Concrete and steel have taken the construction world by storm since people discovered they could build stable and functional buildings with them. However, it’s no secret that these materials generate tons of waste and energy, and, above all, aren’t sustainable.
Since the green movement spawned, environmentally conscious architects have racked their brains to try and come up with a way of maintaining the stability and insulation offered by steel and concrete, but is less harsh towards our environment.
In a similar article, we discussed the idea of constructing buildings and high rises using wood. Plus, we even got feedback from Maltese architects on whether timber would be a viable material to invest in. If you’re interested in reading more about this, you can check our article out via this link.
Can a plant be the key to building sustainably?
Hemp, or industrial hemp, is a strain of the Cannabis sativa plant species that is grown specifically for the industrial uses of its derived products. It is one of the fastest growing plants and was one of the first plants to be spun into usable fiber 50,000 years ago. It can be refined into a variety of commercial items, including paper, textiles, clothing, biodegradable plastics, paint, insulation, biofuel, food, and animal feed.
Hempcrete or hemplime is biocomposite material, a mixture of hemp hurds (shives) and lime, sand, or pozzolans, which is used as a material for construction and insulation. It is marketed under names like Hempcrete, Canobiote, Canosmose, and Isochanvre. Hempcrete is easier to work with than traditional lime mixes and acts as an insulator and moisture regulator. It lacks the brittleness of concrete and consequently does not need expansion joints. The result is a lightweight insulating material ideal for most climates as it combines insulation and thermal mass.
The case for building with Hemp
Located in Asheville, North Carolina, the 3,400 square foot Push House features walls made from ‘hemcrete’. Hemcrete is actually less like concrete and more like infill straw bale, as it is non-structural. Hemp has the unique ability to capture airborne pollutants over time — it absorbs carbon when it is grown and in place. The material’s high thermal mass helps keep a steady interior temperature as well.
These buildings are made with hemp – yes, the same thing your hemp milk and your protein powder is made of. What makes it durable and fit to hold structures is combining hemp with a special Hydraulic Lime binder. The two are combined along with other chemicals to form Hempcrete.
The lime doesn’t only bind, it also preserves the natural hemp fibres. This makes it super durable, fire-resistant, and mold resistant. According to Art du Chanvre, vermin are also less likely to enter a hemp-built house.
So, why hemp?
According to Highland Hemphouse, ‘Hempcrete is essentially reconstituted limestone. It is not dissimilar to many buildings of antiquity that used burned lime as a binder and a surface treatment.’ Old Maltese buildings were traditionally made out of limestone and many of them are still standing. This is a great point in favour of Hempcrete.
In fact, Hempcrete is one of the only materials that architect Art du Chanvre opts to build with. He claims that building a hempcrete house ‘is easier than building a conventional one.’
Among the other things listed above:
- Hemp is solid enough to hold its own weight
- Controls humidity
- Self-regulating air quality
- Natural insulation
- Has good thermal resistance
- Hempcrete buildings have superior energy performance
- It’s sustainable
Some cons on hempcrete
While some people think hemp is the answer to the world’s building problems, other don’t seem to think so. Here are some cons worth thinking over:
- Not enough research has been done on hempcrete.
- Because hempcrete walls are thicker, we risk losing carpet area.
- Lime based construction is tricky and requires a certain amount of training to be imparted to personnel.
- Hempcrete might not be best suited for all climatic conditions. For example, in hot and humid regions, like south of France or Malta, the increased uptake of moisture could bring about a super influx of heat inside the building.
3-D Printing making Hemp a viable alternative
An Australian based biotechnology company called Mirreco, has recently unveiled plans for 3D printed hemp homes. The company cites environmental concerns as some of their primary motivations.
The company has developed hemp panels that can be used in both residential and commercial building projects. Furthermore, the panels can be manufactured directly through a 3D-printer, and then used to build the structure of the home.