Torran Glas (Grey Hill) is a self-build home on the remote Scottish island of Colonsay. Designed to be carbon neutral, the structure is composed of a timber frame with hempcrete sprayed onto the exterior structure. The lime rendered finish allows the structure to blend in with the local vernacular whitewashed rendered cottages. Split into 3 levels; 2 of the bedrooms occupy the lower ground floor; whilst the kitchen,dining and master bedroom are located on the upper ground floor. The first floor contains a large living and music room with a large panoramic window. The house is designed to be heated by a multifuel stove.
- Project type: New dwelling house
- External floor area: 172.4m2
- Number of storeys: Two
- Architect/Designer: Chris and Sally Walker of Native Architects
- Client: Chris & Sally Walker
- Contractor: Chris Walker + associates
- Product consultant: Native Architects
- Construction type: Timber frame
- Standard: Zero Carbon
- Cost: £160,000
- Completion date: Projected December 2014
- Self build element: All of it
- Site training: N/A
- Airtightness (designed & measured): Untested
- Wall u-value: 0.15
- Roof u-value: 0.12
- Floor u-value: 0.14
- Building ventilation: Trickle vents and extract fans with integral heat recovery
- Fabric’s role in moisture control: Vapour Open / Hygroscopic
- Materials used: Timber frame with sprayed hempcrete and wood fibre roof insulation with fibre-cement roof finish. Concrete beam & block, hempcrete floor.
- Reasons for selection: Low embodied carbon. Putting our money where our mouth is!
- Comments on local sourcing: Difficult!
- Did this help with achieving planning consents: No
- Was a whole building embodied carbon study conducted: No
- Were materials mixed on site: Yes, hempcrete and lime render, by The Limecrete Company
- Were there any issues with quality, winter working or extended drying times: Yes, the
- 300mm of hempcrete floor took an extended timeframe to dry.
- Who is the building warranty provider: Native
BUILDING PERFORMANCE EVALUATION
Description of studies with link to further information: Data-logger to be installed measuring temperatures and relative humidity over a year.
- Indicate issues and how they were resolved: BBA Certification was requested by Scottish Building Standards, so we had to specify The Lime Technology system.
- The building inspector could not grasp the concept of not having a vapour barrier as a way of preventing interstitial condensation.
- The lack of certification of non-Lime Tech variants of hempcrete is a problem.
- What would be done differently next time: Paint the lime render earlier as the winter exposure eroded some west facing render.
- Are there tools or resources that would have been useful, that need developing: A Crane would have been useful.