Scope 3 Category 5: Operational Waste
Category 5 covers the GHG emissions from the treatment and disposal of waste generated in your own operations — landfill gas, incineration emissions, and the energy used in waste processing. It is typically a small-to-medium Scope 3 category but one where the data already exists in waste contractor invoices.
Category 5 covers the GHG emissions from the treatment and disposal of waste generated in your own operations — landfill gas, incineration emissions, and the energy used in waste processing. Category 5 covers emissions from the treatment and disposal of solid waste and wastewater generated in the reporting company's operations — in facilities not owned or operated by the reporting company.
What Category 5 covers and how emissions are generated
Category 5 covers emissions from the treatment and disposal of solid waste and wastewater generated in the reporting company's operations — in facilities not owned or operated by the reporting company.
Waste generated in your own operations (offices, factories, warehouses) that is collected by waste contractors and treated at third-party facilities is Category 5. Waste treatment at facilities you own and operate is Scope 1 (direct emissions from the treatment process).
How waste generates GHG emissions:
Landfill: organic waste (food waste, paper, wood) decomposes anaerobically in landfill, producing methane (CH4) — a potent GHG with GWP100 of 27.9 under IPCC AR6. Landfill gas capture systems reduce net emissions but are not universal. Landfill disposal is typically the highest-emission waste disposal route.
Incineration: combustion of waste produces CO2 from fossil-carbon materials (plastics, synthetic textiles) — biogenic carbon from organic waste is excluded from the Scope 3 figure but disclosed separately. Incineration with energy recovery (waste-to-energy) is lower net emission than incineration without recovery.
Recycling: processing of recyclable materials requires energy — aluminium recycling, paper reprocessing, plastic sorting all consume electricity. However, recycling emission factors are significantly lower than landfill — and recycling avoids the upstream emission from producing virgin materials (counted in Category 1 of the companies purchasing recycled content).
Composting and anaerobic digestion: organic waste composted produces small amounts of CO2 and N2O; AD produces biogas (methane captured for energy). Both are lower-emission than landfill for organic waste.
Calculating Category 5 emissions
The calculation approach for Category 5:
Weight-based: mass of waste by type (tonnes) × waste-type-specific emission factor by disposal method (kg CO2e per tonne) = kg CO2e.
Emission factors by waste type and disposal route (approximate, DEFRA 2025 basis): Mixed municipal waste to landfill: 0.45–0.55 kg CO2e/kg Food waste to landfill: 0.60–0.70 kg CO2e/kg (high CH4) Food waste to anaerobic digestion: 0.01–0.03 kg CO2e/kg Paper to landfill: 0.40–0.50 kg CO2e/kg Paper to recycling: 0.02–0.05 kg CO2e/kg Plastic to incineration: 0.08–0.12 kg CO2e/kg (fossil carbon only) Metal to recycling: 0.005–0.02 kg CO2e/kg
Data sources: waste management contractor invoices (which specify waste type and weight collected); waste transfer notes (legally required in many jurisdictions — specify waste type and disposal route); and environmental management system waste logs.
For wastewater: Category 5 includes the emissions from treatment of wastewater generated in your operations at third-party treatment facilities. Use DEFRA wastewater treatment emission factors (kg CO2e per m³ treated) applied to wastewater volumes discharged to sewer.
Category 5 reduction — waste hierarchy in practice
The waste hierarchy — prevent, reuse, recycle, recover, dispose — is the strategic framework for Category 5 reduction. Moving waste up the hierarchy reduces both the volume of waste and the emission intensity per tonne.
Prevention: reducing waste generation at source is the most effective Category 5 strategy. For food manufacturers, reducing production waste reduces both Category 5 and the upstream Category 1 footprint of the wasted inputs. Lean manufacturing and food waste prevention programmes directly reduce Category 5.
Diversion from landfill: for companies currently landfilling significant volumes of recyclable or compostable waste, diversion to recycling or anaerobic digestion can reduce Category 5 by 80–90% for those waste streams. Set a landfill diversion target and track progress annually.
For ESRS disclosure: Category 5 reduction should be linked to both ESRS E1-3 (climate action) and ESRS E5 (circular economy). The same waste reduction programme reduces Scope 3 emissions (E1 disclosure) and improves circular economy metrics (E5 disclosure). Collect data once, report to both standards.
Frequently asked questions
Do we include construction waste from office fit-outs in Category 5?
Construction and demolition waste from renovation, fit-out, or decommissioning of your facilities is Category 5. It can be significant — a major office renovation can generate 50–100 kg of waste per m² of floor area. Obtain waste transfer notes from your construction contractors specifying weights and disposal routes.
Is wastewater treatment always Category 5?
Wastewater discharged to the public sewer and treated at a third-party treatment works is Category 5. Wastewater treated in your own on-site treatment plant is Scope 1 (direct emissions from the treatment process). For most office-based businesses, wastewater is entirely Category 5. Industrial companies with on-site effluent treatment have a mix of Scope 1 and Category 5.
How do we account for waste that is sold as a by-product?
Waste sold to another company for use as a raw material (e.g. steel slag sold to cement producers, food processing waste sold as animal feed) transfers the end-of-life emission responsibility to the purchasing company. These material outflows are Category 5 of the company they leave and Category 1 of the company that purchases them. Disclose the methodology for handling by-product waste in your Category 5 methodology note.