Temperature changes are known to induce specific couplings in clay, in particular, an anomalously high thermal pressurization in undrained conditions, or a thermal compaction in drained conditions, both of which are potential threats for the mechan- ical stability and sealing capacity of the geomaterials. Thermodynamical analysis of those peculiar thermo-mechanical couplings points to a potentially important latent energy which in turn could limit the temperature change upon heating or cooling. The direct measurement of latent energy developed during a laboratory geomechanical test is challenging. Instead, proper identification of thermal hardening in conven- tional experiments with temperature changes provides an alternative route to estimate latent energy. In this work, existing laboratory thermomechanical tests of clays are analyzed with a rigorous thermodynamic framework to quantify the magnitude of latent energy in thermo-mechanically loaded clays. A thermodynamically consistent constitutive model for fully saturated clays that combines two key features: i) the temperature dependence of the blocked energy and ii) the framework of bounding plasticity, is proposed. The performance of the model is validated by reproducing results obtained in laboratory tests for Boom and Opalinus clays. The thermomechan- ical loads considered to validate the model performance, were then used to estimate the percentage ofwork that remains latent in the clayey material during plastic yield- ing. We find that the magnitude of latent energy is quite significant, typically a few tens of percent of the total dissipated energy, and increases significantly with temper- ature. Accordingly, it is expected to play an important role in the thermo-mechanical response of clays.