ISO 20915:2026

International
Standard
ISO 20915
Second edition
Life cycle inventory calculation
2026-09
methodology for steel products
Méthodologie de calcul de l’inventaire du cycle de vie des produits
en acier
Reference number
© ISO 2026
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ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Basic conditions for LCI of steel products . 5
4.1 General requirements .5
4.2 Function and declared unit .5
4.3 System boundary . .5
4.4 Data quality .7
4.4.1 General .7
4.4.2 Time-related coverage .7
4.4.3 Geographical coverage .7
4.4.4 Technology coverage . . .7
4.4.5 Sources of the data .7
4.4.6 Primary data share .8
4.4.7 Data quality rating .8
4.4.8 Cut-off criteria .8
5 Methodological procedure for LCI calculation of steel products with provision for scrap
recycling . . . 8
5.1 General .8
5.2 Collecting data .9
5.2.1 General .9
5.2.2 Co-products .9
5.2.3 Ferrous raw materials .11
5.2.4 Process coal .11
5.2.5 Non-ferrous raw materials . 12
5.2.6 Ferro alloy . 12
5.2.7 Other input materials . 12
5.2.8 Fuels . 12
5.2.9 Process gases . 12
5.2.10 Electricity . 13
5.2.11 Steam . 13
5.2.12 Sea water . 13
5.2.13 Fresh water . 13
5.2.14 Grey water . 13
5.2.15 Industrial gases . 13
5.2.16 Emissions to air, water and soil .14
5.2.17 Flares .14
5.2.18 Transportation .14
5.2.19 Waste for disposal .14
5.2.20 Packaging of steel products .14
5.3 Allocation procedure for co-products .14
5.3.1 General requirement . .14
5.3.2 Application of system expansion with substitution to all co-products excluding
slags from iron and steel production .14
5.3.3 Exclusions . 15
5.4 Calculation of cradle-to-gate LCI without allocation for scrap input . 15
5.5 Allocation for scrap recycling .16
5.5.1 General .16
5.5.2 LCI calculation methodology for scrap .16
5.5.3 Calculation of the burden for scrap input to produce the specific steel product
under study .16

iii
5.5.4 Calculation of the credits for scrap recovery .17
6 Reporting . 17
7 Critical review .18
Annex A (informative) Calculation example of data quality rating . 19
Annex B (normative) LCI calculations for electricity, steam and biogenic fuels .20
Annex C (informative) Example uses of co-products outside of the system boundary .22
Annex D (informative) Example for calculating X .23
pr
Annex E (informative) Details for calculating the scrap input rate .26
Annex F (informative) Example of LCI result reporting .28
Annex G (informative) Cross reference table of related standards .35
Bibliography .42

