What is 'wind washing' in relation to insulation?

'Wind washing' refers specifically to the phenomenon where airflow moves through insulation and reduces its thermal resistance. When air penetrates insulating materials, it disrupts the intended thermal barrier by carrying away heat, thereby decreasing the overall effectiveness of the insulation.

In properly designed insulated spaces, insulation should act as a barrier to heat flow. However, if wind or other air movement can move through or around the insulation, it creates conditions where the insulation cannot perform its function effectively, leading to increased heating or cooling costs. Thus, understanding how air movement interacts with insulation helps in designing buildings that maintain energy efficiency.