Öffnungsflächen

Öffnungsflächen means the max. size a window can be opened up to. Does anybody know the words used in (EU and DIN) norms to describe the term?

not me. But you make me wonder if anyone really uses the term fenestration when they're not talking about the defenestration of Prague. I didn't think so, but I googled it, and I guess it is a regular word. Oh well.

BTW try here: http://www.designbuild-network.com/glossary/