We have NO AC, it gets fairly warm in the summer but certainly livable. In the winter we try to heat by wood about 50% of the time, in those cases the upstairs is cool, but very comfy for sleeping. When we heat with the furnace it is still cool upstairs and generally cool in the house. We keep the main area around 20 and the balance of the home cooler than that. It's a good idea to warm up a plate in this house prior to eating your toast!
Mind you, our home is over 100 years old. Nobody has had air conditiong and central heat was certainly an afterthought.
We love it.