A house made of hemp? It won’t get you high, but it ensures good living, plus it’s eco-friendly. Can hemp be the building material of the future?
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00:00Are you aware that cannabis can help save our climate?
00:06Though not by smoking it.
00:09It can be used to build houses like these the world over.
00:15But what are the advantages to building with hemp?
00:21I break into a sweat listing advantages, there are so many.
00:25It's not that cannabis might help the world fight climate change.
00:28Cannabis will help the world fight climate change.
00:32Just how this plant can do its part for the climate and be used to build houses is what you'll find out now.
00:41This is what many of the world's cities look like.
00:44Lots of concrete buildings.
00:46Concrete is robust, relatively cheap and highly versatile.
00:50The problem is that making it consumes lots of energy and is causing about 8% of global CO2 emissions.
00:57Reinforced concrete is extremely stable but doesn't insulate well.
01:01And I'd say it's actually the wrong material to use to build houses.
01:04We need reinforced concrete for bridges and infrastructure.
01:07It makes sense for things that carry heavy loads.
01:11For some years now, civil engineer Henrik Pauli has been exploring hemp as a building material.
01:17It grows rapidly and almost anywhere, like here in the German state of Hessen.
01:22And it stores huge amounts of carbon dioxide.
01:27The hemp I plant is purely for industrial use, for harvesting seeds.
01:32It can't be used as a drug because the THC content in this variety is so low, it's no good as a drug.
01:40Here we are in a hemp field.
01:42This will be the building material we like to use.
01:45I'll pull up a plant.
01:47Here we see the entire stem.
01:50You can also tell it's got hardly any branches, so it grows to be straight and even.
01:56And that's very beneficial for a building material.
01:59Because after it's treated, the fibers are loosened out.
02:05Those are what we use for building.
02:07The woody pith of the hemp plant, the hemp herds, are used to make hempcrete for insulation.
02:15All of which is being used in this house.
02:18This old stable on a manor farm is being converted into two apartments.
02:27The hemp herds, the coarse parts of the hemp fibers, are mixed with water.
02:35Lime is added to serve as an adhesive and a blend of minerals to enhance the hardening process.
02:45The advantages of hempcrete as a building material are that it's CO2 negative, it insulates well and at the same time it stores warmth.
02:53And as far as fire safety goes, it's not flammable.
02:56It dampens well and releases it again, so it regulates humidity.
03:04On the construction site, once the mixture is done, I yell out material, so everyone knows we're good to go.
03:11Hempcrete can be built into walls in various ways.
03:15For example, by pouring it into molds in layers, tamping it down and letting it dry, or as prefabricated hemp blocks.
03:23But a house still can't be built entirely of hemp. It needs a supporting frame.
03:30You always have to consider the material's qualities. What do I need it for and what material is able to deliver these qualities?
03:38So why is it that, given all its positive qualities, hemp isn't used more often in construction?
03:44For one, it still costs 10-20% more than conventional materials.
03:49There are other reasons too.
03:52After World War II, we banned cannabis as a drug, as hashish, marijuana, the famous reefer.
03:58The soft drugs were prohibited, and that deprived us of one of humanity's most useful plants.
04:04It was an accidental victim of the hunt for cannabis consumers.
04:08Steffen Geyer is the director of Berlin's Hanfmuseum.
04:12This is the place to learn about the uses people have found for hemp over the past several millennia.
04:18Not only for building, but also to make clothing.
04:21On ships and boats.
04:25In medicine.
04:27And, of course, for recreation.
04:31Our great-grandparents wouldn't have battered an eye at this museum.
04:35They would have asked why we're talking about such trivialities.
04:38Everybody knows you build with hemp, and so on.
04:43Germany legalized planting industrial hemp in 1996, but many people still associate cannabis with only one thing.
04:51I still have to deal with lots of stoner clichés, and actually, I don't think it's all that bad.
04:56Hemp is also very helpful medicinally.
04:59Sure, it can be used to get high, but that just goes to show how versatile hemp is.
05:03Some people get high off of it, and others get a different high because it's used to make a wonderful, cozy place to live.
05:10Henrik is hoping more people will start using hemp materials to build their houses and to advance construction technology.
05:21What I've done here, and what motivates me, is to bring it to a professional level and create a broad awareness of the possibilities for using hemp.
05:28Not just for houses and apartment blocks, but maybe even skyscrapers.
05:33That's how cannabis can help make construction more sustainable and help the climate.