Written by: Louise Deltheil
Edited by: Othmane Oukrid
According to the Canada Mortgage and Housing Corporation, the average household had to devote close to 60% of its income to housing in 2021 (Canada Green Building Council [CAGBC], 2024). With housing shortages being the primary culprits for rising costs, quality homes need to be built quickly and on a large scale.Sustainable homes offer the opportunity to create durable homes with minimal environmental impact. Their design process focuses on the entire lifecycle of the building, from material sourcing to demolition (Shahbaz, 2024). Sustainable housing integrates multiple principles to create different styles of eco-friendly homes, including energy efficiency, waste minimization, and water conservation (Sustainability Success, 2023). Common solutions include building with sustainable materials like hempcrete or rammed earth.
Hempcrete homes have walls, insulation, and flooring made entirely of hempcrete. Hempcrete is made from the inner woody core or hull of the hemp plant, mixed with a lime-based binder. The high silica content of the hemp hull, along with the lime binder, allows for a lightweight cement-like material that weighs one-seventh of the weight of concrete blocks. Relative to conventional concrete, hempcrete is sustainable: it has a lower carbon footprint—it sequesters CO2—and allows for 50% to 70% relative energy savings. Hempcrete blocks are also highly durable and fireproof, with high thermal insulation. They absorb and release moisture, preventing condensation and dampness. Hempcrete blocks come with a built-in framing system that is more robust and durable than traditional concrete, eliminating the need for an additional framing system and its associated environmental impacts (Eva, 2022).
The SUNIMPLANT project in Morocco is a single-family hempcrete home created for the Solar Decathlon, a global competition focused on developing highly efficient and innovative buildings. This building is one of the first of its kind in the world, utilizing a hemp composite created using vegetable-based bio-resins. The SUNIMPLANT building includes a double-skin façade made from a mixture of locally sourced hemp, earth, pozzolan, and lime, as well as bio-composites and high-performance glass (HempToday, 2020). The design is inspired by ancient African architecture and uses hempcrete with high thermal effusivity and conductivity for better wall insulation. The materials also work together to create a healthy interior space, improving air quality (UrbanNext, 2019).
Rammed earth homes utilize an ancient building method that has resurged in recent years as a sustainable, natural alternative to conventional methods. Rammed earth walls are simple to construct: a frame is first built, then filled with a layer of damp earth, including sand, gravel, clay, and a stabilizer. The layer is then compressed before the next is added, and the process continues until the frame is filled, after which it is removed (Cao, 2020). Rammed earth walls are incombustible, thermally massive, strong (with a maximum compressive strength of 4.3 MPa), and durable, though they are susceptible to water damage if not properly maintained. The necessary materials are typically locally sourced, minimizing embodied energy and construction waste. The availability of useful soil for local climatic conditions makes rammed earth homes popular on every continent. They can be found in temperate and wet regions of northern Europe as well as semi-dry desertic regions, mountainous areas, and the tropics. In fact, Antarctica remains the only continent with no rammed earth buildings (Green Building Canada, 2013).
After deliberation, Wes and Julia decided to use rammed earth for their sustainable home project in Cramahe, Ontario. Although building with rammed earth is a more time-consuming approach—as the construction process relies on gradually transforming loose earth into solid rock—they decided that the strong, fire-resistant, and energy-efficient resulting structure was worth the wait. The material's thermal properties provide excellent insulation, helping them better regulate indoor temperatures and keep the space cooler in warm conditions. Another historic example of rammed earth construction is the Great Wall of China, where sections of the structure were built using this technique (CBC, 2019).
Various approaches can be employed to design eco-friendly homes, with some of the most effective ones combining different techniques and using low-impact materials. Hempcrete, a newer material, and rammed earth, a time-tested material, are two examples of such materials. As the housing crisis worsens, the need for sustainable homes is more urgent than ever. If even a fraction of the additional 3.5 million housing units needed by 2030 (Canada Mortgage and Housing Corporation [CMHC], 2023) incorporate sustainable principles, the crisis can be addressed with high-quality, durable homes of minimal environmental impact.
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References:
Canada Green Building Council. (2024, December 10). Two million green homes: Canada needs quality affordable housing. Canada Green Building Council (CAGBC). https://www.cagbc.org/news-resources/cagbc-news/two-million-green-homes-canada-needs-quality-affordable-housing/
Canada Mortgage and Housing Corporation. (2023, September 13). Estimating how much housing we’ll need by 2030. CMHC. https://www.cmhc-schl.gc.ca/blog/2023/estimating-how-much-housing-we-need-by-2030
Cao, L. (2020, February 11). How rammed earth walls are built. ArchDaily. https://www.archdaily.com/933353/how-rammed-earth-walls-are-built
CBC. (2019, April 18). This sustainable “rammed earth” home is a sparkling example of earth-friendly living. CBC. https://www.cbc.ca/life/video/this-sustainable-rammed-earth-home-is-a-sparkling-example-of-earth-friendly-living-1.5103612
Eva. (2022, March 28). What is a hempcrete or hemp block house? Alternative Housing Options. https://alternativehousingoptions.com/what-is-a-hempcrete-or-hemp-block-house/
Green Building Canada. (2013, September 23). Rammed earth. Green Building Canada. https://greenbuildingcanada.ca/rammed-earth/
HempToday. (2020, April 14). Project in Morocco combines hemp and solar to go totally off grid. HempToday. https://hemptoday.net/moroco-hempcrete-project/
Shahbaz. (2024, March 6). What is sustainable housing design? Sustainable Design. https://sustainabledesign.com/what-is-sustainable-housing-design-sustainable-design
Sustainability Success. (2023, October 25). 8 sustainable housing types: Guide to eco-friendly homes. https://sustainability-success.com/sustainable-housing/
UrbanNext. (2019). SUNIMPLANT: An avant-garde off-grid hemp building. UrbanNext. https://urbannext.net/sunimplant/
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