Yes they will help you can add R 1- 4 with cullular shades with a track
and curtains. A single pane window is R 1, a tri pane lowEargon R 3.3
apx. So you may depending on what you have you may tripple its R value.
A typical wall is only apx R8 to R 12. But you dont say what you have or
why you may be heating with electric since for most electricity is still
50% more than Ng. You don`t mention insulation, zone and the overall
condition. Do an energy audit of your electric, you can do it with a
clamp on amp meter and a Kill-A Watt meter. I reduced my electric from
60 a month to 16-30 by redoing everything. Even an old tv unused may
take 3$ a month in standby and old friges can cost 15-20 a month a new
unit can cost 5$ a month or less.