Choosing the right insulation for your attic is crucial for staying warm in cold weather. Cellulose insulation offers excellent thermal performance, superior air sealing, and eco-friendly materials, making it ideal for colder climates. Fiberglass insulation, while cost-effective and moisture-resistant, may allow more air movement, reducing its efficiency in extreme cold. Both options have benefits, but cellulose generally provides better heat retention and energy savings in freezing temperatures.