Increased water exchange according to DIN 1988-200

Good day. The aforementioned DIN is supposed to specify from when, for example, fresh water with a reduced temperature (below 60 degrees) can be operated. Here, it is important to know, among other things, whether one is a large system or has increased water exchange. But clearly, unfortunately, no one can determine this exactly. These are probably only guidelines, and not legal requirements... But I would be interested to know if there is increased water exchange here. 1 fresh water system for 5 residential units in a new building. Circulation line The longest hot water pipe from the circulation line to the outlet is max. 6 meters! So the requirement of 3 liters between the circulation line and the outlet is adhered to here! The residential complex is also constantly occupied, and hot water generation is started about 50 times daily. To avoid scalding and significant lime scale buildup, yet avoid the residual risk of Legionella (these are only reliably killed above 70 degrees), I would like to operate with a set hot water temperature of 55 degrees. This would have several advantages (no lime scale buildup, less scalding than at 60 degrees, possibly Legionella reproduction is prevented). However, a binding confirmation that fresh water can be operated here at 55 degrees instead of 60 degrees does not exist anywhere... Thank you very much