XFrCool1 is a free cooling controller with direct control of DC fan and standby cooling (AC unit) for BTS shelter (indoor telecommunication base station shelter). XFrCool1 uses in-house developed algorithm based on 10-year experience in free cooling area resulting in high savings in kWh and big OPEX cost reduction for telecom operators. Seven temperature thresholds can be set in order to suit every application in every climate surrounding.