When you've tired of building greenhouses (or green buildings - we're very inclusive here you know), or just of having green temporary accommodation while building something not quite so green (see previous entry), how about going on holiday to, erm, a greenhouse?
OK, so it's an 'earthship' rather than a greenhouse, and there's only one in Europe (in France), so you may have to book ahead. But it sounds good. And if that tickles your fancy, you can even buy a book about them. Better than buying another trashy novel at the airport anyway.