Though data usage will vary slightly on actual usage of the system the following numbers are accurate to exact type of usage. We have found with these numbers the average usage would be roughly 0.09-1.2 Mbytes a month.
The most persistent usage in a broadband system is likely to be handshakes and keep alive packets that keep the VPN open. These use just 3 Kbytes per day.
Other common activities and their usage include:
Arm/disarm command: 240 bytes
Zone open or close: 120 bytes
Z-Wave device activation: 120 bytes
Though the system would run efficiently on less, we recommend a 1Mbps internet connection.