New Embodied Carbon Calculation & Design Efficiency Assessment

Tekla Structural Designer
Tekla Structural Designer

New Embodied Carbon Calculation & Design Efficiency Assessment

With an exciting further development of recent features to assess the Carbon Impact of design, Tekla Structural Designer 2021 adds an automated and comprehensive new built-in calculation of embodied carbon quantities, together with powerful new options for graphical review/ optimization and reporting of this aspect of design. For information about recently added related features see the 2020 SP6 release note sections Review View - Design Status Enhancements and Material List Enhancements (material quantity improvements detailed in this are directly used in the new Embodied Carbon calculation) and the help topic on the Export to One Click LCA feature (released in 2020 SP5).

For more background on Embodied Carbon calculation see this Institute of Structural Engineering guide “How to calculate embodied carbon”. With reference to this, the new calculation in Structural Designer essentially deals with stages A1 to A3 for the construction products in a project (commonly termed the ‘Product stage” or “cradle to gate” stage), over which the design engineer has direct influence and which typically account for some 50% of all Embodied Carbon in a building project life cycle. The picture directly below shows an example of the new graphical review capability for Embodied Carbon together with just a small sample of the reporting options; the Overview report giving totals for the entire model (both by entity and grouped by plane) and just part of a Detail report for steel composite beams.

Here, and also in this related video, we will highlight some key aspects of the settings and workflow for this feature.

  • Embodied Carbon Factors (ECF) - at the heart of this new feature is the Embodied Carbon Factors (ECF) definitions dialog shown below, which lists the factors and controls how they are assigned to the entities in the model. The ECF value is the key value required for the calculation, being the mass of embodied carbon per unit mass or area of a material or surface e.g. kgCO2e/kg. The ECF dialog is accessed from the new “Embodied Carbon Factors” button on the Home tab of the Ribbon. Assignment of ECFs to the model entities and the resulting Embodied Carbon calculation is entirely automatic and updates in real-time following edits to the list/ factors. Automated ECF assignment is controlled first by the order of the factor list then by the criteria set for each individual factor.

  • This feature is applicable to all Head Codes & Countries. Some sample ECF definitions have been added to the Settings sets for all countries/ codes for the following categories in general; Concrete, Metal Deck, Reinforcement, Steel, Timber. Note the following:

    • We would note that there is potentially considerable variability/ uncertainty in ECFs - for example for Concrete, many mix variations are possible for every strength grade and all could be unique. Hence the sample ECF’s are included principally for guidance and are not a complete set - the engineer is advised to review, edit and add to them as they need. To establish ECF values you can for example consult an Environmental Product Declaration (EPD) where available from construction product suppliers/ manufacturers.

    • Existing Installations - for an existing installation, your current settings sets (from the latest currently installed version) will be copied to this release. Hence, to use the sample ECFs, it is necessary to first import the new 2021 Settings sets for your preferred country/ countries into global settings. New models created with these new settings set(s) active will then contain the new ECF definitions. For existing models the ECFs can be loaded via Home > Embodied Carbon Factors > Load… (from the currently active global settings).

      • If you wish to add the ECF definitions to your own settings set(s), you can do this as follows:

        • Step 1 - import a new 2021 settings set, set it to be Active, OK this then create a new model - this will contain the sample ECF definitions.

        • Step 2 - open Home > Settings and set your settings set to be Active.

        • Step 3 - open the ECF dialog and click the [Save…] button, you can then confirm the load the ECF definitions into your settings set from the model as shown in the picture below.

  • Steel Connections Allowance - note that there is also a new model setting for the Embodied Carbon calculation to make an allowance for the additional amount within steel connections. This is found in both Global and Model Settings > Embodied Carbon > Steel connections. There are separate settings for the allowances for Pin-ended (default 5%) and Fixed-ended connections (default 10%).

