Hempcrete as a sustainable building material!
The Minka Project was started in 2015 and completed in 2017 with Hempcrete. The 350 year old Japanese post and beam frame was integrated into walls cast with hemp core and lime creating a high performing, vapor permeable, carbon capturing thermal envelope. Despite its many benefits, Hempcrete does have a few disadvantages that make it less than ideal as a building material for modern skyscrapers.
For instance, the porous structure of the Hempcrete decreases its mechanical performance in structures taller than three stories and increases its ability to retain water. The fact that it is mold resistant and petrifies over time to become harder and stronger than concrete makes it ideal for builds near beaches and waterways. This factor makes Hempcrete something that is increasingly desirable in this age of sea rise and extreme weather events!
Hempcrete recently received certification in US Residential Building Codes. The certification allows hemp-lime mixtures (hempcrete) to be used as a standard material in residential construction beginning in 2024. This will expand the need for hemp crops and also influence building practices worldwide. Hempcrete homes are long lasting. The average Hempcrete home is estimated to last 50-100 years. Hempcrete itself, on the other hand, has an incredible life span of at least 300-500 years , if not longer and it is recyclable. Board is also gaining in popularity as it is resistant to termite attack although one can conclude that hemp is susceptible to termites; those that consumed the mineralized hemp fibers, had high mortality slowing the ability of a nest to grow and cause major damage.
Because of the increase in hemp availability generally, whatever the standard price is for a build per square foot, add a minimum of $20 to that. So where it may cost an average of $120 per square foot on a traditional build, a hempcrete structure may cost $140 per square foot or more.
The eco-properties of hempcrete don’t end post construction. Hemp sequesters carbon, meaning it stores significant amounts of carbon dioxide, helping to decarbonize the atmosphere. The Bristol Hemp Company estimates that one ton of harvested hemp fiber should sequester 1.62 tons of carbon dioxide. In the construction industry, the United Nations Environment Program estimates it contributes up to 30% of the global annual greenhouse gas emissions, and uses up to 40% of all energy. In order to protect future generations and profitability in the industry, reducing carbon emissions must become a top priority if we are ever to fulfill net zero ambitions in order to slow or stop global warming.
Apart from the environmental benefits of using hempcrete, there are also many practical advantages. For one, hempcrete is up to eight times lighter than concrete. This means shipping it costs eight times less and uses less energy to transport and move around a construction site.
As noted above, Hempcrete is also perfect for moist environments. The blocks can actually absorb water from the air, with one cubic metre absorbing up to almost 600kg of water. This reduces the growth of mould, especially in particularly humid conditions.
Hempcrete is also known for being more physically flexible than concrete. In areas where earthquakes may occur, it’s often being used to make structurally stable buildings, as the walls can literally shift and bend to cope with seismic activity. This advantage is likely to become even more crucial as the climate crisis makes natural disasters more common. This is something countries like China and African nations where China builds its cheap Tofu Dreg projects are coming to terms with. Tofu-dreg construction stems from speedy, shoddy work and often uses cheap and quick materials, mainly concrete. The speedy construction and pouring of sub-standard concrete leads to poor building and infrastructure quality, causing the issues and losses of lives seen during natural disasters like the Wenchuan Earthquake.
China produces and consumes about 60 percent of the world's cement — the Three Gorges Dam alone required 16 million tons of it. In fact, from 2011 to 2013, China used 6.5 gigatons of cement. That's more than the United States used during the 20th Century. There is a lesson in this in the age of climate change we need materials that offer resilience in the face of the changing and often hazardous conditions wrought by climate.
Overall, hempcrete offers a sustainable and environmentally friendly alternative for construction, with its unique combination of insulating properties, breathability, long life, and carbon sequestration potential. A densely and quickly growing plant, hemp literally chokes out any competing plants. This means harsh chemical herbicides aren't necessary. Hemp also naturally reduces pests, so no pesticides are usually needed. Amazingly, it also returns 60-70% of the nutrients it takes from the soil.
Most of all the Hurds (the coarse parts of flax or hemp that adhere to the fiber after it is separated, also called "Hards" ) that are used for hempcrete are the last part of the plant to be utilized in fact the plant on average provides seed for food such as; hemp flour, milk, oil that is high protein and omega 3s,fiber for textiles for clothing superior to cotton and hemp fuel, inks, paint, biodegradable plastics, and CBD oil for medicinal purposes and pain management. With 10,000 industrial uses growing hemp is one of the most profitable crops in the world!
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