Hempcrete Ticks the Boxes

David Leigh
11.07.11 2:54 am

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I recently downloaded a copy of the GREEN PUBLIC PROCUREMENT (GPP) PRODUCT SHEET, published by European Commission as a training kit for building and purchasing of building materials. The EU takes climate change and the human impact on our environment seriously and has legislated to protect the earth and mitigate the impacts of man’s industry. Reading the contents of this 29 page PDF document it comes as no surprise to me that the regulation is strict and complete in its focus.
Chart from European Commission GPP Training Toolkit – Module 3

The above chart lists the criterion for purchasing and use of materials used in construction and it seems a good exercise to examine commercial hemp, to see how it fits with these standards.

Hemp hurds or shivs (woody core material chipped) when mixed with lime and a little water, undergoes a transformation. A chemical reaction between the fibrous hurds and the lime, activated by the water, causes petrification. The material literally turns to stone. This action takes place immediately and continues to strengthen the bond and structure throughout its life. There is evidence that buildings in Egypt, made from this mixture, have lasted for thousands of years. Straight away the LIFE CYCLE ASSESSMENT (LSA) part of the chart has been satisfied. There is also an added bonus in that the process that turns the mixture into stone actually sequesters carbon as part of that process. So not only do we have a material that is durable enough to last many lifetimes but also a carbon sink and oxygen supply at the same time. The walls literally breathe oxygen into our homes.

Walls built from this material are thermally insulated and as long as good ceiling insulation is installed (see below) require little heat or cooling to make the building liveable. That ticks the energy consumption and the Passive Houseboxes also.

Carbon Neutral

The whole procedure of hemp use is carbon neutral in that it is a renewable source. The plant absorbs carbon in the form of CO2 from the atmosphere as part of the natural photosynthesis process. On harvesting it releases much of that carbon into the soils as fertilizer for the next growth cycle and as a soil improvement. The Carbon that is stored in the plant cells remains there and is added to by subsequent sequestration.

Because the plant can be grown on the site or nearby it saves carbon normally used in transportation, ticking yet another box. Walls made from hempcrete are also good sound insulators allowing us to tick the noise control part of the box as well.

Waste reduction and recycling are easily achieved with hempcrete because the materials are natural and can be crumbled and used over. Mixing only what is needed for the construction of the building allows for good waste management also and the remaining hurds can be used to make insulation, garden mulch and a myriad of other items or just ploughed back into the soils with no harmful effects.

Hemp fibres from the hurd (core) and the bast (Bark) parts of the plant make excellent insulation for buildings and motor vehicles and are used quite a bit in EU countries and other parts of the world.

Chipboard made from hurd fibres are stronger and lighter than conventional particleboard and have better water resistance. Kitchens, vanities and internal doors can be fashioned from this material further adding to the insulation properties of the house.

All that is needed is a roof and yes, that can be made from hemp also. It is possible to press sheets of roofing or roof tiles from hemp to complete the picture of a hemp house. Of course there are problems, as one would expect, because nothing ever seems to run smoothly. There is the question of legislation.

Still classed as a drug by many governments, including the Australian Federal Government and especially the Tasmanian State Government, complex licencing regulation makes it difficult to gain the best benefits from this plant.

The Tasmanian State Government has hemp listed as a poison and that has made the licencing laws far stricter.

All the products are readily available in EU countries and can be purchased from the local building supplies company.

There is Limited Recognition

Hemp is partially recognised in Australia as a source of fibre, however human consumptionof the seed is not permitted and only our pets and livestock can reap the health benefits of this plant. The seed contains the 8 amino acids normally only found in meat. It is therefore high in protein and at 24 – 25% protein it makes for a meat substitute that is better than the product it replaces. The seeds are high in naturalantioxidants and the omega 3, 6 and 9 oils contained in the seed are in the perfect harmonic balance for the human body. It is recognised in many countries for proven health benefits and has become an essential ingredient for health food stores overseas.

It is the value adding of processed, high protein hemp seed meal and oils that create the real wealth from this plant and allow us to get the benefits of cheaper fibre as a by product.

And not just for Building

Hemp is also an excellent source of bio-fuels. Both petroleum and diesel substitutes can be made easily and in abundance from hemp, giving us a renewable and independent supply of fuels for transport. All this adds up to construction and transport industries that are carbon neutral and therefor exempt from carbon tax.

Green Jobs and Emissions Targets

Many thousands of sustainable jobs could be created in Australia, if hemp regulations followed the EU principles. Climate change targets could be more easily reached and our health departments would be better able to cope with a far healthier population. It is imperative then that hemp is adopted into our programs for sustainability, sooner rather than later. Other countries are ahead of us in its uses and we stand to loose out financially by not building a hemp-based economy.