You may want to consider "warm windows" for your old windows. A bit pricey but worth every penny when it comes to old windows in a cold area. You can make them one at a time, or maybe buy the fabric at a discount somewhere. Let me know and I'll send you directions for them. It's the special fabric and magnets that make them work. I did it over 20 years ago and when they were down and the wind was blowing you could actually see them balloon out slightly. My husband use to say, boy can I tell you had the warm windows open today. The additional plus/minus is that they make the room absolutely dark. Like Vegas dark. Great for people who work at night. Bad if you need the daylight to keep your spirits up.