On the continent these are almost always used as infill for a cast in situ reinforced concrete frame. That may be good enough, in terms of thermal performance, in Greece or Spain or Southern France or whatever, but it isn't good enough for here. There would always be "cold bridging" through the concrete structure, no matter how warm the rest of the walls were. That's why these things, which are ubiquitous on the continent, aren't typically seen here.
I'd be interested to know more about the building they're being used to construct. I have never seen these extruded clay blocks used in a load-bearing situation, so I'd like to see what is holding up the roof and first floor. I'm betting that there is a steel or concrete frame somewhere, which only means a whole lot of detailing issues getting insulation onto the insides of the framework.
