There is also some discussion involving "active" living walls. An active living wall actively pulls or forces air through the plants le quality to the point that the installation of other air quality filtration systems can be removed to provide a cost-savings. Therefore, the added cost of design, planning and implementation of an active living wall is still in question. With further research and UL standards to support the air quality data from the living wall, building code may one day allow for our buildings to have their air filtered by plants.