Insulation slows the transfer of heat. It keeps buildings warm in winter and cool in summer. Materials like fiberglass, foam, cellulose, and mineral wool trap air in tiny pockets. Air is a poor conductor of heat. The trapped air does the work.

Effectiveness is measured by R-value. Higher R-values mean better insulation. A cold climate needs more insulation than a mild one. Walls, attics, floors, and basements all need attention. Gaps and cracks matter as much as the material itself. A well-insulated wall with a leaky window still loses heat.

Insulation saves money and energy. It reduces the load on heating and cooling systems, which lowers bills and emissions. It also improves comfort, cutting drafts and noise. Retrofitting older buildings is a major challenge and opportunity. Many homes were built before modern codes and waste enormous amounts of energy. Sealing and insulating them is one of the cheapest ways to cut emissions.

Common materials

• Fiberglass batts
• Spray foam
• Cellulose
• Mineral wool
• Rigid foam boards