iv
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 21, Environment
related to climate change in the iron and steel industry.
This second edition cancels and replaces the first edition (ISO 20915:2018), which has been technically
revised.
The main changes are as follows:
— stainless steel has been included;
— definitions have been clarified [product, scraps, recycling rate, coal and fuel (fossil and biogenic)];
— declared unit has been used instead of functional unit;
— alternative recycling methodologies have been allowed;
— explanations of primary data share (PDS) and data quality rating (DQR) have been added;
— examples of main outputs include CO (for CCU);
— contractual instruments (energy attribute certificates, RECs, guarantees of origin, green energy
certificates) and residual mix information have been included in electricity;
— co-product allocation has been modified to avoid double counting the benefits of co-product;
— for clarification, process gas in allocation specifies inclusion of combustion.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
Introduction
The life cycle inventory (LCI) of steel products is an important component in the support of life cycle
assessments for a wide range of products and applications that contain steel or where steel is used to
[1]
support the manufacture, production or delivery of products. ISO 14044 explains as follows.
LCA addresses the environmental aspects and potential environmental impacts (e.g. use of resources and
environmental consequences of releases) throughout a product's life cycle from raw material acquisition
through production, use, end-of-life treatment, recycling and final disposal (i.e. cradle-to-grave). There are
four phases in an LCA study:
a) the goal and scope definition phase,
b) the inventory analysis phase,
c) the impact assessment phase, and
d) the interpretation phase.
The life cycle inventory analysis phase (LCI phase) is the second phase of LCA. It is an inventory of input/
output data with regard to the system being studied. It involves collection of the data necessary to meet the
goals of the defined study.
This document describes the methodology for the analysis of the steel life cycle inventories that should be
applied to a wide range of steel products, and represents the main process routes for global steel production.
This includes the extraction of raw materials from the earth through to the production of steel products at
the factory gate, as well as provision for scrap recycling of steel products and the treatment of steel scrap.
[2] [1]
The methodology conforms to the principles and framework set out in ISO 14040 and ISO 14044 and
demonstrates how these principles should be applied to steel product manufacture and steel recycling.
The life cycle of steel products consists of the following stages (see Figure 1):
— sourcing of natural resources (which includes mining, transportation and intermediate processing of
raw materials) and scrap (recovered from both the manufacturing processes and the end of life of final
products);
— production of steel products at the steelworks, including scrap recovery;
— manufacturing of final products by downstream users, for example, by customers of the steel industry,
such as automotive, construction and engineering industries;
— use of final products, where the environmental performance of the final product depends on the steel
products being used; for example, the fuel (or energy) consumption of an automobile depends partly
upon the weight of its steel components;
— end of life of final products, including scrap recovery.
— recycling of scrap from both the manufacturing process and the end of life of final products to substitute
the use of raw materials from the earth.
This document covers life cycle stages including sourcing of raw materials from the earth and scrap,
production of steel products at the steelworks, and recycling of scrap. It does not cover the manufacturing of
final products and the use of final products.
All global steel production is sourced from different ratios of scrap and primary ores. Therefore, an
understanding of the value of steel recycling becomes a necessary part of the steel product LCI.
It is generally understood that the recycling of metallic materials makes a positive contribution towards
reducing resource consumption and energy requirements, and helps to avoid the potential impacts of raw
materials extraction and processing. However, all recycling routes (including the processing and transport
of recycled materials) carry environmental burdens and these should be quantified as part of a life cycle
assessment.
vi
A critical factor in the understanding of the benefits of materials recycling is the quality of the materials and
products produced from the recycled material. Where the recycled products which are made to the same
inherent properties as those sourced from primary materials, this is described as closed-loop recycling.
With the existing process and scrap quality controls, steel sourced from (scrap-based) steel recycling can be
made to the same specification as steels sourced from the (iron ore based) primary routes. The properties of
the different steel grades are achieved through different alloying concepts as well as process steps, such as
heat treatment and secondary steel metallurgy allows the control of alloying and tramp element levels. This
proves the judgement that steel recycling is to be regarded as closed-loop recycling.
Life cycle assessment may be used to quantify the potential benefits of recycling to conform to the guidance
[3]
set out in ISO 14044:2006 , 4.3.4.3.
Figure 1 — Schematic diagram of the life cycle of steel

vii
International Standard ISO 20915:2026(en)
Life cycle inventory calculation methodology for steel
products
1 Scope
This document specifies guidelines and requirements for conducting life cycle inventory (LCI) studies of
steel products reflecting steel’s capacity for closed-loop recycling, including:
a) specification of the declared unit used for LCI calculation of steel products;
b) definition of the system boundaries used for LCI calculation of steel products;
c) evaluation of scrap in LCI calculation of steel products;
d) evaluation of co-products in LCI calculation of steel products;
e) reporting of LCI calculation results of steel products.
The application of LCI results, including life cycle impact assessment (LCIA), is outside the scope of this
document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 6929, Steel products — Vocabulary
ISO 14040, Environmental management — Life cycle assessment — Principles and framework
ISO 14044, Environmental management — Life cycle assessment — Requirements and guidelines
ISO 14044:2006, Environmental management — Life cycle assessment — Requirements and guidelines
3 Terms and definitions
For the purposes of this document, the terms and definition given in ISO 6929, ISO 14040, ISO 14044 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
life cycle inventory
LCI, noun
phase of life cycle assessment involving the compilation and quantification of inputs and outputs for a
product throughout its life cycle
[4]
[SOURCE: ISO 14040:2006 , 3.3]

