Abstract: The present invention relates to those devices for enabling and disabling heating and cooling equipment and providing supplemental ventilation to an enclosure. An air intake unit is ducted to a central heating and cooling installation. The intake fan unit has an outside temperature thermostat associated therewith and which is wired to a control circuit that also monitors temperature in proximity to a thermostat-equipped exhaust fan unit located in an attic or upper crawl space. Sensing devices are used in association with the plurality of thermostats to selectively enable or disable the heating and cooling equipment and to actuate the intake and exhaust fan units, thereby providing ventilation.