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<B><FONT SIZE=鈥�+2鈥�>How the co-location centre market developed</FONT></b>Co-location centres are services-packed buildings designed to provide a secure environment for IT and telecommunications equipment. Although the bursting of the internet bubble in 2000 affected short-term demand for these buildings, strong long-term growth forecasts make this a significant market sector.
The centres are provide access to primary optical fibre networks, together with the allowing clients the guaranteed uninterrupted operation of their equipment. Co-location centres, also known as internet hotels or server farms, are a relatively recent phenomenon. In London in late 1998 only 14,000 m2 of space was available. Since then, more than 100,000 m2 has been developed in and around the capital.
There are two basic models of co-location centre. Carrier-specific facilities have a single link to the network and are operated by a carrier to accommodate their own equipment, or to provide co-location services to their corporate clients. By contrast, carrier neutral co-location centres are speculative developments, providing serviced space for rent and access to multiple fibre networks.
The market for these buildings has huge potential. Until spring 2001, 500,000 servers were being connected to the web each month, and most of these would be located in co-location centres. Growth in the number of companies using corporate websites, the development of high-bandwidth services such as video-streaming and the development of the application service provider model of software distribution 鈥� which involves 鈥渉iring鈥� software over the internet 鈥� are all sources of long-term growth.
However, the co-location centre development market is high risk, requires a large up-front capital investment and exposure to tenants with a short trading history and poor covenant. Unsurprisingly, the dramatic fall in confidence in internet investment has also had an effect on the roll-out of co-location centres. However, development is continuing, and long-term prospects are positive.
<B>Business drivers</b>
Co-location centres have evolved from secure off-site back-up facilities, originally developed for financial services companies. Although many of the business drivers still relate to outsourcing trends, such as cost reduction and the achievement of economies of scale, issues such as the fragmentation of the telecommunications market and the demand for internet services are also significant. In particular, websites have been the engine for recent growth, taking advantage of the low cost and fast start-up provided by co-location centres.

<B><FONT SIZE=鈥�+2鈥�>Where to build a co-location centre</FONT></b>Co-location centre requirements are very specific, and well understood. Primary requirements include adjacency to fibre-optic network nodes, access to very large power supplies and proximity to important clients, facilitating easy maintenance and systems management.
Optical fibre networks cost 拢500,000/km to lay, so facilities will continue to cluster around existing 鈥渢ier one鈥� network nodes until a comprehensive broadband network is in place. Such concentration results in unprecedented pressure on power supplies, and although the power is available, the local supply infrastructure will usually need to be upgraded if loads in excess of 10 MVA are required. Constraints on the available power supply have significant effects on cost and programme. A typical 12 MVA load for a 10,000 m2 centre will cost between 拢500,000 and 拢2m, and requires a lead-in of between six and 18 months.
Planning issues also have the potential to be a constraint on the future development of new-build co-location centres. The main problems are noise, related to the 24-hour operation of plant, and low levels of job creation, which could be seen to adversely affect the commercial base of a local economy. Because of these and other factors, planning consent may be difficult to obtain and additional expenditure on planning gain agreements may be required in connection with the development.

<B><FONT SIZE=鈥�+2鈥�>Design issues</FONT></b>Co-location centre projects are dominated by engineering services, and 80% of the budget will be spent on the M&E installations that guarantee uninterrupted operation. Co-location centres are built for machines, not people, employ few staff, and, as a result, the design of the workplace is given a lower priority. To date, the conversion of existing warehouse and industrial space has enabled facilities to be completed quickly. However, there is a finite supply of suitable existing buildings in the right locations, and purpose-built projects are becoming more common.
<B>Phasing of the services installation</b>
Developers of co-location centres need to balance fast completion requirements and the desire to minimise initial capital outlay with the high levels of investment in power supply and mechanical plant required at the outset. The phasing of the development, facilitated by a flexible infrastructure that permits expansion without affecting the operation of completed space, is an important contributor to the viability of a scheme. There are two main approaches to providing flexibility in the services installation:

 

 

 

• Central distribution: where the complete primary distribution network is installed as part of the first phase, but plant is only brought online in response to tenant demand. Based on this option, although services disruption is minimised, the initial investment in the primary distribution circuits is high.
• Modular services: modular services strategies involve the development of localised 鈥渄istribution networks鈥�. Substations, uninterruptible power supply systems, chillers and so on, together with their primary and secondary distribution, and are only installed in response to increased demand.

