Thermal and blackout curtains both block either light or air from passing through your windows and into your living space. They are heavyweight, often insulated curtains, and, because of this, both types of curtains can be somewhat effective at blocking both heat loss and light, but thermal curtains work best at preventing heat loss, while blackout curtains are designed to block light.
Thermal Curtain Materials
Thermal curtains are made out of heavyweight drapery fabric and insulated with duck fabric, which is a heavyweight and tightly-woven fabric. The double layer of nearly impenetrable fabrics works very well at preventing the seepage of cold air from draughty windows into the heated interior of your house.
Thermal Curtain Uses
Thermal curtains can be used anywhere there is a draft in your house. They can be hung across windows or in front of doors, but they must be pulled across the window or door to effectively prevent drafts. Thermal curtains hung across doors are less common in houses than they are in coffee shops and bars where people frequently enter and exit the shop while others sit inside.
Blackout Curtain Materials
Blackout curtains are designed to block light from passing through them. They can be manufactured in a similar fashion to thermal curtains by using multiple fabric layers to block the light, or they can be made out of a single layer of very heavyweight fabric such as felt. Blackout curtains can also be built to fit nicely inside your window frame; hook and loop tape holds them in place so that there are no light leaks anywhere.
Blackout Curtain Uses
Blackout curtains block light from passing through them. Because of this, they are very useful in light-sensitive areas, such as photographic dark rooms where film and prints are processed. They can also be used in bedrooms to block early morning light from coming into rooms where light-sensitive people sleep.