Lawn & Garden Equipment

Material Composition Assumptions

The default bill of materials represents a walk-behind rotary lawn mower (approximately 25 kg total weight), the most common lawn care power equipment unit globally by unit volume. Riding mowers and zero-turn units are addressed in methodology notes.

Steel components (~60–65% of total weight, ~15–16 kg):

• Mowing deck: The largest single component by weight (~8–10 kg for a standard 21-inch walk-behind). Stamped from hot-rolled sheet steel (2.5–3.0 mm gauge for residential; 4.0+ mm for commercial-grade). Emission factor for hot-rolled steel ~1.9–2.1 kgCO2e/kg (blast furnace route) or ~0.5–0.9 kgCO2e/kg (electric arc furnace, high-scrap content).
• Blade: Hardened carbon steel (~0.5–0.7 kg). Heat-treated for wear resistance; higher alloy content than deck steel. Emission factor approximately 2.5–3.5 kgCO2e/kg including heat treatment energy.
• Chassis and handlebar frame: Welded steel tube or stamped frame (~3–4 kg). Often electro-galvanised or powder-coated for corrosion resistance.
• Axles, fasteners, and hardware: Approximately 1–2 kg of mixed steel components.
• Powder coat and paint: 50–150 g of coating applied electrostatically. Emission factor for powder coat application approximately 1.5–2.5 kgCO2e/kg of coating; primer and base coat included.

Engine (~5–7 kg for a typical 140–190cc single-cylinder OHV engine):

• Cast iron cylinder block (traditional) or aluminium block (modern): The largest engine component by mass. Traditional cast iron: ~3–4 kg, emission factor ~1.8–2.5 kgCO2e/kg for grey cast iron including melting and casting. Modern aluminium block: ~1.5–2.5 kg, emission factor ~8–12 kgCO2e/kg primary or ~1.5–2.0 kgCO2e/kg recycled.
• Aluminium cylinder head: ~0.8–1.2 kg, die-cast; same emission factor as aluminium above.
• Steel crankshaft, connecting rod, and camshaft: Forged steel components; ~0.5–1.0 kg combined. Emission factor approximately 2.5–3.5 kgCO2e/kg including forging and heat treatment.
• Carburettor, ignition system, and air filter assembly: Small components (~0.3–0.5 kg combined) with varied material content (aluminium, steel, plastics, rubber, copper windings).
• Engine oil (factory fill): ~0.4–0.6 litres; petroleum-derived, approximately 0.5–0.8 kgCO2e/kg.

Plastic components (~10–15% of weight, ~2.5–3.5 kg):

• Engine hood/shroud and top cover: High-impact polypropylene (PP) or ABS; ~0.8–1.2 kg. Emission factor ~2.0–2.5 kgCO2e/kg for PP.
• Fuel tank: HDPE blow-moulded; ~0.2–0.4 kg. Emission factor ~1.9–2.2 kgCO2e/kg.
• Grass catcher bag: Polypropylene mesh or fabric; ~0.4–0.8 kg.
• Handle grips, control levers, and trim components: PP and ABS; ~0.5–1.0 kg combined.

Wheels and tyres (~1.5–2.5 kg):

• Wheels: Polypropylene hub with steel axle interface; ~0.4–0.8 kg total.
• Tyres: Natural rubber and synthetic rubber compound; ~0.3–0.5 kg per wheel. Natural rubber ~2.0–3.0 kgCO2e/kg; synthetic rubber ~3.0–4.0 kgCO2e/kg.

Battery-electric mower variant note: Battery-electric walk-behind mowers (increasingly common in the 2020s) substitute the petrol engine (~6 kg) with a brushless DC motor (~1.5 kg) and lithium-ion battery pack (~3–5 kg at 40–80V, 4–7 Ah). The battery pack adds approximately 20–40 kgCO2e to the manufacturing footprint but eliminates ongoing petrol engine exhaust emissions in use. Net lifecycle comparison is favourable for battery-electric in low-carbon-grid contexts.

Manufacturing Geography

Lawn and garden equipment manufacturing is distributed across North America, Europe, and East Asia:

• USA: The largest market and significant domestic producer. Major brands — Toro, Husqvarna North America, Ariens, Deere & Company — operate assembly facilities in the USA (Wisconsin, Minnesota, Missouri, Tennessee). Grid intensity ~390 gCO2e/kWh. Steel and aluminium components often sourced from domestic or Canadian suppliers; engines sourced from Briggs & Stratton (USA), Honda (Japan/USA), Kawasaki (Japan), or Kohler (USA).
• EU: Significant production in Sweden (Husqvarna), Germany (STIHL, Bosch Garden), France, and Italy for European markets. Grid intensity ~300 gCO2e/kWh. EU production benefits from lower grid intensity and established steel supply chains (ArcelorMittal, Thyssenkrupp EAF routes with growing green steel supply).
• Japan: Honda, Kawasaki, and Kubota manufacture engines and equipment domestically for global export. Grid intensity ~450 gCO2e/kWh. Japanese production is known for high manufacturing quality and precision machining.
• China: Growing production base for entry-level and private-label equipment. Grid intensity ~565 gCO2e/kWh. Chinese production serves cost-sensitive market segments; brands include Loncin, Lifan, and OEM production for Western brands.

