- 20th July 2018
- Posted by: Sophie Bunker
- Category: Projects
A new ‘Granny House’ was designed to replace a derelict croft house on a Hill Farm near Loch Tay in Scotland. It used the existing footprint of the house and extended it south west to create a sheltered courtyard garden.
The structural engineering challenge was to design a structure that used natural and renewable materials including timber and hempcrete to create a beautiful, healthy and energy efficient home. Using these materials can drastically reduce the ‘carbon footprint’ of a building, and the widespread adoption of these materials may make a significant contribution to meeting our emission targets to limit the effects of climate change.
We have worked with Ecological Architecture LLP and UK Hempcrete previously on a private house at Rynachulig. Learning lessons and working with them again, we carried out the structural design using timber and hempcrete to its maximum benefit.
Hempcrete will be used in the floor, walls and roof to create a continuous, air tight thermally insulating layer similar to the ‘passivhaus’ concept. However, whilst passivhaus concentrates on energy efficiency it does not take into account the environmental acceptability of the building materials. Therefore, the design selected materials that are ‘low carbon’ may be easily recycled or easily disposed of without causing environmental harm.
Structural design included a structural steel stability system that avoided the use of ‘timber sheet materials’. Sheet materials prevent drying out of the hempcrete, and cannot be easily recycled into high value goods or allow moisture movement through the structure.
An airtight thermally efficient building will be achieved, with a high amount of thermal buffering, natural light and generous spaces. All materials used in construction may be easily recycled or disposed of without causing environmental harm.
The building shows that it is possible to build comfortable energy efficient buildings using materials with a low embodied energy. Currently under construction, the next stage will be to see how well the building performs when in use.