For more than 30 years, a german based market leader has used its in-house experimental combustion furnace to independently drive the development and approval of new products and to test special solutions. This is a unique selling point, as no other competitor has such a facility available on-site. Doors, including all attachments, must withstand temperatures exceeding 800 °C for a specific period to qualify as fire doors. The resulting flue gases contain combustion residues from various coatings, attachments, and sealing materials. These are filtered and then released into the environment below the strict air quality limits of the German Technical Instructions on Air Quality Control (TA Luft). As a manufacturer of climate-neutral doors, the company has long recognized its responsibility to produce sustainably and in an environmentally friendly manner. This includes the goal of continuously reducing emissions and pollutants from its facilities. The flue gas cleaning system, successfully commissioned in the summer of 2021, is another important step in this direction. The investment in the system was made voluntarily to further promote environmental responsibility. The 20 x 5 meter flue gas system filters both the exhaust gases from the fire tests in the chimney and the extracted room air from the hall where the furnace is located.