The membrane duct can allow cooling and heating from the same duct.
When heating a membrane covers the cooling diffuser holes on the top of the duct allowing warm air out of the bottom heating diffuser holes.
When cooling the membrane blocks the bottom heating holes and allows the cold air to exit more slowly through the cooling holes at the top of the fabric duct. If the cold air was allowed through the heating holes on the bottom it would have a velocity that was too high and uncomfortable for any users below.
The membrane is moved by a small motor which receives a signal to change position.