This document presents a fuzzy logic-based routing algorithm (FLBRA) for indoor wireless sensor networks, aiming to optimize packet delivery rates by dynamically assessing link costs using parameters such as received signal strength indicator (RSSI), its standard deviation, and packet error rate (PER). Simulation results indicate that FLBRA outperforms traditional RSSI-based protocols by ensuring more reliable communication paths within building management systems. The paper details the algorithm's structure, operational phases, and procedural steps for both setup and operation in a changing indoor environment.