3.2
steel product
item manufactured from steel and shipped out from steelworks
EXAMPLE Semi-finished products (e.g. slab, billet, bloom, ingot), steel powder, hot rolled steel, pickled hot rolled
steel, cold rolled steel, finished cold rolled steel, electrogalvanized steel, hot-dip galvanized steel, tin-free steel,
tinplated steel, organic coated steel, section, plate, rebar, engineering steel, wire rod, seamless pipe, UO pipe, welded
pipe, and forged steel.
3.3
final product
product containing steel that requires no additional transformation prior to its use
EXAMPLE Automobiles, building structures, building envelopes, components, packaging, kitchen equipment and
industry process equipment.
[5]
[SOURCE: ISO/TS 18110:2015 , 2.2, modified — The example has been added.]
3.4
scrap
ferrous scrap (iron and steel material) in metallic form that is recovered in multiple life cycle stages,
including in steel production processes (home scrap (3.6)), the manufacturing processes of final products
(3.3) (external pre-consumer scrap (3.7) and the end of life of final products (post-consumer scrap (3.8) ), and
is recycled as a raw material for steel production
3.5
internal scrap
scrap diverted from the waste stream during a crude steel making unit process that is then recycled within
the same unit process (e.g. basic oxygen furnace (BOF) or electric arc furnace (EAF))
Note 1 to entry: Internal scrap is excluded from the definition of home scrap (3.6).
3.6
home scrap
internal pre-consumer scrap diverted from the waste stream during a steel manufacturing process, for
example from the rolling and processing mills
Note 1 to entry: internal scrap (3.5) which can be recycled within the same process (e.g. basic oxygen furnace (BOF) or
electric arc furnace (EAF) is excluded from this definition.
3.7
external pre-consumer scrap
scrap diverted from the waste stream during a manufacturing process of final products (3.3), such as vehicles,
white goods and buildings and includes scrap generated outside the boundaries of the steel production
Note 1 to entry: home scrap (3.6) generated outside of the product boundary under assessment would be included.
3.8
post-consumer scrap
scrap generated by households or by commercial, industrial and institutional facilities in their role as end
users of the final product (3.3) which can no longer be used for its intended purpose.
Note 1 to entry: This includes returns of scrap from the distribution chain. Returns of scrap from the distribution
chain are products that have reached end of life status before use, due to damage etc.
Note 2 to entry: This includes scrap from any facilities which are not parts of steel making process.(e.g. any disposable
scrap from the office)
[6]
[SOURCE: ISO 14021:2026 , 3.4.10, modified]

3.9
external scrap
scrap provided from outside of the steelworks, including external pre-consumer scrap (3.7) and post-consumer
scrap (3.8), which are outside the boundaries of the steel production site. This also includes home scrap (3.6)
from the steel production facility which is external to the product boundary.
3.10
scrap input rate
ratio of the mass of external scrap (3.9) recovered for recycling to the mass of steel products to be shipped
out from the steelworks gate, calculated as shown in Formula (1)
(1)
where
a is the mass of external pre-consumer scrap (3.7) recycled including external home scrap to the
product boundary.;
b is the mass of post-consumer scrap (3.8) recycled;
P is the mass of steel products shipped out of the gate
Note 1 to entry: Scrap input rate does not refer to the % recycled content in the steel produced.
3.11
end of life recycling rate
ratio of the mass of post-consumer scrap (3.8) recovered for recycling to the mass of steel in final product
(3.3) , calculated as shown in Formula (2):
(2)
where
b is the mass of post-consumer scrap (3.8) recycled;
F is the mass of steel products contained in the final product (3.3)
3.12
manufacturing yield
ratio of the mass of steel contained in final products (3.3) to the total mass of steel products (3.2) used for
manufacturing the final product
3.13
ferrous raw material
raw material from the earth that becomes one of the main constituents of steel products (3.2), and which
may have undergone intermediate processing to prepare it for iron making
EXAMPLE Lump ore, iron ore fine, sinter, pellet, hot briquetted iron (HBI), direct reduced iron (DRI).
3.14
process coal
coal used in iron and steel making processes
EXAMPLE Coking coal, injection coal, sintering coal, BOF coal, EAF coal, DRI coal.
Note 1 to entry: Coal can be of both fossil and biogenic origin.
3.15
non-ferrous raw material
non-ferrous material for steel products (3.2) other than ferrous raw material (3.13) or process coal (3.14)
EXAMPLE Zinc, tin, aluminium, chromium, nickel, molybdenum and manganese.

