Energy efficient houses

Engineer Livia Souza built on this question from Jim...

Livia - So typically mineral wool which is a type of material that can trap a little bit of air inside and it's very good for insulation of the house. I just came back from a bio based conference and they were talking about straws as well to be used as insulating material and they seem to be very very good.

Chris - Is this like bales of straw?

Livia - It's a good material. There is a lot of research being done right now to do it. It's a bio based material so the carbon footprint is great. And on top of that, there is a very cool material as well that is just air bubbles around the house that can work for installation as well.

Chris - So you're saying live in a bubble?

Livia - You put the bubble in the wall.  It’s not very good for the wallet though!

Chris - Like bubble wrapping your house? You put an air bubble like a bubble wrap in the cavity between the inside the outside. But we already do that don't we? Don't we don't we fill those cavities with an expanding foam or something which is doing sort of that?

Livia - That's what we called polyurethane that could expand and fill. So basically we're talking about having more air around the house and decreasing the thermal conductivity so to decrease the heat loss. That's the general idea around it.

Chris - And have people like yourselves interested in the materials we're going to use of tomorrow,  and having an eye on the carbon footprint,  has anyone done this sort of calculation to work out what the best way to build a house is now in terms of what sorts of materials to use and what sorts of proportions? Do we know?

Livia - That's the key question. Yes there is a lot of people working on it. What I would say for now is it depends from place your place. Because it depends which are the demands in each place that you build and what are the products around to build the house as well.

Chris - So there is not going to be a generic answer. A house that's good at staying warm in winter is not going to be the same as a house that stays cold in summer, there are going to be differences and we're gonna have to find out how to do that, place to place?

Livia - Yes.