Environmental Impact Calculation Methodology
How Dawn calculates environmental impact — a white paper for domain experts, auditors, and third-party verifiers.
A white paper for users, domain experts, and verifiers
1. Introduction
This document explains how Dawn calculates the environmental impact of products, parts, and assemblies. It is intended for sustainability professionals, LCA practitioners, auditors, and third-party verifiers.
Dawn models a finished product as the sum of its life cycle contributions: raw materials, purchased components, manufacturing utilities, transport, packaging, use, waste, and end of life. Each contribution is calculated according to life cycle assessment (LCA) principles and assigned to a life cycle stage.
This paper covers:
- emission-factor sources and dataset selection,
- the quantity × emission-factor calculation,
- bill-of-materials (BOM) aggregation and variants,
- production and installation losses,
- transport, utilities, packaging, use, waste, and end-of-life calculations,
- location-based allocation of utilities and site waste,
- EN 15804 output flows and biogenic carbon indicators,
- assumptions, limitations, and auditability.
2. Key Concepts and Terminology
| Term | Meaning |
|---|---|
| Part | Any item in a product structure, including a purchased component, manufactured sub-part, raw material, packaging item, transport service, or utility. |
| Material | A raw material such as steel, cotton, or ABS. Materials carry per-kilogram environmental data and waste-pathway settings. |
| Material composition | A part's or packaging item's material mix, expressed as percentages that sum to 100 %. |
| Assembly / BOM | The hierarchical definition of which parts and subassemblies a product contains and in what quantities. |
| Assembly variant | A sellable configuration whose BOM differs from the assembly's base configuration. Assembly-level life cycle data is shared. |
| Core BOM | The base BOM used when no variant is selected. |
| Variant delta | A variant-specific exclusion, addition, quantity change, or production-loss change applied to the core BOM. |
| Activity / dataset | An LCA record describing the impact of producing or providing one functional unit, such as 1 kg of aluminium or 1 tonne-kilometre of freight. |
| Emission factor / impact factor | Impact per functional unit for one indicator, such as kg CO₂-eq per kg of material. |
| Impact category / indicator | A measured environmental pressure, such as climate change, acidification, or water use. |
| Functional unit | The reference quantity of a dataset, such as 1 kg, 1 kWh, or 1 tonne-kilometre. |
| Life cycle module | A calculation context mapped by the organisation to a reporting stage, such as raw materials, production, use, or end of life. |
| Production loss | Input scrapped during manufacturing, declared per BOM line. |
| Installation loss | The assembly-level share damaged or rejected during installation before use. |
| Production location | A site where an assembly or subassembly is manufactured. It may hold site utility totals, waste streams, and waste-transport routes. |
| Output allocation | The allocation of site totals among the products made at that location. |
| Annual volume | Units of an output produced at a location during the reporting period. Required for location-based per-unit allocation. |
3. Data Foundations: Where Emission Factors Come From
Dawn uses emission factors from:
- ecoinvent — Dawn makes the latest available version available and supports updates when ecoinvent releases a new version:
- Cut-off: recycled materials enter burden-free, and waste producers receive no downstream recycling credit. This is widely used in product footprinting and EPDs.
- Consequential: models the consequences of marginal demand changes. It is available to organisations that require it and is intended for expert users.
- Environmental Footprint (EF) 3.1 datasets — European Commission reference data for Product Environmental Footprint studies.
- EPD datasets (EN 15804) — verified Environmental Product Declarations used in place of generic data where appropriate.
- Custom datasets — organisation-specific data, including supplier primary data.
Each dataset contains the indicator set defined by its impact-assessment method. Dawn's default method is EF 3.1. EN 15804+A2 EPD data uses a related indicator set based on EF 3.1.
Calculations use only databases licensed to the organisation.
4. The Fundamental Calculation
For every impact indicator i:
Impact(i) = Q × EF(i)
where:
- Q is the activity quantity in the dataset's functional unit;
- EF(i) is the emission factor for indicator i per functional unit.
The same calculation is applied across the dataset's complete indicator set.
4.1 Unit conversion
User-entered quantities are converted to the dataset's functional unit before multiplication. Common conversions include:
- grams ÷ 1 000 → kilograms,
- tonnes × 1 000 → kilograms,
- MJ × 0.27778 → kWh,
- kg·km ÷ 1 000 → tonne-kilometres.
