Temperature

Damp housing is often reported to feel colder.

When a room is heated, the air warms up first. The walls warm up much more slowly (this is particularly true of cob and stone buildings where the walls have a very high thermal mass).

As the air warms, any residual condensation on the walls evaporates. This evaporation takes energy, so rather than heating the room, heat is expended on drying the walls out.

Moisture will naturally move from a cold area to a warm area, so where the structure of the wall is damp, moisture will move towards the interior of the room and evaporate, further wasting heat energy.