What Are Thermal Curtains?

Updated February 21, 2017

Thermal curtains help reduce the amount of electricity, heating oil or gas needed in homes and buildings. They do this by insulating the windows inside a room. Most thermal curtains have linings that resist temperature change and seal off air that infiltrates from windows, even in the summer. This helps to reduce heat gain from the sun. From a decorating and design perspective, thermal curtains can be as attractive as non-thermal varieties, and both layers provide insulating properties.


Windows can be a source of heat or cold in a room. Thus, thermal curtains stabilise the temperature inside a room by blocking the air. The University of Texas at Austin studied the effects of insulated drapes on single and dual pane windows and found that insulated drapes reduced heat loss at a single pane window by 56 per cent and 48 per cent in dual pane windows.


Unlike other kinds of curtains, thermal curtains are typically heavy, making them better able to provide the mass needed to insulate windows. Pleated drapes offer the best protection from heat or cold. Some thermal curtains include a layer of foam applied to the back. Others use tightly woven fabric to keep out drafts. Thermal curtains are almost always hung on rods and open vertically.


Some thermal curtains are washable, while others need to be dry cleaned. This can be an important consideration when selecting thermal curtains. If your budget is a factor, it's possible to make your own thermal curtains by attaching reflecting lining or heavy fabrics to an existing curtain or drape. During exceptionally hot or cold weather, you could also create temporary thermal curtains by attaching blankets or comforters to existing drapes.


Thermal curtains provide the most insulation when they reach the floor and are sealed at the top with a cornice board, creating a vapour barrier. According to the U.S. Environmental Protection Agency, thermal curtains may cut heat loss in a room as much as 10 per cent. When curtains reach the floor, and are tightly closed at the top of the window and on the sides, the energy savings could be as much as 25 per cent. While saving money on a utility bill helps, being more comfortable indoors provides intangible benefits during both hot and cold weather.

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About the Author

Jackie Johnson is a published writer and professional blogger, and has a degree in English from Arizona State University. Her background in real estate analysis prepared her for objective thinking, researching and writing.