Raised access flooring at WWF HQ

The Living Planet Centre is the new UK HQ for the World Wildlife Foundation and the brief for its design was inextricably linked to the ethos and aspirations of the client. Sustainability was at the forefront of every decision in not only the design but also the whole procurement process. The Raised Access Flooring System became a very integral part of the design not only with regard to its ‘Green’ credentials but also in meeting a host of challenges posed by the proposed site conditions.

The building was designed by the world renown Hopkins Architects with the aim of achieving the highest possible BREEAM ‘Outstanding’ rating. Particular attention was paid to the sourcing of the materials and as timber was used in abundance within the building, strict criteria with regards to Full Stewardship Council (FSC) certification was required within the Main Contractor’s Supply Chain. The System from MERO-SCHMIDLIN (UK) PLC was the only Raised Access Flooring System under consideration which met all of the strict criteria with regards to the procurement brief and also contained a high element of recycled content in its boards, pedestals and in many cases the eventual floor covering itself.

The Site

The planning consent for the project was for it to be sited in Woking town centre, enabling staff to use the most sustainable modes of transport to reach the premises. The challenge to the designers was that the existing municipal car park on the site needed to be retailed and any building would need to be constructed to ‘bridge’ the car park. Whilst this has been achieved very successfully from an aesthetic perspective it required a high degree of specialist design input from the MSUK design team, the consultants and architects in addition to the M/C’s Willmott Dixon.

Cold Bridging

With a fair faced concrete plinth being formed around the car park it enabled very cool air to lay beneath the building and as such ‘cold-bridging’ was an obvious concern that had to be addressed within the floor package design. One of the benefits of a quality raised access floor system is that it creates a very adaptable void which can hide a multiple of building service equipment whilst allowing vital components to be attended to with a minimum of disruption for servicing or repair. The Cold Bridging was particularly important as the void beneath the floor was also being used as part of a natural air distribution and ventilation system. Having carried out the necessary thermal loss calculations, a bespoke insulation build up was integrated into the raised access flooring system taking into account its position within the building and its eventual floor covering. The Concrete Floor Slab was covered with a waterproof membrane over which a rigid insulation slab was added further topped by a vapour barrier and finished off with a cementitious board system which is robust enough to take the weight of the mechanically fixed recycled steel pedestals supporting the floor surface.

Ventilation

Having dealt with the cold- bridging, the void beneath the flooring was again implemented as a substantial component of the BREEAM aspirations. With modern building design the trend has long been against the use of air conditioning with a preference in using Natural Ventilation. This development makes full use of the many benefits provided by the raised access flooring but does involve a high level of monitoring during the design and installation of the flooring. Parts of the floor void are used to provide a Plenum through which the air is passed before re-entering the structure through strategically placed floor vents. It is of course vitally important that both the system itself and the floor panels are airtight so they are fitted with neoprene seals to minimise any air leakage which might compromise the ventilation performance. The system is subject to pressure testing at various stages in construction but it is also paramount that the supports are strategically placed and the boards above them do not flex. Any movement could damage the seals within the support boards or indeed the flooring finish itself. As part of the sustainability focussed design the WWF HQ uses cowls within the roof system to draw in air and the flooring system to re-distribute it.

Fire Proofing

One of the many benefits of raised access flooring is that to the casual observer it appears to be just a ‘normal’ floor and its ability to carry a complete range of flooring finish options only enhances that view. In addition to heating, cooling, providing various routes for a multitude of building services wiring, data cables, pipework and trunking the floor void could also provide both access and air, vital components of any fire. It is then of course imperative that areas under the floor are able to be isolated, not only to prevent the fire spreading but also to avoid compromising the floor supports and components.

Sustainability

Working with an organisation such as the WWF, the brief was always going to be sustainability lead. With the flooring system The Mero System met, or indeed exceeded, the brief both in its component sourcing in addition to some of the floor coverings used as part of the flooring package. The adjustable support pedestals contain a percentage of recycled content within the components and the two types of floor panels were chipboard or calcium sulphate both of which feature high levels of recycled content within their composite construction. All of the timber content was sourced by MERO-SCHMIDLIN via a fully certified Forest Stewardship Council supplier under FSC Guidelines and a full FSC Chain Of Custody certification provided. This was a pre-requisite at tender stage and was vociferously monitored by Willmott Dixon during the whole construction process. The building has a variety of floor coverings to suit the needs of particular areas and much of the reception zone has a Strata Italian Merazzo composite ceramic type tile which has very high levels of recycled material and was factory applied by MERO-SCHMIDLIN.

As Neil Burrows explains, having a car park beneath the building presented several challenges:

“The void presented several thermal insulation issues and he use of calcium sulphate hollow floorboard laid onto the insulation as part of the Raised Access Flooring System allowed some of these to be addressed.

The possibility of cold bridging from the car park beneath was addressed by the architects with 100mm high density insulation being fitted by Mero Schmidlin. The insulation however must not be compressed by any flexing (deflection) of the sub-floor and Mero-Schmidlin carried out extensive levels of testing on this issue. In order to avoid any installation, product performance conflicts with regard to warranty, the main contractors were very keen for one company to complete the whole package and MERO-SCHMIDLIN were very happy to be able to meet the challenge.”