Sustainable Design

Integrate sustainability into a design: strategy selection, certification pathways (LEED / BREEAM / Passive House / Living Building Challenge), and performance evaluation. Works at concept stage (massing, orientation) and design development (envelope, systems).

When to use

• "Make this building more sustainable" — at any stage
• Planning a LEED/BREEAM certification and choosing credits
• Reviewing a passive solar / massing / glazing strategy
• Checking a design against a net-zero or Passive House target

Workflow

1. Clarify goals: certification target (and level), climate zone, budget, site constraints. Certification credits have performance requirements — target them from the start, not after design.
2. Site & massing first (cheapest wins):
   • Orientation for passive solar: glazing-weighted facades face equator, minimize east/west exposure
   • Solar shading tuned to latitude (fixed overhang geometry for cooling vs. heating)
   • Compact massing to reduce envelope area / volume ratio
   • Daylighting: perimeter depth, glazing height, light shelves, skylights, SDA/ASE analysis
3. Envelope (biggest operational lever):
   • U-values/R-values per IECC climate zone or Passive House targets (PHI: U ≤ 0.15 W/m²K typical for walls)
   • Glazing: U-factor, SHGC, VLT, solar heat gain control, low-E coatings, triple glazing in cold climates
   • Airtightness (PHI: ≤ 0.6 ACH@50Pa; commercial often target ≤ 1.0)
   • Thermal bridge free detailing (continuous insulation, balcony breaks)
4. Systems: efficient HVAC (VRF, heat pumps, ERV/HRV with ≥75% efficiency), LED lighting + controls, water efficiency (low-flow fixtures, dual-flush), on-site renewables (solar PV sizing).
5. Certification pathway — see references/certification-credits.md for LEED v4.1 and BREEAM; choose achievable credits and track them in a credit scorecard.
6. Report: recommendations with expected impact (savings %, certification points, cost signals), prioritized by effort.

Output format

Sustainable Design Review — L2 office, climate zone 5
Priority  Recommendations                        Impact        Effort
1        South facade 40% WWR, fixed overhangs    ~8% cooling   Low
2        Triple glazing U-0.20                     ~6% heating   Med
3        Airtightness target 0.8 ACH@50Pa          ~9% heating   Med
4        ERV 85% eff.                             ~12% HVAC     Med
5        PV 200 kW → ~35% on-site                 offset        High
LEED v4.1 scorecard: 42 pts projected (Silver) — close with daylighting + renewables

Edge cases & cautions

• Climate zone matters — a strategy correct in Miami is wrong in Minneapolis. Use IECC climate zones as the baseline and adjust.
• Don't oversell: expected savings are estimates; state assumptions (occupancy, hours, utility rates) so they can be challenged.
• Certification credits are complex — a table of "points possible" without documentation of the prerequisite requirements misleads; distinguish prerequisites (mandatory) from credits.
• Embodied vs operational carbon: mention both; an all-electric building with low-carbon concrete is the current best practice direction, but don't treat any single metric as definitive.
• Codes interact: energy code (IECC/ASHRAE 90.1) minimums are floors; Passive House is a stretch target — say which you're designing to.

Files

• references/certification-credits.md — LEED v4.1 / BREEAM / Passive House credit map.
• references/strategy-library.md — strategy catalog by climate zone and cost band.