For a dataset expressed per tonne, a 2 kg quantity is calculated as 0.002 tonnes.
4.2 Headline results and inventory indicators
Dawn derives two headline results:
Carbon footprint (GWP100). The total climate-change indicator in kg CO₂-equivalents, including fossil, biogenic, and land-use components as defined by the applicable method. It is an unweighted physical result.
EF single score. A weighted aggregate of the 16 EF 3.1 impact categories:
EF single score = Σ [Impact(i) / NF(i) × WF(i)]
where NF(i) is the official EF 3.1 normalisation factor and WF(i) is the official weighting factor. The result is calculated in points (Pt) and displayed as millipoints:
mPt = Pt × 1 000
Sub-category indicators are excluded when their parent category is included. Inventory indicators are physical resource, waste, energy, or carbon-content flows rather than impact categories; they are reported separately and excluded from the single score. This inventory-versus-impact distinction applies throughout this document.
4.3 Worked example
A 0.5 kg steel bracket uses a dataset with a climate-change factor of 2.1 kg CO₂-eq/kg:
Carbon footprint = 0.5 kg × 2.1 kg CO₂-eq/kg = 1.05 kg CO₂-eq
5. Rolling Up the Product Structure
An assembly total combines:
- cradle-to-gate impacts of its parts;
- part-level modules, scaled by effective part quantity;
- assembly-level modules, applied per assembly functional unit.
Each contribution retains its indicator values, life cycle stage, source part, and source dataset.
5.1 Quantity propagation
Quantities multiply down nested BOM paths:
Effective quantity of a part
= quantity per parent × effective quantity of the parent
The assembly result is:
Impact(assembly)
= Σ [part impact per unit × effective quantity]
+ Σ [part-module impact × effective quantity of its owner]
+ Σ [assembly-module impact]
Child assemblies follow the same rule recursively. Each occurrence of a part is counted at its own effective quantity. Circular references are detected and excluded.
5.2 Production loss
Each BOM line can declare a production-loss rate L. Dawn supports two models, selected under Settings → Parts & Assemblies.
Yield model
The declared quantity represents manufacturing input:
Input quantity = declared quantity
Scrap quantity = declared quantity × L
Output quantity = declared quantity × (1 − L)
The input carries its production burden. The scrapped share is reported under Production loss and feeds production-waste treatment. Only the surviving quantity continues to downstream BOM levels and later life cycle stages:
Quantity in finished product
= Π [declared quantity at step × (1 − loss rate at step)]
Fixed BOM model
The declared quantity represents product content:
Output quantity = declared quantity
Scrap quantity = declared quantity × L
Scrap is additional, so total material burden scales as quantity × (1 + L). Product weight, downstream transport, and end-of-life mass use the full declared quantity. This is the default model.
| Yield model | Fixed BOM model | |
|---|---|---|
| BOM quantity represents | Manufacturing input | Product content |
| Downstream quantity | quantity × (1 − L) | quantity |
| Scrap | Included within input | Additional to product content |
Published snapshots retain the model used at publication. A settings change affects live calculations and new snapshots.
5.3 Weight and packaging mass
Assembly weight is rolled up from declared part weights:
Weight(assembly)
= Σ [child weight × child output quantity]
Under the Yield model, child output quantity includes the survival factor. Under the Fixed BOM model, it uses the declared quantity.
Packaging mass follows its transport context:
| Attachment | Transport treatment | Disposal treatment |
|---|---|---|
| Packaging on a part or subassembly | Added to that item's inbound shipped mass | Production-phase packaging waste |
| Packaging on the finished assembly | Added to distribution mass | Use-phase packaging waste |
Inbound shipped mass
= part weight + part-level packaging mass
Distribution mass
= assembly output weight + assembly-level packaging mass
5.4 Assembly variants
A variant changes only the BOM. Utilities, packaging, distribution, use-phase inputs, installation loss, disassembly, end-of-life settings, and declared production volume remain assembly-level inputs shared by every configuration.
