Sustainability Advantages to Building with Hempcrete
Hempcrete isn't just ideal for builders looking to achieve a low carbon footprint; there are several practical benefits to using it as well. Photo courtesy of Global Hemp Group
By Global Hemp Group
The scientific consensus around climate change and its prospective irreversible effects have put the need for global environmental sustainability front and center on the world stage. As the search for viable strategies continues, it's up to elected government leaders to implement and incentivize sustainability-oriented regulations in their respective commercial, industrial, and residential sectors.
Hempcrete house. Photos courtesy of Global Hemp Group
Let's look at the building industry as an example. According to a 2019 World Building Council report, building and construction are responsible for 39% of all carbon emissions in the world, with operational emissions (heating, cooling, lighting etc.) accounting for 28%. The remaining 11% are attributed to embodied carbon emissions in the materials used and the construction process itself.
In 2018 commercial and residential structures accounted for approximately consumption 28% energy used in the United States, according to the U.S. Energy Information Association. According to researchers, energy inefficiency in construction sites is a key component in these statistics.
With the emergence of alternative technologies and materials — such as bio-aggregates and electric tractor motors — there's no shortage of new, sustainable approaches to construction.
Data from Global Hemp Group
One particularly notable arrival in this field is a rapidly renewable, incredibly versatile bio-aggregate known as hempcrete.
What is hempcrete, and how can it be used?
As its name suggests, hempcrete is essentially an eco-friendly alternative to concrete, made by combining woody hemp cellulose (known as “hemp hurd") with lime and water.
This wet-mixing process produces a building compound that can be rendered into modular masonry units such as blocks or bricks. It can also be used as loose-fill material or cast into molds, hardening as it dries. Hempcrete can even be used to form walls around wooden structural frames, giving it an impressive range of utility in construction and insulation.
In this post, we explore the advantages of sourcing and using hempcrete, as well as its current drawbacks when compared to conventional building materials.
Hemp Farms, Bio-Sequestration & The Carbon-Negative Advantage
It's worth noting that hemp farms are much more than reliable suppliers of quality biomass for companies producing CBD isolates, wholesale terpenes, or Rick Simpson Oil (RSO). Hemp absorbs more carbon per hectare than any industrially-grown crop due to its rapid growth rate, even outperforming trees grown for the lumber industry.
In essence, hemp farms are the most effective natural carbon sinks on the planet, due to what is known as carbon biosequestration — a function they perform at an estimated rate of 15 metric tons per hectare annually. As of this writing, the production of hempcrete is one of only a few large-scale incentivization for the creation of more hemp farms.
CARBON BIOSEQUESTRATION- HOW IT WORKS?
Hemp, as with all plants, is carbon negative, as it locks in CO2 during its growth process. It's also rapidly renewable, given its impressive rate of growth with proper crop management. When hemp is mixed with lime to make hempcrete and used in construction, its trapped carbon is rendered into a dormant state for the lifetime of the buildings produced. The hemp-lime mixture continues to sequester carbon throughout its life as the mixture decarbonates over time. These buildings are the longest-running examples of applied carbon sequestration to date.
Practical Benefits of Choosing Hempcrete Over Conventional Building Materials
Hempcrete isn't just ideal for builders looking to achieve a low carbon footprint; there are several practical benefits to using it as well. Let's look at three of the most notable hempcrete advantages over conventional building materials:
Hempcrete walls provide superior breathability, allowing moisture to be absorbed and released when ambient moisture varies. This is highly desirable from a health point of view. The porous nature of the hempcrete wall ensures low thermal conductivity. The combination with lime makes these walls highly resistant to mold. This means hempcrete walls are incredibly well insulated — facilitating 60-70°F temperatures all year round in many climates, which in turn leads to reduced energy costs and consumption.
Hempcrete is lightweight and flexible, resilient enough to safely absorb everything from natural temperature-induced expansion or contraction to the volatility of most earthquakes. Because of its low density, hempcrete can withstand vibration and movement without cracking or the need for steel expansion joints, as more brittle building materials like concrete do.
Hempcrete is also naturally pest and fire-resistant, unlike wood which is particularly susceptible to termite infestations. Testing has shown that hempcrete walls can be subjected to temperatures of 1200°F for up to four hours without catching fire.
Are There Any Downsides to Using Hempcrete?
There are essentially two downsides to Hempcrete construction: the structural weakness of hempcrete and the construction price.
Hempcrete walls do not resist very well to compression and require structural elements to withstand any weight. This is why hempcrete has been used in conjunction with a wood frame around which it is molded. Moreover, a hempcrete wall cannot be poured all in one shot, but in several layers, which must be given time to harden. Such a process is time-consuming, weather dependent, and costly.
Over the past few years, several innovations have solved the structural issues and somewhat closed the gap on prices. Two such innovations are worthy of mention. The first one is the manufacture of blocks that incorporate the structure. Isohemp and JustBioFibre are two prime examples of this type of innovation. The second innovation uses traditional hemp construction with wood frames and shutters but moves the process inside a plant where prefab techniques are used. This removes the weather constraint and allows for economies of scale as workers can work on several units at the same time while drying takes place.
HEMPCRETE CONSTRUCTION ON THE POSITIVE SIDE
While these innovations are very promising in making hempcrete construction more competitive it is worth mentioning, that the competitive process is not really fair. Indeed, hempcrete construction brings along a private good through the lower operations cost of healthy houses, and a public good through a lower carbon footprint. Should traditional construction be brought to bear its share on environmental damage, hempcrete construction would be at a great advantage.
Reprinted with permission from the Global Hemp Group website.
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