Our first straw bale building
What do a planning officer, a bodger, an aspiring cob wall builder, a wedding dress designer; a visual artist and a National Trust Regional Director have in common?
The answer is they all had hands-on involvement in the Footprint project, an innovative and inspirational new development which has taken place at St Catherine’s Woods, near Windermere in the Lake District National Park.
Work began on the Footprint in April 2006, and created the first straw bale building in Cumbria, and the first to be built by the National Trust.
Our team wanted to develop a classroom, allowing school groups a space to learn and engage with us. But, rather than constructing a ‘normal’ classroom type space of modern day conventional building materials, the team at St Catherine’s wanted to do something different. So it was agreed we would build a environmentally friendly structure.
We wanted the building to provide space for a good sized group of children or adults, that could be easily accessed and flexibly used by all visitors and which was welcoming and pleasing on the eye.
We wanted the design to be sympathetic to the existing buildings (which now house National Trust offices and a staff flat), and not impose too much on the natural environment.
In the longer term, at the end of the building’s natural life (some straw buildings are in use after more than 100 years), we wanted it to leave a very small impact. This will be partly achieved through the choice of construction materials, favouring those that will naturally biodegrade or can be recycled in the future.
We also wanted the building to have a small ecological footprint (how much agricultural or ecologically productive land area it takes to sustain a person or a group, or in our case, a building).
To achieve a small ecological footprint, the building materials need to be from sustainable, realistically renewable resources, or from recycled materials, so that the impact of construction in the present is reduced. To cut down on transport these need to be as locally sourced as possible.
We also recognised that our design needed to incorporate good use of natural light and have excellent insulation, thereby reducing electricity and heating needs when up and running.
Because the building will be mainly used for education, we also wanted the construction process and the end result to be a learning project. In doing all this we wanted to inspire a positive emotional response towards the building and excite people about achievable, low environmental impact living.
The use of straw bales in building has been widespread in Canada and the USA for over a century. It has been increasing in the UK and in Europe over the last two decades.
Straw bale walls
The walls of the Footprint are a combination of straw and glass. Approximately 380 standard straw bales were needed. These were sourced from a farm in Yorkshire.
This might sound like a lot of 'straw miles', given that it is grown nearer to Windermere, but straw for construction needs to be as strong, as straight and as tightly baled as possible. The bales also need to be consistent in size and density, and be dry, with no hint of mould or mildew.
The main environmental advantages of building with straw are:
- Sustainability: straw is an annually renewable natural material and approximately four million tonnes are surplus to requirements in the UK alone.
- Biogradability: at the end of the building’s life, the straw will biodegrade naturally, leaving no trace.
- CO2 emissions: it is estimated that over 50 per cent of all greenhouse gases are produced by the construction industry and its associated transport. By using regional sources, we can contribute to a reduction in emissions through transport. Straw bales don’t need to be fired like bricks and don’t need cement. Additionally, as a resource, straw has absorbed and stored CO2.
- Insulation properties: with almost three times the insulation value of standard building materials, straw is extremely efficient at reducing the heating demands of a building.
- Financial sustainability: or a fancy way of saying it is cheaper in the short term to build your walls of straw, and cheaper to heat your building in the long term.
- Opportunities for involvement: a straw bale build gives interested parties such as planners, builders, self-builders, environmental advocates and local volunteers an opportunity to become involved in a very 'participant friendly' building method