What indicates that insulation is not performing effectively?

Insulation that appears compressed is a strong indication that it is not performing effectively. Compression can significantly reduce the insulation's R-value, which measures its effectiveness at resisting heat flow. When insulation is compressed, the air pockets that trap heat are reduced, making it less effective in maintaining temperature and energy efficiency within the home. Proper insulation should maintain its thickness and structure to provide the intended thermal resistance.

In contrast, insulation that is well-ventilated or dryer than the surrounding air does not inherently signal poor performance. Good ventilation helps maintain moisture levels, which is vital for preventing issues like mold growth. Age alone, such as being over 10 years old, does not automatically determine effectiveness because the material's condition, maintenance, and environmental factors play significant roles in its performance.