Imperceptible perhaps, but a whole range of bio-based materials are now being used in conjunction with modern engineered timber products on some very sophisticated buildings. Sophisticated, that is, in their low energy, carbon storage and life cycle credentials rather than the conventional use of that word as an indicator of complex technical specifications and high-tech components. This is not the hand-knitted world of straw bales and mud with attendant construction imperfections that conflict with the technological apparatus that now surrounds us 24/7: new architectural thinking about the way contemporary and traditional technologies can be combined is beginning to alter perceptions about the potential of natural materials in construction.
The Enterprise Centre at the University of East Anglia is a prime example of a large, non-domestic building in which locally-manufactured engineered timber products have been combined with other bio-based materials: Whilst this may seem to be a radical approach, it has delivered the client’s and architect’s aim of achieving a ‘BREEAM Outstanding’ rating as well as full Passive House Certification through its innovative use of vernacular techniques and locally available materials. As the building’s client, the University’s Adapt Low Carbon Group raised a very simple question: why had no-one previously tried to create a large-scale ‘bio-building’? The answer now stands in the Norwich Research Park and sends a highly pertinent message to every university in the country: they need to lead in the research and development of new construction approaches and technologies through the refurbishment and expansion of their own estates. This particular client group has no requirement to build speculatively or for subsequent sale: it has specific needs which can - and should - inform and support significant academic research programmes designed to drive the construction industry forward.
So what exactly is radical and innovative about UEA’s Norwich Research Park’s new gateway by architects Architype? The brief was fairly conventional: a 300 seat lecture theatre, an innovation lab, teaching and learning facilities and flexible workspaces as well as business hatcheries and incubator units for SMEs and start-up businesses in the low-carbon sector. This last criterion provided the impetus to combine new timber technologies with other bio-based materials in the creation of what has been described as “the most sustainable large building in Britain”.
The building’s most obviously unusual characteristic is its use of thatch, a traditional building material in East Anglia which, in this instance, is made from local straw varieties such as Foster Special, Maris Huntsman and Yeoman Wheat. The thatch is, however, applied in prefabricated form: 300 panels/cassettes (in 14 variations) assembled in local joinery shops by six thatchers during winter months when they would normally have no opportunity to work. Thatch is not known for having an extended lifespan but in a brief that required the building to stand for 100+ years, its use in vertical rainscreen cladding panels suggests it could last well over 50 years, with any panels requiring renewal simply unclipped and replaced.
The Centre’s timber frame too charts new territory in that it is largely manufactured from Corsican Pine grown in Thetford Forest, just 30 miles from the Enterprise Centre site. After initial sawing at Thomson Sawmills north of Norwich, the material was sent to specialist timber frame manufacturer Cygnum to be kiln dried, planed and strength graded to meet the structural engineer’s requirements. This highly localised use of home grown material creates new, higher-value possibilities for a species normally only considered suitable for low grade purposes (fencing and decking products) but which now offers a local solution to the region’s ever-increasing housing demand. Similarly, larch sourced from Brandon Fields Estate in Suffolk has been fabricated into glulam beams.
The walls use a twin frame system in which each structural stud plane has been filled with 140mm of cellulose insulation produced from recycled newspapers. With breathable wood fibre to the exterior and 18mm oriented strand board (OSB) acting as an airtightness layer, the building achieves a remarkable 0.21 air changes per hour, whilst the thermal insulation strategy delivers a U-value of 0.11 W/m2K that results in a minimal energy requirement (≤ 120KwH/m2) meaning that the building requires virtually no heating.
So, does this building offer new avenues for engineered timber products in combination with natural building technologies and the possibility of new bio-based construction components and systems? The answer to both questions must be yes, with the added bonus that craft skills can be employed to deliver solutions normally associated with serial production processes. The new Enterprise Centre easily demonstrates that true sustainability doesn’t stop at the outer skin of a building, but can be reflected in design approaches that recognise the opportunity to use local resources and thereby help sustain good quality employment in local communities.