Fire Safety Science Digital Archive

Air gaps are often included in thc walls of structures such as buildings, ships, refrigerators and ovens, for the thermal insulation which they provide. The insulation of an air gap is dependent on the mean temperature of its bounding surfaces and the best effect is achieved when the gap is at the position where it is at the lowest possible mean temperature. The value of the insulation afforded by air gaps under various praotical conditions in given graphically. The expression assumed for convective transfer should only be considered valid when an air gap is at least 3/4 inch wide.