Granovi Air Solutions was developed by Jan de Graaf. Jan de Graaf founded Tulderhof 30 years ago. Tulderhof produces air inlets, daylight and outdoor products for poultry, pig and calf houses. Jan has designed and developed all Tulderhof products himself, including the successful patented FLASH inlet valve and the 4-season ventilation valve. He sold his company in 2012 but is still involved with Tulderhof.