The active BOM is resolved deterministically:
Resolved BOM = merge(Core BOM, Variant deltas)
Resolution starts from the core lines, applies exclusions and overrides, adds variant-only lines, and resolves each child assembly using its selected child variant or base configuration. All BOM-dependent calculations use this resolved structure, including quantity, loss, weight, material impact, production waste, and end-of-life inventory.
Each variant and the base configuration maintain separate version histories as described in Section 10.
5.5 Installation loss
Installation loss is an assembly-level percentage I applied before the use phase. It creates three contributions under Installation loss:
Installation loss total
= prior-stage impact share
+ premature end-of-life treatment and benefits
+ transport of installation waste
The successfully installed product retains its complete use-phase and post-consumer end-of-life model. Section 6.6.1 defines the calculation.
6. Life Cycle Modules
Organisations map calculation modules to their own ordered life cycle stages. This supports stage structures such as EN 15804 modules A1–A3, A4, B, C, and D.
6.1 Materials and purchased components
A part's cradle-to-gate manufacturing impact comes from one of:
- a background dataset scaled to the declared amount;
- a linked, published LCA;
- the per-kilogram datasets of Materials in its composition.
6.1.1 Materials and composition
Materials store manufacturing impact per kilogram. A part or packaging item can define a material composition whose shares sum to 100 %.
Composition serves two purposes:
- manufacturing impact when the part has no child BOM and no own dataset or linked LCA;
- material mass for waste and end-of-life calculations.
Composition impact
= part quantity × part weight × material share × EF per kg
Material mass
= part quantity in product × part weight × material share
A positive part weight is required. Missing Material data is reported as a coverage gap.
6.1.2 Manufacturing-source precedence
At each part, Dawn applies this order:
- A part with child BOM lines receives manufacturing impact from those children.
- A leaf part with its own dataset or linked LCA uses that source.
- A leaf part with composition and positive weight uses its Materials' per-kilogram data.
- A leaf part with none of these sources contributes no manufacturing impact.
Composition continues to define end-of-life mass when a part's own dataset supplies its manufacturing impact. A parent subassembly's composition can likewise describe end-of-life mass while its child BOM supplies manufacturing impact.
6.1.3 Worked example
A 0.5 kg housing contains 80 % ABS and 20 % steel. Their climate factors are 3.0 and 2.1 kg CO₂-eq/kg:
ABS: 0.5 × 80 % × 3.0 = 1.20 kg CO₂-eq
Steel: 0.5 × 20 % × 2.1 = 0.21 kg CO₂-eq
Total: 1.41 kg CO₂-eq
If the housing later receives its own LCA of 1.0 kg CO₂-eq per unit, that value supplies manufacturing impact. The 80/20 composition still supplies end-of-life mass.
6.2 Inbound transport
Supplier routes consist of transport segments with a distance and mode dataset. For each segment:
Transport work
= distance × inbound shipped mass
[kg·km converted to t·km]
Segment impact = transport work × EF of transport mode
Part-level packaging contributes mass to transport and receives its own packaging-production impact under Section 6.4.
For multiple suppliers:
Part transport impact
= Σ [supplier allocation × Σ supplier-segment impacts]
Undeclared allocations are split equally. Once any allocations are declared, entered shares are used and suppliers without a share contribute 0 %. The result scales with the part's effective BOM quantity.
6.3 Production energy and utilities
Direct and location-based utility quantities are combined under the production-utilities module.
6.3.1 Direct utilities
Utility impact = consumed amount × EF of utility dataset
Assembly utilities apply once per assembly functional unit. Part and subassembly utilities apply per item and scale with effective BOM quantity.
6.3.2 Location-based utilities
A production location can hold total utility consumption for a reporting period. Dawn allocates the total among registered outputs by volume, weight, or price, then divides each allocated total by annual output volume.
For output o, annual volume Vo, and allocation driver Do:
| Basis | Driver |
|---|---|
| Volume | V_o |
| Weight | unit weight × V_o |
| Price | unit price × V_o |
Only outputs with annual volume and a positive driver participate:
Share(o) = D_o / Σ D_j
Per-unit utility(o)
= site utility total × Share(o) / V_o
Direct and inherited quantities for the same utility are added before multiplication by the dataset factors. If an item is linked to several production locations, each location's per-unit allocation is included. A subassembly's per-unit utility then scales with its quantity in the parent BOM.
