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Flat House review – a home made from hemp that will blow your mind

Flat House is made of prefabricated timber-framed cassettes filled with a mulch of hemp, lime and water known as hempcrete. Photograph: Oskar Proctor

Flat House is made of prefabricated timber-framed cassettes filled with a mulch of hemp, lime and water known as hempcrete. Photograph: Oskar Proctor

Practice Architecture’s house is built from the plant growing in the fields around it. The project addresses a vital issue – the energy consumed and carbon emitted during construction

Last modified on Wed 23 Sep 2020 15.25 BST

H ere’s today’s fun fact: the word “canvas” is derived from “cannabis”. (And imagine if the two words had still been identical this past century or so: literature would speak of cannabis-covered deck shoes, of boy scouts enjoying their life under cannabis, of going cannabissing for your parliamentary candidate.) There is a simple reason for this etymology. Among the many uses of hemp, the plant from which the drug comes – uses that include ropes, clothes, food and medicine – was the fabric for the sails of ships.

Once commonplace and useful, and hailed in the 1930s as a “billion-dollar crop”, hemp’s modern promise was cut short by its association with narcotics, which led its production to be taxed and outlawed across the western world. Call it paranoia, call it realism, but there’s a theory that billionaires with interests in plastics and paper pulp successfully lobbied the US government to have their rival product suppressed. A war on drugs, in this account, was whipped up in order to deepen the public’s dependency on petrochemicals.

‘Retains the character of a recently growing thing’: Flat House. Photograph: Oskar Proctor

Now, though, hemp looks like a miracle plant, to a point that seems almost too good to be true. Its growth gobbles carbon and replenishes the soil, killing weeds without resort to chemicals. It can be used to detoxify poisoned land. It can make organic alternatives to plastic. BMW use it inside their car door panels. In December 2018 Donald Trump signed the Hemp Farming Act, which relegalised the cultivation of the industrial, non-psychoactive strain of the plant. He wouldn’t have done this, one might guess, if there hadn’t been money in it.

And you can build with hemp, as a growing global network of enthusiasts wants everyone to know. In this country the plant’s properties have inspired Steve Barron, a producer and director of TV and film, and his business partner Fawnda Denham to buy a farm in Cambridgeshire and – having first been checked out by the police – grow hemp there, which they are developing into commercial products. On that site, Margent Farm, they have commissioned a house.

It is designed by the 10-year-old Practice Architecture, who made their name with the ultra-low-budget Frank’s Café. This structure serves Bold Tendencies, the summer arts programme held each year on the top of a multistorey car park in Peckham, south London. Like other projects by Practice, it exemplifies their hands-on approach, their interest in getting closely involved with the construction as well as the design of buildings.

Flat House, as the home on Margent Farm is called, is the conversion of a steel-framed agricultural shed, within which a new structure has been made of prefabricated timber-framed cassettes that were filled with a mulch of hemp, lime and water known as hempcrete. Once the mulch was dry they were erected into thick, highly insulating walls that also hold the building up. The exterior is covered in corrugated panels, which at first glance looks like the cement cladding typical of farm sheds. It is actually made of fibres from the outer coating of hemp stalks combined with resin taken from agricultural waste. It has a livelier texture and a more translucent quality than cement.

‘Layers of openness and enclosure’: inside Flat House. Photograph: Oskar Proctor

These techniques are not all groundbreaking. Hempcrete goes back to the 1980s; Kevin McCloud used hemp-based insulation on his HAB housing project in Swindon in 2011. What is special at Margent Farm is that the material makes the architecture. Whereas in Swindon the houses are finished with conventional plaster and render, here you get to see the hemp, inside and out.

McCloud, you might say, didn’t inhale. At Flat House you get a feeling rare in contemporary buildings, which comes from its unity of substance and surface. In most modern construction, as Paloma Gormley of Practice Architecture puts it, “you have five or six layers of stuff” – paint, plasterboard, insulation, vapour barriers and waterproof membranes, structure, cladding – which make houses, like modern phones and cars, inscrutable to their users. You can’t see what’s going on. You need an expert to mend it. Flat House is, Gormley says, “legible and fixable, more accessible to clients – you can take ownership of a house like this”. You can see where you can and can’t hammer in a nail, for example, to hang a picture.