This solution suits the modular building approach that has been developed for some of the larger European programmes. The advantages of the strategy include the minimisation of up-front investment and smaller primary cooling circuits. The disadvantages include the need for an extensive external services installation to link the modules and the greater complexity of installation work serving technical spaces.
<B>Redundancy</b>
Secure supplies of power, chilled water and so on are provided by specifying high quality products, adopting modular design principles and providing redundant capacity to guarantee performance in the event of plant failure. Plant designed to provide redundancy is only ever required to operate at full capacity during maintenance or in the event of a breakdown.
Accordingly, the specification of levels of redundancy has significant cost and plant-space implications. The redundancy standard applied to most co-location centres is N+1. Under this standard, the total load is supplied by a number of modular plant units, with back up being provided by one item of plant. Depending on the size of the development, the N+1 strategy results in additional plant capacity of between 20 and 33%. On smaller projects, where fewer main plant modules are needed, N+1 redundancy will result in proportionally higher capital costs, plant space requirements and spare capacity.

<B><FONT SIZE=鈥�+2鈥�>Electrical and mechanical services</FONT></b><B>Electrical services</b>
The availability, size and security of the power supply are the selling points of a co-location centre. Investment in the electrical infrastructure can be viewed as an investment in product differentiation. In some centres, rent levels are varied in accordance with the degree of power supply resilience provided. Currently, although measured power loads on operating centres rarely exceed 300 W/m2, 1000 W/m2 has become the minimum acceptable standard. This compares to the 25-35 W/m2 standard recommended by the British Council for Offices鈥� specification for urban offices. The standard represents the maximum theoretical load if technical areas were filled to capacity. In practice, below optimum use of rack space and diversity of server operation means that this limit is not approached.
The main design issues associated with the electrical design are:

 

 

 

• Resilience strategies
• UPS provision and standby generation.

The strategy for providing resilience is based on eliminating potential sources of failure through duplicate installations. The most common approach adopted involves providing dual supplies into separate high voltage switchgear. However, the most cost-effective solutions involve providing resilience and redundancy at the level of low voltage switchgear, UPS and standby generation, which avoids the necessity of investing in additional high voltage panels and cables. Following this strategy, tenants are provided with a secure supply through connections to two switchgear, UPS and standby power modules. The principle of duplication can be extended upward to dual mains supplies, and downwards to the final supply connections to each rack, which can be doubled-up and fed from different power distribution units.
The UPS provision required in co-location centres is much higher than on conventional buildings. The rule of thumb used to calculate requirements is 1200 W/m2 of technical space. Almost the entire electrical load is critical, which means that no break in supply or load shedding is permitted. Battery-based static UPS systems are the preferred option, although more expensive rotary UPS systems, which combine standby generation with UPS functionality, are becoming more common. Rotary UPS systems cost 5-8% more than an equivalent battery UPS and generator but require less plant room space. More details of UPS and generator options are discussed in the back-up power supplies cost model in the March 2001 edition of 好色先生TV Services Journal.
<B>Mechanical services</b>
The key issues for mechanical services design are:

 

 

 

