Torran Glas

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 INFORMATION

  • 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

FABRIC PERFORMANCE

  • Airtightness (designed & measured): Untested
  • Wall u-value: 0.15
  • Roof u-value: 0.12
  • Floor u-value: 0.14

MOISTURE CONTROL

  • Building ventilation: Trickle vents and extract fans with integral heat recovery
  • Fabric’s role in moisture control: Vapour Open / Hygroscopic

MATERIALITY

  • 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.

LEARNING

  • 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.