Recent years have witnessed an increasing need for wireless sensor networks in a wide range of applications specially for buildings automation. In such networks, many sensor nodes relay the sensed data hop by hop towards the nearest sink. The sensors closest to the sinks drain their energy much faster than distant nodes because they carry heavier traffic which causes prematurely the end of the network lifetime. Relocating the sinks can solve this problem by distributing the high traffic load among the sensors and increase the network lifetime. In this work, we propose a new scalable multi-sink heuristic algorithm (Hop) which regularly moves the sinks towards the distant nodes. We evaluated the performance of our solution by simulations and compared it with others schemes. The results show that it extends significantly the network lifetime and balances notably the energy consumption among the nodes. Such results can provide useful guidelines for real sensor network deployment.