31-05-2012 | Building with straw and hemp has long been associated with green self-builders and small scale, somewhat quirky homes. But the image of well-meaning DIYers is a world away from the sleek and hyper-modern building techniques developed by Bristol based ModCell. The first ever company to produce hemp and straw panels for the construction of modern sustainable buildings, ModCell’s main challenge now is to convince the commercial construction industry that carbon-negative building is feasible and profitable even on large scale projects.
The eureka moment for ModCell wasn’t that straw is a good building material, says director Craig White. No, it was their idea to take this often small-scale and slightly eccentric technique to large-scale, mainstream building. To date, most sustainable building has been limited to reducing water and energy usage. With this new technique, large buildings can themselves be carbon negative. As straw grows, it absorbs carbon and releases oxygen. By using it as a construction material, carbon is stored safely in the building itself, leaving a negative carbon footprint.
Building on the idea of going large, ModCell designed prefabricated timber panels filled with locally sourced straw or hemp. This way, building with straw is like using Lego bricks which makes it cheap, quick and sustainable. The panels are constructed off -site in so called flying factories. Often local barns close to the building site are used to limit transportation costs and to enable the local workforce to take part in the construction. For example, last March, students from Hayesfield Girls School in Bath helped construct the timber panels on a farm just three miles from their school.
“We have a great product but yes, we do have to keep on explaining that building with straw is not hairy or soggy.”
Margret Cooke, co-director, ModCell
Another plus point of building with straw panels is their outstanding thermal insulation. ModCell is now expanding into Spain where their panelled houses excel at keeping homes cool during the summer and warm in winter. The panels also offer significantly better sound insulation than conventional walls, making the panels particularly attractive for residential housing.
Three little pigs
While ModCell’s order books are expanding with an increase in orders of more than 500% over the last five years, convincing the commercial building industry of the benefits of their panels isn’t without its hurdles.
“We often face deep scepticism and we’ve been criticised, being told our buildings are no better than those of the three little pigs”, White says with a smile. But ModCell are able to demonstrate that the benefits of their techniques are far from a fairy-tale.
Over the last three years ModCell has participated in research programmes to test and develop the panel walls for safety, strength and lifespan. This research shows that ModCell exceeds all the standards required in mainstream construction. But the prejudice against building with straw persists even though straw has been used in building for centuries, and straw bales have been used for over 100 years.
Margret Cooke, co-director at ModCell adds, “we have a great product but yes, we do have to keep on explaining that building with straw is not hairy or soggy”.
Even though straw building is still a long way off becoming mainstream building, current financial and environmental trends plays to the strengths of sustainable building. A growing number of people are looking for ways to save money, and straw building can cut energy bills by 85%. This, combined with their clear environmental benefits, could tip the balance in favour of ModCell’s take on houses of straw and make large-scale carbon-negative building a commercial reality.