3.16
ferro-alloy
alloy of iron with non-iron alloy metals, such as manganese, silicon, chromium, nickel and molybdenum used
in the steelmaking process
3.17
other input material
material input and consumables for steel production other than ferrous raw material (3.13), process coal
(3.14), non-ferrous raw material (3.15), ferro alloy (3.16) and scrap (3.4), which does not ultimately form part
of the steel product (3.2)
EXAMPLE Refractory, electrode, chemical materials, limestone, dolomite.
3.18
fuel
energy source for generating heat, steam and power other than process gas (3.21)
EXAMPLE Boiler coal, fuel oils, natural gas, LPG, biogas.
Note 1 to entry: Fuel can be of fossil and biogenic origin.
3.19
industrial gas
gas for steel production other than fuels (3.18) or reducing agent
EXAMPLE Oxygen, nitrogen, argon, hydrogen, carbon dioxide, compressed air.
Note 1 to entry: Hydrogen can be used as a fuel, or is included here as an industrial gas when used as an uncombusted
industrial gas, e.g. for the provision of reducing atmospheres in production processes.
3.20
co-product
any of two or more products coming from the same unit process or product system
Note 1 to entry: Any recovered material that can be used by another interested party is included.
[3]
[SOURCE: ISO 14044:2006 , 3.10 modified — Notes 1 to entry have been added.]
3.21
process gas
gas that is produced as part of the processes on the steel production site
Note 1 to entry: Coke oven gas, blast furnace gas, BOF gas, DRI gas.
Note 2 to entry: Process gas used by another interested party is regarded as a co-product
3.22
waste
resource that is no longer considered to be an asset as it, at the time, provides insufficient value to the holder
Note 1 to entry: The holder can choose to retain, discard, or transfer the waste.
Note 2 to entry: Value can be assigned to waste as a result of a need from another interested party, at which point the
resource is no longer considered waste, it changes to co-product.
Note 3 to entry: The assignment of value to waste as a resource is linked, in part, to the available technology (e.g.
landfill mining).
Note 4 to entry: Some regulations require the holder to dispose of certain types of waste, while others assign value to
waste.
Note 5 to entry: Because resources include the energy content or energy potential of materials, such energy, when
liberated during a process and not recovered for another use, can be considered a waste.

[7]
[SOURCE: ISO 59004:2024 , 3.3.6 — Notes 3 to entry have been modified.]
3.23
primary data
quantified value of a process or an activity obtained from a direct measurement or a calculation based on
direct measurements
Note 1 to entry: Primary data need not necessarily originate from the product system under study because primary
data might relate to a different but comparable product system to that being studied.
Note 2 to entry: Primary data can include emission factors and/or activity data.
[8]
[SOURCE: ISO 14067:2018 , 3.1.6.1, modified]
3.24
secondary data
data that do not fulfil the requirements for primary data
Note 1 to entry: Secondary data can include data from industry association, databases and published literature,
default emission factors from national inventories, calculated data, estimates or other representative data, validated
by competent authorities.
Note 2 to entry: Secondary data can include data obtained from proxy processes or estimates
[8]
[SOURCE: ISO 14067:2018 , 3.1.6.3, modified]
3.25
stainless steel
steel with at least 10,5 % (mass fraction) Cr and maximum 1,2 % (mass fraction) C
[9]
[SOURCE: ISO 15510:2014 , 3.1]
3.26
declared unit
quantity of a steel product (3.2) for use as a reference unit in an life cycle inventory (3.1)
[10]
[SOURCE: ISO 14050:2020 , 3.7.11, modified]
4 Basic conditions for LCI of steel products
4.1 General requirements
The requirements and guidelines set in this document shall be followed in addition to those set by ISO 14040
and ISO 14044.
4.2 Function and declared unit
The function of steel products is to form a part of final products with a certain function, such as automobiles,
cans and bridges. For steel products LCI, it is more appropriate to use declared unit as steel can be used for
different functions which are defined for the different final products.
For an LCI of steel products, the declared unit should be set as a mass-based unit of a specified grade or type
of steel product to be shipped out from the steelworks gate. Where applications are based on other declared
capacities, suitable explanation and conversion guidance shall be provided.
4.3 System boundary
As shown in Figure 2, the system boundary used for the LCI study of steel products shall include all of the
production steps from input materials (raw materials from the earth, scrap, etc.) to steel products ready to
be shipped from the steelworks, including the recycling of steel products (i.e. cradle-to-gate). This includes
production processes at the steelworks and all the upstream processes, including energy conversion, raw

