That's really hard to say. We keep our house set at 70 degrees in the winter, and just have blankies on the sofa's for them to lay on if they want. Often times they still lay on the tile floors or on the kitchen counters. Even the one with kidney disease. That being said, if your cats are arthritic, heat is good for them. Do you have warming beds or anything like that? Arthritic cats lots of time will lay under lights just to absorb the heat from them.