Abstract The use of building materials with high moisture buffering capacity is a well-recognized strategy to moderate the variation of indoor moisture loads. Many researchers investigated the ability and potential of finishing materials and furniture for the reduction of the amplitudes of indoor relative humidity by characterising their Moisture Buffering Value. Nevertheless, the recent and widespread building practice, which is increasingly trying to reduce the air permeability and thermal transmittance of the envelope, is likely to even worsening indoor humidity conditions, with consequences for durability of materials and inhabitants’ comfort and health. Very performing materials are then needed to act as buffering and quickly dampen high moisture loads. This paper proposes the design of a building internal counter wall equipped with an "active" moisture buffering device. This is able to measure the indoor relative humidity and consequently increase the adsorbing capacity of a porous material through an air-flow. Experimental activities were carried out on different prototypes with the combination of granular Sepiolite with two different pore structures and nonwoven fabrics. The devices effectiveness in terms of MBV has been dynamically tested in a climate chamber according to the DTU Nordtest method. Different “activation” times against several humidity levels were set in order to assess the best solution in different scenarios.