Non-fluorinated refrigerants, commonly known as natural refrigerants, are substances that have been used as refrigerants since the 1950s. They cause no damage to the ozone layer and their global warming potential is zero, or practically zero. The most commonly used substances used for commercial and industrial refrigeration are ammonia (R-717), carbon dioxide (R-744) and hydrocarbons (HC), such as isobutane (R-600a), propane (R-290), ethane (R-170) and propylene (R-1270).