Thermal Energy Storage (TES) systems, which are crucial in Concentrated Solar Power (CSP) plants, provide a cost-effective and efficient way to balance energy demand and supply, outperforming technologies like batteries in cost and CO2 emission reduction. TES, particularly through sensible heat storage in solid media, offers key benefits such as modularity and durability, enhancing renewable energy plant performance, and lowering electricity costs. Cement-based TES (CTES) excels in cost, thermal properties, and wide temperature range suitability; however, faces drawbacks above 100 °C, including mechanical degradation [1]. Thus, enhancing the mechanical and thermophysical properties of cementitious materials is of great importance. This material enhancement can be reached by using different routes such as the use of additives (e.g., fibers or particles) that help overcome the shortages of the cementitious matrix. Numerical simulation tools have become relevant in the assessment of energy materials under operating conditions, using both continuum and discrete modeling techniques. In this sense, several types of lattice-like models have been used in the literature for the analysis of coupled diffusive-mechanical phenomena in quasi-brittle materials. In this work, we extend the lattice-particle formulation proposed in [2] to account for thermally induced cracking in cementitious composites, considering different types of additives (i.e., particles and fibers). The heat transfer problem is solved by means of a one-dimensional transport network and then strongly coupled to the mechanical problem. With this approach, we are able to not only characterize the thermomechanical behavior of the composite material but also to foresee the effect of cracking in the heat transfer process. We apply our model in the assessment of representative volume elements (RVEs) of CTES functionalized with different additive grading, including basalt fibers and ilmenite aggregates. With this approach it is possible to predict the feasibility of the mixes in the low-to-medium temperature range of operation (i.e., 100 to 300 °C), which is critical in solar-driven trigeneration plants that can be used both in building and industrial heating.