DCN May 2017 - Page 21

design & facilities Management As with traditional or newly designed data centres, a key consideration when choosing a raised floor is: What loadings, especially point loadings, will the incoming equipment impose upon the floor? Once these are known, the choice of a raised floor designed and manufactured to the PSA Specification will ensure that it carries a ‘3’ times safety factor. For a data centre, design loadings of not less than 4.5kN over a 25mm square and Uniformly Distributed Load (UDL) of not less than 12kN/ m2 form part of the PSA Heavy Grade Specification, but in certain circumstances the PSA Extra Heavy Specification may be adopted – this calls for a four point load of 11kN to be applied equally on four points, each of 25mm 2 , on a 200mm x 200mm square configuration at any point on the system. Evidence should be sought from an independent third party to prove that the system offered complies with these requirements. Generally this would be from a UKAS accredited organisation such as Building Testing Limited of Woking. However, data centre floors are having to carry ever greater loads as more cooling equipment is added to computer and server cabinets to deal with the increased heat they are generating as a result of the massive flow of electronic information. As a result, there is a requirement for loadings that exceed even the Extra Heavy rating, and manufacturers have responded by producing systems with new pedestal and stringer designs to give more than twice the Extra Heavy Specification loading. Having chosen the performance requirements of the raised floor, ie. point load and UDL, consideration should also be given to how the rack and other equipment is to be moved into place – the static load applied to a raised floor can be increased quite dramatically by dynamic loads as the equipment is positioned. Therefore it is frequently the case that spreader plates will be used during the fit out stage. No containment Physical containment Cooling needs On a daily basis, there is no greater strain put on a data centre than the need to continually cool IT equipment. In fact, up to 50 per cent of a data centre’s total annual energy consumption can come from its cooling needs, which obviously makes the question of how to be both more effective and more efficient a question constantly on the minds of facility managers. In response, raised access floor manufacturers can now provide virtual containment systems that dramatically reduce bypass airflow and maximise the amount of airflow which can be captured and used to cool equipment. Unlike traditional airflow panels, virtual containment utilises directional airflow panels which angle airflow toward the face of the rack, nearly eliminating bypass air while increasing cooling capacity and energy efficiency. These panels can achieve a 93 per cent Capture Index – the amount of air delivered through the panel that directly enters the face of the server rack in front of that panel - significantly reducing the amount of bypass air. Additionally, advances in directional airflow panel design have introduced multi-directional panels where airflow is split evenly and angled in two directions. This allows for directional airflow to racks on either side of a cold aisle in a legacy data centre that has only Virtual containment May 2017 | 21