How do energy saving curtains work?

If you have heard about energy-saving curtains but are not sure whether they actually save energy, here we discuss what they do and how they work. The low-down is that you can noticeably cut energy bills by using properly installed thermal curtains. They work equally well in cold and hot climates because they retard the transfer of heat from warmer to cooler spaces. In addition, there are many varieties and designs of ready-made thermal curtains available in attractive fabrics and styles. You can also make your own, which gives you an array of choices of color, design and thermal attributes.


What Are Energy-Saving Curtains?

Thermal curtains are made of several layers of densely woven fabrics and linings that slow or prevent transfer of heat. Usually they are constructed with four layers:

  • The layer closest to the window is a lining that reflects heat back outside during the summer and keeps it inside during the winter.
  • The core layer is made from a high-density material, such as cotton batting, foam, felt or other material that has good thermal resistance.
  • The layer that faces into the room is decorative, usually made of a tightly woven fabric that adds to the thermal properties of the curtain.
  • Many energy-saving curtains also have a fourth layer that serves as a vapor barrier to protect the curtain from moisture and condensation.


Some manufacturers assign an R-value to their thermal curtains. The higher the R-value, the greater the thermal effectiveness. Standard curtains have an R-value of R-1. Well-made thermal draperies can achieve values as high as R-8, as effective as many thermal windows.

How Do Thermal Curtains Save Energy?

According to the U.S. Department of Energy, windows account for approximately 30% of heat loss in a home during cold weather. During the summer, windows are a major source of heat gain from sunlight. Curtains of any type provide a barrier between heat on one side and cool air on the other by creating a dead air space between the fabric and the window. Standard curtains give some thermal protection, cutting heat loss by approximately 10%. Layering curtains creates more air pockets, which increases thermal effectiveness.

Curtains with light-colored backings reflect light during the summer, preventing heat from entering windows. Medium-colored curtains backed with white plastic can cut heat gain as much as 33%. Densely woven fabrics keep light and heat from penetrating. Because light is often a source of heat, tight weaves contribute to thermal effectiveness. To determine the density of the weave, hold the cloth up to a light. If you can see points of light through the weave, it is not dense enough to prevent air from flowing through the fabric.

Benefits of Energy-Saving Curtains

Many energy-saving tips suggest installing energy-efficient windows, often touted as a good way to reduce energy usage. However, they are expensive and difficult to install. In contrast, curtains are much less expensive and easier to install. A good-quality thermal curtain can achieve R-ratings comparable to a double-pane, energy-saving window. Energy-saving curtains also insulate from sound. In addition, they can be used as room-darkening curtains because they reduce the amount of light entering through windows.

Energy-saving curtains reduce transfer of heat, keeping rooms warmer during cold weather and cooler during hot weather. During sunny days in the winter, open curtains to take advantage of the heat of the sun. Your furnace will not have to work as hard to keep your home warm. Close curtains at night to keep heat in. A controlled study in Britain showed that closing curtains at dusk can reduce heat loss between 15% and 17%.

During the summer, close curtains during the day to reduce solar gain, particularly on west- and south-facing windows. These strategies reduce energy usage, resulting in lower utility bills. You stay more comfortable and save energy and money.

How to Install Thermal Curtains

The effectiveness of any window treatment is compromised if windows are drafty and not properly sealed. To reduce drafts, weatherstrip and caulk around windows before installing window treatments. Properly installed thermal curtains can reduce heat loss through windows by as much as 25%.

Hang curtains snugly against the window frame to stop air flow around the window. Creating a snug barrier prevents air exchange between warm and cool spaces. Curtains should extend several inches beyond the edge the window frame to create the best seal. Ready-made insulated curtains often come with magnetic strips or Velcro to secure the curtain to the window. Attaching a cornice, pelmet or other top piece prevents warm air from flowing up and over the top of the drapery.

Deconovo's thermal curtains come in a wide selection of styles and designs. Peruse our selection to find thermal curtains that help you save energy and complement your home's décor.