Example. A site consumes 12 000 kWh and produces 1 000 chairs and 2 000 tables under volume allocation:
Chair: (12 000 × 1/3) / 1 000 = 4 kWh/unit
Table: (12 000 × 2/3) / 2 000 = 4 kWh/unit
If a chair also has 0.2 kWh of direct electricity, its total is 4.2 kWh per unit.
6.3.3 Location-based waste streams
Location waste streams represent pooled waste not traced to a specific BOM loss. Each stream declares:
- a reporting-period amount and unit,
- a phase: production waste or end of life,
- treatment pathways whose non-benefit allocations sum to 100 %,
- optional benefit pathways,
- for production waste, an optional cradle-to-gate dataset for the discarded material,
- optional pre-treatment or waste-processing data.
The utility allocation driver and annual volume also allocate site waste:
Per-unit waste mass(o)
= stream amount × Share(o) / V_o
Pathway quantity
= per-unit waste mass(o) × pathway share
Treatment impact
= pathway quantity × EF of treatment dataset
Benefits are negative contributions tied to a source pathway:
Benefit quantity
= − per-unit waste mass × source share × benefit share
For a production-waste stream with a material-production dataset, the declared functional amount defines the stored impact per unit of waste mass:
Production impact
= per-unit waste mass × stored per-unit material-production impact
Waste processing similarly uses its declared functional amount to define impact per unit of waste mass and is applied before pathway treatment:
Processing impact
= waste mass × stored per-unit processing impact
Production-phase streams are assigned to production-waste stages; end-of-life streams are assigned to end-of-life stages.
A location may also define transport routes to waste treatment for each phase:
Transport work per segment
= distance × allocated per-unit site-waste mass
This pooled site-waste mass is distinct from BOM scrap under Section 6.5. A product can receive both when both sources exist.
6.4 Packaging
Packaging items use the same environmental-data options as other parts.
- Part or subassembly packaging contributes packaging-production impact per item, adds mass to inbound transport, and enters production-phase packaging waste.
- Finished-assembly packaging contributes impact per assembly, adds mass to distribution, and enters use-phase packaging waste.
Packaging waste is derived from packaging composition and the applicable Material waste pathways.
Packaging impact = packaging quantity × impact per packaging item
Biogenic carbon from packaging is assigned according to Section 7.1.
6.5 Production waste
Production-loss scrap is resolved into Materials and routed according to each Material's production-waste pathways. Non-benefit pathway shares must sum to 100 %:
Treatment impact
= lost material mass × pathway share × EF of treatment dataset
6.5.1 Transport of production waste
Transport work per segment
= distance × BOM lost material mass
[kg·km converted to t·km]
Transport impact
= transport work × EF of transport mode
The mass basis is lost BOM material per functional unit. Routes can be inherited from each registered production location or declared directly on an assembly or part. These routes are additive when both are configured. For multiple production locations, the full lost mass is transported on each inherited site route.
Nested losses are scaled through the resolved BOM and attributed to the entity where each loss occurs.
6.6 Distribution and use phase
Transport to the customer uses the finished assembly's distribution mass:
Distribution impact
= distance × (assembly output weight + assembly-level packaging mass)
× EF per t·km
Use-phase consumption is scaled to a declared lifetime:
Lifetime consumption
= consumption per lifetime unit × number of lifetime units
Use-phase impact = lifetime consumption × EF
Spare parts are added as use-phase part quantities. Installation and maintenance activities use the same quantity × emission-factor rule.
6.6.1 Installation loss
Installation loss requires a positive assembly rate I and a mapped installation-loss life cycle stage.
Prior-stage impact. Dawn sums stages ordered before the installation-loss stage and applies the loss rate:
Prior-stage total
= Σ impacts in stages before installation loss
Installation-loss prior share
= prior-stage total × I / 100
This share is reported in the Installation loss category and target stage. Contribution details retain the earlier stages from which it arose.
When the assembly has a declared total cost, the UI derives an indicative cost:
Prior CO₂ share = prior-stage CO₂ / total assembly CO₂
Installation-loss cost
≈ total assembly cost × prior CO₂ share × I / 100
Premature end-of-life treatment. Dawn calculates the resolved BOM's leaf-Material inventory and applies the installation-loss rate:
Installation-loss material mass
= full BOM material mass × I / 100
Treatment impact
= installation-loss material mass × pathway share × EF
Benefit
= − installation-loss material mass
× source pathway share × benefit share × EF
Material end-of-life pathways and assembly-level pathway overrides apply. Treatment and benefits are assigned to Installation loss.
