General emptiness:
* Empty (most common and straightforward)
* Vacant (suggests a lack of occupants or content)
* Void (implies a complete absence of anything)
* Hollow (suggests a lack of substance or meaning)
Emptiness related to emotions or feelings:
* Desolate (implies a feeling of sadness and loneliness)
* Bleak (suggests a feeling of hopelessness)
* Barren (implies a lack of life or vitality)
* Lonely (implies a feeling of isolation and longing)
Emptiness related to physical space:
* Unoccupied (suggests a lack of people or objects)
* Unfilled (suggests a lack of completion or purpose)
* Bare (implies a lack of decoration or adornment)
The best adjective to use will depend on the specific context.