The u value of the roof was reduced from 0 59 to 0 42 with a green roof and 0 38 for the green roof with water storage.
Green roof cost savings.
Over its estimated lifespan of 40 years a green roof would save about 200 000 of which nearly two thirds would come from reduced energy costs.
Cost benefit evaluation of ecoroofs 2008 pdf 37 pp 2 1 mb about pdf this report attempts to quantify the private and public costs and benefits of green roofs or ecoroofs in portland oregon.
An extensive green roof is the most common and least expensive type of green roof with costs ranging from 10 20 a square foot 2.
Over its lifetime though the green roof would save about 200 000.
Ecoroofs are expected to be an important part of the city s urban strategy as it grows and density increases in the decades to come.
The green roof provided an annual energy saving of 1 6 in cooling and 0 5 in heating.
The university found that the green roof would cost 464 000 to install versus 335 000 for a conventional roof in 2006 dollars.
The largest reductions were seen in rooms directly below the green roof and no reductions were found more than three floors down.
The economic benefits of any individual green roof will however depend on its design geographic location surroundings and the building itself.