Occupied spaces require a certain minimum
amount of ventilation. In many countries, ventilation
requirements are dictated by building codes, which require
ventilation rates that are fairly high. (See Measure 4.2.1
for details.) In principle, air leakage can comprise part of
the needed ventilation. If the leakage rate is less than the
ventilation requirement, it does not “waste” energy, and
there may be no economic merit in stopping it.