Abstract: A built-in combination cooling and heating device for a residential building comprising peripheral wall members, a floor member and a ceiling member which are high thermally conductive and define a room of said residential building, an outer jacket surrounding said room defining members in a peripherally spaced relationship to the members to define an annular air space therebetween and having a hole in the center of the funnel-shaped lower end portion and the conical upper end portion provided with exhaust ports, a heater disposed in said center hole of the outer jacket lower end portion, a tunnel provided below said floor in communication with said center hole, a porous heat radiation plate suspended from said floor member right above said heater, a cooler suspended from the center of said upper end portion of the outer jacket, a porous cooling air dispersion plate suspended from said upper end portion of the outer jacket and a ventilator provided in the attic defined between the roof of said building and up