Photograph: Oskar Proctor

The cassettes in which the hemp is formed, eight foot by four foot, give a rhythm and scale to the interior that comes from the making of the building. The exposed material, its texture reminiscent of straw bales, retains the character of a recently growing thing, given a ghostly sheen by the whiteness of the lime. It creates, together with the pale timber that frames it, a soothing tonal range of pinkish greys. The acoustic is soft and restful too. Although the house is built of organic and relatively light materials, it has some of the sense of mass and substance you get in old masonry construction.

The house, which is quite small, is given generosity by both a high living area and a big glazed conservatory that occupies the full height of the old shed. The skinny steel and the thick walls create layers of openness and enclosure between inside and out, and different degrees of contact with and shelter from the elements. All around are the fields – a lovely fact, this – from where the stuff of the house came. A little way off is another structure built with similar techniques, a single-storey studio constructed by students from the Cass school of architecture in London, under the guidance of Gormley and the photographer David Grandorge, who teach together there.

All this is, in principle, environmentally wonderful, the house being made mostly of materials that absorb rather than emit carbon. The project therefore addresses a vital issue that was until recently neglected by most architects, which is the energy consumed and the carbon emitted while buildings are constructed, as opposed to while they are in use.

The challenge is how to scale the techniques up to the extent that they make a significant impact on the emissions of the building industry. To this end Gormley has set up a not-for-profit organisation, Material Cultures, in partnership with her fellow architect Summer Islam, the engineers Arup, the University of the Arts London, University College London, and the brick manufacturers HG Matthews. Its aim is to research building systems and components using hemp and other natural materials, to manufacture them at HT Matthews’s Buckinghamshire factory, and to apply them more widely than on the occasional delightful house.

The studio, made from the same materials, built by students from the Cass school of architecture. Photograph: David Grandorge

With this combined technical expertise Paloma Gormley wants “to put figures to things that we know are inherently true”, that what she called “low technology high performance methods” can produce genuinely sustainable architecture. They want to prove the point in both theory and practice. A proposed development of 40 new houses in Cornwall is, it is hoped, the next step.

Miracle materials can have a way of turning out less so in practice. Unexpected costs and consequences tend to arise. Established industries are reluctant to adapt to them. But hemp, benign in both production and in use, which can also beautify the experience of living in a house, deserves its shot at becoming a mainstream building material. And no, nothing was smoked in the writing of this article.

Practice Architecture’s house is built from the plant growing in the fields around it. The project addresses a vital issue – the energy consumed and carbon emitted during construction

Hemp House: South Africa’s Most Sustainable Home Made From An “Illegal Narcotic”

Architecture
  • 06/20/2011
  • under Architecture, Eco Textiles

Tony Budden and his partner Duncan Parker aimed to give the Hemp House the lightest carbon footprint possible, but had to import most of the materials since South Africa lacks a domestic supply of hemp products. The internal modular walls are comprised of hemp insulation and sealed with magnesium oxide boards, while the external walls are made from a lime-based hempcrete that is considerably less energy intensive to produce and less dense than traditional cement. But what makes the building South Africa’s most sustainable?

It is passively cooled, heated, and ventilated, incredibly well insulated, and partly powered by solar energy. The floors are made from sustainably-sourced cork, 85% of the furniture and cabinetry is made from hempboard, and all of the grey and black water will be treated and recycled. Also included are LED lamps to reduce energy use, eco-paints to prevent harmful off-gassing, and reclaimed stone.

Not only is the Hemp House an impressive achievement in sustainable building, but Budden’s determination to overcome misguided regulatory roadblocks to illustrate the huge environmental and social advantages of growing hemp locally puts this groundbreaking home on par with Nelson Mandela and Desmond Tutu peace efforts. Already government officials are reconsidering their formerly-held bias against what is actually an excellent antidote to water and chemical-happy fibers such as cotton.

