Is "Current non-green Systems" timeframe configurable?

[Charles Jones]

I'm being asked how long the time period is for e historical events in 
the "All non-green view" page is, and well, I'm just not sure. I have 
seen it say "No events received in the last 240 minutes", so I take that 
to mean that the history only shows the last 4 hours worth of events. 
That begs the question of, can that value be changed, and if so, where?

-Charles