To prevent thermal energy losses of borehole heat exchanger (BHE) storages an insulation of the top surface of the storage is an option which brings the efficiency of such an insulation into focus. Numerical studies on insulated BHE storages show higher thermal gradients in the upper domain of the storage in comparison to storages without insulation. However, no significant gradient differences are noticeable at larger depths. Therefore, following numerical studies on the benefits of BHE storage insulations were carried out. A numerical heat load test was applied to investigate the advantage of different configurations of insulation and showed just slightly better performances of the insulated models.