Use thermal curtains
Thermal curtains are a simple and effective way to insulate your rooms from the cold outside. By closing them as soon as night falls, you’ll add an extra layer of insulation that will help keep the heat inside. Make sure your curtains completely cover the windows to maximize their effectiveness.

Optimize the use of the sun
Take advantage of the sun’s free energy by opening your curtains and shutters during the day to let natural light and warmth into your home. Remember to close your curtains as soon as the sun sets to retain the heat accumulated during the day.
Rearrange your furniture
Position your furniture so that it doesn’t block radiators or natural heat sources like sunny windows. A sofa placed in front of a radiator absorbs a lot of the heat that would otherwise warm your room. Also, remember to keep the areas around heat sources clear for more efficient heat distribution.

Use blankets and rugs
Adding rugs to tiled or wood floors can help insulate your room and keep your feet warm. Using blankets on cold evenings can also add an extra layer of warmth without needing to turn up the thermostat.