• Cooling loads
• Diversity and security of supply
• Environmental control

The IT equipment housed in co-location centres produces a huge quantity of waste heat, but is considered very intolerant of temperature fluctuation. Failure of the cooling system would result in very rapid increases in temperature and the failure of IT equipment. Consequently cooling loads are very high, and requirements for standby capacity are exacting. Despite increases in processor efficiency, cooling loads of up to 1000 W/m2 are specified. In practice, due to diversity in the operation of the IT systems, the design loads are not met. Secure operation is a must for the cooling installation, and redundancy is provided at the level of chiller plant, chilled water distribution and close control units.
Close control of dust, temperature and humidity levels in technical spaces is also required. An operating temperature of 21掳C 卤 1掳C is typical, while humidity has to be kept at RH 50% 卤 5% to prevent the development of static or condensation. Further important design considerations include leakage prevention and detection from both high-and low-level services.
One area of building services design where extensive central plant is not required is ventilation. Technical spaces require high levels of cooling but are generally unoccupied and can be maintained on minimum permissible air change levels of half to one change per hour.
<B>Structure</b>
The main requirements for structure are heavy floor loadings, large spans, high slab-to-slab dimensions and requirements for extensive openings. Loads of up to 15 kN/m2 are required in technical areas, whilst the main switchgear may require floor loads of up to 20 kN/m2. Floor-to-floor heights of 4.5 to 5 m are required to allow for deep raised floor and suspended ceiling zones, together with column grids of 7.5 or 9 m to optimise the flexibility of racking layouts in technical spaces.
<B>Security and fire protection</b>
Security installations dealing with fire, intrusion and access control are necessarily extensive. Fire detection utilises conventional smoke detectors and VESDA systems that can detect very early signs of a fire risk. Gas fire suppression systems based on FM200 and other gases are commonly specified, but can be very costly as a result of the volumes of the technical spaces. As a cheaper alternative, pre-action mist sprinklers can also be specified. Although there will be some water damage in the event of a fire, pre-action systems provide sufficient security against accidental water damage to be used in technical areas.
Intrusion is dealt with by using physical barriers at the site and building perimeters, together with access control within the building. Voids within floor and ceiling zones should also be secured to prevent unauthorised access. Intensive CCTV installations, linked to intruder detection will include the monitoring of tenants鈥� areas. CCTV coverage of every aisle in technical areas is becoming increasingly common.
Access control systems in co-location centres use very high technology solutions. Up to four levels of security clearance are provided to protect the most sensitive elements of the IT installation. Physical control is provided by means of a series of 鈥渕an traps鈥� linked to scanners reading identify cards, palms and retina. In addition to door controls limiting access to technical spaces, racks and cabinets are also lockable, with keys tracked by database systems.

<B><FONT SIZE=鈥�+2鈥�>Combined heat and power plants</FONT></b>The large requirements for power and cooling in co-location centres make them ideal candidates for the application of combined heat and power technology. The benefits of using CHP systems include highly efficient power generation (60% efficiency), 鈥渇ree cooling鈥� using waste heat and absorption chillers, and exemption from the climate change levy, which came into force on 1 April 2001.
Despite these benefits, the take-up of CHP systems has been low. The main reasons for this are:

 

 

 

• Timing: national grid power can generally be online earlier than a purpose built CHP
• Size: CHP plant requires a very large plant area. A 36 MW plant comprising nine engines will require plant space exceeding 4000 m2
• Environmental issues: noise is the main concern. CHP systems based on gas turbines are very noisy and would run continuously
• Modularity: it is not practical to design a CHP installation in modules, so the whole investment has to be made up front
• Resilience: Gas mains are more difficult and slower to repair than electrical supplies

<B><FONT SIZE=鈥�+2鈥�>Procurement</FONT></b>The essential issues associated with the procurement of co-location centres involve the detailed design and co-ordination of the services installation, pre-ordering of major items of plant and thorough testing and commissioning.
Co-location projects are engineering-led, and the lead contractor is often a service specialist. The buildings themselves are relatively simple, but the services installation needs to be carefully considered to deliver a cost-effective solution that is easy to maintain and adapt while in operation. Projects are typically let as lump-sum contracts to specialist contractors on the basis of a fully detailed and sized service design. Detailed design of the services is essential for co-ordination purposes, which are particularly difficult because of the size of pipework and cable feeds involved. The detailed design process will also contribute to the identification and elimination of single points of failure at an early stage.
Early orders are required to secure main plant items such as chillers and standby generators. Generators are currently available on a six-month lead-in, while other plant is available on a four-month delivery. Full testing and commissioning is critical to the handover of the project and clients will not permit slippage on testing periods set out in the programme.

<B><FONT SIZE=鈥�+2鈥�>Co-location facility cost breakdown</FONT></b>The cost model is based on an 8300 m2 two-storey development. The scheme comprises 5000 m2 of technical space, 2800 m2 of associated plant areas and 500 m2 of support facilities. The technical space is fully fitted out, including on-floor power feeds, uninterruptible power supply and standby generation, extensive security installations, and is ready to receive racks. The support space includes fixed partitions, on-floor power and enhanced lighting, but excludes partitions and office furniture.
The cost breakdown does not include the costs of site preparation, external works and external services. The costs of the incoming dual-feed high-voltage supply of 6 MVA, a major component of the external services installation, could range from 拢250,000 to 拢1m, depending on availability. The cost breakdown also excludes professional and statutory fees and VAT.
Costs are given at second quarter 2001 price levels, based on a location in south-east England. The pricing level assumes competitive procurement based on a lump-sum tender. Adjustments should be made to account for differences in specification, programme and procurement route.
Because of the high proportion of specialist services installations in co-location centres, regional adjustment factors should not be applied.