Helping bricks go green in Uganda

DW (English)

Bricks used in construction have a huge climate footprint. Engineers in Uganda are seeking to change that. It’s an urgent task in a country with a booming population and construction industry.

Transcript

00:00 These bricks are dry-pressed and not fired in a kiln.

00:05 They are made of sand and a bit of cement and a lot of muscle power.

00:10 And no wood since there is no kiln.

00:12 Ugandan architect Stephen Juko believes a switch to alternative construction materials

00:18 is long overdue.

00:20 When you drive through many forests, they are no longer forests, you don't feel that

00:24 darkness surrounding you.

00:26 So the problem is dire that we need to stop firing bricks to make our houses.

00:33 About a quarter of each brick is made out of cement though, and cement manufacturing

00:38 produces a lot of CO2.

00:40 But the interlocking bricks are easy to assemble, so they need less cement than regular ones

00:46 do.

00:49 The block that comes out is the interlocking.

00:52 Interlocks at the top, at the sides and the bottom.

00:55 So by that way as well we reduce the amount of cement used to build a structure.

01:00 In that way we are reducing the emissions by reducing the cement and the amount of trees

01:07 that or vegetation that would have been cut down to, in order to produce a brick or to

01:14 build a house.

01:16 In Uganda, most houses are still made out of kiln-fired bricks, which mostly use firewood.

01:23 There are thousands of small brick-making businesses like this throughout the country.

01:29 And the ongoing housing shortage means their bricks are in high demand.

01:34 Using pressed bricks instead could help save a lot of firewood.

01:38 The homes still look the same, and for the homeowners, they also offer other benefits.

01:45 Constructing with interlocking bricks enabled us to have our building in less than two months.

01:54 It fit in our budget and then we also saved because the money that we would have used

02:02 to transport materials.

02:06 The construction industry is a major climate killer.

02:10 Cement manufacturing accounts for some 8% of global carbon emissions.

02:18 That's why engineers are studying ways to reduce or eliminate cement in brick-making,

02:23 including Marion Nwahereza.

02:26 She works for Eco-Concrete, a company that makes cement using of volcanic ash.

02:32 Traditional cement is made out of limestone and firing it emits massive amounts of CO2.

02:38 When you heat one kilogram of limestone, you emit about 44% of it as carbon dioxide.

02:47 You only retain 55.

02:49 So for one ton, when you put in all other production emissions, you find that for one

02:54 ton, you're emitting about 500 kilograms of carbon dioxide.

02:58 That is about half of it.

03:01 The engineer has been working with students at Makarera University in Kampala on the new

03:06 process.

03:07 Volcanic ash is plentiful in Uganda.

03:10 Just like in ordinary cement, the recipe calls for sodium hydroxide.

03:14 But the mixture doesn't need to be heated, so the process uses five times less energy

03:19 than limestone-based cement.

03:22 The result is what's called geopolymer cement.

03:25 Their tests have shown that this product could cut emissions by 80% compared to Portland

03:31 cement, which is used around the world.

03:36 We've been using it in blocks, building blocks.

03:39 And we've also done water absorption tests, and these materials are proven to be better

03:44 than Portland cement.

03:46 The engineer and the architect share a common goal - to help make Uganda's construction

03:51 industry more sustainable.

03:55 The majority of people can do our work, what they eat, how they get to work.

03:59 But with engineers it's different.

04:00 They actually have the space to innovate and reduce carbon dioxide emissions.

04:07 As someone who studied in the building profession, architecture, and then with my colleagues

04:13 in engineering, we're responsible for many of the designs.

04:17 So the process starts with us.

04:19 The recommendations we make, or the specifications we give to our clients.

04:25 While Stephen Juko has been using his bricks for several years, Marion Nwa-Hereza is starting

04:31 pilot production, and hopes she'll soon get the green light from local authorities.

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