A wind tunnel with a closed design operates independent of the weather and is thus suitable for being converted into a climate tunnel. Heating up the air at a closed return requires a cooling device to protect the models mainly consisting of non-heat-resistant materials. The resulting pressure loss and the necessary cooling power reduces the advantage of the low propulsive power due to the design.
The wind tunnel with a closed design is more suitable for the automotive industry since it also doubles as an acoustic chamber forming a so-called aero-acoustic wind-tunnel.