3 LCAmethodology

3.1Declaredunit

The functional unit being declared is1m2 of steel structuraldeck or liner traywith a working width of 930mm for the reference profile. In the sNMD functional descriptions, the category is 27.2 Roofs; construction – structural roofs.

3.2Scope

ThisEPD can be regarded asCradle-to-Gate (with options)and the modulesconsidered in the LCAare;

A1-3: Production stage (Rawmaterial supply, transport to production site, manufacturing)

A4& A5: Production stage (Transport to the construction site and installation)

B1-5: Usestage (related to the building fabric including maintenance, repair, replacement)

C1-4: End-of-life (Deconstruction,transport, processing for recycling & reuseand disposal)

D: Reuse, recycling and recovery

Allof the life cycle stagesare explained in more detailin Figure 4, but where the text isin light grey, the impacts from thispart of the life cycle are not considered for thisparticular product.

ModuleD:Benefits&loadsbeyondthe systemboundary

Includes impacts from;

•Deck/trayreuse(0%)and recyclingof thesteel(95%)

ModuleC:End-of-lifestage

Includes impacts from:

•Deconstructionof compositedeck/tray system

•Transportfromsitetoend-of-life

•Processingof deck/traysystemfor reuseorrecycling

•Disposalto landfillof steel(5%)

ModuleB:Usestage

Includes impacts from;

•Useorapplicationofthecomposite deck/trayin abuilding

•Maintenance,repair,replacement, refurbishmentof the system

ModulesA4&A5:Construction processstage

Includes impacts from;

•Deliveryof steel decks/liner trays and othercomponentstosite

•Installationof steel decks/linertrays withfixings, at the construction site construction site

Life CycleAssessment ofSABColorcoat® pre-finished steel structural deep deck and liner trays

ModuleA1:Productstage(primary processing)

Includes impacts from;

•Rawmaterialextractionandprocessing (ironore,coal)

•Steelmaking, casting, and production of cold rolled coil at IJmuiden

•Preparation of recycled scrap

•Hot dip metallic coating and production of pre-finished steel at IJmuiden

•Production of paints for coatings

•Responsible sourcing of materials to BES 6001 standard

ModuleA2:Productstage(transport)

Includes impacts from;

•Transportof pre-finishedsteelfrom IJmuidento themanufacturingsiteat IJsselstein

ModuleA3:Productstage(deck/liner traymanufacture)

Includesimpacts from;

•Profilingandcuttingof pre-finishedsteel

•Packagingofdecks/linertraysfordelivery tosite

3.3Cut-off criteria

Allinformation from the data collection processhasbeen considered, covering all usedand registered materials, and allfueland energyconsumption. On-site emissionswere measured and thoseemissionshave been considered. Data for allrelevant siteswere thoroughlychecked and also cross-checked with one another to identifypotentialdata gaps. No processes, materialsor emissions that are known to make a significant contribution to the environmentalimpact of the steeldeck or liner trayhave been omitted. On thisbasis, there is no evidence to suggest that inputsor outputs contributing more than 1% to the overall massor energy ofthe system, or that are environmentallysignificant, have been omitted. It is estimatedthat the sum of any excluded flowscontribute lessthan 5% to the impact assessment categories. The manufacturing of required machinery and other infrastructure isnot considered in the LCA.

3.4Background data

For life cyclemodelling of the cladding system, the GaBiSoftware System for Life CycleEngineering isused [17]. TheGaBi database containsconsistent and documented datasetswhich can be viewed in the online GaBidocumentation [18]

Where possible, specific data derived from Tata Steel’sand SAB’s own production processeswere the first choice to use where available. Data wasalsoobtained directly from the relevant suppliers, such as the paint which is used in the coating process.

Specificdata [24] were used to model the primarysteel manufacture at TataSteel, using Ecoinvent 3.6 [25,26] to complywith the requirementsof the NMD. All other relevant processesandlifecyclestageswere modelled using Ecoinvent background data (including energy and transport), available as part of the GaBidatabase.

3.5Data quality

The data from Tata Steel’sown production processesare from 2016, and the SAB production datawasfrom 2018. The technologieson which theseprocesseswere basedduring that period, are those used at the date of publication of thisEPD. All relevant background datasetsare taken from the GaBisoftware database, and the last revision of allbut one of thesedata sets took place lessthan 10 yearsago. However, the contribution to impactsof thisdataset is smalland relativelyinsignificant, and therefore, the study isconsidered to be basedon good qualitydata.

