Europe's first straw bale cold room.

 

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Cosmetics manufacturer Lush wanted to drive down carbon emissions, reduce waste and improve energy efficiency by building what it claims is Europe's' first straw cold room for its fresh creams, shower gels and skincare products. The building, made from straw and wood, has a much lower global warming impact than a conventional cold room made from steel, uPVC and expanded foam.

"Straw is a very unused waste product," says Nick Read, Lush's green manufacturing co-ordinator. "When you look at the insulation value of straw, you can get the same performance from it compared to traditional materials, and it's cheaper too. It can also be composted at end-of-life. We wanted to reduce our carbon impact in our manufacturing operations going forward and it was the right material to use."

Nick knew of Bee Rowan who has decades of experience in straw construction work. The company chose to use English straw for lower carbon impact which was sourced from a farm in Milton Keynes.

   
           

Hand tools and traditional techniques were employed throughout the build, including a sharpening horse to sharpen the wooden hazel pins that hold the bales together. Other materials used included clay, which was leftover and recycled from a previous project Rowan was involved in, and eco-paints.

The wall thickness of the room was determined by the width of the bales while the fabric of the external walls comprises 90% recycled newspaper and 10% recycled gypsum. The end-of-life reuse and recovery potential of every material was an important consideration for the company - once construction was finished, only 134kg of waste was sent to landfill at a total cost of £11.50.

"We sifted through all our waste streams by hand to separate them out and find a use for them where possible," Read explains. Wood waste, for instance, totalled 1,257kg of which 140kg was used to feed the company's biomass boilers, 209kg was stored for future use, and the remainder sent to an organic recycler. There were also ten 1-tonne bags of leftover straw and leftover clay which Bee Rowan took to her next straw build.

Project cost stayed within the allocated £36,000 budget and only went over timescale by a few days due to it being the first of its type. Being load-bearing brought some additional complications, mainly from a fire regulation perspective.

"[At the time] because there wasn't a fire regulations test for load-bearing straw in the UK, it couldn't be given a fire risk rating," Read explains. "As a result we are probably going to carry out the fire risk test ourselves - by doing that, we also give something back to the straw building community as we will have shared our knowledge and it enables us to carry that through to future developments."

While the straw bale building isn't expected to bring any additional energy usage savings compared to a conventional unit, its global warming potential is a lot lower. The embodied energy value of straw is 0.24 MJ/kg compared to rolled aluminium (155 MJ/kg), plastic uPVC film (69.4 MJ/kg), polyurethane rigid foam (101.5 MJ/kg), steel plate (25.1 MJ/kg) and steel beams (20.1 MJ/kg).