Natural Materials
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Friday 27th October 2017
Dr Jim Carfrae
Main themes: My straw bale house. What natural materials are available? Why use natural materials?
The Totnes straw bale house.
Straw bale construction
Straw bale history
Container City: Reuse/recycle
Cob house: Local materials, built by hand
Charlie and Megan’s house:
Low impact, under the radar.
Straw bale cabin: What is the unique feature of this small house?
What sort of materials are available?
Structural – Timber, Engineered timber Earth – Cob, Adobe, Rammed earth Straw (plus timber) Hempcrete (plus timber)
Insulation – Cellulose Woodfibre Sheep’s wool Hemp shive
Renewable materials:
Structural – Steel PFA and GGBS in Concrete (Pulverised Fly Ash, Ground Granulated Blast-furnace slag) Foam Glass – Rubble and Blocks
Insulation – Cellulose (newspaper) Denim Plastic Bottles Wood waste
Recycled materials:
Use of Timber as structural element. Using iBeams to increase strength, and add depth for insulation
Use of Timber as structural element. Glulam – Glued, Laminated timber Used for beams to increase spans - and create interesting shapes
Proprietary system: Timber structure with woodfibre insulation (insulation is by-product of structure)
Cross Laminated Timber (CLT) Offsite CNC cutting – Fast and clean construction
Renewable insulation materials
Sheep’s wool Either in manufactured ‘batt’ form, as in Thermafleece (contains a proportion of recycled plastic reinforcement)
Renewable insulation materials
Blown Cellulose Fiber: Recycled newspaper, blown in place slightly damp. Main supplier ‘Warmcel’ Lambda value:
Recycled insulation materials
Supaloft – recycled plastic bottles (same as duvet filling)
Ultra Touch – recycled denim
Foam glass rubble used as insulation under slab
Why use natural materials? Aesthetic qualities Healthy Homes Environmental impact Locality Renewable Minimising use of fossil fuels
Embodied Energy Calculated through ‘Life Cycle Assessment’
Embodied energy:
Life Cycle of concrete block
Resource
Extraction
Manufacturing
Processing
Use on Site
Maintenance
/Replacement Demolition
Reuse,
Recycle.
Disposal
Cradle
Gate
Grave
Transport
Transport
Transport
Quantifying embodied
energy
Inventory of
Carbon and
Energy (ICE)
Energy in use and Embodied energy: Compare two houses
Operating Energy 73kWh/m2/yr.
Operating Energy 96kWh/m2/yr.
Materials: Timber, straw bale and lime
render.
Embodied Energy:
10,000 kWh
Materials: Concrete, phenolic foam and
cement render
Embodied Energy:
120,000 kWh
Adapted from Jukka Heinonen
Embodied energy against energy in use
Proportion over 50 years?
Now!