  • ECF Definition & Assignment - key aspects of the ECF definition and assignment process are:

    • Open the ECF dialogue to review the current assignment of ECFs which is constantly active, starting at the top of the list of ECFs and working down, so the top factor has first priority and so on. The list order can be changed simply by dragging and dropping factors with the mouse. The assignment of factors updates automatically as edits are made to the list order, and the number of entities to which an ECF is assigned to is given at the right of each factor entry - e.g. 60 for the top “UK rolled hollow sections…” ECF shown in the picture below.

      • Once an entity in the model has a factor from the list assigned the process stops for that entity and category, hence there is no duplication of factor assignment within a category where lower (in the list) ECF definitions are also applicable.

        • It is important to note here that there is not a one-to-one relationship between model entities and ECFs - for example a reinforced concrete member will have different ECFs assigned for both its concrete material and its rebar.

      • Factors can also be activated/ inactivated via the checkbox at the left of each factor entry.
    • To use the ECF dialog you first select the main Category you wish to view/ edit at the top left e.g. “Steel” in the picture above. You can then review for this category the ECF list order, description (which can be any variation of text and numbers etc)value, and the number of assigned entities where applicable.

      • The list of factors in the main dialog can be further controlled by additional filters below the main Category, those available being dependent on the selected category - e.g. by a Grade filter for the material categories and/ or by a Country filter for categories such as Reinforcement and Metal deck.

      • Next, via the Add/ Edit factor options, you can review/ edit the description and/ or value for ECFs and add additional ones. You can also set the Category and Entity filters which control the grades and/ or entity types to which the factor applies. For example you could set a factor for the Concrete category that applies only to the specific grade C32/40 and only concrete columns and beams.

        • The category and entity filters available in the Edit Factors dialog are dictated by the main Category filter set at the top left of the dialog - e.g. “Concrete”, “Steel”, “Cladding” etc. Thus for example only steel entity types are listed in the Edit Factor dialog’s Entity filter list when “Steel” is set as the main dialog Category.

  • Review, Adjustment & Reporting - while the key result of focus is the total Embodied Carbon quantity for the whole model (as shown in the Embodied Carbon Overview Table in the picture above), the engineer will also likely wish to drill down to see how this is calculated and identify areas/objects with high carbon impact that can potentially be improved. A good deal of the development focus for the new features has gone into this aspect. The engineer can review the Embodied Carbon results as follows:

    • Graphical Review/ Adjustment - Review View > Show/Alter state now has powerful new commands to rapidly review and edit the embodied carbon result and settings; “Carbon Factors” and “Utilization and embodied carbon”. These are activated via the new “Embodied Carbon” button in the Show/Alter state group of the Review ribbon and then controlled by their Properties Window settings.
      • Carbon factors - the new Carbon Factors attribute has both Review and Override modes. In the Review mode you can see the distribution of carbon factors throughout the model via a colour coded view. The view legend lists the factor values with the number of entities for each being shown adjacent to the factor value in brackets, as shown in the picture below. Here you can see that different factors are assigned based on the steel section shape; the hollow sections having a slightly higher ECF of 2.5 than the open sections (see picture of ECF’s above). The cursor tooltip also lists the ECF value for a selected member.

        • Note also the Carbon Source category and Entity type filters which allow you to restrict the view to specific categories/ entity types e.g. Steel Members as shown in the view below.
        • You can also use the “Set override” mode to directly apply carbon factors as shown in the picture below - the legend and color coding adjust appropriately to the current override value to show entities with values above/ below it, with the override value set and with other override values > and < this. Overrides can also be removed with the “Remove override” mode.

          • Note that we recommend Set override is used to make limited changes to ECFs rather than for the majority of the model - managing and application of ECFs is most effectively done via ECF definitions which are automatically assigned for you as discussed above. Setting overrides is primarily recommended for entities that require different factors but are indistinguishable in terms of their data (and so cannot be assigned automatically) such as Roof/ Wind panels (in the “Cladding” category).