material mining, material preparation and transportation of materials to the steelworks site. The effect of
scrap recycling, or the burdens of using scrap and the credits for the recovery of steel products, should be
considered according to the procedure described in 5.5. The calculation of steel product LCIs should include
allocation on scrap to reflect the nature of closed-loop recycling. Cradle-to-gate LCIs without scrap allocation
may be reported when this is aligned to the goals and scope of the study. Additionally, care should be taken
that if no burdens are assigned to scrap inputs, then no credits should be applied to steel recycling. Also, the
recovery and use of steel industry co-products outside of the steelworks shall be taken into account. The
allocation procedure is described in 5.3. The system boundary does not include the manufacturing of final
products using steel products or their use in society.
Figure 2 — System boundary
The following items should be excluded from the system boundary. If any of them are included in the system
boundary, this shall be clearly stated and explained.
— Transportation of steel products beyond the gate.
— Transportation of co-products beyond the gate.
— Manufacturing of final products.
— Use of final products.
— Research and development.
— Business travel of employees.
— Production, decommissioning, repair and maintenance of capital goods unless impacts are known to be
non-negligible or have an impact.
— Cleaning and legal services.
— Marketing.
— Operation of administration offices.

4.4 Data quality
4.4.1 General
The data quality requirements set out in of ISO 14044:2006, 4.2.3.6, shall be followed, including time-related
coverage (4.4.2), geographical coverage (4.4.3) and technology coverage (4.4.4). Additionally the share of
primary data should be calculated using the methodology in subclause 4.4.6 of this document.
4.4.2 Time-related coverage
The timeframe of data collection should be one full representative year to adjust for seasonal variations.
If the data set is not possible for a full year, this shall be explained and justified. Moreover, since the LCI
results are prone to change over time for reasons, such as changes in operational rate due to economic
conditions and technological improvements, the time period in which the data are collected shall be stated
clearly. Primary data sets used in LCI studies should not be more than five years old. Any secondary data
used should be less than 10 years old, unless its ongoing validity is justified. When using data outside of the
reference year, the choice shall be explained and justified.
4.4.3 Geographical coverage
An LCI study of steel products may be reported with various geographical representations, for example, one
steelmaking site, one steel company, national, regional or global coverage. When the study covers multiple
steelworks (or companies, regions, etc.), the geographical coverage and representation should be clearly
stated. The LCI should be presented as a weighted average by the production quantity of the covered scope,
not a simple arithmetic average. For example, Product A produced by sites 1, 2 and 3 with mass M1, M2 and
M3 would be averaged as: (LCI1 × M1 + LCI2 × M2 + LCI3 × M3)/(M1 + M2 + M3). Manufacturers contributing
to the LCI shall be documented, and use of the data set shall be noted as applicable within the bounds of the
contributing manufacturers.
4.4.4 Technology coverage
[11]
This document covers production technologies of non-alloy steel and alloy steel, as defined in ISO 4948-1 .
[11]
NOTE According to ISO 4948-1 , alloy steel includes stainless steel.
4.4.5 Sources of the data
Steel production data shall be directly sourced from steel producers based on primary data, such as
measurement, engineering calculations and purchasing records.
Primary data should be used instead of secondary data for at least the processes over which the manufacturer
of the specific product has influence, as well as for the most relevant materials inputs, if available, and if it
meets or complies with the data quality requirements herein. Data from the site(s) under study shall be
prioritized.
Upstream data produced by suppliers should be used. If the information is not available, secondary data may
be used. All secondary data should be representative for the scope of the LCI conducted.
Secondary data selection hierarchy:
a) Industry association data
b) General LCA data, e.g. commercial LCA databases, and default emission factors from national inventories
c) Other documented references, e.g. reviewed scientific literature
d) Proxy data with justification

