Make’s ‘new agricultural aesthetic’ demonstrates an innovative way to build with straw, writes Hattie Hartman
‘Every building needs a story,’ Bob Leung of Make told me recently as we visited the practice’s Gateway Building for Nottingham University, completed in May.
This building has a fantastic story. The exterior envelope, which encloses 3,100 square metres of laboratories, teaching spaces and offices, contains more than 300 metric tonnes of straw. The use of straw is particularly fitting because the Gateway Building joins two academic departments, Biosciences, and Veterinary Medicine and Sciences, which are located on the university’s agricultural campus in the village of Sutton Bonington, 12 miles south of Nottingham.
This is the ultimate in locally sourced materials. Forget BedZed’s 25-mile radius for sourcing – you can look out of the Gateway Building’s generous windows and see the fields where the straw was harvested. In fact, it was Make’s proposal for a straw construction which clinched them the commission, according to Tim Brooksbank the university’s development director. Ironically, the casual passer-by would never know it is made of straw. The only place where the straw is visible is in the entrance atrium, where three ‘truth’ windows cut into the interior surface of the timber cassettes reveal what’s inside.
Traditional straw construction is load-bearing, and relies on compacting straw with earth and the application of an exterior render coat to protect it from the elements. Recently, straw has been making a comeback. It is renewable, an excellent insulator, easy to handle and cheap. White Design established the ModCell building system in 2003 as a contemporary take on straw construction. ModCell’s approach sandwiches straw bales between timber panels to form load-bearing walls, suited to one- and two-storey buildings.
The three-storey Gateway Building demanded a different system. Make worked with specialist timber engineering firm Eurban, co-developer of ModCell, to develop bespoke box panels for the project. At 825mm wide by 545mm deep, the cassettes are dimensioned to take two straw bales side-by-side for the full 13.5-metre height of the building. In fact, floor-to-floor heights had to be slightly reduced to suit the maximum cassette length that could fit on the back of a lorry for delivery to site from a nearby farm, where the cassettes were prefabricated. Eighty cassettes combine with a conventional curtain wall system to make up the facade, which cost 30 per cent less than ModCell, and is comparable to a mid range, conventional curtain wall system, according to cost consultant Sand Project Management.
The Gateway Building merits a detour because of its inventive use of straw. It is part of a new wave of budget-conscious academic buildings which use timber – and in this case straw – to simultaneously deliver value for money and reduce their carbon footprint (see Sheppard Robson’s LICA in AJ 27.10.11). But this is not great architecture in terms of aesthetics. Despite the building’s synergy with its rural setting and with the academic departments housed here, the marriage of rendered timber cassettes (which Make refers to as a ‘new agricultural aesthetic’) with a conventional, unitised curtain wall system is not a happy one.
Nonetheless there are some clever moves, such as the grouping of larger, more densely occupied rooms to the northern side of the building, more glazing on the north elevation (27 per cent) than on the south (20 per cent), and the use of parallel-opening windows which automatically provide high-level ventilation. Make drew on its experience at the previously completed Jubilee campus for the university (see AJ 02.10.08), where the students rarely opened the upper windows of the high- and low-level windows provided. Large windows provide views out of the main circulation routes – double-loaded corridors and stairwells – but this is no more than one would expect of any architect.
Make has been working on a masterplan of the Sutton Bonington campus since 2008. The Gateway is the first new building to breathe life into the masterplan by starting to define a hierarchy of pedestrian routes through the sprawling campus. The interior spaces are full of light, and the creative use of straw is to be applauded. If the exterior disappoints, it should nevertheless point the way to further innovation with this abundant, affordable and renewable material.
Start on site May 2010
Completion May 2011
Gross internal floor area 3,100m2
Type of contract/ procurement OJEU competition, Design and Build
Total cost £5.5 million
Cost per square metre £1,774
Client University of Nottingham
Structural engineer Price & Myers
M&E engineer Couch Perry & Wilkes
Laboratory planning consultant Nightingale Associates
Electrical engineer Electract
Services contractor William Bailey
CDM coordinator WPP Safety
Project manager/ cost consultant Sand Project Management
Main contractor Herbert Baggaley Construction
Straw bale facade specialist Eurban
Glazed facades / curtain walling RKN Aluminium
Rainscreen cladding system Metclad
Estimated annual CO2 emissions 23.6kg/m2
Airtightness at 50pa 5m3/h.m2
Annual heating load 44kWh/m2
Annual hot water load 8.8kWh/m2
U-values Roof: 0.15W/m2K; Walls: 0.135W/m2K