15   h , which is shown in detail in  FIG. 3 , contains a power metering panel for monitoring the power consumed by each rack in the rack room module, two electrical distribution panels  32 , a control process panel  31 , a VESDA (Very Early Smoke Detection Apparatus) fire detection monitoring panel, and an uninterruptible power supply and back-up batteries. These apparatus are mounted on the walls of section  15   h , which is the only section of the data centre building  10  to have any wall-mounted mechanical and electrical apparatus. A metal grille  33  separates the electrical distribution panels from the other panels. The grille  33  includes a portion that can be opened to allow personnel access to the electrical distribution panels  32 . 
     Each of the IT sections  15   b - g  also has its own sub-control panel, referred to as an outstation. The outstations are located directly above the vented doors  19 , and are integral with the door frames. Each outstation monitors and controls the position of the louvres in the vented door in its section, based on airflow velocity data for the cold aisle in its section. This data is provided by sensors located in ducts which link each cold aisle to an adjacent hot aisle. 
     The control process panel  31  receives data, such as temperature and humidity data, from various sensors inside and outside the data centre building  10 . It also receives information about the positions of the louvres in the vented doors  19  from the outstations. It uses this information to control the air treatment equipment and the various controllable intake and outlet vents in order to achieve effective and energy efficient cooling of IT equipment in the racks. 
     The control process panel  31  communicates with the outstations, sensors, air treatment equipment and controllable vents using a wired network. Each outstation, sensor, item of cooling equipment and item of mechanical and electrical equipment which is monitored and/or controlled by the control process panel  31  must therefore be connected to it by a network cable. Network cables must also be connected to all of the IT equipment in the racks. Other services which must be distributed around the data centre building  10  include power, which is distributed using busbars, fire suppression gas, and lighting. In data centre  10  this is achieved by mounting all of these services to the ceiling using a system of service cassettes. 
       FIG. 4  shows a cold corridor service cassette  40 , for use in the cold corridor of data centre  10 . The cassette  40  consists of a metal framework  41  which supports a length of main busbar  42 , a length of back-up busbar  43 , two lengths of UPS busbar  44  (which distributes power from the uninterruptible power supply), a cable tray  45 , and a light fitting  46 . A smoke sensor (not shown) is also attached to framework  41 . 
     The busbar lengths  42 ,  43 ,  44  are provided with connectors  47  at each end so that they can be joined to adjacent busbar lengths on neighbouring service cassettes. The main and back-up bus bar lengths  42 ,  43  are also provided with junctions  48  which allow right-angled connections to be made with other busbars. The UPS busbar lengths have similar junctions (not shown) at a different point along their length. It will also be seen that the main busbar length  42  and the back-up busbar length  43  are each actually made up of two separate sections connected together. The light  46  is connected directly into the main busbar, and is wired to infrared sensors (not shown) attached to framework  41 . The infrared sensors detect when the area immediately surrounding the light  46  is occupied and activate the light  46  only when this is the case. There is therefore no need for light switches to be provided on the walls. 
     The length of the cold corridor service cassette  40  is equal to the width of a section  15 . One cassette  40  is mounted on the ceiling of each section  15  so that when the sections  15  are arranged adjacent each other, the busbar lengths in neighbouring service cassettes meet and can be connected together. Hence four busbars (main, back-up, small power UPS, and general lighting and power) are formed which run along nearly the entire length of the cold corridor, on the ceiling. 
       FIG. 5  shows a cold aisle service cassette  50 , for use in the cold aisles of data centre building  10 . Service cassette  50  consists of a metal framework  51  which supports the UPS and general busbar lengths  52 , a cable tray  53 , a length of fire suppression gas pipe  54 , a light fitting  55  and its associated infrared sensors, and a smoke sensor (not shown). The UPS and general busbar lengths  52  are provided with connectors at each end. As with the light  46 , light  55  is arranged to activate automatically when the area immediately surrounding the light is occupied. 
     The length of the cold aisle service cassette  50  is such that three cassettes  50  placed end-to-end are the same length as each of the cold aisles. Thus, when three cassettes  50  are mounted on the ceiling of a cold aisle and connected together they provide a small power UPS busbar, a general lighting and power busbar, and a fire suppression gas pipe which run the entire length of that cold aisle. The UPS busbar provides an uninterruptible power supply to the IT equipment in the racks facing onto that cold aisle. 