Engine manufacturing (whether in-house or outsourced) is the highest-precision and most energy-intensive sub-process, involving casting, machining, heat treatment, and assembly operations. Engine manufacture alone contributes approximately 15–25 kgCO2e per engine unit.

Regional Variation

Region	Grid Intensity	Estimated Score Adjustment
USA (default blend)	~390 gCO2e/kWh	Baseline
EU production	~300 gCO2e/kWh	-7% on Scope 2 (saves ~0.56 kgCO2e)
Japan	~450 gCO2e/kWh	+4% on Scope 2 (adds ~0.32 kgCO2e)
China	~565 gCO2e/kWh	+11% on Scope 2 (adds ~0.88 kgCO2e)
EU (green steel, renewable grid)	~30 gCO2e/kWh	-20% total (saves ~11 kgCO2e)

Note: Scope 2 (assembly electricity) accounts for approximately 14.5% of total footprint. The dominant driver is Scope 3 — steel (~38%), engine components (~22%), and aluminium castings (~14%). The steel production route (blast furnace vs. electric arc furnace) has a larger effect on total emissions than manufacturing country grid intensity. A unit made entirely from EAF steel with high scrap content could reduce the steel contribution by approximately 50–65%, saving ~10–14 kgCO2e per unit.

Provenance Override Guidance

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

1. Product-level lifecycle assessment (LCA) per ISO 14040/14044 or product carbon footprint (PCF) per ISO 14067, covering the specific equipment SKU from material extraction through manufacturing gate. OPEI provides industry LCA guidance and aggregate data; product-specific verified PCFs are preferred.
2. Steel supply chain data — mill-level emission factor per tonne of steel, specifying production route (BF/BOF or EAF), scrap content percentage, and grid intensity at the steel mill. WorldSteel’s EPD programme provides standardised mill-level data from member companies.
3. Engine manufacturer emission factor — supplier-declared manufacturing carbon footprint per engine unit or per kg of engine weight, covering casting, machining, assembly, and test operations. Available from major engine OEMs (Briggs & Stratton, Honda, Kawasaki, Kohler).
4. Aluminium sourcing documentation — primary vs. secondary aluminium percentage with verified emission factors. ASI (Aluminium Stewardship Initiative) certified aluminium provides chain-of-custody and emission factor data.
5. Renewable energy certificates (RECs) for assembly plant and paint/coating line operations.
6. Battery-electric variant battery chemistry data — cell chemistry (LFP vs. NMC), cell manufacturer emission factor, and pack-level energy density for battery-electric equipment variants.

Methodology Notes

• CCI score of 55.0 kgCO2e represents a conservative mid-range estimate for a standard 25 kg walk-behind rotary mower with a petrol engine (~140–190cc), manufactured in the USA or EU. OPEI industry data supports a range of approximately 40–75 kgCO2e at manufacturing gate, depending on steel sourcing, engine size, and aluminium content. This is consistent with the per-kg score of 2.2 kgCO2e/kg.
• Scope breakdown: Scope 3 dominates at ~82% (45.0 kgCO2e), driven by steel (~38%), engine components (~22%), and aluminium castings (~14%). Scope 2 (assembly line electricity, painting operations) accounts for ~15% (8.0 kgCO2e). Scope 1 (direct machining heat, weld station energy) accounts for ~4% (2.0 kgCO2e).
• Functional unit: One walk-behind rotary lawn mower, approximately 25 kg including engine, deck, handle, and catcher — cradle-to-gate. Fuel consumption, maintenance, and end-of-life are excluded from the CCI score; these are significant in the total lifecycle for petrol-powered equipment.
• Medium confidence rating reflects the availability of OPEI industry guidance and Ecoinvent datasets for constituent materials, partially offset by wide variation in equipment specifications (engine size, deck dimensions, self-propulsion), opacity around engine manufacturer emission factors, and limited publicly verified product-level EPDs from major brands.
• Riding mower and zero-turn units: Riding mowers (100–250 kg) and zero-turn units (150–300 kg) scale approximately linearly by mass — expect 200–600 kgCO2e at manufacturing gate. Battery-electric riding mowers add substantial battery pack mass (~30–80 kg of lithium-ion cells) but eliminate exhaust emissions.
• Use-phase emissions: A petrol walk-behind mower consuming ~0.3–0.5 litres/hour produces approximately 0.7–1.2 kgCO2e/hour of exhaust emissions. Over a 10-year product life at 50 hours/season, this adds approximately 350–600 kgCO2e — 6–10x the manufacturing footprint. This CCI score captures only manufacturing embodied carbon; the use-phase disparity between petrol and battery-electric equipment is the dominant lifecycle consideration.
• Battery-electric transition: The industry is undergoing rapid electrification driven by CARB regulations restricting small off-road engines in California (phased implementation 2024–2028) and similar EU initiatives. Battery-electric mowers have higher manufacturing footprints (~65–90 kgCO2e depending on battery size) but dramatically lower total lifecycle emissions in low-carbon-grid contexts.