Basically, you need to purchase a CONDENSER DRYER. Rather than venting the damp air out through a duct, it passes it over a set of internal coils withing the unit, thus converting it back to water. The water is then drained as per your washer etc. I think it may also need a water supply as this is the source of cold fluid that runs through your coil (the coil is a heat exchanger where you get cold water runnning internally and the hot, damp air externally). The condenser dryer needs no ventillation at all.