After two years of intensive engineering research, Glasgow-based Page\Park Architects’ new headquarters for the Loch Lomond National Park Authority opened in May 2008.
The elegant double-gabled office building stands in the quiet town of Balloch, on the banks of the loch, and has one of Britain’s largest post-and-beam frames.
Page\Park is already known for its timber projects, which include the Scottish Centre for Ecology and the Natural Environment Field Station in Rowardennan, also on the banks of Loch Lomond, the National Museum of Rural Life at the edge of East Kilbride, and the Inverness Maggie’s Centre. But this project is the practice’s first time using greenwood - untreated timber which has a lower carbon footprint than other timbers due to the lack of processing - as a structural material.
The 78 x 20m Douglas fir frame is the result of a collaborative effort between Page\Park, engineers Buro Happold, Timber Engineering Connections and SKM Anthony Hunt, and Carpenter Oak & Woodland (COW). The building’s size and its integration with modern engineered timber makes it, according to Scott Fotheringham from project carpenter COW, ‘architecturally a one-off’. ‘[It] integrates many different timber structures into one frame,’ he adds.
With Sitka spruce available from within the national park, the design initially called for Sitka stress-laminated timber, but this proved unfeasible given the large spans needed due to shrinkage and fire-resistance issues. In response, Buro Happold and COW developed a spruce/OSB I-box and ply-composite floor, and a ply/spruce-composite loadbearing system to support the upper storeys.
The I-box system is similar to an I-joist system, and comprises wide spruce top and bottom flanges with a double spruce OSB web. The webs need only be continuous where the loads require, making the beams light and easy to handle on site while providing clear pathways for the running of services within the floor structure. The development of the frame jointing was also important, and the team settled on SKM Anthony Hunt’s special steel flitch plates.
The timber frame is made up of 26 separate post-and-beam sections. Buro Happold project engineer Neil Dely says: ‘Trying to create an open, column-less, second-storey space in a timber building was the hardest part of the work.’ The timber-frame system comprises 315 pieces of Douglas fir, many of which are hidden behind internal wall finishes, and which carry the first floor and roof structure across the 20m-wide open workspace in three separate spans. The frame is stiffened by loadbearing external walls.
Along the central corridor running through the building, a total of 105 300 x 650cm Douglas fir posts are fully exposed, rising up 6.5m high to the roof. The posts also provide much of the roof-span support for the open ground-floor street and its two glazed ground-floor atria spaces, which house the library and restaurant. Here, some 82 Douglas glulam beams from France frame the structure in locations where the design couldn’t accommodate the shrinkage of natural timber.
Along with the specification of natural materials - larch cladding, slate roof, south-facing stone walls - the building ticks many sustainability boxes. The mix of natural and minimal mechanical ventilation is a good example of designing out energy-consuming systems at the early stages of design.
U-values have been increased by 20 per cent by using Thermafleece sheep’s-wool insulation instead of phenolic foam. Daylight-linked controls have reduced background lighting from 500 to 280 lux. A conventional boiler system has been replaced with an Austrian Fröling biomass primary-heating system, which uses woodchip pellets sourced from the park and makes the heating carbon neutral.
Outside, a sustainable urban-drainage-system reed bed treats both rain and grey water. With this suite of eco-features, the building has achieved a BREEAM Excellent rating.
The result is a light, airy working environment for the authority’s 120 staff, with the exposed post-and-beam system adding wood’s warm, natural materiality to the mix. According to Page\Park partner David Page, the building is designed around ‘working communities rather than the traditional office block’ - what he calls ‘an oatmeal, healthy, well-being building’.
The building has also contributed to the debate on using greenwood in construction, and to Scotland’s emerging homegrown timberbuild tradition. Page talks of an ‘embryonic’ native timber industry and hopes the building will significantly propel the Scottish timber sector forward.
Tender date November 2006
Start on site date January 2007
Contract duration 12 months
Gross external floor area 2,400m2
Form of contract Design and Build
Cost £5 million
Client Loch Lomond and Trossachs National Park Authority
Architect Page\Park Architects
Structural and services engineer Buro Happold
Quantity surveyor/planning supervisor Gardiner and Theobald
Contractor Mike Whitfield Construction
Main contractor CBC
Green Douglas fir frame Carpenter Oak & Woodland
Annual C02 emissions 29kgCO2/m2