Supply and exhaust ventilation device

A supply and exhaust ventilation device comprising:

• a main body provided with an indoor-side inlet, an indoor-side outlet, an outdoor-side inlet, and an outdoor-side outlet;
• and
• the supply and exhaust ventilation device comprising, in the main body:
• a supply air path which communicates outdoor air from the outdoor-side inlet to the indoor-side outlet;
• an exhaust air path which communicates indoor air from the indoor-side inlet to the outdoor-side outlet;
• a heat exchange element which is disposed on a crossover part of the supply air path and the exhaust air path and exchanges heat of the outdoor air and heat of the indoor air;
• an air supply fan disposed in the supply air path and an air exhaust fan disposed in the exhaust air path;
• an air supply motor which drives the air supply fan;
• and
• an air exhaust motor which drives the air exhaust fan,
• wherein the exhaust air path comprises:
• a heat exchange exhaust air path which exhausts air via the heat exchange element;
• a normal ventilation air path which exhausts air not via the heat exchange element;
• and
• a damper which switches between the heat exchange exhaust air path and the normal ventilation air path,
• the indoor-side inlet is provided with an indoor temperature sensor which detects an indoor temperature and an indoor humidity sensor which detects indoor humidity,
• the outdoor-side inlet is provided with an outdoor temperature sensor which detects an outdoor temperature and an outdoor humidity sensor which detects outdoor humidity,
• the supply and exhaust ventilation device further comprises a controller which controls the air supply motor, the air exhaust motor, and the damper,
• the controller comprises:
• a damper controller which drives the damper;
• a heat quantity calculator which calculates an indoor enthalpy from detection results of the indoor temperature sensor and the indoor humidity sensor, and calculates an outdoor enthalpy from detection results of the outdoor temperature sensor and the outdoor humidity sensor;
• and
• a comparator which compares the indoor enthalpy with the outdoor enthalpy,
• when the damper controller determines that the indoor temperature and the outdoor temperature are both in a predetermined temperature range based on a discomfort index, the damper controller causes the damper to switch the exhaust air path to the normal ventilation air path, and
• when the damper controller determines that one of the indoor temperature and the outdoor temperature is out of the predetermined temperature range, the damper controller causes the damper to switch between the heat exchange exhaust air path and the normal ventilation air path, based on an output result of the comparator.