conversation between the young worker and the girl

Have you got any idea about how the conversation between the young worker and the girl who is hanging out the washing was shot?
I suppose that in the scenes of the couple who are smoking heroin, for instance, they had a small and quiet place to get, after many hours of working for the movie staff, a natural and spontaneous sequence. But shooting the other scene I mentioned had to be very tricky, because the guy is attempting to pick up the girl, they almost didn’t know each other and were in different buildings. So I’d like to know, if you had read something about it, what kind of orders Guerín gave them (if he did, of course). Anyway, if you’d want to say anything about 'En construcción'('Work in progress'), write a post. I think it’s an unique film!