It's a generally accepted principle of sustainable planning that density is better for the environment than sprawl. Among other things, it encourages more efficient use of space, makes processing of waste-water and solid wastes more efficient, it provides a better platform for recycling programs, and it provides a canvas for walkable communities and a variety of inter-modal transportation options. Density bonuses in exchange for preservation is an excellent way to encourage landowners to preserve open green spaces and minimize a project's footprint on the environment.
An excerpt from the Seattle P.I.:
Monday's arsons threw into high relief a simmering debate over how eco-friendly "sustainable" design really is. Though homes featured in last year's Street of Dreams were intentionally built with a smaller footprint -- about half the size of the 8,000-square-foot homes featured in previous years -- some neighbors said even eco-friendly materials, decreased water consumption, and lower heating bills can harm the environment.Full article at http://seattlepi.nwsource.com/local/353498_arson04.html.
The five showcase homes were the first completed as part of a 100-acre rural cluster development, or RCD, with about 50 homes called Quinn's Crossing. Per the cluster formula, Snohomish County allows more density per lot in exchange for preserving wetland, wilderness or other open space. The rest of the site was rural and woodsy,
broken only by meandering trails.
The arsonists made an apparent mocking reference to Quinn's Crossing in its message left at the scene: "McMansions + RCD's R not GREEN.