An additional advantage of polymerization is form- stability of the PCM elements. Moreover, it avoids leaking of the PCM in its “liquid” state so that macro-encapsulation is not necessary. Finally, the thermal conductivity of the PCM of λ = 0.19 W/(m K) was increased by adding a specific graphite (THERMOPHIT GFG, SGL GROUP), depending on its mass frac- tion ω by up to a factor of 20 to λ = 3.95 W/(m K) for ω ≈ 0.3 g/g.