The process of photosynthesis consumes CO₂ and releases O₂, but this process also works in reverse.  When you add up the total amount of CO₂ consumed by a plant compared to the total amount of O₂ produced by a plant, if the plant is healthy and does not die back, then the CO₂ consumption value is usually higher.  If kept in good health and maintained properly, 10m² (~100ft²) of G-SKY Extensive Green Roof consumes approximately the same amount of CO₂ as a 13 foot-high tree per year.   

G-SKY Extensive Green Roofs also consume trace amounts of Nitrus Oxide (42.8g/year) and Sulfur Dioxide (1.8g/year). 

CO₂, NOx and SO₂ consumption rates vary greatly depending on the plant selection, our values reflect sedums from our G-SKY Sedum Plug product-line.