The new Enterprise Centre at the university of  East Anglia is an exemplar low carbon building that delivers several impressive sustainability objectives, achieving ’BREEAM Outstanding’ and full  Passive House certification through its use of locally sourced materials and renewable energy sources.

Volume 24, No.08 - August 2016

The new world
of bio-based construction materials


 

Something is changing in the world of architecture and construction. Long considered the stuff of eco-warriors, a whole range of bio-based materials are beginning to be employed 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.

 

Yes, we’ve all seen the worthy types on Grand Designs self-building the homes of their dreams from straw bales and mud with all the attendant imperfections in construction that can often conflict with the technological apparatus that now surrounds us 24/7 and which are deemed to be an essential part of modern life, but a number of recent developments in architectural thinking are likely to radically alter our perceptions in this area. 

And it is not only in the world of domestic buildings that we are seeing change: large projects too are making greater and more effective use of bio-based materials. But having maligned Grand Designs, I need now to give some credit to Kevin McCloud for putting his money where his mouth is in establishing the Hab development company to provide what are known as Custom Build (an expanded form of self-build) eco-homes around the country. The Triangle project in Swindon, a joint venture between Hab and West Country housing agency Green Square to create 42 housing units around a central landscaped area is a good example of a low-energy, bio-based approach being applied at scale.

Designed by Glenn Howells Architects, a firm with outstanding sustainability credentials (having been responsible for the construction of the remarkable gridshell roof of the Savill Building in Windsor Great Park from trees grown within 600 meters of the site), this multi award winning housing project is built using Tradical Hemcrete, a bio-composite material made from hemp shiv (the woody core of industrial hemp) and a lime-based binder. Aside from its ability to lock up significant volumes of atmospheric carbon dioxide, the material provides high levels of thermal insulation and thermal inertia which, in combination with lime-based renders and plasters, delivers a stable internal environment. 

Vertical thatching: prefabricated thatch panels provide a unique cassette cladding system

The interiors of first floor meeting rooms are each finished in a different natural material - reed, earth and clay plaster whilst also displaying the glulam beams and columns of the building’s primary structural timber frame.

Examples like this are not only passive in terms of their technological approach, they are passive insofar as you wouldn’t know from first sight that these materials have been used in preference to conventional masonry solutions. A more visible - and striking - demonstration of the use of locally available materials is Naturum, the visitor centre at Lake Tåkern in Sweden’s Östergötland County. A popular nature reserve and the annual nesting habitat for over one hundred species of bird, the location understandably attracts large numbers of twitchers. The building is designed by renowned Swedish architect Gert Wingårdh who has described it as ”quiet architecture, using traditional local materials to break new ground with crystalline geometry.” Indeed, the visitor centre’s asymmetric form folds around an entrance courtyard with traditional building techniques evident in the use of locally-cut golden reeds in the walls and roof. The reeds have weathered to grey over time and now match the nearby bird-watching tower that Wingårdhs completed in 2009. The building’s thatched exteriors reflect the typical temporary hides constructed by bird-watchers and which provide nesting materials and hiding places for small birds such as pipits and wagtails. Quiet architecture it may be, but despite its traditional cladding, this is very much a dynamic modern building. 
 
The latest and most comprehensive use of bio-based materials in a large, non-domestic building is undoubtedly the new Enterprise Centre at the University of East Anglia. The building’s radical design approach has delivered the client and architect’s aim of achieving a ‘BREEAM Outstanding’ rating as well as full Passive House Certification through innovative use of vernacular techniques and locally available materials. As the building’s client, the University’s Adapt Low Carbon Group led by plant scientist Dr John French asked what seemed to be a very simple question: why had no-one previously tried to create a large scale natural bio-building? Well, now they have and it sends out a strong message to every university in the country: why are our academic institutions not universally leading in the research and development of new construction approaches and technologies through the refurbishment and expansion of their own estates? Too often we see variations of commercial development approaches being applied by a client group that, by its very nature, has no requirement to build speculatively or for subsequent sale, but has specific needs that - if properly considered - could inform and support significant academic research programmes. 
But back to this exemplary project. What exactly is radical and innovative about it? Well, the building (by architects Architype) forms a gateway to UEA’s Norwich Research Park and contains 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, so what better place to apply bio-based materials and technologies in the creation of what has been described as “the most sustainable large building in Britain”. 
 
Lets start with its use of thatch, a traditional building material in East Anglia and in this instance made from local straw varieties such as Foster Special, Maris Huntsman and Yeoman Wheat. The radical part of this though is that the thatch is used in prefabricated form: 300 panels / cassettes (in 14 variations) put together in local joinery shops by six thatchers during winter months when they would normally have no opportunity to work. Thatch of course is not known for having an extended lifespan but in a building required in its brief to stand for 100 years plus, its use in vertical rainscreen cladding panels suggests it could last well over 50 years, with those requiring renewal simply unclipped and replaced. Less visible, the roof makes use of local reeds from Woodbastwick on the edge of the Norfolk Broads and from the RSPB’s Dingle March reserve at Saxmundham.
 
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. This particular species is more conventionally used for fencing and decking but, following initial sawing at Thomson Sawmills north of Norwich, the material was sent to  timber frame specialist Cygnum’s factory to be kiln dried, planed and strength graded to meet the structural engineer’s design calculations. To those familiar with timber frame construction, this is ground-breaking stuff and creates new higher value possibilities for a species normally only considered for low grade purposes but which can now contribute a local solution to increasing demand for housing in the region.

Whilst the outer facades are heavily insulated with thatch, the inner courtyard elevations feature timber cladding and large windows to facilitate maximum daylight penetration

The walls use a twin frame system into each structural stud plane 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 that delivers a U-value of 0.11 W/m2K results in a minimal energy requirement: ≤ 120KwH/m2 - effectively meaning that it requires virtually no heating. 
 
The list of bio-based materials used in the buildings goes on: larch sourced from Brandon Fields Estate in Suffolk has been fabricated into glulam beams; the first floor meeting rooms and board rooms are each clad in a different material - reed, earth and clay plaster, nettle fabric - but eschew any sense of being ‘hand-knitted’. Even the corn dollies at window reveals - whilst throwbacks to traditional architecture - are a tried and tested solution for finishing tight, visible corners. 
 
So, does this building and the other examples mentioned here offer new avenues for natural building technologies and indications of possible new bio-based construction components and systems? The answer must be yes, with the added bonus that craft skills can be employed to deliver solutions normally associated with serial production processes. The message is clear: true sustainability doesn’t stop at the outer skin of a building - it is reflected in design approaches that recognise the need to use local resources and which help sustain good quality employment in local communities. Innovation from the country’s academic, design and engineering communities in the use of bio-based materials has the potential to impact positively upon the UK’s indigenous skill base and provide it with new opportunities suited to 21st century environmental imperatives. What’s not to like?

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