A dryer is provided that includes a drying chamber for items to be dried; a supply air duct; a process air duct; an exhaust air duct; and a heat pump having a heat sink and a heat source, wherein the supply air duct and the exhaust air duct can be connected to each other through a recirculating air duct by means of a mechanism in order to adjust a proportion of recirculating and exhaust air in the dryer, and wherein the dryer has a first sensor for determining a process air temperature. A method for operating the dryer and a method for controlling the temperature and/or the humidity of the air of a room using the dryer are also provided.