Cement-based materials as insulators are unable to conduct electrical charge. However, when cement is mixed with a small amount of carbon black, the contrast between the hydrophobicity of carbon black and the hydrophilicity of cement leads to the build up of a volumetric wire throughout a load bearing porous matrix. When polarized, this volumetric wire is the backbone of the supercapacitor technology and permits storing energy in form of counterions along the carbon black surface. The stored energy scales with the volume of the material. In this talk, I will show different ways of approaching this energy storage capacity from an engineering mechanics point of view. First I will show that energy storage properties can be assessed by analogy by using the correspondence principle of viscoelasticity, when replacing stress by current and strain by voltage (potential difference). I will then dive deeper into the electrochemistry of the underlying process which permits deriving the fundamental scaling relations for designing concrete structures not only for strength but for energy storage as well. This multifunctionality of electron-conductive cement-based materials and structures opens interesting perspectives for engineers to redesign our built environment for sustainability.