Here's an interesting article featured on CNN.com about sustainability where they interview Jonathan D. Solomon, an Assistant Professor of Architecture at Hong Kong University about a concept known as "Urban Densification."
The term seeks to find wasy to develop plans that are more environmentally sustainable and to build homes that are more compact and closer together but that can also seek to preserve open and public spaces.
I found this quote interesting when it comes to people's perceptions about density:
"Tokyo is one of the densest cities on earth but not very high rise. New Jersey is the densest state in the U.S. and it is entirely suburban. Dense doesn't mean higher, it means being better organized.
When you fill in vacant lots around the city with low rise buildings, you increase density and also link broken communities together. In doing so you increase both environmental and social sustainability. We have the ability to build all these different structures. "
To read more about the article, click here.