In 2005, the Ontario Centres of Excellence (OCE)) for Earth and Environmental Technologies of Toronto installed a vegetal wall in an Ontario university. Four floors are covered in a vegetal substrate made of moss, ferns, orchids and subtropical plants. These naturally absorb and destroy pollutants. The system, installed on a porous substrate that lets air flow encourages interior ventilation which reduces energy demand; it purifies and filters the air. This vertical garden favours thermal and phonic insulation.