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!