       FIG. 6  shows a hot corridor service cassette  60 , for use in the hot corridor of data centre building  10 . Most of the mechanical and electrical services are routed through the cold corridor, so cassette  60  simply consists of a metal framework  61  which supports a cable tray  62 . A light fitting (not shown) and its associated sensor, and a smoke sensor (not shown) are also fixed to the framework  61 . The length of the hot corridor service cassette  60  is equal to the width of a section  15 . One cassette  60  is mounted on the ceiling of each section  15  so that when the sections  15  are arranged adjacent each other, cable trays and lighting are provided along the entire length of the hot corridor. 
       FIG. 7  shows a hot aisle service cassette  70 , for use in the hot aisles of data centre building  10 . Cassette  70  consists of a metal framework  71  which supports a length of main busbar  72 , a length of back-up busbar  73 , and a light fitting  74 . Infrared sensors (for operating the light) and a smoke sensor are also fixed to framework  71 . The busbar lengths  72  and  73  are provided with connectors at each end. The length of the hot aisle service cassette  70  is such that three cassettes  70  placed end-to-end are the same length as the hot aisles. Thus, when three cassettes  70  are mounted on the ceiling of a hot aisle and connected together they provide a main busbar and a back-up busbar which run the entire length of that hot aisle. These busbars provide the main power supply for the IT equipment in the racks backing onto that hot aisle. 
     The service cassettes  40 ,  50 ,  60  and  70  are mounted to the ceiling via rails attached to the ceiling portions. The cassettes  40 ,  50 ,  60  and  70  have gripping members (not shown) which fit around the rails. These gripping members secure the service cassettes to the ceiling whilst also permitting sliding movement along the rails, which facilitates the task of connecting adjacent cassettes. Each gripping member includes a bolt which, when the service cassette is in the desired place, can be screwed in so as to press against the rail. When screwed in the bolts prevent the service cassette from sliding. 
     Adjacent cassettes of the same type are connected end-to-end as described above. However, busbars carried by the hot aisle service cassettes  70  and the cold aisle service cassettes  50  must also be connected to the busbars carried by the cold corridor service cassettes  40 . For the cold aisles this is achieved by connecting the ups busbars in the cold corridor to each of the outstations using the junctions provided on the UPS and general busbars. The UPS and general busbars in each of the cold aisles are then also connected to their respective outstations by the connectors at the end of the busbar lengths. 
     The main and back-up busbars in the hot aisles are connected directly to the main and back-up busbars in the cold corridor at junctions  48 , by way of additional lengths of busbar which pass through slots in the internal wall between the cold corridor and each of the hot aisles. These additional lengths of busbar connect at one end to connectors on the hot aisle service cassettes  70  and at the other end to the junctions  48 . The slots in the internal wall are arranged to seal around the busbars (and any cables) which pass through them so as to prevent air passing between the cold corridor and the hot aisles. 
     The fire suppression gas pipes carried by the cold aisle service cassettes  50  are sealed at the ends which terminate at the internal wall separating the cold aisles from the cold corridor. At their opposite ends, each of the pipes passes through a hole in the internal wall between the cold aisle and the hot corridor. These holes are sealed around the pipes so as to prevent air passing from the cold aisle to the hot corridor. In the hot corridor each gas pipe runs vertically down the internal wall to connect with a pair of cylinders in which fire suppression gas is stored. 
     The method by which a data centre building  10  is constructed will now be described with reference to  FIGS. 8-15 . 
     The air treatment sections  15   a  and  15   h  are composed of the set of components listed in table  1   a . The IT sections  15   b - g  are composed of the set of components listed in table  1   b . These components may all be manufactured in a central factory, alternatively the manufacture of some of the components may be outsourced to specialist manufacturers to reduce costs and build time. If the data centre building is to be located in a different country from the central factory, or even a considerable distance away in the same country, it is advantageous to source these components from a manufacturer local to the data centre site. In the case of the floor and roof coverings a particular local supplier is nominated to ensure high levels of consistency and quality. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Components of an air optimiser section 
               
