64 24/7. It actually costs MORE
to change the temps between night and day. Just keep the thermostat at on,e consistent temp.
It costs more because it takes approximately 20-30 minutes to raise the temp one degree. Dropping it 4 degrees during the night could take almost 2 hours to bounce back when you call for the "normal" heat temp again.
Just maintain the same temp and you'll be ahead of the game.
Same is true with air conditioning...except it'* a little more drastic. With cooling, on average, it takes one full hour to reduce the temperature in the house. The biggest influence on how long it takes to cool is the level of humidty in the home.
<---- Owns a heating and cooling company.
Complete Comfort LLC in Michigan.