A damp building is a cold building. Damp reduces the effectiveness of insulation and increases heating costs. Water in a material increases heat loss over the same material when dry. A dry building has lower energy costs.
A damp historic building is at risk of material degradation. Damp can be linked to degradation by salt, frost action, chemical or biological decay of materials. Damp stone can cause damp timber which puts it more at risk of rot.
An effective remedy saves money overall. Identifying the problem and using breathable, traditional repair methods in the right place generally saves money over piecemeal reactive repair. Accurate diagnosis will help to differentiate between water rising from the ground, penetrating through the walls or condensing from the inside. This helps to target correct treatment such as better drainage, repointing, fixing leaking rainwater goods.
The overall aim of conservation should be to preserve the building while reducing waste by preventing unnecessary repairs.