life-cycle-assessment

name	life-cycle-assessment
description	Life cycle assessment (LCA) — ISO 14040/14044, system boundary, functional unit, inventory analysis, impact categories (GWP, AP, EP), carbon footprint, eco-design, EPD.
metadata	{"priority":7,"promptSignals":{"phrases":["life cycle assessment","LCA","carbon footprint","global warming potential","GWP","environmental impact","eco-design","cradle to grave"],"minScore":3}}

Life Cycle Assessment (LCA) — Complete Skill

LCA Framework (ISO 14040/14044)

Four Phases

1. Goal and Scope definition: purpose, functional unit, system boundary, assumptions
2. Life Cycle Inventory (LCI): data collection — all inputs (energy, materials) and outputs (emissions, waste)
3. Life Cycle Impact Assessment (LCIA): translate inventory into environmental impact scores
4. Interpretation: identify hotspots, sensitivity analysis, conclusions

Functional Unit

Standardizes comparison: e.g., "1 tonne of steel delivered to customer" or "1 passenger-km of transportation" Must be consistent across compared systems

System Boundaries

Cradle-to-gate: raw material extraction to factory gate (excludes use + disposal) Cradle-to-grave: includes use phase and end-of-life Cradle-to-cradle: closed loop; recycling brings material back Gate-to-gate: process-specific; component manufacturing only

Life Cycle Stages

1. Raw material extraction: mining, farming, forestry
2. Material processing: refining, alloying, purification
3. Manufacturing: machining, welding, assembly, surface treatment
4. Transport (logistics): all transportation throughout supply chain
5. Use phase: energy consumption in operation, consumables
6. End-of-life: recycling, landfill, incineration, reuse

Impact Categories (Midpoint)

Category	Abbreviation	Unit	Example contributor
Global Warming Potential	GWP	kg CO₂-eq	Combustion, CH₄
Acidification Potential	AP	kg SO₂-eq	SO₂, NOx emissions
Eutrophication Potential	EP	kg PO₄³⁻-eq	N, P to water
Photochemical Ozone Creation	POCP	kg C₂H₄-eq	VOCs, NOx
Ozone Depletion	ODP	kg CFC-11-eq	Refrigerants
Resource Depletion (fossil)	ADP_fossil	MJ	Fuel combustion
Human Toxicity	HTP	kg 1,4-DCB-eq	Heavy metals, chem
Land Use	—	m² yr	Agriculture, mining

Characterization factors: convert specific substance emissions to impact category units From IPCC, EDIP, ReCiPe, CML methodologies

Carbon Footprint (GWP100)

Most common LCA metric; Global Warming Potential over 100-year horizon

GWP100 characterization factors (IPCC AR5): CO₂: 1 kg CO₂-eq/kg CH₄ (biogenic): 28 kg CO₂-eq/kg CH₄ (fossil): 36 kg CO₂-eq/kg N₂O: 265 kg CO₂-eq/kg HFC-134a: 1430 kg CO₂-eq/kg SF₆: 23,500 kg CO₂-eq/kg

Material carbon footprints (typical, kg CO₂-eq/kg): Primary steel: ~2.0; Recycled steel: ~0.4 Primary aluminum: ~11–16; Recycled Al: ~0.6–1.5 CFRP: ~20–35 (energy-intensive fiber production) Concrete: ~0.1–0.2 (but high volumes) Plastic (HDPE): ~2.0; ABS: ~3.5

LCI Data Sources

Databases: ecoinvent: gold standard; Swiss; 18,000+ datasets; commercial license GaBi (Sphera): industry-oriented; North America, Europe ELCD (European Commission): free; basic processes EPD (Environmental Product Declaration): verified manufacturer LCA data

Primary data: measured from specific processes (preferred for foreground) Secondary data: from databases (background system; upstream)

Energy Carbon Intensity (Electricity)

GWP of electricity varies by grid mix:

Grid	kg CO₂-eq/kWh
Norway (hydro)	0.017
France (nuclear)	0.056
EU average	0.275
US average	0.390
Germany	0.366
India	0.710
Coal-dominated	0.9–1.0

Use regional grid data for operational phase calculations

LCIA Methods

ReCiPe 2016: comprehensive; hierarchist perspective; midpoint + endpoint CML 2002: established European; conservative; midpoint only TRACI 2.1: North American; EPA; different impact categories ILCD: EU preferred; harmonized

Eco-Design Principles

Identify hotspots → redesign for lower impact: Material selection: lower embodied carbon (e.g., bio-based, recycled content) Weight reduction: less material use; lower use-phase energy (automotive, aerospace) Design for disassembly: separable components → higher recycling rate Energy efficiency (use phase): often dominates for appliances, vehicles End-of-life design: single materials, marked polymers, no hazardous coatings

Sensitivity and Uncertainty

Foreground data variation: ±10–30% typical Background data: ±20–50% Impact characterization: ±10–40% Total GWP uncertainty: factor of 1.5–3× typical for product LCA

Environmental Product Declaration (EPD)

Verified third-party LCA disclosure; PCR (Product Category Rules) define scope ISO 21930 (construction); ISO 14025 (general EPD) Used in: green building certification (LEED, BREEAM); procurement requirements

Output

Provide: functional unit, system boundary, GWP per functional unit [kg CO₂-eq], top three impact category results (with units), life stage breakdown (% contribution from manufacturing/use/EoL), key hotspots, eco-design recommendation, EPD applicability.