Here are the ranges of temperatures for pigs:
If you house is between 60 and 80 degrees, the pigs should be fine, although you want places where they can get warm if it's close to 60, and places where they can cool off if it's close to 80. The higher the temperature above 80, the more you work to bring it down. The lower it is below 60, the more you work to have places they can snuggle to stay warm.
If the temperature is between about 65 and 80, you don't need to put snugglies in, or frozen water bottles, unless your pig just likes them.
We have one guinea pig on here who survived several nights in a snowbank with below freezing temperatures, and lived to tell the tale. But above 85, you have to worry about heat stroke.