Additional Resources

Sustainable Building

7 thoughts on “Hemp House: South Africa’s Most Sustainable Home Made From An “Illegal Narcotic””

Hi Tony, I fully support your cause. This is the direction the world needs to take in order to not only utilise the thousands of benefits hemp provides but also the environmental benefits linked directly to the very existence of human kind. Thank you for your commitment. How can I get involved?

http://www.limetechnology.co.uk/pdfs/projects/Adnams_Brewery.pdf check this link to see the amazing industrial/commercial capabilities of hemcrete. It doesn’t really come out in the SA house article but because of hemcrete’s ability to maintain a constant temperature no heating system is required. AMAZING!!

DaggaParty, thanks for your comments, but there are a few points you would like to raise. Firstly, with a carbon saving of around 500kg’s per m2 of wall when compared to brick and cement, event putting the transposrt of one 20ft container from France to SA, the hemp will still be lessening emissions. Please can you let me know where you get thet amount of 40t/ha of biomass for dagga from? Hemp is harvested after 100 days for fibre, while outdoor dagga is usually in the ground for 6 or 7 months. Hemp left to go for that long would also have a much higher biomass yield, but the quality of the fibre would be inferior. Dagga cultivars may give good biomass, but will not provide good fibre and will be very difficult to process for fibre due to too many branches. In Australia,, growing chinese hemp cultivars, they are getting 50t/ha of wet biomass from hemp in a similar climate to ours. Saying that, even if hemp is only getting 20t/ha, it is still way better than many other alternatives and should be encouraged, especially with the byproducts of seed and good quality fibre. What we have done here is showcase what is possible with building from hemp, and if we had not have done it, thousands of people would be reading these articles or hearing about hemp on radio/TV etc, and would remaining thinking that Cannabis is only good for burning. One major assumption you make is that everyone who is involved with hemp had their first interaction with Cannabis through Dagga. While this is true in some cases, I can assure you that many of our partners, supporters, as well as the architects/scientists/builders that I have met in the industry internationally have never come close to a joint in their lives. Cannabis does not belong solely to those that wish to smoke it or use it for medicine, that is an attitude that will keep it marginalised forever, as the plant has many more things to offer than THC. We may not be approaching it from the angle you are, but essentially we are aiming for the potential for hemp/cannabis to be recognised as way more than a drug/evil weed, and support and constructive critisism would be appreciated.

We are on the moment doing an ecological impact study about the hemp house project, it will take all the facts in account, like transport and import, water, waste, land coverage etc. The Carbon foot print is only one part of the ecological study, but will be shown. in the end result which will take some time before its finished.

@DaggaParty I think you’re missing the point here on a number of levels. The house is a MODEL, it shows what can be done if the growing of hemp is legalised in SA. To build the model, the materials had to be imported. If the materials were available here, the footprint would be very low. Again, the house is a model to show people what can be done and to change mindsets. Yes, dagga should be legal but that is a different issue to what the hemp house is trying to achieve. Saying that, there are many ways to skin a cat and changing peoples’ perceptions of hemp may be a step in the right direction regarding the legalisation of dagga too. Simply accusing hemp enthusiasts of not helping the dagga cause is shortsighted, as well as inaccurate.

Wow, what a beautiful home!

Cannabis sativa ‘dagga’ (high THC) is more productive (approx 30-35tons biomass/ha/season) than imported low THC varieties of Cannabis sativa (approx 17-20 tons biomass/ha/season). We will never see hemp legalized in South Africa until we get over our “dagga verskriktheid”and recognise that dagga (THC and other cannabinoids) is a medicine that prevents and cures cancer. Hemp enthusiasts who turn away from the dagga issue are not helping our country. I would like to ask where did all the hem used in Tony’s house come from? Imported? perhaps the calculations on the house’s carbon footprint can take that into account. Citizens could be growing their own houses if dagga was leglaized in South Africa. This house is a good example of what can be done, but it will only be viable for everyone when dagga is legalised.

Although South Africa considers hemp an illegal narcotic, Tony Budden and Erwin van der Weerd forged ahead with the country's very first hemp house. ]]>