With double-glazed windows, unscrew the window panes and thoroughly clean all four surfaces (if heavily soiled possibly multiple times) so that no film or «clouds» are visible.
For this purpose you can find good ammonia-based cleaning agents. After cleaning, leave the casings open for one to two hours so that they can dry out well. In this way, no condensation can build up
Clean blinds (each slat) and roller shutters inside and whenever possible outside with warm water to which you have added a gentle cleaning agent. Be absolutely sure to rinse them off with clean water. Don’t forget the fittings and winding crank. On roller shutters, also replace any defective belts.
Finally, hand dry the roller shutters and slat blinds. Treat wooden blinds with oil, brush off sun shades thoroughly and wash them as needed.
Watch out – don’t use any cleaning agents that include an alkaline solution, any acidic fluids or aggressive materials.