SHT21 Sensirion - connect to I2C network in home ??

Hello all,

I have a great idea. Connect a SHT21 (Temp+Hum by I2C) to my home I2C network.
For best information ... I have a I2C thermostats each with extender P82B715 for longer distances. Every thermostat operate on 5V (each has an arduino nano). Is there a posiibility to connect to this network SHT21 ? Because it operates on 3.3V.
Voltage supply is no problem (LD1117 on board directly with SHT), but I don't have a knowledge, if SDA/SCL of network can be on the same level, then I2C SHT21 ???

Thanks for all helps. Bobo