Houston is 7 hours behind Barcelona
Best overlap: 3:00 PM to 6:00 PM in Barcelona is 8:00 AM to 11:00 AM in Houston.
For a call that suits both sides, look at 3:00 PM to 6:00 PM in Barcelona / 8:00 AM to 11:00 AM in Houston. Around 3 hours of overlap is enough to work comfortably, as long as meetings don't drift to the end of one team's day.