We develop a wireless system that can (partially) substitute the wired infrastructure underlying Building Automation and Control Networks (BACnet) of the Building Management System (BMS). There are efforts (e.g. from ZigBee alliance) in developing the wireless components for BMS, they build from bottom up which may lead to change and re-standardization of a new BACnet protocol. There are also entirely new infrastructure proposed (e.g. sMAP) to collect physical information, however, these schemes require a longer time to be adopted. Our system is designed to support BACnet without any modification. We believe that our design experience is useful for other applications where wired infrastructure and upper layer protocols that are complete and well established, and is considered to be cost-effective in converting the system to (partially) wireless. Our experience shows that a direct replacement of wires into wireless links does not work. There are a number of difficulties, including the strict and harsh time constraints for frames to be transmitted before the system consider it as timeout. Our solution is to propose an asynchronous-response framework so as to keep the control flow of the upper layers protocol intact. In this demo, we will 1) bring the physical devices and explain our system on-site and 2) play a experiment video of our system that recorded in real environment.