The present study experimentally investigates the possibility and characteristics of free cooling of fresh air of air
conditioning systems using SP-24E PCM plates. This passive technique of building free cooling substantially
reduces electric consumption and gas emissions. Building free cooling by storing weather cold during night time
in Phase Change Materials (PCMs) to be used in free cooling of the building fresh air during day time is
experimentally tested in the present work is a method of energy saving. The effects of fresh air flow rate and
outdoor temperatures on discharging and charging processes, energy saving in the air conditioning system and
number of the PCM plates needed to satisfy the fresh air requirements are investigated. The results showed the
decrease of the discharge time and the increase of the number of the PCM plates with increasing fresh air flow
rate and outdoor air temperature. The energy saving in the air condition system decreases with increasing the
time from the start of discharging process. The numbers of needed PCM plates are determined in the study for
different air flow rates and outdoor air temperatures.