             
          
           
               
                 Section 
                 Component 
                 Source 
               
               
                   
               
               
                 Air optimiser 
                 Building management system 
                 Central factory 
               
               
                 section (15a 
                 controls 
               
               
                 and 15h) 
                 Power metering apparatus 
                 Central factory 
               
               
                   
                 Fans 
                 Central factory 
               
               
                   
                 Humidifier and humidifier control 
                 Central factory 
               
               
                   
                 panel 
               
               
                   
                 DX cooling controls and expansion 
                 Central factory 
               
               
                   
                 valves 
               
               
                   
                 Trim packs 
                 Central factory 
               
               
                   
                 Sensors 
                 Central factory 
               
               
                   
                 Louvre actuators 
                 Central factory 
               
               
                   
                 Building Management System 
                 Central factory 
               
               
                   
                 Fire alarm and fire suppression 
                 Central factory 
               
               
                   
                 systems 
               
               
                   
                 Floor portion 
                 Locally sourced 
               
               
                   
                 Ceiling portion 
                 Locally sourced 
               
               
                   
                 Corner and intermediate posts 
                 Locally sourced 
               
               
                   
                 External wall panels 
                 Locally sourced 
               
               
                   
                 Internal wall panels 
                 Locally sourced 
               
               
                   
                 Internal and external doors 
                 Locally sourced 
               
               
                   
                 Air intake and return air vent louvres 
                 Locally sourced 
               
               
                   
                 Coldlocks and easipaths 
                 Locally sourced 
               
               
                   
                 Transit covers/lifting eyes/locating 
                 Locally sourced 
               
               
                   
                 plates 
               
               
                   
                 Fixings 
                 Locally sourced 
               
               
                   
                 Air optimiser chassis 
                 Locally sourced 
               
               
                   
                 Low voltage electrical panels 
                 Locally sourced 
               
               
                   
                 Service cassettes 
                 Locally sourced 
               
               
                   
                 Cabling 
                 Locally sourced 
               
               
                   
                 DX units 
                 Locally sourced 
               
               
                   
                 Floor covering 
                 Locally sourced 
               
               
                   
                   
                 from nominated 
               
               
                   
                   
                 supplier 
               
               
                   
                 Roof covering 
                 Locally sourced 
               
               
                   
                   
                 from nominated 
               
               
                   
                   
                 supplier 
               
               
                   
               
             
          
         
       
     
     The components which are marshalled in the central factory include the controls for the building management system and for the DX cooling units, all of the power metering apparatus for the data centre building, the humidifiers and their associated controls, the various sensors used to control the data centre, and trim packs, which include the external cladding and fascias, internal skirting and ceiling trims, and trims for the doors and louvre frames. These components are packaged up and transported to a local assembly facility relatively near the site where the data centre is to be located. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Components of an IT section 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 IT section (15b-g) 
                 Outstation 
                 Central factory 
               
               
                   
                 IT room network switches 
                 Central factory 
               
               
                   
                 Vented doors and actuators 
                 Central factory 
               
               
                   
                 Power metering apparatus 
                 Central factory 
               
               
                   
                 Trim packs 
                 Central factory 
               
               
                   
                 Floor portion 
                 Locally sourced 
               
               
                   
                 Ceiling portion 
                 Locally sourced 
               
               
                   
                 Corner and intermediate 
                 Locally sourced 
               
               
                   
                 posts 
               
               
                   
                 External wall panels 
                 Locally sourced 
               
               
                   
                 Internal wall panels 
                 Locally sourced 
               
               
                   
                 Internal and external doors 
                 Locally sourced 
               
               
                   
                 Blanking panels 
                 Locally sourced 
               
               
                   
                 Exhaust air outlet louvres 
                 Locally sourced 
               
               
                   
                 Coldlocks and easipaths 
                 Locally sourced 
               
               
                   
                 Transit covers/lifting eyes/ 
                 Locally sourced 
               
               
                   
                 locating plates 
               
               
                   
                 Fixings 
                 Locally sourced 
               
               
                   
                 Service cassettes 
                 Locally sourced 
               
               
                   
                 Cabling 
                 Locally sourced 
               
               
                   
                 Fire alarm and fire 
                 Locally sourced 
               
               
                   
                 suppression systems 
               
               
                   
                 Floor covering 
                 Locally sourced from 
               
               
                   
                   
                 nominated supplier 
               
               
                   
                 Roof covering 
                 Locally sourced from 
               
               
                   
                   
                 nominated supplier 
               
               
                   
               
             
          
         
       
     
