Building with Biofibres
Where the past meets the future for energy efficiency and reduced environmental impact
How Did I Get to Be “That Straw Bale Guy”?
• Wanted to build a house that was: • Affordable • Energy Efficient • Environmentally Sound
Straw Bale? • Our house has many unique features, including: – – – – –
Off-grid with solar and micro-hydro power Solar hot water Radiant floor heating Passive solar Etc….
• But Straw Bales get all the glory!
Straw Bales: Blessing & Curse • Blessing because it’s gained a lot of attention without a lot of budget • Curse because: • It shouldn’t be such a big deal • Three little pigs and big bad wolf jokes suck • It makes the idea sound “fringe”
• Change “straw bale” to “structural fibre insulation (SFI)” or “bio-fibre building”
What Do We Do With This “Bio-Fibre”? 1) 2) 3) 4)
Straw bale wall systems Structural fibres in plasters Straw/Clay wall systems Hempcrete • • •
Insulated foundation walls Insulated building walls Window frame insulation
How Do Bale Walls Work?
• Bale walls operate as a stressed skin panel, with two skins of strong, brittle plaster bonded to the dense, insulative straw.
Structural Fibres in Plaster • Replace synthetic (glass and poly) fibres in cement, lime and earthen plasters – Comparable strengthening effect – Lower costs – Better curing due to moisture retention of natural fibres – Less toxic to workers during mixing
Straw/Clay Walls
• Old European wall system for timber framed structures, many over 400 years old with same walls intact! • Loosely chopped straw is tossed in a light clay slurry until lightly coated, then packed into slip forms to create insulated wall fill
Straw/Clay Walls cont’d
• Excellent for retrofitting existing frame wall buildings • Good R-value • Good fire resistance • Simple, low-cost, effective insulation
Hempcrete • Mixture of chopped hemp and hydrated lime • Creates “aerated” cementitious material with good structural properties and good insulation properties • Long history in France, now commercially available in France and England
Hempcrete Foundations
• Self-insulated, structural foundation material • Saves cost of adding styrofoam or other insulations
Hempcrete Walls
• Excellent for retrofitting existing frame wall buildings • Good R-value • Good fire resistance • Simple, low-cost, effective insulation
Hempcrete Window Insulation
• Makes tight seal around windows • Good insulation value • Good restriction of air movement
Why Build With Biofibres? 1) Reducing “Embodied Energy” 2) Increasing energy efficiency 3) Supporting local economies
Embodied Energy: The Hidden Criteria What goes into harvesting a Straw bales = 31MJ/m3
material? Processing it? Transporting it?
Fiberglass = 970MJ/m3
Embodied Energy? The Canada Mortgage and Housing Corporation (CMHC) estimates that for a standard house in Toronto with a 40year life, the total embody energy is 2,352 Gj. The total operating energy over 40 years is 9,060 Gj.
What Does This Mean? • Every home in Canada uses the equivalent of 392 barrels of oil to build • Every home in Canada uses the equivalent of 40 barrels of oil per year to operate • Poor indoor air quality in homes is responsible for vast numbers of health problems
• Can straw bale techniques really make a difference to the environment? • “The embodied energy for the conventional frame house was 509,000 KBtus. The embodied energy for the low impact straw bale house is 41,000 KBtus, or about one twelfth that of the frame house.”* *Investigation of Environmental Impacts, Straw Bale Construction, by Ann V. Edminster, University of California, Berkeley, 1995. Zabludofsky low-impact residence, Madoc, Ont..
• Will a bale home be less expensive to heat? • “Straw bale construction, along with appropriate building conservation technologies and simple passive solar design, could provide up to a 60% reduction in building heating loads over current practice.” •
*US Department of Energy (DOE) straw bale assessment program, 1995
Masonry heater, Robin’s Nest B&B, Norwood, Ont..
How to Assemble Bio-fibre Components Into Sustainable Buildings • Combine low embodied energy materials into energy efficient buildings utilizing passive heating and cooling strategies, renewable energy sources, minimize or eliminate fossil fuel use and eliminate offgassing and toxic materials
Fleming College Sustainable Building Program Projects 2005: 4Cs Food Bank and Thrift Store in downtown Haliburton
Earthbag SFP foundation, earth plastered hemp bale walls, 1kW grid-tied PV, solar hot water, earthen floors with radiant heat, recycled insulations, solar light tubes, triple glazed fiberglass windows, passive solar orientation, non-toxic finishes, compressed strawboard partitions, hempcrete walls, pop bottle walls, locally milled lumber, earth tube ventilation, light clay/straw walls
Fleming College Sustainable Building Program Projects 2006: Kinark Sustainable Living Centre, Carnarvon
Earthbag SFP foundation, AGS heating, waste wood structural columns, round timber framing, earth plastered hemp bale walls, light clay/straw walls, sheep’s wool insulation, recycled door cut-out insulation, earthbag mass wall with radiant heating, off-grid PV electrical system, solar hot water, eastern white cedar shingles, cordwood wall, earthen floor, rainwater harvesting, Eco-flow septic system, clay countertops, passive solar orientation
Fleming College Sustainable Building Program Projects 2007: RD Lawrence Place, Minden Museum and Cultural Centre
Helical pier foundation, slag/fly ash SFP slab, earth and lime plastered hemp bale walls, indoor constructed wetland grey water treatment, composting toilets, Bullfrog power contract, radiant floor heating, locally milled lumber, recycled insulations, fiberglass windows, solar hot water, PV-run display centre
Fleming College Sustainable Building Program Projects 2008: Community Arts Centre, Madoc, Ontario
Earthbag SFP and hempcrete foundations, geothermal heating, round straw bale structural columns, round timber framing, earth plastered hemp bale walls, light clay/straw walls, hempcrete walls, sheep’s wool and recycled cotton batt insulation, grid-tied PV electrical system, solar air heating, all locally milled or FSC certified lumber, cordwood wall, earthen floor, rainwater harvesting, clay countertops, passive solar orientation
The Future of Biofibre Building
• Prefabricated straw bale SIP panels
Prefabricating straw bale wall panels removes most of the impediments to building with bales and reduces costs to well below that of conventional construction.
Anyone interested?...
Other marketable biofibre products… • • • • • •
Hempcrete blocks (ICF-style) Hempcrete wall panels Premade hempcrete window insulation Pre-bagged hempcrete mixes Pre-bagged plaster fibres Straw/clay mixing devices and fibres
For more information: • • • • • •
[email protected] www.sustainablebuilding2008.ca www.strawbalebuilding.ca More Straw Bale Building Design of Straw Bale Building The Last Straw Journal www.thelaststraw.org
