Benchmarking is often claimed to be a powerful means of continuous improvement for facility managers but benchmarking tools in facility management are less developed than for other services businesses. The most common information which Facility Managers can get from benchmarking results is their positions of performance. Rankings on performance, without further analysis, cannot help much for the achievement of continuous improvement. A new approach, called Data Envelopment Analysis (DEA), is proposed in this article to evaluate and improve the efficiency of facility management operation units. By applying DEA in two cases with collected and computer generated facility management data respectively, we showed facility managers not only could identify inefficiencies but also be given hints on the ways to catch up with their efficient peers. Based on the cases, it was illustrated that DEA could work with facility management quantitative data with clear indications for improvements. One of the cases demonstrated how DEA could be applied with Excel formulae. Further research is suggested with more collected data to test the sensitivity and reliability of DEA application on facility management and whether DEA can produce satisfactory results with qualitative data in Facility Management.