     Locally sourced components, which include the components making up the structural frame of the sections, are delivered to the local assembly facility from the local manufacturer from which they have been commissioned. 
     At the local assembly facility, the roof and floor coverings are installed on the ceiling portions  22  and the floor portions  21 . Then the service cassettes carrying most of the mechanical and electrical apparatus required in the data centre building  10  are fitted to the ceiling portions  22  for the IT sections  15   b - g . To allow easy fitting of service cassettes to a ceiling portion  22 , in the local assembly facility the ceiling portion is supported on columns  81  which are just tall enough to allow a person to stand underneath the ceiling portion, as shown in  FIGS. 8 and 9 . 
     As a first step, rails are fitted to the underside of the ceiling portion  22 , along the width of the portion in the regions that will form parts of the ceilings of the hot corridor and the cold corridor, and along its length in the regions that will form the ceilings of the hot aisle and the cold aisle. A cold corridor service cassette  40  is then engaged with the rails on the cold corridor ceiling region and slid into place so that the ends of the service cassette  40  line up with the long edges of the ceiling portion  22 . When in place the bolts on the gripping members are screwed in to prevent further movement of the cassette  40 . 
     Three hot aisle service cassettes  70  are engaged (in series) with the rails on the hot aisle ceiling and slid into position. Connections are made between the busbar lengths  72  and  73  carried by the service cassettes  70  and the bolts on the gripping members are screwed in to secure the service cassettes  70  in position. This process is repeated for the three cold aisle service cassettes  50  and the hot corridor service cassette  60 . 
     Bulkheads  91  which fill the space between the top of the racks  20  and the ceiling are also fixed to the ceiling portion  22  at this point. The ceiling portion  22  is then ready to be packed up with rest of the structural components of the IT section. 
     All of the structural components of the IT section can be arranged into a compact space for transit by arranging them as follows. The external wall panels  25 , vented door assembly  19 , corner posts  23 , intermediate posts  24  and internal wall panels  29  are laid out flat on top of floor portion  21  as shown in  FIG. 10 , and temporarily fixed into place using any suitable removable securing means known in the art. The ceiling portion  22 , with attached service cassettes and bulkheads is then placed on top of these components as shown in  FIG. 11  to form a package  111 . 
     The corner elements  28  are formed such that the corner elements of the ceiling portion  22  have a wide section and a narrow section, with a lip where these two sections meet. The narrow section can be inserted into the corresponding corner element on the floor portion  21 . The lip then rests on the top of the floor portion corner element and supports the weight of the ceiling portion  22 . The height of the corner elements  28  is such that when the floor and ceiling portions are fitted together in this manner there is a small gap between the bottom of the service cassettes and the components laid out on top of the floor portion  21 . Thus the ceiling portion  22  covers and protects the components laid out on the floor portion  21  but does not bear any weight onto them. The corner elements  28  of the floor and ceiling portions are then bolted together to allow the entire package  111  to be handled as a single unit. 
     The process of assembling and packing the components of the air optimisation sections  15   a  and  15   h  is very similar to that described above for the IT sections  15   b - g , however service cassettes are not used in these sections. The packing process for an air optimisation section therefore involves just arranging and securing the components of the air optimisation section between the floor and ceiling portions  21  and  22  and fixing the floor and ceiling portions together to form a package  112 . Because the floor and ceiling portions of the air optimisation sections are identical to the floor and ceiling portions of the IT sections, the packages  111  and  112  are of identical shape and size. Three such packages stacked one on top of the other, as shown in  FIG. 12 , will fit into a standard ISO shipping container. A cover  121  protects the floor and ceiling portions  21 ,  22  from incurring cosmetic damage during transit. 
     The remaining components of the data centre which are not packed up with the IT sections and air optimiser sections are packaged up separately. In particular, the DX units are packaged into self-contained DX modules  131 . A DX module  131  is shown by  FIG. 13 a   . In each DX module  131  the DX units  132  are secured into a stackable metal frame  133  which is designed to fit within a standard ISO shipping container. All of the DX condensers  132  in a DX module  131  are connected up to power and control cabling and refrigerant gas pipework which meets at a single connection point (not visible). The DX modules  131  can be installed onto the data centre building  10  in this form, and only require connection to the appropriate utilities (i.e. power, a supply of refrigerant gas, and the process control panel  31 ) before being ready for use. 
