What is a common feature of insulation products like shredded-fiberglass?

High thermal resistance, often referred to as R-value, is a critical characteristic of insulation products such as shredded fiberglass. This quality is fundamental to their function in minimizing heat transfer, helping to keep spaces warm in the winter and cool in the summer. Insulation materials with high thermal resistance effectively slow the rate at which heat moves through them, thereby enhancing energy efficiency in buildings. This attribute is not only essential for comfort but also significantly contributes to energy savings over time.

While the other options present certain attributes related to insulation, they do not share the universal importance and utility that high thermal resistance has in the context of insulation materials. Some insulation products may be lightweight or easy to install, but these features can vary widely based on the specific type of insulation. Additionally, while certain insulation materials may incorporate recycled materials, not all do. As for the release of harmful fumes, this condition is generally not characteristic of fiberglass insulation, especially when properly handled and installed.