I don’t think cleaning windows at ground level is too difficult, however the higher they are the more awkward they become to clean. They will either require climbing a labber or using a very long pole to reach the window with the cloth. Windows at skyscraper heights then require lifts on the outside or the cleaners to abseil down the building. Skyscraper window cleaners usually look like they’re dressed for rock climbing rather than as a conventional window cleaner.
I have heard that many skyscrapers have windows that have a coating on the outside that prevents dirt from sticking to them. This theoretically means that they won’t have to be cleaned or at least not be cleaned as often as conventional windows. I’m not sure how much it costs to clean the windows of a skyscraper, but I wouldn’t have thought it’d be cheap. This is because it will include the cost of the external lifts and safety equipment for the cleaners; I suspect the cleaners also earn quite a bit more than conventional ones with the risk involved.
I think there can be a change that can be made to window cleaning in skyscrapers that could potentially save money in the long term. From my experience and observation, window cleaning usually involves three elements: applying water and the cleaning solution to the window, wiping the window, and drying it. If these stages could be applied automatically to the window without human input, especially from the outside, then the window cleaning process can potentially be made cheaper and safer.
A possible method to apply these stages to windows in skyscrapers would be to use a system similar to vertical blinds. In the first stage, water and cleaning solution can be sprayed onto the window from above. A slider with a soft cloth can then move up from the bottom to the top of the window, which would effectively wipe it. Finally, a drying slider (similar to a windscreen wiper) would come down from the top to the bottom of the window and push all the water off.
Using an automated window cleaning solution in skyscrapers would mean that all windows can be cleaned at once and at any time. Maintenance can also be carried out inside the building if there are ports to access the window cleaning parts above and below the windows.
This solution only covers windows in skyscrapers, so if you think you have a solution or if you have a problem you would like me to try to solve then please feel free to comment it.