They often had multiple houses, which housed the people deemed 'unsuitable for labour' who would eventually be exterminated. The people who were suitable were sent to labour camps or heavily moderated factories, where they'd be forced to endure hours of labour making machinery or munitions to fuel the already dead Wehrmacht and Luftwaffe.

However this only went into full-scale from 1943-1945, anything before that and extermination/forced labour wasn't considered a high priority, taking land was. After the blow of the Soviet union, they focused on extermination of the people deemed unfit for labour and who didn't meet the generic specifications for a 'Honorary Aryan' or a 'Good German' if you will.

By 1944 Hitler wanted to speed up the process dramatically, he knew the war was lost already, so he probably wanted to take the people deemed unfit down with him.