A negative volume means that your room is "inside-out".

EASE distinguishes between the acoustically effective side (yellow frame) and the exterior side (white frame) of a face.

All acoustically active sides (yellow frames) must be orientated facing in instead of out of the room.

Wrong		Right

The easiest way to change the orientation of all faces for a simple room is to fix the orientation of one face (right-mouse click and Invert), keep the face selected and choose the Check Holes option from the Tools menu.

Uncheck all boxes except Auto – Orientation and press Close Holes. EASE will adjust all faces relative to the one that is selected.

Note: If you are looking at your room from above, your floor should be a yellow face.