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The Adnams Distribution Centre in Suffolk, England, instills the green approach to building throughout.
By Helen Elias
Designed by architects Aukett Fitzroy Robinson and structural engineer Faber Maunsell Aecom, the 90m long, 45m wide new central distribution center for the Suffolk brewer Adnams is being widely acclaimed as Britain’s greenest warehouse.
The client, known across England as a brewer of high quality traditional beers, set a strict brief for their new distribution building—the new warehouse had to allow them to get the freshly brewed beer from the brewery to the pubs and bars quickly, but with the minimum of environmental impact. Beer is a tricky product to move—it needs to be kept at carefully controlled temperatures and treated with respect as it matures over a defined cycle to the point where the barrel is ready to be taken to the pub, put into the cellar, tapped and pints pulled for thirsty punters. If there is one thing the UK pubic takes very seriously, it’s the quality of their real ale. So this distribution building just had to get it right…
The distribution center is sunk within 88 acres of grassland in a disused gravel pit, immediately removing the need for excavation to create a building that sits low within the landscape. Successfully combining a number of pioneering construction techniques, the 4400m2 structure, the UK’s first commercial building to be built using lime hemp blocks, is covered by what may be the largest green roof in Britain.
The layout of the warehouse reflects its use—with revered bottled and casked beers arriving from the Southwold brewery for loading onto trucks for countrywide distribution. A large central store is flanked by end bays where the incoming lorries deliver the beer. A marshalling area runs along one entire side, with a loading bay for the larger trucks. Overhanging eves and brise-soleil, and a buffer space at all warehouse entrances, help maintain ambient temperatures inside, and prevent excessive heat gains or loss of cold from the warehouse area.
The main structural driver was to create a column-free space with a constant cool beer-friendly environment of ideally 11°C, whatever the season or time of day. Faber Maunsell Aecom’s strategy was to design in passive ways to reduce energy use and lessen environmental impact. The biggest influence in achieving this brief is a combination of the widest spanning glulam beams to be deployed in the UK, sitting over dense walls built from lime hemp blocks.
Lime hemp blocks use less energy to manufacture than conventional concrete blocks, with the Adnams Warehouse the first large scale use in the UK. Advantages as a construction material lie in its low embodied energy compared to conventional concrete, as well as a high thermal mass. The warehouse walls use unfired, air cured blocks each weighing about 19kg, and measuring 100mm x 254mm x 356mm. The 90,000 blocks produced by compressing limestone quarry waste (for strength) with hydrated lime, blast furnace slag, and hemp. Each block produces about one tenth of the CO2 of a conventional concrete block.
The 480mm thick, 8m high warehouse diaphragm walls were built from two skins of blocks. Traditional bricklayers laid blocks in a similar pattern to conventional concrete blocks, using a lime based mortar. The two walls were tied by laying blocks cross ways every meter, and finished externally with a lime render. To enhance thermal performance, the cavity is filled with Tradical Hemcrete—a fibrous hemp insulation material—giving a wall U-value of 0.18 W/m2K.
Hemp construction effectively locks CO2 into the finished structure. Hemp actually absorbs CO2 as it grows, while the lime mortar and lime render absorbs carbon dioxide as it sets. Thus the Adnams Warehouse represents over 150 tonnes of carbon dioxide locked within its walls. A building of a similar size constructed using more traditional methods would typically have generated around 600 tonnes of CO2 emissions.
The large green roof rests onto a simple steel frame. Glulam beams were manufactured from laminated wood sourced from sustainable forests. With the biggest at a length of 41.6 m, these glulam beams are the longest to ever be installed in the UK. The beams run approximately 60m across the building, creating a 35m column free space within the main warehouse. The 16 gently arched beams spanning the main warehouse oversail the walls by 4m to each side of the building, and at each end, creating extra shade. Massive solar “sails” hang beneath the overhanging eve to the south façade. Fabricated from sail cloth, the huge 7m deep by 4m wide sails provide shading from direct sunlight to the windows for the office suite inside.
The green roof is a high performance insulator to again maintain steady temperatures within the warehouse below. A thin steel liner tray sits under spacers and a second steel tray, the space between filled with insulation. The top tray supports an egg crate system to hold a layer of a lightweight pumice based growing material, thickly planted with sedum, locally grown at Mildenhall. The insulating topsoil prevents heat loss in the winter and reduces heat gain in the summer. The sedum plants play a dual role in helping shade the building and also softening the impact of the warehouse within the environment. Roof lights puncture the roof itself, saving energy by allowing natural daylight into the warehouse space below.