Headphones & Earbuds

Material Composition Assumptions

The default bill of materials represents a pair of true wireless stereo (TWS) earbuds with a charging case (approximately 60 g combined for earbuds; charging case adds a further 40–50 g). A second reference product is an over-ear noise-cancelling headphone (approximately 250–300 g). The default CCI score of 8 kgCO2e applies to TWS earbuds; over-ear models score approximately 20–30 kgCO2e.

For TWS earbuds (~60 g per pair), the approximate bill of materials is:

• Bluetooth SoC and codec chip: Custom or off-the-shelf wireless SoC (e.g., Apple H2, Qualcomm S3), signal processor — approximately 0.5–1 g by mass, but high emission intensity due to semiconductor fabrication
• Battery cells: One small lithium-ion cell per earbud plus a larger cell in the charging case — approximately 10–15 g total across system
• Speaker drivers: One balanced armature or dynamic driver per earbud, wound voice coil, rare-earth magnet (neodymium) — approximately 5–8 g per pair
• PCB and passive components: Multi-layer board with surface-mount passives, microphones, touch sensors — approximately 5–6 g per pair
• Plastic enclosure: ABS or polycarbonate injection-moulded shells — approximately 20–25 g per pair
• Ear tips and accessories: Silicone ear tips, cable (wired models), documentation — approximately 5–10 g
• Charging case: Plastic shell, USB-C port, battery, PCB — approximately 40–50 g additional

For over-ear headphones (~250–300 g), the bill of materials is heavier but semiconductor content is lower as a proportion of total mass. The over-ear category typically uses larger dynamic drivers (40–50 mm), more substantial plastic/metal headband and cup construction, larger batteries for ANC, and is associated with longer use lifetimes (3–5 years vs. 2–3 years for TWS earbuds), which reduces per-use-year emissions.

The Bluetooth SoC is the most carbon-intensive component per gram. While the chip may weigh less than 1 g, it is manufactured on an advanced semiconductor process node (22–45 nm typical for audio SoCs), requiring significant fabrication energy per die.

Manufacturing Geography

The default manufacturing region is China, with some final assembly in Vietnam for brands shifting supply chains post-2020. Semiconductor and speaker driver component fabrication also occurs in Taiwan, South Korea, and Japan.

• China grid intensity: 565 gCO2e/kWh (IEA 2024). The majority of TWS earbud assembly (SMT board population, driver integration, enclosure assembly, acoustic tuning, QA) takes place in Guangdong province facilities.
• Vietnam grid intensity: ~490 gCO2e/kWh. An increasing share of Apple and Samsung audio accessory assembly has moved to Vietnam.
• Taiwan/Japan: Balanced armature driver manufacturing (Knowles, Sonion) and some PCB fabrication occurs in Taiwan and Japan at lower grid intensities.

The default blended estimate uses China grid intensity, which provides a conservative upper bound for Scope 2 emissions at assembly. The relatively modest Scope 2 contribution (15% of total) means grid location has a limited effect on total score — upstream component emissions dominate.

Apple manufactures AirPods primarily in Vietnam and China, and has reported that its supply chain clean energy program covers an increasing proportion of component manufacturing electricity. This is not reflected in the default conservative score.

Regional Variation

Region	Grid Intensity	Estimated Score Adjustment
China (current default)	~565 gCO2e/kWh	Baseline
Vietnam	~490 gCO2e/kWh	-13% on Scope 2 (saves ~0.16 kgCO2e)
EU assembly	~300 gCO2e/kWh	-47% on Scope 2 (saves ~0.56 kgCO2e)
India	~700 gCO2e/kWh	+24% on Scope 2 (adds ~0.29 kgCO2e)

Note: Scope 2 represents approximately 15% of total emissions. Regional variation has a limited effect on total score. The dominant driver of score variation between products is semiconductor content and the number of battery cells — premium multi-driver earbuds with advanced ANC chipsets score significantly higher than basic single-driver models.

Provenance Override Guidance

A supplier or manufacturer may override the default CCI score by submitting:

1. Product Environmental Report or Product Carbon Footprint per ISO 14067, covering the specific model and generation. Apple publishes detailed PERs for AirPods models; Sony, Bose, and Samsung publish partial environmental data.
2. SoC emission factor from the foundry or chip supplier specifying the process node and per-die cradle-to-gate carbon footprint.
3. Battery cell declaration from the cell manufacturer, specifying cell chemistry (lithium-ion polymer typical), capacity in mAh, and cradle-to-gate carbon footprint per Wh.
4. Driver unit declaration from the driver manufacturer, covering magnet material (neodymium content), voice coil, and assembly emissions.
5. Recycled content verification for enclosure plastics. High post-consumer recycled content polycarbonate reduces enclosure emissions by 50–70% versus virgin material.

Note: Published data for this category is less comprehensive than for smartphones. Apple AirPods PERs are the most detailed publicly available source. The confidence rating of “medium” reflects the relative scarcity of third-party verified data for non-Apple audio products.

Methodology Notes

• CCI score of 8 kgCO2e represents a mid-range estimate for a pair of TWS earbuds with charging case, consistent with a product similar to second-generation AirPods (Apple reports ~14 kgCO2e for AirPods 3rd gen including case). The lower default reflects simpler non-ANC configurations without active noise cancellation chipsets. ANC models with custom SoCs score 12–22 kgCO2e.
• Scope breakdown: Scope 3 dominates at 84% (6.7 kgCO2e), driven primarily by Bluetooth SoC fabrication (25%), batteries (20%), and drivers (20%). Scope 2 (assembly electricity) is 15% (1.2 kgCO2e). Scope 1 (direct process emissions) is minimal at ~1% (0.1 kgCO2e).
• Functional unit: One pair of TWS earbuds with charging case, cradle-to-gate. Use-phase and end-of-life excluded.
• Category range: Budget wired earbuds score approximately 1–3 kgCO2e. Mid-range TWS earbuds score 5–12 kgCO2e. Premium ANC earbuds (AirPods Pro, Sony WF-1000XM5) score 15–25 kgCO2e. Over-ear headphones (Sony WH-1000XM5, Bose QuietComfort 45) score 20–35 kgCO2e.
• Use lifetime: TWS earbuds have relatively short replacement cycles (2–3 years), which reduces their per-use-year carbon advantage over wired alternatives. Wired headphones with no battery and minimal electronics may score lower and last significantly longer.
• Confidence is medium because published lifecycle data is available for Apple products but limited for the broader industry. Speaker driver and SoC emission factors carry moderate uncertainty.