Another name that comes to mind is Vicente Guallart. He has an architecture studio in Barcelona and is the worldwide main authority about the concept of the sustainable / self-sufficient city (more details). Not sure in what way you could talk to him or his peers as we don’t have a direct contact yet, but since it fits so well for both Barcelona and eco-compatible living I though I’ll just mention it.
Another person to meet and greet is @hazem, Egyptian urban planner and designer, now settled in Barcelona.
And Berlin Holzhaus sounds a lot like the CSOAs (“squats”) in Spain. Barcelona is quite famous for its CSOAs … I just never visited myself yet, so I can’t give particular recommendations which ones to vist …