     The other items of air treatment apparatus required by the data centre are also provided packaged in stackable metal frames  135  with single connection points, as shown by  FIG. 13 b   . Five such frames carry all of the air treatment equipment required by a single air optimisation section  15   a ,  15   h . Frame  134   a  carries sound attenuators. Frame  134   b  carries a bank of variable speed fans. Frame  134   c  carries humidifiers. Frame  134   d  carries the DX cooling coils. Finally, Frame  134   e  carries air filters. Each frame  134   a - e  also carries a door  135  to allow access to the air treatment equipment. The frames  134   a - e  can be connected together to form an air optimisation module  136  which can then be inserted into an air optimisation region  16  in one of the air optimisation sections  15   a ,  15   h.    
     Once packed up, all of the components of the data centre building  10  are transported to the site where the data centre is to be located. This site must be provided with a flat, level foundation and connections to supplies of electricity and water, drainage facilities, and a communications network. 
     Erecting the data centre building  10  from its constituent components requires no skills beyond what a typical construction worker would possess, and as such it is possible to use a construction team hired locally to the data centre site. The process of erecting the data centre building  10  will now be described with reference to  FIGS. 14 and 15 . 
     The first step in the erection of the data centre building  10  is to separate the section packages  111 ,  112  and remove the components which are secured to the floor portions  21 . Each section  15  is then erected as follows. The corner posts  23  and intermediate posts  24  are connected to the floor portion  21  and bolted in place. The ceiling portion  22  is then lifted onto the corner and intermediate posts. The corner elements  28  of ceiling portion  22  and the corner posts  23  are shaped such that the top portion of each corner post  23  receives within it the narrow part of the corresponding corner element  28 . The corner elements of the floor portion  21  and the bottom portion of each corner post are similarly complementarily shaped; however the bottom portion of each corner post is received within the corresponding floor portion corner element. The top and bottom ends of the intermediate posts  24  are received into recesses in the ceiling portion  22  and floor portion  21  respectively. This ensures that the structure formed by the floor portion  21 , corner posts and ceiling portion  22  remains securely in place until all of the corner elements  28  can be bolted to the corner posts  23 . 
     Once this basic section structure has been assembled, the internal wall panels  29  are fixed into place as shown by  FIG. 14 . The vented door  19  and outstation is installed at this stage, as are the busbar sections which connect the cold corridor busbars to the busbars in the hot and cold aisles. Then the external wall panels  25  are fixed to either end of the section and, where necessary, the external doors and/or louvres are fitted. This can be done simultaneously with the internal walls being installed. These are the only steps involved in the assembly of an IT section. 
     For an air optimiser section  15   a ,  15   h , the following additional steps are required. External wall panels  25  are fitted on one of the long sides of the section. Internal walls and doors are fitted to enclose the air treatment region  16 . Power management zone panels (which include the control process panel  31  and electrical distribution panels  32 ) are fitted to the inside surfaces of the space behind the air treatment region  16 . The air optimisation module  136  equipment is installed in the air treatment region  16 . 
     The assembled sections  15  can be moved around using the crane or combi-lifter. In this manner the sections are arranged adjacent each other as shown in  FIGS. 15 a  and 15 b   . The left-hand air optimiser section  15   a  is placed in position first. Then IT section  15   b  is positioned and fixed next to section  15   a . The remaining sections  15   c - h  are positioned and fixed together, including connecting the hot corridor service cassettes  60  and cold corridor service cassettes  40  in adjacent sections, to form the complete data centre building  10 . 
     By this stage, most of the mechanical and electrical apparatus is already installed in the building by virtue of the service cassettes. The remaining mechanical and electrical fitout tasks include installing a pair of fire suppression gas cylinders in the hot corridor of each section and connecting these to the fire suppression gas pipe on the ceiling of the hot aisle in that section, installing the control process panel  31  and the electrical distribution panels  32  into section  15   a , running network cables around the building to connect the control process panel  31  to the various sensors, louvres, outstations and air treatment equipment which it monitors and/or controls, and connecting the busbars to the electrical distribution panels. It will be appreciated that these tasks are rendered fairly minor because the distribution of power, cables, lighting, sensors and fire suppression gas pipework throughout the IT sections of the data centre  10  has already been taken care of by the service cassettes. 
     At this stage the data centre is ready for the racks to be installed and for it to be connected up to the local utility supplies, which is a simple matter of making a connection at a single point. The data centre building can then be commissioned and populated with IT equipment. Using the method described above, the entire manufacture and construction process from order to completion can take less than six weeks. 
