Is climate change affecting the way we build?

Lívia Souza, Cambridge University engineer, weighed in on this question from Steph...

Lívia - It is affecting how we we’re planning our cities and how we are building our buildings basically. The main thing to keep in mind is CO2 emission -when we are talking about this conversation, as we are talking about how do we minimise CO2 emissions on our buildings basically. For that, concrete can be very damaging.

Chris - It’s something like 20 percent of the world’s CO2 emissions is just making concrete - I think - isn’t it? It’s a very large number.

Lívia - I think it’s around 7 - 10 percent? But it’s still quite big.

Chris - It’s still a big number... I mean, obviously, you get a bit of payback because the concrete takes down some carbon dioxide from the atmosphere when it goes off doesn't it and turns back into a solid. But even so, you have still got to bake this mineral at very high temperature to make the concrete in the first place.

Lívia - I think we have the massive payback in terms of infrastructure for people that is provided with concrete. That's amazing. But we are paying a price for it because - another conversation on that - when we're talking about reducing the use of concrete for buildings, so we could be using timber, for instance or bio based materials in general. When we are talking about changing the technology we are talking about developed countries. What if we're talking about developing countries? How is this moving forward?

Chris - Duncan?

Duncan - In 20 years time, do you still think that we'll be using concrete as we currently use it or is your vision that we'll have come up with some - not timber - but some alternative substance?

Chris - Why not timber? I mean, timber is pretty good as a material isn't it? I mean it's carbon neutral, potentially, and it's very long lived and it's very strong, what's not to like?

Duncan - I'm sure it's great for certain kinds of structures but I'm guessing there are lots of structures that we might want to build - like airports for example - in the future which it might be difficult to make it out of timber. You know you can pour concrete, you can set it, you can do all sorts of things to it

Chris - Well, you wouldn't build a nuclear bunker out of - probably - paper. I grant you that. You probably would need concrete for that. Wood’s a pretty good material - I mean - surely that's going to be one of the things that's factoring into the equation more and more?

Lívia - More and more we are thinking about straws, we're thinking about hempcrete - concrete with hemp bits in it...

Chris - The bits you can’t smoke?

Lívia - Can set fire in the house

Chris - Nadia?

Nadia - Referring back to the self-healing concrete - can we use it as a building material?

Lívia - That's the idea. The buildings that we are making right now. The idea is to make it as resilient as possible. So for the future they need very little repair and maintenance.

Chris - What you’re saying is rather than having to make more cement and more CO2 carbon footprint in the future, make the building once and make it last longer - and also make it repair itself into the bargain.

Lívia - Yes. To reply to your question Duncan - a challenge. Because to think about new materials replacing concrete we are also talking about changes in policies, isn't it? And the UK may think about it but other countries may be not thinking about it and concrete is still quite cheap to produce. Environmentally it's not so much but cost is very good.