http://lumion3d.com/products/ says -
"Minimum System Requirements
OS: 64-bit Windows Vista, 7 or 8
System memory: 4GB (for simple scenes)
Graphics card: NVidia GeForce GTS 450 or ATI/AMD Radeon HD 4890 (minimum 1,500 PassMark points), with at least 1GB dedicated memory (not shared system memory).
Harddrive: 7.5GB of disk space
Using Lumion via Remote Desktop is not supported
Lumion 4 requires an internet connection."