Hemp refers to the plant Cannabis Sativa.
While the C. Sativa plant contains tetrahydrocannabinol (THC), the psycho-active ingredient associated with marijuana, industrial hemp cultivars are very low in THC and are grown specifically for seed or fibre.
The industrial plant has three useful parts:
- Shiv – the inner woody core of the stems, also known as hurd.
- Bast – the outer fibres.
- Seeds
From those three parts, uses range from textiles and cosmetics, to building materials and food.
Hemp is an eco-friendly crop as it does not require herbicides or pesticides. Due to its rapid growth and growing densely, it shades out weeds which eliminates the need for herbicides.
In addition, fibre crops do not demand pesticides because pests do not have a significant impact on fibre yields. There is no need to use dangerous chemicals to grow industrial hemp and it has minimal fertiliser and irrigation requirements.
Why Is It So Effective As A Building Material?
In 2013, the construction sector was responsible for 18.1% of Australia’s carbon footprint.
Materials were the second largest contributor to that number due to the extensive use of carbon-intensive materials throughout the industry.
It is widely accepted that bio-based building materials can assist in reducing our carbon footprint. The general concept being that renewable, plant based materials may be substituted for non-renewable, carbon intensive materials.
Shiv derived from industrial hemp is an ideal plant aggregate because the cellulose structure of shiv exhibits the key factors required for bio-based construction.
Hempcrete
Hempcrete on the other hand is carbon negative. It is a carbon sink.
Approximately 180kg of CO₂ is sequestered within the hemp shiv of 1m³ of hempcrete. Even once the CO₂ emitted by producing the lime binder is accounted for, hempcrete remains carbon negative.
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