When were people dumping their fieces out building windows?

Medieval era. Continued in the British Isles into the early 18th Century. This is why Tudor houses were built with the upper storey overhanging the lower thus ensuring that the sh*t didn't hit the downstairs windows.

Also said to be why some Brits refer to the WC as the loo. When throwing the waste out the window, more considerate people shouted 'Garde l'eau!', which comes from the French meaning 'Watch out for the water!'

In Europe this happened in medieval and early modern times, and continued through the 19th century in places where indoor plumbing was not common. However, most cities had regulations about not just dumping waste anywhere, and it wasn't something you could do with impunity in most places.

A good answer from cymry3jones, as usual.

However, I was taught that the overhangs on Tudor buildings were because there was a property tax relating to ground area. The ground floor was made as small as possible and space was created by making upper floors wider..

As long as there have been windows and buckets to hold it. ... Rome had "public lavatories", but it wasn't until the invention of the flush toilet that people found a better way of getting their waste out of the house.

fieces? you mean feces or poop? you are thinking of medieval European cities with poor sanitation practices