Well, I guess that's the down side of having an historic home. We looked at a few of those, too, before we bought this house 3 years ago. In the end, we decided that there was too much work involved with renovations, etc. Little did we know how much we would spend on this house! But, the heating/AC have had minimal problems. At times, though, I wish we were living in the historic district, because it is FLAT... my driveway is already iced over, from a little 2 inches of snow and some drizzle. It's not enough for the plow guy to come. Oh well.
Have a good time in Portugal. I taught in a system that had mostly Portuguese students (or Brazilian) and it looks so pretty from the pictures. My friends did a cycling trip there a couple of years ago. The hills looked challenging!