'Sustainable city' is a goal of how cities are developing to overcome climate change. Many countries develop their cities sustainably in various aspects including population growth, food production, sanitary and water treatment, residential planning and energy production. Although all aspects play important roles, energy is the key to powering all nations. Equipping sustainable cities with renewable energies can enhance the resilience of energy supply and halt climate change. To promote efficient land use, this research focuses on combining sustainable energy production with land reuse, making use of available brownfields land. It identifies potential brownfield sites to be developed for solar, wind and heat energy harvesting by employing the multicriteria decision-making method (MCDM) combined with geographic information systems (GIS). Three criteria were identified relevant for solar PV and wind turbine installations, they are solar radiation, site size and flood risk zone for solar PV and wind speed, site size and slope for wind turbine. The importance of the criteria to development was ranked by experts in planning and renewable energy using the Analytic Hierarchy Process (AHP), a branch of MCDM applying free software, AHP-OS. This method was tested in the context of Greater Manchester. Using the ranking contributed by experts in the MCDM workshop, the criteria were weighted and applied in determining the potential of brownfield for development. In the case of solar PV deployment, it was found that using the Inverse Linear scale in the AHP-OS, the best results were produced with the highest group consensus and relatively low consistency ratio. The results were almost comparable to the results obtained using weightings consistent with the literature, where solar radiation was assigned 50% weighting and site size and flood risk zone were assigned 25% weighting each. The Inverse Linear scale produced better results than the same set of weightings grounded from literature (50% for wind speed, 25% for site size, 25% for slope) for the wind energy case. For ground source heat pump installations, sites with sandstone and conglomerate bedrock were preferred due to the high thermal conductivity level besides the preference for highly populated areas. While identifying feasible brownfield sites for renewable energy development, this research also produced a transferable process model based on guidelines from the Department of Communities and Local Government combined with the steps taken in this research. The model can be adopted by other renewable energy planning projects in other locations to achieve a sustainable city goal.