A crosslinked rubber composition, process for preparing same, and a flexible component based on at least one room-temperature vulcanizing “RTV” silicone elastomer and including at least one phase change material (PCM) is provided. The flexible element includes at least one elastomer layer capable of storing thermal energy and of releasing it which includes the crosslinked rubber composition. Also provided is a thermal control or regulating system incorporating the flexible element. The composition is such that the silicone elastomer has a viscosity measured at 23° C. according to the ISO 3219 standard which is less than or equal to 5000 mPa·s. The silicone elastomer includes two components A and B and is crosslinked by polyaddition or polycondensation, and the composition includes the PCM, which is not encapsulated and is in the micronized state, in an amount of greater than 50 phr (phr: parts by weight per hundred parts per elastomer(s)).