Which type of curtain fabric is best for blocking out light or insulating against heat/cold?

For curtains specifically designed to block out light or provide insulation against heat/cold, here are some recommended types of curtain fabrics:

These curtains are specially lined to block out light and also provide some insulation against heat and cold. They are typically made from materials like polyester, cotton, or a blend, with a thick backing that effectively blocks light and helps regulate temperature.

Similar to blackout curtains, thermal curtains are designed with an insulating lining that helps to trap heat in winter and keep heat out in summer. They often use multiple layers or special thermal coatings to achieve this effect.

Velvet is a heavy fabric that naturally provides insulation against both heat and cold due to its thickness and density. It also has the added benefit of blocking light effectively.

Wool curtains provide excellent insulation properties, keeping rooms warm in winter and cool in summer. They are breathable and can help regulate humidity as well.

These natural fiber curtains, especially when tightly woven, can provide moderate insulation and light-blocking properties. They are versatile and can be used in various climates.

When choosing curtains for light blocking or insulation purposes, consider the fabric's weight, thickness, and any special linings or treatments that enhance its functionality. Blackout curtains with thermal linings are particularly effective for bedrooms and areas where light control and temperature regulation are important.