Transport to waste. The assembly's end-of-life transport route is reused:
Installation waste mass
= assembly output weight × I / 100
Transport impact
= distance × installation waste mass × EF per t·km
Missing pathway or route data produces zero for that component and remains a data-coverage issue. The installed product's normal end-of-life inventory remains based on 100 % of the product functional unit.
6.7 End of life
Dawn walks the resolved BOM to leaf Materials:
Material mass at EOL
= part weight × output quantity × material share
Each Material has percentage pathway allocations; non-benefit shares must sum to 100 %. For each pathway:
EOL treatment impact
= material mass × pathway share × EF of treatment dataset
Disassembly, waste processing, and transport to treatment can be modelled before pathway treatment.
Benefits represent recovered material or energy that substitutes another activity:
EOL benefit
= − material mass × source pathway share
× benefit share × EF of substituted activity
Benefits are reported separately from gross treatment impacts.
6.8 EN 15804 output flows
EN 15804 requires EPDs to report output flows. Dawn therefore calculates and exports the applicable physical mass and energy flows from modelled waste pathways and incineration Lower Heating Value (LHV). Emission factors do not enter these calculations.
| Code | EN 15804 name | Unit | Dawn calculation |
|---|---|---|---|
| MFR | Materials for recycling | kg | Recycling mass adjusted by recycling-benefit efficiency |
| CRU | Components for re-use | kg | Mass allocated to reuse |
| MER | Materials for energy recovery | kg | Exported as 0; manual entry is required when applicable |
| EEE | Exported electrical energy | MJ | Electrical energy recovered from incineration |
| EET | Exported thermal energy | MJ | Thermal energy recovered from incineration |
Automatic mapping uses standard treatment types. Custom pathway types are excluded.
Output flows are assigned to production-waste or end-of-life output-flow stages, with the corresponding waste-pathway stage used when a dedicated output-flow stage is not mapped. Related impact credits remain in the benefit stages.
6.8.1 Mass flows
CRU = waste mass × reuse pathway share
MFR = waste mass × recycling pathway share
× recycling-benefit efficiency
MFR is zero when no recycling benefit or efficiency is configured. Incineration mass does not create MER.
MER remains zero because Dawn does not currently implement an auditable automatic derivation rule. A required non-zero MER value must be entered manually after export.
6.8.2 Exported energy
For incineration mass m, incineration share as, LHV H in MJ/kg, and linked benefit efficiency ab:
Energy output = m × a_s × H × a_b
Electrical recovery contributes to EEE; heat recovery contributes to EET. Each benefit uses its own efficiency, and both may use the same incineration LHV. Missing or zero LHV produces zero recovered energy.
6.8.3 Scope and export behavior
Flows are calculated per finished-product functional unit from:
| Source | Mass basis | Settings |
|---|---|---|
| Post-consumer end of life | Resolved BOM Material inventory | Material pathways, assembly overrides, LHV, and benefits |
| Production waste | BOM production-loss scrap by Material | Material production-waste pathways, LHV, and benefits |
| Site waste | Per-unit allocated location waste | Location pathways, LHV, and benefits |
Packaging follows the applicable waste source and material composition. Flows from all sources are summed at product level.
The assembly End of life view and EPD export include MFR, CRU, MER, EEE, and EET. Export uses the pathway/LHV-derived values for MFR, CRU, EEE, and EET. MFR, CRU, EE, EEE, and EET values originating in linked LCA reports or background datasets are removed from output-flow stage columns and LCI rows before the calculated values are written. This ensures that the EPD contains one consistent calculation source. MER is exported as 0.
