At the cutting edge of envelope engineering the members of the Architectural Cladding Association (ACA), are playing a crucial role in facilitating and resolving client and designer relationships. British Precast’s Chief Executive Officer, Martin Clarke, explains.
As the skin between the outside and interior of structures, precast cladding serves a significant function in providing external protection from the elements and assuring ideal indoor environments for living and working.
The job is rising. Designers have moved away from glass, partly a fashion trend but mostly driven away by the experiences of summer overheating and winter frost. External wood cladding is no longer popular because to concerns about the spread of fire between floors.
Many specifiers are concerned about the high embodied energy of curtain walling systems.
In the apartment and non-residential sector, concrete facades are consequently poised to grab a larger share, and the inherent advantages of precast are coming to light. The Olympic athletes’ village being constructed in London for the 2012 Games serves as an excellent illustration. Precast cladding is being utilised to cover the entire hamlet as part of the ODA initiative, making it the largest precast cladding project in the UK to date.
Architectural cladding has been the precast industry’s pride and joy for decades, famous for its superior quality. There has never been a greater variety of finishes available than there is right now. New approaches have embedded graphics into the concrete itself.
Lighting characteristics and translucence can now be included thanks to fibre optics. Glazing is now regularly placed as part of the production process. Sandwich panels can be used to include the most recent advancements in thermal and sound insulation. utilities such as plumbing, electrical circuits and IT cabling are commonly pre-installed in panels. Externally, solar gain can be limited by the use of brise soleil, shutters and shading measures.
Internally, comfort and health can be improved by leveraging the thermal mass of concrete and the regulated purge of stale air.
Building sustainability is an important goal for the ACA, but the organization’s members are also working on ways to make architectural cladding more sustainable as a whole. In order to accomplish this, the British Precast Concrete Federation, to which the ACA belongs, has implemented a number of different strategies.
Firstly on health and safety our Concrete Targets 2015 programme which has been endorsed by all Federation members wants to move the precast industry to becoming a zero harm sector both within the manufacturing plant and during the installation phase. Although we’ve made great strides over the last decade, we still have a ways to go before we accomplish our goal.
In May 2011 all members of British Precast will be expected to sign up to the Federation’s sustainability Charter. As part of our Raising the Bar campaign, which aims to improve the construction sector as a whole, we will be the first trade association to do so.
The aim to minimise embodied and operational carbon is fully incorporated into our programmes and success is published annually with the release of our key performance indicators.
More information can be found at www.britishprecast.org.
STUDY OF A REAL-WORLD SITUATION
Decomo contributes to the Bodleian Library’s next chapter
Having opened back in 1602 and today with more than 11 million books already on its shelves, the Bodleian Library at Oxford University had been swiftly running out of space for many years. Additionally, because it receives a copy of every book published in the United Kingdom, this means that it must find space for more than three kilometres of shelving every year, or more than 1,000 new volumes every day.
The Bodleian Book Storage Facility in South Marston, Swindon, is now complete, with the capacity to store 8.4 million volumes over 153 kilometres of shelving.
The new book warehouse will hold lower-usage items from the libraries’ collections that had overrun the existing bookstacks and necessitated additional temporary storage in various places in and outside Oxford. Books, maps, manuscripts, microfilms, magazines, and newspapers, all dating from the 18th century and earlier, will be housed at the BSF. Over the next year, the Bodleian will move approximately six million books into the BSF, making it the largest book shift in the library’s history.
Decomo UK Ltd teamed with primary contractors Mace Plus and architects Scott Brownrigg to create this new huge storage facility. Precast concrete sandwich panels were the chosen material for the façade, permitting speedy erection on site and delivering a durable finished surface both inside and out.
An added obstacle to Decomo’s package of services for the design, fabrication and installation, was that the walls needed to give a minimum of four hours’ fire protection to defend the costly contents from any external fire. Since the concrete sandwich panels have two layers, they already provide good fire protection, but to achieve the strict requirement, special consideration had to be given to the thickness of each individual concrete layer section and the panel-to-panel jointing mechanism.
The external faces of architectural grade precast panels were grit-blasted. It was more common for them to be 7.5 metres long by 3 metres high and weigh 12.5 tonnes each, however some were larger and closer to 18.5 tonnes. The front elevation, which houses the reception and offices, has relief panels that mimic the look of bookshelves filled with books.
Decomo was able to accommodate the short lead-in period for this project. Design began in August 2009, with all 254 cladding panels (totalling 5200m2) made by Decomo and placed on site commencing in January 2010. Despite some of the country’s biggest snowfalls in decades, the installation was completed in just eight weeks. All facade panels were fitted using a 70-tonne crawler crane, except for the section above the reception/ office block, where a 200-tonne mobile crane had to be employed.
The following trades could begin work on installing the 2200 linear metres of 11-meter-high raking, which offers 95,000 shelf levels, once the structure was watertight. Work has already begun on relocating the millions of books from the original Bodleian and other temporary storage facilities to the new facility in Swindon.