          • Overrides also appear in the ECF dialogue as ‘Custom’ values where they can be edited or deleted. Deletion removes the override for all entities linked to the factor.
      • Utilization and embodied carbon - this mode enables you to see the distribution of the amount of embodied carbon for each entity. Again you can use the category and entity type filters to tailor the view to what you want to focus on - e.g. Reinforcement in members as shown below.
        • It is important to note here again, as we did earlier, that there is not a one-to-one relationship between entities and ECFs - for example a reinforced concrete member will have different ECFs assigned for both its concrete material and its rebar, both of which will contribute to the member’s total embodied carbon quantity. Hence the facility to restrict the view to specific categories.
        • The Utilization and embodied carbon attribute also features additional filters for Utilization ratio (UR) and Embodied carbon, both of which allow you to set thresholds for the visible entities; either above/ below an absolute value or a highest or lowest % proportion. You can use these filters singly, or simultaneously for example to focus on entities with both a low UR and high embodied carbon by setting the UR filter to “Value below” with a value limit = 0.5 and the Embodied carbon filter to “Highest X%” and Highest = 50%, as shown in the picture below.
    • Tabular Review & Reporting - a comprehensive set of tables for the Embodied Carbon results is added in Review View > Tabular Data. These give both a brief overview and summary of model totals and a potentially highly detailed table for individual entities allowing the engineer to dig right into the details of the calculations. The new report tables ``Embodied Carbon Overview” and “Embodied Carbon Details” are available from the drop list of tabular results at the top left of the Review Data Ribbon tab, as shown in the picture below. Embodied Carbon Mass values are also included in a new column added to every material list (Including the associated report item).

      • Filtering - as for the existing tabular data reports, you can control the new table content using the Ribbon filter buttons for Material Type, Characteristic and Construction etc.

      • Sorting - the tables also feature automated sorting by selected column header - simply click the column header you wish to sort by, then click it again to reverse the sort order, or click another header to sort by that.

      • Reporting - for rapid reporting, the currently configured table can also be exported directly to Excel by clicking the Export Excel Ribbon button. The Overview tables have associated report items and so can also be included in a Report (see below).

      • Locating - as with the Material List tables, you can locate in the model the entity or entities associated with a row in the tables simply by double-clicking the row. This will automatically activate the Structure 3D view, then select, highlight and arrow the associated entity/ entities. Together with the filtering and sorting facilities this enables the engineer to rapidly home in on and locate entities with high Embodied Carbon.
      • Embodied Carbon Overview - this features two additional button controls below the drop list “Group by Plane” and “Toggle Selection”. With Group by Plane active, Embodied Carbon totals are given for each construction plane (commonly the floors). When off the total are grouped by Characteristic e.g. Slabs, Beams, Columns etc (see the first picture in this section above for how this looks). Toggle Selection turns on/off all of the Ribbon filter buttons with a single click, so the engineer can quickly set them all on to see the full model results, or set them all off to begin a specific filter such as Material = Concrete and Characteristic = Beams.

      • Embodied Carbon Detail- this table has two levels controlled by the “Summary Only” ribbon button which works in a similar manner to the Material List tables;

        • “Summary Only” on (the default) gives a brief summary table giving the Embodied Carbon Mass quantity for each entity together with their reference (for continuous beam/ columns/ walls a reference and value are given for each span/ stack/ panel).

        • Set the button off to see the Detailed level which gives a much higher level of detail for every entity included in the table, including Embodied Carbon quantities for the individual parts and surfaces of each entity appropriate to the entity type. So e.g. for concrete beams, for each span it gives quantities and Embodied Carbon values for; Concrete, Coating and Reinforcement. For steel composite beams it gives values for; Steel, Coating, End 1 & 2 Connections (allowance), Shear Connectors and (Transverse) Reinforcement.
  • Reports - new report chapters are added for the Embodied Carbon factors and both Overview result tables options of by Plane and Construction Type discussed above. The Overview tables are also included in a new default Embodied Carbon report style (for new models started in this release).

Further details on the above topics are also given in the new Help topic Embodied carbon workflow.
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