Through the design and construction of Earth Lab, we are aiming to apply the same care and philosophy as we do to managing our green spaces. We want to encourage sustainable behaviours and are focusing on choosing the right materials and partners to realise our design, as well as reduce manufacturing impact and construction waste. We want to explore close-to-market sustainable materials (which contain lower embodied carbon) whilst thinking about the long term performance of the building.
A natural alternative to steel or bricks, we have chosen ‘glulam’ beams – literally ‘glued laminate’ – to form the structural elements of the walls and roof. Glulam is a strong and attractive material comprising wood layers, which can be customised to unusual shapes and designs.
All of the straight glulam beams have been made by a German glulam manufacturing firm, specialising in the mass production of standard spruce glulam. For this type of product they have very energy efficient machinery and manufacturing systems, which goes a long way to offsetting the carbon emissions of the haulage. The curved beams were manufactured by UK specialist Buckland Timber, based in Devon. The raw glulam materials are machined by hand, before fitting metalwork as necessary and sending them to site.
All of the timber used to manufacture the glulam beams in this project was sustainably grown PEFC certified spruce of Scandinavian origin. The energy used to fabricate a glulam beam is 5-6 times less than a steel or concrete beam of the same mass and length.
Rammed Earth Wall
One of the prominent features of the project will be the Rammed Earth wall that is constructed inside the Earth Lab. Rammed Earth walls act as a natural heat and humidity regulator, which is extremely useful for spaces with significant flows of people. Advice has been sought from Rammed Earth Specialist Rowland Keble, who was most significantly involved in the Eden Project in Cornwall. The materials for the wall have been carefully selected from spoil arising from the reduced level and foundation excavations on the site, mixed with soil from the archaeological excavations at Little Wittenham.
To date a small demonstration section has been erected outside the Earth Trust Centre, in order to test the suitability of these local materials.
‘Modcell’ is a prefabricated cell that contains shredded and compacted straw for insulation. The cells are constructed from a timber frame, insulated with straw and clad to the faces with plywood. Straw has excellent thermal insulation qualities, as well as being 100% renewable material with carbon sequestering properties. The frames are constructed using FSC or PEFC timber sourced in the UK.
Waste generated during the manufacturing process is also reused. Trimmings from the straw bales can be used as animal bedding or turned into biomass fuel along with the timber off cuts and used in the manufacturer’s biomass boiler. Being prefabricated, the journeys to site are minimised. Deliveries will arrive to site on two vehicles and lifted into their final position; this reduces the labour force on site and any noisy or dusty operations generated from traditional construction methods.
The roof of the Earth Lab will be a true green roof with the ability to support wildflowers and will offer multiple benefits including habitat creation, increasing biodiversity, water filtration and creation, and carbon capture. Species planted will be reflective of the wildflowers native to the area, and will be introduced through a combination of plug planting and seeds.