3.6Allocation

To align with the requirementsof EN 15804, a methodologyisapplied to assign impacts to the production of slag and hot metalfrom the blast furnace(co-productsfrom steel manufacture), that wasdeveloped by the World Steel Association and EUROFER [19] Thismethodologyisbased on physical and chemical partitioning of the manufacturing process, and therefore avoidsthe need to useallocation methods, which are based on relationships such as mass or economic value. It takesaccount of themanner in which changesin inputsand outputsaffect the production of co-productsandalsotakes account of material flowsthat carryspecific inherent properties. Thismethod isdeemed to provide the most representativemethod to account for the production of blast furnace slag asa co-product.

Economicallocation wasconsidered, as slag isdesignated asa lowvalue co-product under EN 15804. However, asneither hot metal nor slag are tradable products upon leaving the blast furnace, economic allocationwould most likelybe based on estimates. Similarly BOF slag must undergo processingbefore being used asa clinker or cement substitute. The World Steel Association and EUROFER also highlight that companiespurchasing and processing slagwork on long term contracts which do not followregular market dynamics of supplyand demand.

Processgasesarise from the production of the continuouslycast steelslabs at IJmuidenand are accounted for using the system expansion method. Thismethod isalsoreferenced in the sameEUROFER document and theimpacts of co-product allocation, during manufacture, are accounted for in the product stage (Module A1).

End-of-life assumptions for recovered steel and steelrecycling are accounted for asper the currentmethodologyfrom the World Steel Association 2017 LifeCycle Assessment methodologyreport [20]. Anet scrap approach isusedto avoid double accounting, and the net impactsare reported asbenefitsand loads beyond the system boundary(ModuleD).

3.7Additional technical information

The main scenario assumptionsused in the LCA are detailedin Table4. The end-of-life percentagesare based upon valuesin the sNMD Determination Method document [8]

The environmental impactspresented in the ’LCAResults’section (4) are expressed with the impact categoryparametersof LifeCycle Impact Assessment (LCIA)using characterisation factors. The LCIAmethod usedisbasedupon that of the CML [21] and denoted in GaBibySBK-NMD Jan 2021.

3.8Comparability

Care must be taken when comparingEPDs from different sources. EPDsmay not be comparable if theydo not have the same functionalunit or scope (for example, whether theyinclude installation allowancesin the building), or iftheydo not followthe same standard such asEN 15804. The useof different generic data setsfor upstream or downstream processesthat form part of the product system mayalso mean that EPDsare not comparable.

Comparisons should ideally be integrated into a wholebuilding assessment,in order to capture anydifferencesin otheraspects of the building design that may result from specifying different products. For example, a more durable product would require less maintenanceand reduce the number of replacementsand associated impactsover the life of the building.

Table4 Main scenario assumptions

Module Scenarioassumptions

A1toA3–Productstage

A2–Transporttothedeckmanufacturingsite

A4–Transporttoconstructionsite

A5–Installationatconstructionsite

B1toB5–Usestage

C1–Deconstruction&demolition

C2–Transportforrecycling,reuse,anddisposal

C3–Wasteprocessingforreuse,recoveryand/orrecycling

C4-Disposal

D–Reuse,recycling,andenergyrecovery

Manufacturing data from Tata Steel’s site at IJmuiden is used, as well as data from SAB-profiel at IJsselstein

The deck and liner tray manufacturing facilities are located at IJsselstein and the pre-finished steel coils are transported there from IJmuiden a distance of 69km by road. A 30 tonne payload truck was used for all road journeys

A transport distance of 150km by road on a 30 tonne capacity lorry was considered representative of a typical installation

Energy consumption estimated based upon published data for the erection of steel constructions in Germany [22]

This stage includes any maintenance or repair, replacement or refurbishment of the steel deck or tray over the life cycle. This is not required for the duration of the reference service life of the product

Energy consumption estimated based upon published data for the dismantling of steel constructions in Germany [22]

A transport distance of 100km to landfill or to a recycling site is assumed, while a distance of 250km is assumed for reuse. Transport is on a 30 tonne load capacity lorry

Steel deck or liner tray that is recycled is processed in a shredder

At end-of-life, 5% of the steel deck or tray is disposed in a landfill, in accordance with the data in the Determination Method document

At end-of-life, 95% of the steel is recycled in accordance with data in the Determination Method document