4.4.6 Primary data share
The primary data share (PDS) is defined as the proportion (percentage) of an LCI that is derived from
primary data.
Where the goal and scope of the study determine which environmental impacts are of most importance -
for these impacts, the primary data share should be reported. For example, where the scope of the study
focuses on greenhouse gas (GHG) emissions and climate change, the PDS should be reported for the carbon
footprint of a product (CFP). The primary data share of each relevant environmental impact is expressed as
a % of the cradle-to-gate environmental impact, not including recycling where absolute values are used to
avoid negative impacts and therefore a potential negative PDS.
Alternatively, information should be provided alongside the LCI which states clearly which data points were
derived from primary or secondary data – this allows the user of the LCI in a study to determine the PDS
score for their product system.
4.4.7 Data quality rating
Alongside the LCI results, a data quality rating (DQR) should be reported. For more information, see Annex A.
4.4.8 Cut-off criteria
As stated in ISO 14044:2006, 4.2.3.3.3, the cut-off criteria for initial inclusion of inputs and outputs and the
assumptions on which the cut-off criteria are established shall be clearly described. In particular, for LCI of
steel products, cut-off criteria may be established for all energetic inputs and outputs to the process stages,
including fuels, electricity, steam and other converted energy as well as for all inputs and outputs to the
process stages of ferrous raw materials, process coal and non-ferrous raw materials. To avoid the need to
pursue trivial input and outputs to the system, cut-off criteria should be applied as follows:
— all energetic inputs to the process stages should be reported including fuels, electricity, steam and
compressed air;
— each excluded material flow should not exceed 1 % of mass, energy or environmental relevance for each
unit process;
— the sum of the excluded material flows in the system should not exceed 3 % of mass, energy or
environmental relevance.
5 Methodological procedure for LCI calculation of steel products with provision for
scrap recycling
5.1 General
In this document, allocation on scrap to reflect the nature of closed-loop recycling is applied. Cradle-to-gate
LCIs applying other allocation methods for scrap may be reported when this is aligned to the goals and
scope of the study.
To evaluate the benefits of steel recycling it will be necessary to allocate an LCI value to scrap and to apply
this value to both the inputs (burdens) and outputs (credits) of the system. The reporting of this will depend
upon the goals of the study, but if no burdens are assigned to scrap inputs, then no credits shall be applied
to the external scrap (i.e. post-consumer and external pre-consumer scrap). It is important to be consistent
with the allocation of credits and burdens throughout the scope of the life cycle study. Note also that the
value assigned to scrap reflects the initial investment of the primary production of steel, which if recycled,
will be carried forward for future generations. The resulting formulae show that the LCI burdens of steel in
an application are reduced by higher end of life recycling rates (R) and by improving the yield of the recycling
process (y). This indicates that the sustainability of product designs involving steel products should make
provision for high values of R and y.

The LCI for steel products which takes account of end-of-life methodology is calculated in three stages (see
Figure 3), as follows.
— X: In a first step, the LCI of the steel product to the factory gate is calculated without allocation for scrap.
At this stage, scrap will appear as a mass input but will not be allocated with an LCI (inventory flows to/
from earth related to scrap).
— Y: Secondly, an LCI value for scrap (as described in 5.5) is calculated. It is then applied in the substages
Y1 and Y2 as described in Figure 3. Both of these steps have to be conducted.
— Y1: The LCI value is applied as a burden for the mass of scrap consumed in the process.
— Y2: The same LCI value for scrap is credited for the mass of scrap that is going to be recovered. (See 5.5.4)
— Thirdly, by aggregating the three components (X + Y1 + Y2) the LCI value for the steel product with
consideration for scrap recycling is determined.
Key
X cradle-to-gate LCI without allocation for scrap input
Y1 LCI for scrap consumed in the steel making process
Y2 LCI for scrap recovered for recycling
X+Y1+Y2 LCI with allocation for scrap
Figure 3 — Illustration of LCI of steel products
5.2 Collecting data
5.2.1 General
In the system boundary described in 4.3, all inputs and outputs of materials, energy and co-products across
each unit process shall be captured.
5.2.2 Co-products
Outputs listed in Table 1, which are used beneficially, are referred to as main products and co-products
of steel production. Co-products other than main products (e.g. coke, hot metal, DRI, slab, bloom, billet,
steel products) shall be allocated in accordance with 5.3. If there are co-products other than those listed in
Table 1, they may also be allocated.
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