       FIGS. 16 a , 16 b    and  17  show a data centre building  210  according to a second embodiment of the invention.  FIG. 16 b    is an exploded view of the main parts shown in  FIG. 16 a   . In contrast to the first embodiment, the data centre building of the second embodiment is a multi-storey data centre. The interior layout and operation of each storey of the data centre  210  is very similar to the single-storey data centre of the first embodiment, and for example each level comprises two air optimiser sections, and six IT sections. There are however differences between the first and second embodiments which are described below. 
     In this second embodiment the ceiling portions  222  of the ground floor storey also serve as the floor portions  221  of the sections immediately above. This does not require any alteration to the basic structure of the ceiling portion; rather it is simply a matter of fixing flooring material to the top of the ceiling section  222  rather than roofing material. Thus, as shown in  FIGS. 16 a  and 16 b   , the ceiling portion  222  comprises a framework consisting of two long side steel beams  226 , two short end steel beams  227 , and four steel corner elements  228 , which are designed to connect with the ground floor corner posts  223   a  (shown in  FIG. 16 a   ) which support the ceiling portion  222 . The lower surface (not visible) of the ceiling portion  222  is made from steel plate with a plastic coating finish. 
     On top of the ceiling portion  222 , the floor  221  is defined by means of a plywood floor deck supported on the joists of ceiling portion  222 . 
     In this second embodiment, the corner elements  228  also support the corner posts  223   b  of the first floor. Similarly, intermediate support posts  224   b  for the first floor extend upwardly from the ceiling portion  222 . 
     As best shown in the exploded view of  FIG. 16 b   , a cold corridor service cassette  40 , a cold aisle service cassette  50 , a hot aisle service cassette  70 , and a bulkhead  91  are mounted on the lower surface of the ceiling portion  222 . 
       FIG. 17  shows (on the right hand side) a cut-away perspective view of the two-storey data centre  210  once installed in a larger building. In this embodiment, the floor  300  of the building accommodating the data centre  210  provides the floor of the ground-level storey of the data centre  210 . It will be appreciated that the larger building may, as a result of housing a data centre, itself be considered as a data centre or a data centre building, despite possibly performing other functions. In the case where a larger building is used to house the data centre, there may be less of a requirement for water-proofing of the top storey of the data centre  210 . It may for example be provided without additional roofing elements. The uppermost ceiling portions  222  of the data centre  210  of  FIG. 17  are not for example provided with any roof linings or sloped roof panels for draining rain water. As shown schematically on the left hand side of  FIG. 17 , the uppermost ceiling portion  222   b  comprises a steel structure  294  onto the underside of which are mounted the service cassettes (labelled collectively as item  299 ). The ceiling portion  222   a  between the ground and first floors, also shown schematically on the left hand side of  FIG. 17 , similarly comprises a steel structure  294  onto the underside of which are mounted the service cassettes  299 , but also has floor covering (collectively represented by numeral  295 ) mounted on top of the joists. 
     Whilst not shown in  FIG. 17 , an external metal staircase is fixed to the outside of the modules to provide access to the upper level of the data centre. 
     Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described. 
     The data centre building  10  of the first embodiment is designed to be installed on an outside site. The present invention may equally well be used for a data centre (single or multi-storey) which is to be located inside an existing building, for example a warehouse. In this case the roof portions do not need to be covered with roofing material, and there is no need to provide floor portions at all. Instead corner elements  28  can be provided separately for fixing to the floor as supports for the corner columns. Packages  131  require a base board onto which the section components can be secured since there are no floor portions. This results in the packages being considerably lighter and slightly smaller in volume. When assembling the data centre building, each section must be constructed in its final position since the sections do not form complete volumetric units that can be moved around after being assembled. 
     The data centre components which are centrally manufactured or locally sourced may be different from the lists set out above. It will be appreciated that any division is possible, and indeed all of the components may be sourced locally or manufactured centrally. If all of the data centre components are manufactured centrally then the sections  15  will be packed into packages  111 ,  112 , and the DX units will be packed into DX modules  131 , in the central factory and will be sent straight to the final site. 
     The bulkheads  91  mentioned above could instead be provided as steel structure incorporated in the ceiling portions  22 . 
     The data centre building could be constructed as a multi-storey data centre building, having more than two storeys. 
     Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.