An accessible place is one where you have several choices of how you access the place, especially including the self-propelled ways of walking and biking. If you're able-bodied and living in an accessible place, you'll always be able to get around no matter how much the price of gas rises.
This porch is quite close to the sidewalk… so close, in fact, that people might feel less comfortable sitting on the porch. But Eric did a nifty thing by building an elevated bed, which gives the plant material a year or two headstart at creating a more opaque boundary between the porch and the sidewalk. A street is a more interesting place to walk when people are sitting on their porches than when it is deserted.
Properly-designed porches contribute to sustainable places in several ways, including enticing people to spend time outdoors so they begin to enjoy living in season, potentially saving thousands on utility bills. But they can contribute mightily to the walkabilty of a place as well. If properly placed in relation to the sidewalk with good railing and fence design, you enhance the chances that someone on the porch might have a conversation with someone walking by. Conversations lead to relationships, and as cheesy as it sounds, relationships lead to people acting like neighbors again.