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Nº 142 – Why not use hemp?

Saturday the 11th of February 2023.

These days, if you are thinking about building a house or restoring an old ruin you really will be forced to conduct a thorough study of your building materials and prices. Over the course of the past year alone, the price of construction materials such as steel, glass, cement and bricks increased by 30 to 40, some even up to 50 per cent. Add to this substantially higher interest rates applied to bank loans and more demanding efficiency specifications for new buildings, as well as the possibility of falling real estate prices. And this is without even mentioning ecological construction techniques. Not only is there a lack of flats, they also emit too much CO2 during their heating and cooling processes. As the European climate goals are impossible to reach with conventional construction methods, the EU Commission decided last year to create stronger guidelines on the one hand, and to lower subsidies, on the other.

Now, since 1 January 2023 the following rule applies: every new building has to comply with the Efficiency Standard 70, while subsidies are only available for more efficient buildings, i.e. category A houses with low-energy consumption. The real estate sector is anything but pleased with this. Efficient Houses are those boasting a high level of energy-efficient construction and building technology and achieving a higher energy efficiency than required by law. The energy efficiency level of a building is calculated by measuring the transmission heat loss through the building envelope (such as wall insulation and windows), and subsequent annual primary energy requirement. Here, a major influence is the energy source used, whether through photovoltaics or by harnessing wind energy, or indeed facilities combining heat and power, powered to 100% by forms of renewable energy. Last not least the time-honoured question arises: which material to use for construction?

In Colos, situated in the southern part of the Alentejo, you’ll find the Cânhamor Lda. company. Their goal is to provide a CO2-neutral, sustainable and locally sourced building material, to enable owners to create high-performing green living spaces. Just such a house is in the process of being built in the district of Vila do Bispo, in Barão São Miguel to be exact. ECO123 visited the project and spoke to the owner and manufacturers about their experiences with this new 185 m² prototype building. „In the production of our hemp bricks we are close to reaching 100 % zero waste and azero carbon footprint.

We don’t use any chemical additives in our brick composition, even if this extends the cure time. Nor do we use any heating processes. No emissions are generated during our production process,“ emphasises one of the company’s two managing directors, Elad Kaspin, during the ECO123 conversation. Hemp, he says, is a natural agricultural product, as well as being fire-resistant, noise-repellent and boasting isolating properties against cold, humidity and heat. According to Kaspin, hemp is also a breathable building material.


After harvesting, the leaves and branches of the hemp plant are first shreddered before the resulting mixture, reminiscent of cake dough, is pressed into blocks. In order to harden, the blocks have to be dried out over the course of several weeks. Subsequently, they can be used as bricks of various strengths in construction.

Fac-símile Screenshot Intro Video https://canhamorhemp.com/

According to the European Parliament’s industry committee, all buildings begun after 31 December 2018 should satisfy their energy needs locally. And the best way to generate energy on site is to first of all save energy on site: with a good level of insulation and an autonomous, independent and sustainable energy supply. Hemp blocks guarantee a very low energy requirement per square metre, with no need for further insulation.

Fac-símile Screenshot Intro Video https://canhamorhemp.com/
For more information, see: https://canhamorhemp.com


Uwe Heitkamp (62)

trained TV journalist, book author and hobby botanist, father of two grown-up children, knows Portugal for 30 years, founder of ECO123. Translations: Dina Adão, John Elliot, Ruth Correia, Patrícia Lara, Kathleen Becker
Photos: Fac-símile Screenshot Intro Video https://youtu.be/EAD_1Kauaik / https://canhamorhemp.com



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