<http://schema.org/about>
"A new study finds that in California, single-family homes sporting green labeling such as LEED or EnergyStar are valued at as much as 9 percent more than their"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/your-home/remodeling-design/blogs/study-green-home-labels-garner-extra-green-in-california-real-esta>