Data centres are one of the most intensively serviced elements of a commercial fit-out project. The design and specification of their building services involves a careful balance between requirements for protection, redundancy and back-up on the one hand, and plant space availability and initial capital cost on the other. Issues related to procurement, co-ordination of site-works, and testing and commissioning need to carefully considered to ensure that following data installation trades can be completed on programme.
Cost Breakdown
The cost breakdown details the services fit-out costs of a generic data centre with a net floor area of 1000 m2. The data centre serves a financial services headquarters building with a gross internal floor area of 35 000 m2.
The fit-out works, taken from shell and core, include all mechanical, electrical, protective and communication installations necessary to supplement the services capacity of basic office floor space.
The scheme upon which the cost model is based uses the existing capacity of the base-building plant. Where necessary, the capacity of existing plant is upgraded to serve the increased loads associated with the operation of the data centre. The cost model does not include upgrade costs to other areas, such as trading floors or builders work items such as shielding for electromagnetic interference.
Electrical installation costs are based on a load requirement of 1000 W/m2, which is a substantial allowance, providing significant capacity for expansion of voice and data services within the office, together with limited diversity for a secure power supply. It should be noted that no allowance is made for the additional costs of an higher capacity hv supply to deal with the increased load, or a dual feed to provide a more secure supply.
The sizing of plant within the cost model is based on a redundancy level of n+1. This standard, based on the use of modular plant, provides 100% back up for a single machine only. It also provides an appropriate level of resilience for most users, with minimal additional capital cost and plant space implications.
Design and construction
Sub-equipment rooms house the interface between the main data backbone and on-floor distribution. The number of sub-equipment rooms on a floor will be determined by the maximum runs permitted using category 5 cable.
The design criteria for sub-equipment rooms are generally identical to the main data centre, although costs (£/m2 of room area) may be higher due to the costs of some items of plant such as room cooling units.
For redundancy, the most common standard used for data centres is n+1. Normal capacity is provided using modular plant, while 100% back up is provided for only one of the modules.
This strategy typically results in the provision of spare capacity of 25-33%. On smaller buildings where there are fewer chiller or standby generator modules, the adoption of this redundancy strategy will result in a proportionately higher capital costs, space requirements and spare capacity.
Higher levels of redundancy can be provided, up to 100%. This level of protection is sometimes considered for internet hotels, but is generally found to be impractical due to cost and space requirements. When determining the appropriate redundancy issues related to strategy, the main driver is usually the availability of plant space rather than cost.
Early completion of data centres is often essential to enable the installation of cabinets, the data backbone and outlet boxes to be completed as part of the main fit out programme. Many of the plant items associated with a data centre fit out have long lead-in items and, as a result, design must be frozen early to ensure that the programme is met.
The principle co-ordination issues relate to the size and availability of plant space and riser space. The requirement for additional space to accommodate plant to the appropriate level of redundancy may result in the requirement for alterations to the base building. Where the installation is taking place in an office already fitted out to a Category A standard, allowances should be made for the costs of stripping out and capping off services and finishes.
Research into efficient IT cooling
The BSRIA is starting research to investigate the cooling needs of IT communications rooms. Working in partnership with consulting engineers Foremans, BSRIA researchers aim to produce a design guide for the integrated design of IT communications rooms. BSRIA reports that the number of IT outlets has grown in the UK by 20%/y over the last five years. A typical server room now consists of a variety of equipment, often assembled with little thought given to the means of providing distributed cooling to maintain reliability. While individual devices may operate perfectly in isolation, even at high ambient temperatures, groups or racks of equipment can create thermal and reliability problems. Simply supplying more cooling to the server room as a whole is inefficient and may cause other problems such as cold spots, condensation risk and excessive air velocities. What BSRIA researchers believe is needed is a means of properly distributing cooling to individual devices, or groups of devices, so that they operate under optimum conditions, with cooling applied directly to the sources of heat generation. The project will start this January. Partners are invited to influence the direction of the work and guide the production of the final results through a project steering group. For more details contact BSRIA on 01344 426511.Source
Building Sustainable Design
