I was watching a TV show called Grand Designs the other night, and saw a house designed and built by the architects using polystyrene blocks for walls. These blocks fit together like lego, with hollow channels through the middle. Concrete is then poured into the top of the wall creating a structural wall capable of holding the roof load. This building technique saves time framing, as well as providing greater insulation than concrete by itself.

I looked up the technique, and found a large company called ReddiForm Polystyrene which deals in this trade.

They advertise an average of 44% less energy to heat, and 32% less energy to cool, compared to a conventional timber frame house. Coupled with savings in labour and construction time, forms of polystyrene construction may be a competitive modern building alternative.