damp damage

Your relocation agency has not given to you the manual of the perfect tenant in Belgium?
Here is an extract about condensation issues:
CONDENSATION
You are liable for damages caused by condensation to the decorations, walls, floors, ceilings, window frames, etc… Properly ventilate the premises especially the bathroom, the kitchen and all the bedrooms (you breathe out approximately 1 litre of water a night per adult). Ensure a sufficient and constant temperature. Remember that dry air requires fewer calories to be heated. Proper ventilation of rooms allows heat savings. Don’t turn off the heat and the hot water heater for short term absences. It can take more energy to heat up the cold water than you saved (depending on the thermal inertia of the rooms). For short term absence, just lower your thermostat by two or 3 degrees: it will be sufficient to prevent condensation problems and to reduce the energy bill. If you see condensation on your windows, it is often the result of insufficient ventilation and / or heating