4.1 SITES v2 & LEED Site Credit Rating Systems

Core Focus: Sustainable site design integrates natural ecological processes with built infrastructure to restore degraded ecosystems, conserve finite resources, and enhance community health. Candidates preparing for LARE Section 2 must master the Sustainable SITES Initiative (SITES v2) rating framework, contrast LEED v4.1 site credits (such as Rainwater Management, Heat Island Reduction, and BUG lighting metrics), analyze Life-Cycle Assessments (LCA) and embodied carbon in landscape materials, and apply ecosystem service valuation to site planning.

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1. The Sustainable SITES Initiative (SITES v2) Rating System

The Sustainable SITES Initiative (SITES v2) is the premier comprehensive rating system for creating and certifying sustainable land design, development, and management. Developed through a collaborative partnership between the Lady Bird Johnson Wildflower Center at The University of Texas at Austin, the American Society of Landscape Architects (ASLA), and the United States Botanic Garden, SITES is administered by Green Business Certification Inc. (GBCI).

Unlike building-centric rating systems, SITES applies to landscapes with or without buildings. Eligible project types include urban civic parks, public plazas, corporate campuses, streetscapes, botanical gardens, commercial developments, residential communities, and ecological restoration sites.

SITES v2 Rating System Architecture (200 Total Base Points)
┌────────────────────────────────────────────────────────────────────────┐
│ Section 1: Context (P1.1, C1.2–C1.4)                                  │
│ Section 2: Pre-Design Assessment + Planning (P2.1–P2.3, C2.4–C2.6)     │
│ Section 3: Water (P3.1–P3.2, C3.3–C3.6)                               │
│ Section 4: Soil + Vegetation (P4.1–P4.3, C4.4–C4.11)                  │
│ Section 5: Materials (P5.1, C5.2–C5.10)                               │
│ Section 6: Human Health + Well-Being (P6.1, C6.2–C6.11)               │
│ Section 7: Construction (P7.1–P7.3, C7.4)                             │
│ Section 8: Operations + Maintenance (P8.1, C8.2–C8.5)                 │
│ Section 9: Education + Performance Monitoring (C9.1–C9.2)             │
│ Section 10: Innovation or Exemplary Performance (C10.1)                │
└────────────────────────────────────────────────────────────────────────┘

The 10 Credit Sections & Mandatory Prerequisites

SITES v2 is structured across 10 sections containing 18 mandatory prerequisites and a cumulative 200 possible base points. Prerequisites carry zero point value but must be satisfied 100% for a project to be eligible for certification:

1. Section 1: Site Context
   • Prerequisite 1.1: Protect floodplain functions — Requires avoiding development within the 100-year floodplain (1% annual exceedance probability) or restoring degraded floodplain functions.
   • Credits 1.2–1.4: Brownfield redevelopment, connecting to multi-modal transit networks, and preserving prime farmland and critical wetlands.
2. Section 2: Pre-Design Assessment + Planning
   • Prerequisite 2.1: Use an integrative design process — Mandates assembling a multidisciplinary team (landscape architects, civil engineers, hydrologists, ecologists, soil scientists, community stakeholders) at project kickoff.
   • Prerequisite 2.2: Conduct a pre-design site assessment — Requires documenting baseline hydrology, soils, vegetation, climate, and cultural resources.
   • Prerequisite 2.3: Designate vegetation and soil protection zones (VSPZ) — Demarcates protected natural areas prior to any construction staging or grading.
3. Section 3: Site Design — Water
   • Prerequisite 3.1: Preserve water resources & design water features to conserve water — Bans the use of potable water in decorative water features after initial filling.
   • Prerequisite 3.2: Manage stormwater on site — Mandates retaining the 60th percentile precipitation event using Low Impact Development (LID) green infrastructure.
   • Credits 3.3–3.6: Managing 80th to 95th percentile events, designing restorative stormwater conveyance, using non-potable water for 100% of landscape irrigation.
4. Section 4: Site Design — Soil + Vegetation
   • Prerequisite 4.1: Create and communicate a soil management plan — Documents topsoil salvaging, compaction avoidance, and post-construction organic amendments.
   • Prerequisite 4.2: Control and manage invasive plants — Mandates identifying and eradicating state- and federally listed invasive species across the site.
   • Prerequisite 4.3: Use appropriate, non-invasive plants — Prohibits introducing invasive plants; requires plants adapted to site microclimates.
   • Credits 4.4–4.11: Preserving native plant communities, conserving water through drought-tolerant palettes, supporting pollinator habitat, enhancing biomass density index.
5. Section 5: Site Design — Materials Selection
   • Prerequisite 5.1: Eliminate use of wood from threatened species — Prohibits CITES-listed endangered timber species unless salvaged or FSC-certified.
   • Credits 5.2–5.10: Specifying Environmental Product Declarations (EPDs), utilizing salvaged materials, sourcing local/regional materials within 500 miles (800 km), reducing embodied carbon in concrete and masonry.
6. Section 6: Site Design — Human Health + Well-Being
   • Prerequisite 6.1: Protect and maintain cultural and historical places — Identifies and preserves cultural resources per national/state historic preservation registers.
   • Credits 6.2–6.11: Providing outdoor physical activity amenities, mental restoration spaces, community food production (urban agriculture), universal accessibility exceeding ADA minimums, visual access to nature.
7. Section 7: Construction
   • Prerequisite 7.1: Control and retain construction pollutants — Implementing Stormwater Pollution Prevention Plans (SWPPP) and sediment erosion barriers.
   • Prerequisite 7.2: Restore soils disturbed during construction — Decompacting subgrades to a minimum depth of 12 inches and incorporating organic compost.
   • Prerequisite 7.3: Protect air quality during construction — Fugitive dust suppression and limiting equipment engine idling.
8. Section 8: Operations + Maintenance
   • Prerequisite 8.1: Plan for sustainable site maintenance — Developing an operations manual detailing organic turf care, non-chemical weed control, and pruning regimes.
   • Credits 8.2–8.5: Diverting 100% of organic landscape waste from landfills through on-site composting, eliminating toxic chemical pesticides, using zero-emission maintenance equipment.
9. Section 9: Education + Performance Monitoring
   • Credits 9.1–9.2: Installing educational interpretive signage and conducting post-occupancy environmental performance monitoring (soil respiration, infiltration rates, pollinator counts).
10. Section 10: Innovation or Exemplary Performance
    • Credit 10.1: Exceptional performance exceeding standard credit thresholds or piloting innovative ecological technologies.

