In the Netherlands and other countries around the world there are extensive canals and rivers with banks supported by walls. Especially in the historic inner cities of the Netherlands, quay walls currently need to be replaced. During construction, temporary valuable underground space is created that can be used to accommodate energy installations for the benefit of the surrounding buildings. The quay wall itself can also be a thermal active structure relying on a combination of aquatic and geothermal energy. Two different designs for quay walls incorporating thermal energy infrastructure have been designed: (i) based around a sheet pile; and (ii) based around a concrete pile with a ‘L’ wall on top. An evaluation of the energy, mechanics, finances and CO2 saving is presented for a case study in this paper. It is seen that for the case studies elaborated, both walls can supply sufficient thermal energy for the houses along the canals improved by good use of surface water, reduce CO2 emissions by more than 1 tonne per meter length and can be financially positive. The influence on the mechanical performance of the energy quay wall (settlements, bearing capacity and bending) has been evaluated and found to be reassuringly small.@en