Page 82 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

LEED Sustainable Sites 63

benefits humans in the form of potential medicines and other products. SSc5.1 is worth
one point in LEED 2009 and was worth one point in LEED 2.2.
USGBC Rating System
LEED-NC 2.2 lists the Intent, Requirements, and Potential Technologies and Strategies
for this credit as follows, with modifications to LEED 2009 as noted:

Intent
Conserve existing natural areas and restore damaged areas to provide habitat and promote
biodiversity.
Requirements
LEED 2009 CASE 1: On greenfield sites, limit all site disturbance to 40 feet beyond the
building perimeter; 10 feet beyond surface walkways, patios, surface parking, and utilities
less than 12 inches in diameter; 15 feet beyond primary roadway curbs and main utility
branch trenches; and 25 feet beyond constructed areas with permeable surfaces (such as
pervious paving areas, stormwater detention facilities, and playing fields) that require
additional staging areas in order to limit compaction in the constructed area.
LEED 2009 CASE 2: On previously developed or graded sites, restore or protect a minimum
of 50% of the site area (excluding the building footprint), or as additionally required in LEED
2009, a minimum of 20% of the total site area, whichever is the greater with native or adapted
vegetation. Native/adapted plants are plants indigenous to a locality or cultivars of native
plants that are adapted to the local climate and are not considered invasive species or noxious
weeds. Projects earning SS Credit 2 and using vegetated roof surfaces may apply the vegetated
roof surfaces to this calculation if the plants meet the definition of native/adapted.
Greenfield sites are those that are not developed or graded and remain in a natural state. Previously
Developed Sites are those that previously contained buildings, roadways, parking lots or were graded
or altered by direct human activities.

Potential Technologies and Strategies
On greenfield sites, perform a site survey to identify site elements and adopt a master plan for
development of the project site. Carefully site the building to minimize disruption to existing
ecosystems and design the building to minimize its footprint. Strategies include stacking the
building program, tuck-under parking and sharing facilities with neighbors. Establish clearly
marked construction boundaries to minimize disturbance of the existing site and restore
previously degraded areas to their natural state. For previously developed sites, utilize local
and regional governmental agencies, consultants, educational facilities, and native plant
societies as resources for the selection of appropriate native or adapted plant materials.
Prohibit plant materials listed as invasive or noxious weed species. Native/adapted plants
require minimal or no irrigation following establishment, do not require active maintenance
such as mowing or chemical inputs such as fertilizers, pesticides, or herbicides, and provide
habitat value and promote biodiversity through avoidance of monoculture plantings.

Calculations and Considerations
The LEED definitions for building footprint, development footprint, native (or indigenous)
plants, adapted (or introduced) plants, invasive plants, and previously developed sites are
given in App. B, and many of the symbols used to represent them are given in the Land
Area Definitions section at the beginning of this chapter.
The submittal is part of the LEED Construction Submittal since limiting construction
disturbance and protecting native areas are an important part of the construction phase.
It should be well documented throughout the construction phase that the limits of
construction (disturbance) either do not go beyond the maximum setbacks in the first
option or, for previously developed sites, do not disturb existing natural areas. For both