Conservation subdivisions preserve a significant portion of a tract as open space and direct development away from natural, scenic, historic, and agricultural areas. The open space is typically preserved in perpetuity for the benefit of residents, the public, or as protected natural areas. While the terms "conservation subdivision," "cluster subdivision," and "open space subdivision" are sometimes used interchangeably, for the purposes of this guide, at least 50 percent of the original tract area must be preserved as undeveloped open space to be considered a conservation subdivision. To achieve this level of open space preservation, houses on the site must be located closer together and on smaller lots than found in conventional neighborhoods. Rather than having 50 homes on one acre lots spread over an entire 50-acre tract (conventional), they might be located on one-half or one-third acre lots allowing 25 to 30 acres of the lot to be preserved as open space.
Homes clustered around a scenic pond in Deerfield Knoll, a Conservation Subdivision in Willistown Township.
Conservation subdivision developments should be designed with specific results in mind, including harmonizing with the landscape, preserving natural and historic features, minimizing environmental and visual impacts, and providing continuity with off-site open spaces and greenways. A four-step design process that institutionalizes these results by determining first, what should be protected on a site, and then where development is most appropriate is detailed in the Conservation by Design section of ConservationTools.org. Using this or a similar design process is encouraged to achieve consistently low impact developments with a high quality of protected open space.
What are the advantages of conservation subdivision vs. conventional residential layouts?
Conservation subdivisions provide numerous benefits for developers, municipalities, and residents. They facilitate the protection of natural and historic resources, farmland, scenic viewsheds, and the provision of recreational activities and are typically more economical to develop.
Open Space Preservation Significant open space, natural areas, and scenic views can be protected. In fact, as of 2021, over 17,000 acres in Chester County were preserved as open space within developments. This accounts for about 12% of all preserved land within the county.
Environmental Protection Conservation subdivision development can result in fewer environmental impacts than conventional development through reduced disturbance to natural resource areas, woodlands and steep slopes, minimized stormwater runoff off into wetlands and streams, and less impervious surface.
Recreational Opportunities The preserved open space can be used for active and passive recreation as well as to accommodate trails.
Design Flexibility The flexibility of conservation subdivision design can be used to locate development in the most appropriate areas of a site while using open spaces to provide buffering and screening for residents and between potentially less compatible land uses.
Economic Benefits Homes that are located within ¼ mile of protected open space are valued at approximately $11,000 more than similar homes not located near open space, according to Chester County's 2019 Return on Environment study. These higher property values generate additional tax revenue.
Neighborhood Development A greater sense of community can result from good conservation subdivision when dwellings are placed closer together and pedestrian facilities are promoted or required.
Energy Conservation Less land disturbance and infrastructure can result in reduced energy consumption.
Reduced Maintenance Costs Conservation subdivisions typically result in lower infrastructure and maintenance costs due to shorter roads, sidewalks, and water and sewer lines.
Reduced Stormwater Management Costs Conservation subdivisions reduce costs for developing and maintaining stormwater management infrastructure. Chester County's Return on Environment study found that on average, each acre of open space avoids $4,600 of stormwater infrastructure construction costs, $479 of annual operations and maintenance costs, and $1,870 of annual pollutant load reduction costs. These savings accrue to developers and municipalities.
Good Design Well-written conservation subdivisions ordinances promote and control design of the development and homes to produce a more attractive, functional and cohesive neighborhood.
Chester County Policies that Support Conservation Subdivision Development
Three county-level plans provide policy guidance that supports conservation subdivision development over conventional development. Landscapes3 (2018), Chester County's Comprehensive Plan; Watersheds (2024), an integrated water resources plan for the county, and the County-wide Act 167 Stormwater Management Model Ordinance (2022).
Increase protected farmlands.
Expand protection of natural habitats.
Create additional recreation properties.
Enhance protection of historic resources.
Expand the network of protected open space.
Encourage restoration and stewardship.
Support open space policies and ordinances.
Promote innovative practices for improved water quality.
Enhance flood resiliency.
Promote healthy lifestyle choices.
Advance multi-modal transportation.
Revise municipal ordinances to reduce required impervious cover.
Ensure that ordinances require minimal site disturbance, protect existing natural resource and treat stormwater on site close to its source.
Encourage trails within new developments to access stream corridors.
Promote culturally-sensitive aesthetics within land developments.
Implement design practices to eliminate or reduce the size of stormwater basins.
Delineate and integrate riparian buffers within the subdivision design.
Require proposed land development projects to inventory and protect existing natural resources to the maximum extent possible.
This model ordinance or a version thereof must be adopted by all Chester County municipalities. The model ordinance includes a description of the required site design process developers must follow to minimize disturbance to land, existing hydrology patterns, and natural resources. Because cluster/conservation design inherently involves a design process consistent with these requirements, the ordinance features an appendix that describes Conservation Design and Low Impact Development Site Design Process.
