When most people think about room darkening curtains, they are focused on the light-blocking properties of the curtains. They are thinking about how to get the room dark for a home theater, or how to block light to sleep better during the day.
What most people do not realize, until after they buy them, is that room darkening curtains are also able to help you save money. They provide insulation for the windows, and provide benefit in both the summer and the winter.
In summer, the obvious benefit comes from the fact that hot, direct, intense sunlight can be blocked from a room during the day. This can easily reduce the temperature of that room by 10 or 15 degrees, reducing the need to run the air conditioner all day.
In winter, the opposite effect is true. If you let the sun in during the day, it raises the temperature naturally, without needing to pay for heating. However, at night, the biggest source of heat loss from a home is through the windows. Because room darkening curtains tend to be thicker and heavier than regular curtains, they act like a blanket on the windows, reducing the amount of heat lost overnight. This further reduces the money needed to pay for heating.
So, year-round, room darkening curtains can help make a difference in your heating and cooling bills.Christy - Room Darkening Curtains info from http://roomdarkeningcurtains.net