UNIVERSITY PARK, CENTRE COUNTY - At last month's Ag Progress Days - Penn State showed home and businesses owners a new kind of roof - a green roof. Instead of shingles, metal, or rubber, a green roof uses plants to cover the top of a building.

The environmentally friendly building design has been popular in Europe for 30 years, and is now catching on here. At Penn State, the university's Forestry Resources Building uses a green roof and so do many other new buildings. It will cost someone about twice as much to top off a building with a green roof instead of a conventional roof. But cost isn't everything – a Penn State Professor of Horticulture said a green roof will last three times as long and that is not where the benefits end.

“The green roof actually acts as a cooling evaporative cooler on top of the roof and it's just like a lawn you know if you go out on a lawn on a hot summer day versus sitting on an asphalt parking lot on a hot summer day it's a whole lot nicer to sit on the lawn than it is the asphalt parking lot,” Associate Professor of Agriculture at PSU, Robert Berghage said.

Green roofs are most popular for government buildings schools and at universities