Smart Growth / Smart Energy Toolkit Modules - Open Space Design (OSD)/Natural Resource Protection Zoning (NRPZ)

Learn about the Smart Growth/Smart Energy Open Space Design (OSD)/Natural Resource Protection Zoning (NRPZ) module.


OSD/NRPZ is a tool to protect natural resources and open space. It includes elements of conservation subdivision regulations and cluster development bylaws and is used to regulate new subdivisions of land in a manner that maximizes the protection of natural resources (wetlands, forests, agriculture lands, open space) while providing for new construction and adequately compensating landowners.

The Problem

Thousands of acres of open space are developed in Massachusetts each year, much of it as residential sprawl. In recent decades the rate of land development for homes and businesses has far exceeded the rate of population growth, meaning that more and more land is being used by fewer and fewer people. Sprawl development has contributed to a variety of problems for Massachusetts communities including loss of community character, a lack of diverse and affordable housing, social isolation of residents, and threats to natural resources and water quality.


Introduction to OSRD/NRPZ

OSRD/NRPZ helps mitigate suburban sprawl impacts by addressing both open space/natural resource preservation and construction of housing. This technique is an innovative form of subdivision design that maximizes resource protection while providing economic profit. OSD provides the flexibility to allow various lot sizes, setbacks, and frontage within the development.

The OSD approach begins with effective site planning which focuses on:

  • mapping of environmental resources to be preserved
  • identification of building areas which can support development economically and ecologically
  • the use of design techniques to reduce impervious cover and impacts to water quantity and quality, such as clustering, permeable surfaces, reduced roadway pavement widths, and the preservation of natural drainage pathways.

Graphics: Arendt, Randall, 1996. Conservation Design for Subdivisions, Washington, D.C.

Characteristics of Open Space Design / Natural Resource Protection Zoning

The core concept behind NRPZ is the linking of low underlying densities with compact patterns of development so that significant amounts of land can be permanently protected and forever available for agriculture, forestry, recreation, water supply protection, carbon sequestration, and wildlife habitat.

A Creative Partnership Approach to Development. At the root of every OSD effort is a bylaw that facilitates residential development. OSD does not require a cumbersome permitting procedure but instead makes it quick and easy to build the type of project the community desires.

Consistency Between Boards and Departments: Because the NPRZ/OSD model zoning and subdivision regulations deal specifically with the site design process, communities should review and amend other local provisions to avoid conflicts among boards, commissions, and departments. In addition, a community will benefit from close cooperation between other committees involved in natural resource based planning including Agricultural Commissions, Community Preservation Committees, and Open Space Committees.

Linking Density Bonuses to Community Goals: Ideally density bonuses will be directly linked to goals discussed in municipal planning documents, such as Planned Production, Open Space and Recreation, or Master Plans.

Linking Use of Open Space to Community Goals: Municipalities should carefully discuss the use and ownership of the open space to match local goals. Some communities will only want to allow passive uses of the open space, while others will want to allow active recreation.

Planning Board Understanding of Core Concepts: Communities adopting OSD zoning should be comfortable with the site analysis and conservation findings process. The Board should be open to a flexible design process that allows various lots sizes, frontages, and setbacks within the site design, rather than the usual "one size fits all" or “cookie cutter” approach.


NPRZ/OSD allows a community to accomplish its land conservation goals, while building needed homes and treating developers and landowners equitably.

In addition, implementing OSD/NRPZ in local subdivision development can successfully meet several Sustainable Development Principles including:

Concentrate Development and Mix Uses: The use of OSRD will concentrate development on to smaller areas of a site than what would generally happen under conventional zoning practice. It also provides flexibility to combine civic, educational, and recreational activities with open space and homes.

Make Efficient Decisions:The NRPZ permitting structure encourages smart growth and facilitates a permitting process that is clear, easy to understand, and cost-effective to developers.

Protect Land and Ecosystems: The planning process for NRPZ inherently protects land and water resources and promotes recharge to underlying aquifers. NRPZ also preserves significant cultural and historic resources.

Plan Regionally: OSD/NRPZ can have significant regional impacts to watershed hydrology, wildlife habitat blocks and corridors, and aquifer protection.

Expand Housing Opportunities: OSD/NRPZ bylaws can expand housing opportunities in a community.

Financial Considerations

  • OSD/NRPZ is by-right, which means a guaranteed outcome and a streamlined plan review process.
  • OSRD, like many other smart growth strategies, saves money for developers and municipalities by concentrating development and decreasing the necessity for and cost of installing and maintaining conventional infrastructure, such as lengthy and unnecessarily wide paved streets and stormwater management practices that collect and pipe runoff away from the site.
  • OSD/NRPZ  decreases site development costs by designing with the terrain.
  • OSD/NRPZ adds valuable amenities that can enhance marketing and sale prices. Massachusetts subdivisions with a considerable amount of conserved open space have appreciated faster and increased their resale value more than conventional subdivisions. Well-designed OSD developments create higher property values than conventional developments with the same type of housing.