AIR CHANGE LOAD
The air changes occurring in the space are brought about almost entirely by infiltration through door openings.
The quantity of outside air entering a space through door openings in a 24 hour period depends on the
(2) size and,
(3) location of the door or doors;
on the frequency and duration of the door openings; and on the densities of the inside and outside air.
Since the combined effect of all these factors varies with the individual installation and is difficult to predict with reasonable accuracy, it is general practice to estimate the air change quantity on the basis of experience with similar applications.
Experience has shown that, as a general rule, the frequency and duration of door openings and hence, the air change quantity, depend on the inside volume of the cooler and the type of usage.