having drapes can cause the problem also.. they stop the heat from getting at the glass so the inside pane of glass is at the same temperature as the room. this can cause the condensation..
i worked on an apartment building 4 years ago installing trim.. at that stage all the units had electric baseboard heat in and running. the owner of the building would turn the heat down to 5 degrees celcius at hte end of the day.. then every mornig the glass was covered in condensation.. he noticed it and was complaining that the windows were leaking and causing the mdf sils to swell. i clearly told him he has to leave the heat at 15 minimum this time of year or its going to keep occuring,