Backyard Home Equity?

As part of my Energy and Equity Project (EE101), I decided to see if I could determine whether the backyard garden and entertainment areas could be valued as a form of home equity. "Outdoor Living" seems to have caught the attention of the media in recent times.  Outdoor kitchens are becoming popular.  I'm wondering what could be the effect of  building of an outdoor structure that could serve as home office could have on home equity?  Could this increase the home equity by a value equal to its cost immediately.  If the office were self sustaining or perhaps created more energy than it needed to serve its purpose of being a home office, could it be a source of ongoing revenue by virtue of its existence as well as serve as a source of accelerating home equity?  In other words, could the outdoor home office turn into a SOHO (small office/home office) for the homeowner and be an asset to the Cottage Industry?