If you observe frost or ice on a dry day (nothing falling from the sky) and the temperature remains below freezing, it will shrink and in time disappear. Evaporation takes place below freezing, just put a "naked" ice cube into your freezer and watch it shrink - even the cubes in a tray in the freezer shrink - and all of this is happening where the air hardly moves at all. Yes, your washing will freeze and stiffen but within a very short time it will dry. Tumble dryers are a monumental waste of energy, they were primarily thought up and used for/by the suburban USA market where it apparently is exceptionally plebeian/primitive/"gauche" to have washing out drying, just not done. Have the courage to use the outdoors for drying and your washing will have the fresh smell that is so characteristic of washing dried outdoors.