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Reference building calculation rules with One Click LCA

Reference building calculation rules with One Click LCA

Background

The new NS 3720 standard provides guidelines for calculating buildings with four pre-defined scopes. However, the standard does not provide guidance for calculating reference buildings.

The reference building provides the users a carbon performance for the building if built according to normal market conditions in Norway. The reference building is used to set carbon reduction requirements for the project, which are in turn quantified using NS 3720 standard.

Further reading

Overview of differences between klimagassregnskap.no and One Click LCA Norge NS 3720 tool

For clarity it is stated that the reference building scope is specific to the reference building, and there is only one such scope, not four different ones. It is based on the standard definition «Basis med lokalisering». The reference building calculation is modular as per NS 3720.

According to NS 3720 several new aspects of the life-cycle for buildings should be accounted for (when compared to the KGR). However, not all of these have established reference values, or even basic data may not be available for some of these.

This leads to a need to fix assumptions and scenarios when reference buildings are used. This document explains and justifies these.

These rules refer to Norwegian reference building 2018

For example, market shares of main construction materials or methods may be updated, or more information may become available to adjust some parts of the reference building information. Therefore, reference buildings are versioned as ‘Norwegian reference buildings 2018’.

If you require documentation on the reference building compliance please write to support@oneclicklca.com or download this summary document.

Reference building assume biogenic carbon and land use carbon flows as zero (0)

This means that reference building value is only calculating the Global Warming Potential (fossil), not the other scopes of the NS 3720. Biogenic carbon flows net themselves out in the cases covered by reference building calculations, and LULUC changes mostly belong to A5 – not in the scope of reference. Biogenic carbon storage and LULUC carbon will be shown in the final klimagassberegning.

Mandatory choices in LCA Parameters and other inputs for the reference building

These values are mandatory for the calculation of reference buildings. The reference building is assumed to be calculated for a defined site. In cases when the reference building must be created prior the final site is known, best understanding of likely area/sites shall be used instead of the actual site.

Choice Mandatory choice Why mandated
Service life default setting Technical service life Otherwise replacement impacts might differ if assumptions differ
Transport distance default setting Nordics Otherwise transportation impacts might differ if assumptions differ
Local compensation (for adjusting electricity of manufacturing for generic materials) Norway Otherwise reference building will not be representing Norwegian reference building
Assessment period Same as in the actual building NS 3720 allows free choice of assessment period, so the reference building must be the same as for actual building
Number of floors (above and below ground) Same as in the actual building Reference model calculates amounts of structural materials based on floors and predefined floor heights. If this changes, reference needs to be rebased.
Transport: The number of users and distances and the goods transport scenario Same users and distances as in the actual building As site is chosen and has strong impact on the transport impacts, these variables must be fixed – only transport mix can be varied. If site is not yet known, use the most likely region instead.
Foundation system matching the site requirements Foundation meeting requirements of the actual building As site is chosen and has determining impact on foundations, the foundations must be suitable for the site. If the site is not yet known use the most likely case instead. Foundation system matching the site requirements.
Construction site impacts Norway default Choose the “Gjennomsnittlig energi og drivstoff bruk i byggeplassen – Norden” and apply BTA as value in the “Byggeplassdrift” query.
Site clearing and land use changes (if required) Site clearing and land use changes as mandatory In most conditions, these should not need to be included. However a site may be built on virgin land, and in such case the clearing and land use changes that the site itself actually would require shall be included.

 

Reference buildings get automatically generated by Carbon Designer with strip footing (for hard soils), which is the economically and environmentally most attractive option. User must adjust this as necessary. The user is responsible for creating the reference building transport scenario for the location they are targeting with the right amount of users and actually planned visitor flows and other parameters (to the extent known).

Reference building scope

The reference building scope includes the scope 2-bygning according to NS 3541:2009. The building installations (groups 3 – 6) and group 7 external areas are not calculated for the reference building.

Please note that for BREEAM NOR 2016, the NS 3541 scope 719 hard landscaping is required.

Scoping of the reference building based on NS 3720

The proposed reference building 2018 scope is: A1-A3 materials, A4 transport, B4-B5 replacement of materials, B6 operational energy, B8 operational transport and C3-C4 end of life waste processing.

Life-cycle stages NS 3720 Included in reference? Explanations
A1-A3 Produktstadiet Yes Essential to include
A4 Transport Yes Can be standardized with Nordic defaults
A5 Anleggs, bygge- og monteringsarbeid Yes For construction site impacts, site clearing and land use changes see instructions above
B4 Utskiftning Yes Included, standardized via service life settings
B5 Ombygning Yes Same as above
B6 Energibruk i drift Yes Essential to include and use TEK17 scenario and not editing “systemvirkningsgrader”
B8 Transport i drift Yes Essential to include and use the settings applicable to the specific location where calculated
C3 Avfallsbehandling Yes Waste handling process as per EN 15978
C4 Avhending Yes Waste handling process as per EN 15978

 

Excluded scopes and justifications

The following scopes are excluded from the reference building with given justifications.

Life-cycle stages NS 3720 Included in reference? Explanations
B1 Bruk No This is largely carbonisation, which depends on how cementious materials are in contact with air. Not possible to have a solid reference value for this at present.
B2 Vedlikehold No Excluded as no detailed reference for this.
B3 Reparasjon No Excluded as no detailed reference for this.
C1 Riving No No accurate reference presently available.
C2 Transport No No accurate reference presently available.
D Konsekvenser utover systemgrensen No It’s not included in the totals, as it’s external impacts (not in the life-cycle).

Foundation calculations

Foundation materials are calculated based on the gross floor area of the building they support to meet the conditions of the soil of the building site. The gross floor area of the building is used as a proxy for the building mass that has to be supported. Default foundation type is strip (footing) foundations. If this is not applicable, the user needs to apply the type of soil condition, and depth to bedrock for this foundation to represent the chosen site. The shape of the building mass is not influencing the calculated foundations, as the mass of the building to be supported remains similar with different shapes. If site has varying depths to bedrock, the user can split the building total area between the different piling depths or between footings and piling. If the building has varying number of floors above different soil types, the shares should be weighed by floor area above each soil type.

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