Conservation design and Low Impact Development (LID) are related site planning and design approaches that cluster buildings and infrastructure to preserve existing natural areas and uses Best Management Practices (BMPs) as a means of utilizing the natural drainage system, reducing the volume of stormwater runoff, and conserving as well as preserving water resources. The design may also include reduced energy consumption, transportation efficiency, and naturalized detention for stormwater management.
Below left is a traditional site design; right is a conservation site design.
According to Chicago Wilderness and the Chicago Metropolitan Agency for Planning (CMAP), conservation design is "a density neutral design system that takes into account the natural landscape and ecology of a development site and facilities development while maintaining the most valuable natural features and functions of the site" (Chicago Wilderness and CMAP). Essentially, conservation design preserves some natural area by developing in a particular pattern that conserves ecologically significant land that is to be preserved is identified, impervious surface areas are reduced, and buildings are clustered. One of the primary goals of conservation design is to create an interconnected network of permanent open space that will be kept in its natural state, thereby affording the local community a multitude of ecological and recreational benefits. Typically, around 50% of the development area is a proposed subdivision is preserved in conservation design methodology.
- Preserves significant natural features and open space to improve views and aesthetics.
- Can lead to an increase in property value.
- Helps minimize the changes in runoff volumes, rates, and water quality typically associated with urban development, while at the same time providing site drainage and water quality functions.
LID is a comprehensive land planning and engineering design approach with a goal of maintaining and enhancing the pre-development hydrologic regime of urban and developing watersheds. LID is focused on achieving a hydrological functionality that mimics the natural, dynamic state. It emphasizes cost-effective, lot level strategies that aim to address runoff issues as close to the source as possible. LID strategies often try to reduce runoff volume by infiltrating stormwater to groundwater. This can be done by installing rain gardens, rain barrels, porous pavement, bioswales, green roof, etc.
Additional LID benefits include improved wildlife habitat, energy savings, smog reduction, enhanced wetlands protection, enhanced property values, thermal pollution reduction and decreased flooding. LID is simple and effective, economical, and flexible for a variety of environments and developing situations.