55F is uncomfortably cold for many people. My heat goes down to 55F at night when I am bundled in bed. My experience is that leak sealing based on results of b

55F is uncomfortably cold for many people. My heat goes down to 55F at night when I am bundled in bed. My experience is that leak sealing based on results of blower air test brings nice heating use reduction while fixing the cold/drafty areas. After that take off window trim molding and spray foam both inside and out. Then apply extra insulation AFTER sealing. Maybe then another blower door test. If you start by replacing windows it will be expensive and less effective.