Green Public Procurement (GPP) can be described as an environmental policy instrument whereby public authorities purchase goods or services by considering sustainable criteria. The objective of this work is to analyse benefits and costs of GPP, as well as comparing it with other environmental policy instruments. The focus lies on procurement of energy efficient electric appliances in public offices. By using the net present value method, an environmental cost benefit analysis was elaborated in order to evaluate the implementation of a green public procurement service for the Austrian region of Styria. As a comparison scenario the allocation to external procurement services was tested. Based on the ranking of the calculated net present values, the contract allocation to existing external procurement services is more efficient and thus preferable. The profitability of an implemented public procurement service is only given if a correspondingly high annual procurement quantity can be guaranteed in order to cover the costs.