7. Additional Environmental Indicators
7.1 Biogenic carbon in product and packaging
EN 15804 distinguishes:
| Indicator | Meaning |
|---|---|
| BCCP | Biogenic carbon content in the product, kg C |
| BCCAP | Biogenic carbon content in accompanying packaging, kg C |
During aggregation, Dawn assigns these indicators by contribution:
| Contribution | BCCP treatment | BCCAP treatment |
|---|---|---|
| Product materials | Retained as BCCP | Removed |
| Packaging | Reclassified to BCCAP | Existing BCCAP removed |
| Transport, utilities, waste, and other modules | Removed | Removed |
This rule places dataset-reported biogenic carbon in the EPD column representing its role in the current product system. It applies automatically to impact views and EPD exports.
8. Dataset Selection and AI Assistance
Users can select licensed datasets manually or use AI-assisted matching. AI supports selection; the resulting calculation remains deterministic and uses database factors.
AI-assisted matching:
- classifies the input as material, component, transport, utility, treatment, or another activity;
- searches licensed datasets using product, material, supplier, and geographic context;
- evaluates technological, geographic, and unit fit;
- derives the quantity in the selected dataset's functional unit;
- records the dataset, amount, and resulting impact report.
Users can review and replace every AI-selected dataset. The displayed evidence includes dataset name, source database, system model, and amount.
For Materials, manufacturing impact is stored per kilogram. End-of-life and production-waste treatment datasets are configured separately from this cradle-to-gate data.
9. Methodological Choices, Assumptions, and Limitations
- Point estimates. Dawn does not currently propagate uncertainty ranges. Available ecoinvent data-quality indicators are retained for review and export but do not modify results.
- System model. Cut-off calculations follow cut-off conventions. End-of-life substitution credits are explicit, separate benefits.
- User inputs and allocation. Users declare supplier shares, compositions, waste pathways, annual volumes, and location allocation bases. Dawn applies these values using the rules in this document. Supplier shares default to an equal split when none are entered.
- Mass dependency. Material, transport, waste, and end-of-life calculations rely on declared weights. Missing mass produces zero in dependent calculations and is surfaced as a data gap.
- Source precedence. Section 6.1.2 governs which manufacturing source is used. Composition continues to govern material inventory.
- Database versions. A result references the database version used at calculation time and remains tied to that version until recalculated.
10. Traceability and Versioning
Dawn supports verification through:
- Part impact reports containing the source dataset, database, system model, amount, and stage;
- immutable published LCA reports containing the indicator set, stage breakdown, and model structure at publication;
- contribution tracking from product totals to parts, modules, datasets, quantities, and factors;
- assembly snapshots containing the resolved BOM and calculated impacts for each base or variant configuration.
The base configuration and each variant have separate version streams. Core-BOM edits update the base and refresh variant snapshots against the changed core. Variant-only edits advance that variant. Shared assembly-level changes refresh snapshots for the base and all variants at their current main versions.
Snapshots freeze calculation-relevant context, including resolved child variants, installation-loss inputs and results, and direct and location-allocated utilities. Changes to production-site utilities, waste, allocation bases, annual volumes, or production links refresh affected assembly and subassembly snapshots.
11. Summary of Calculation Formulas
| Contribution | Formula |
|---|---|
| Single activity | Impact(i) = quantity × EF(i) |
| EF single score | Σ Impact(i) / NF(i) × WF(i) |
| BOM roll-up | Σ impact per unit × effective quantity |
| Composition impact | part quantity × weight × material share × EF per kg |
| Yield-model output | quantity × (1 − loss rate) |
| Fixed-BOM scrap | quantity × loss rate, additional to product content |
| Freight | distance × mass → t·km × EF |
| Site allocation share | D_o / ΣD_j |
| Allocated site amount per unit | site total × share / annual volume |
| Waste treatment | waste mass × pathway share × EF |
| Waste benefit | − waste mass × source share × benefit share × EF |
| Use phase | consumption per lifetime unit × lifetime units × EF |
| Installation prior share | Σ prior-stage impact × installation-loss rate |
| Installation waste mass | full mass × installation-loss rate |
| MFR | waste mass × recycling share × recycling-benefit efficiency |
| CRU | waste mass × reuse share |
| MER | 0 in Dawn; manual entry when required |
| EEE / EET | incinerated mass × LHV × recovery efficiency |
This document describes the calculation methodology implemented in the Dawn platform as of August 2026. Emission factor values themselves originate from the referenced databases (ecoinvent, EF 3.1, EN 15804 EPDs) and are subject to those databases' own documentation and review processes.
