In this paper, a quantitative-based evaluation of the environmental impact of a proposed wind farm is presented using the Rapid Impact Assessment Matrix (RIAM). The paper uses the revised Environmental Statement of the Grove Farm Wind Energy Project, which was rejected during the planning decision consent stage initially and upheld on appeal. The paper evaluates quantitatively the potential impact of an onshore wind farm at the construction and operation stages. Based on the RIAM evaluation conducted, the paper then goes on to apply a mathematical model to the results to determine the indicated potential level and nature of sustainability of the proposed wind farm. The results indicate that the Grove Farm project was deemed, as a whole, detrimental to the environment-human system, particularly in respect to impacts to visual amenity and cultural heritage. The application of the model to the RIAM indicated that in both the construction and operation stages, the project was considered as unsustainable. The results obtained raised legitimate questions as to the benefits of such projects as a major contributor to the UK's renewable and sustainable energy mix.