So i have an application with 19 areas with each area having its own AHU that has 1 HMI panel and 2 Belimo energy valves
Belimo energy valves
(https://www.belimo.ch/ch/en/Product/Water/ValveDetail.cfm?MatNr=EV100F+BAC1&ValveMatNr=EV100F+BAC1&CatNr=11011010&VCat=W1)
Has anyone configured belimo energy valves in tia portal?

And do you have a suggestion on how to approach the networking part of this aplication?

I was thinking to have 19 PLCs (S7-1500) comunicating with each other via profinet each with its own HMI panel
The belimo energy valve can only comunicate via modbus tcp or modbus rtu
There is a switch with 24 ports that can connect all plcs, however i would need a smaller switch with 4 ports at each of the PLCS to connect the 2 energy valves

Your approach sounds like a sound approach. I would suggest using Modbus TCP for speed, maintainability, and speed. TIA Portal has a Modbus communication library with blocks that support Modbus TCP (MB_Client, MB_Server). You will cable the devices to a switch as you describe and define the network as industrial ethernet.
https://cache.industry.siemens.com/dl/files/340/102020340/att_118119/v5/net_modbus_tcp_s7-1500_s7-1200_en.pdf