Straw-bale Research Building at the University of Manitoba

Eco-building



Straw-bale Research Building at U of M


Building covered by tarpaulin for weather protection (Photo: Om Joshi) Exposed roof truss and posts (Photo: Om Joshi)

Research Opportunities

The straw-bale building will provide the University of Manitoba with unique research opportunities in two different streams. 

  1. Study based on soil bin (to be housed within the building)
  2. The building (post-frame straw-bale infill structure) itself as a research tool 

The Biosystems Engineering Department at the University of Manitoba leads Canada in research related to agricultural buildings. To maintain a link with the agricultural-buildings community, and to advance the research opportunities, the Light-Frame Buildings Design Group was formed within the Biosystems Engineering Department. This group will conduct buildings research on the post-frame straw-bale structure. The Light-Frame Buildings Design Group has identified main areas of research, as explained below. 

Durability
Properties of the stucco coating and the straw allow moisture to move through a wall when there is a difference in vapour pressure across the cross section. Such “breathability”, according to advocates of straw-bale structures, meets the criteria of healthy housing, as defined by CMHC. However, there is a lack of verifiable data that supports this behaviour. The straw-bale building is oriented along the true east-west axis so that its longer side (120 ft.) faces south. This side will receive maximum solar radiation to create a vapour pressure difference. Some of the research intentions for the orientation of the building: 

  • The opposite north and south walls will receive minimum and maximum extremes of temperature respectively, which will indicate the relation of solar radiation to vapour movement
  • Long-term performance evaluation of straw-bale walls in high relative humidity environments
  • Long-term durability of straw-bale structures with respect to solar radiation to understand material properties of straw 

Energy and Ecology
Straw-bale structures provide high levels of insulation. This straw-bale building will have an insulation value R50. A typical house in Winnipeg would have an insulation value of R20. In an era of increasing awareness on sustainability, there are greater concerns for effective use of energy and assessment of ecological coasts of buildings through evaluation techniques such as embodied energy and carbon sequestering. This building will provide opportunities for research on aspects related to alternative-energy. Various research directions include: 

  • Testing and evaluation of solar gain techniques through innovative use of recycled products and commercially available products
  • Monitoring of insulation properties to gain more insight into the insulation values of straw-bale structures
  • Evaluation of alternative wall system materials such as different types of straw, log-ends, and insulated panels
  • Feasibility of use of photovoltaic panels for some research projects
  • Alternative heating systems using geothermal energy to be incorporated into the structure 

Structural Design and Integrity
This building is a combination of a post-frame structure and non-load bearing straw, which provides unique structural engineering research opportunities, currently unavailable anywhere across North America.

  • Continuous, real-time evaluation of forces in the post-frame structure to model the interaction response between actual wind, snow and dead loads
  • Real-time monitoring of forces in the lateral bracing system of pre-fabricated wood trusses
  • Evaluation of shear forces transferred into the structure through the roofing material
  • Evaluation of shear forces transferred into the foundation through the end walls
  • Measurement of shear flow at the stucco-straw interface in the walls and the shear flow path
  • Evaluation of loads at the end of the posts and temperature gradient over the depth of the post
  1. (Source: Dick, K.J., Britton, M.G. A Researchable Building - An Overview of the Post-Frame, Straw-Bale Infill Research Building. Winnipeg, CA: University of Manitoba.)

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