SITES v2 Certification Tiers

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2. LEED v4.1 BD+C & Neighborhood Development (ND) Site Credits

While SITES addresses the entire horizontal landscape, the LEED (Leadership in Energy and Environmental Design) v4.1 rating system integrates building envelopes with immediate site surroundings. In LEED BD+C (Building Design and Construction) and LEED ND (Neighborhood Development), the Sustainable Sites (SS) category contains several credits directly authored and coordinated by landscape architects.

Rainwater Management (SS Credit)

The primary objective is reducing runoff volume and replicating natural site hydrologic balance using Low Impact Development (LID) and green infrastructure (bioretention, permeable pavers, bioswales, green roofs, rainwater cisterns):

• Path 1: Percentile Rainfall Events (1–3 points): Retain on site (through infiltration, evapotranspiration, or rainwater harvesting) the runoff volume generated by the 80th, 85th, or 90th percentile 24-hour regional rainfall event.
• Path 2: Natural Land Cover Conditions (3 points): Manage the difference between pre-development natural land cover runoff volume and post-development runoff volume for the 95th percentile event.

Heat Island Reduction (SS Credit)

Urban heat islands elevate ambient temperatures, degrading air quality and increasing building cooling loads. LEED v4.1 mandates treating non-roof hardscapes and building roofs:

1. Non-Roof Hardscape Mitigation: At least 50% of the non-roof site hardscape (walkways, plazas, surface parking lots, driveways) must satisfy one or a combination of the following:
   • Reflective Pavements: Materials achieving an initial Solar Reflectance Index (SRI) ≥ 33 (or 3-year aged SRI ≥ 28).
   • Canopy Shading: Shading provided by existing or newly planted trees projected within 10 years of planting.
   • Architectural Shading: Shading structures covered by solar photovoltaic panels or high-reflectance materials (initial SRI ≥ 39).
   • Permeable Pavements: Open-grid permeable pavements (at least 50% pervious area).
2. Roof Hardscape Mitigation:
   • Low-Sloped Roofs (≤ 2:12 pitch): Initial SRI ≥ 82 (or 3-year aged SRI ≥ 64).
   • Steep-Sloped Roofs (> 2:12 pitch): Initial SRI ≥ 39 (or 3-year aged SRI ≥ 32).
   • Vegetated Roofs: Extensive or intensive green roofs covering at least 50% of the roof surface.

Light Pollution Reduction & The BUG Rating System (SS Credit)

LEED v4.1 and SITES mandate eliminating light trespass, nocturnal sky glow, and high-angle glare to protect migratory birds, nocturnal pollinators, and dark skies. The outdated luminaire classification system (cutoff, semi-cutoff, non-cutoff) has been fully replaced by the IES TM-15-11 BUG Rating System:

IES TM-15-11 BUG Rating Geometric Distribution
                 90° - 180° = UPLIGHT (U)
                       ▲
                 ┌─────┴─────┐
   60° - 90°     │ Luminaire │     60° - 90°
  FORWARD GLARE  │  Housing  │   BACKLIGHT (B)
     (G)         └─────┬─────┘   Light Trespass
                       ▼
                  0° - 60° = Downward Useful Task Light

• B (Backlight): Light emitted behind the luminaire toward the property boundary, causing light trespass onto adjacent properties.
• U (Uplight): Light emitted upward above 90° horizontal into the night sky, causing atmospheric sky glow. Luminaires in pristine dark-sky zones must have a U0 rating (zero uplight).
• G (Glare): High-angle light emitted between 60° and 90° in forward zones that causes visual impairment, disability glare, or blinding contrast for motorists and pedestrians.

Compliance is evaluated against established Exterior Lighting Zones (LZ0 to LZ4) established by the Illuminating Engineering Society (IES) and International Dark-Sky Association (IDA):

• LZ0 (Pristine): Wilderness areas, national parks, wildlife preserves. Uplight must be strictly U0.
• LZ1 (Low): Rural residential areas, nature reserves.
• LZ2 (Moderate): Suburban commercial and light industrial zones.
• LZ3 (Moderately High): Urban commercial and high-density residential districts.
• LZ4 (High): Major metropolitan entertainment districts, transit hubs (e.g., Times Square).

Protect or Restore Habitat & Open Space (SS Credits)

• Protect Habitat: Preserve at least 40% of greenfield site area from all construction activity and vehicle traffic.
• Restore Habitat: On previously developed (brownfield or grayfield) sites, restore at least 30% of the total site area (excluding building footprint) using native or adapted vegetation providing layered ecological canopy, understory, and herbaceous stratigraphy.
• Open Space: Provide outdoor open space equal to or greater than 30% of total site area (including building footprint), with at least 25% of that open space vegetated.

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