Abstract: A ventilator of the heat exchange type includes an air passageway communicating between an interior of a room to be ventilated and the outdoors, a first centrifugal fan for introducing outdoor air to the interior of the room, a second centrifugal fan for discharging indoor air outdoors, both centrifugal fans being disposed within the air passageway so that outlet areas communicates to each other, and two electric motors for alternately driving the centrifugal fans respectively. At least any one of the centrifugal fans is formed of a heat-accumulative material so that heat contained in the indoor air is accumulated in the centrifugal fan formed of the heat-accumulative material and that the heat accumulated in the centrifugal fan is dissipated to the suction air. Heat exchange is thus performed by accumulating the heat in one of the centrifugal fans during indoor air discharge operation and by dissipating the heat to the outdoor air during outdoor air suction operation.

Abstract: Disclosed is a refuse disposal apparatus in which refuse fed into a fermenting vat can be disposed by subjecting the refuse to methane fermentation, the fermenting vat including a heating device for heating the refuse in the fermenting vat to a proper temperature for accelerated methane fermentation, and the refuse being agitated by an agitating device in the fermenting vat, so that methane produced in the fermenting vat by the methane fermentation may be externally collected by means of a gas collecting pipe for use as an everlasting heat source, and that sludge produced by the methane fermentation of the refuse in the fermenting vat may be discharged to the outside through a discharge pipe for use as fertilizer.