Designing asynchronous circuits by reusing existing synchronous tools has become a promising solution to the problem of poor CAD support in asynchronous world. A straightforward way is to structurally map the gates in a synchronous netlist to their functionally equivalent modules which use delay-insensitive codes. Different trade-offs exist in previous methods between the overheads of the implementations and their robustness. The aim of this paper is to optimise the area of asynchronous circuits using partial acknowledgement concept. We employ this concept in two design flows, which are implemented in a software tool to evaluate the efficiency of the method. The benchmark results show the average reduction in area by 28% and in the number of inter-functional module wires that require timing verification by 67%, compared to NCL-X.