Carbon Index — Overview & Carbon Breakdown Structure (CBS) Engine

The Overview & CBS view is the executive analytics and spatial decomposition interface of the Carbon Index application. Built to align with RICS Whole Life Carbon Assessment (WLCA) 2nd Edition and BS EN 15978, it provides real-time embodied carbon estimation, benchmark rating assessment ($A$ to $G$), NRM elemental breakdown, top material contributors, and an interactive Carbon Breakdown Structure (CBS) hierarchy.

Page Layout & Executive KPI Dashboard

Carbon Index Overview Header & Dashboard

The top section of the Overview tab displays high-level sustainability performance metrics calculated dynamically across all active model elements:

KPI Card	Formula / Basis	Statutory Purpose
Total Upfront Carbon ($A1–A5$)	$\sum (A1\text{-}A3_{\text{Product}} + A4_{\text{Transport}} + A5_{\text{Site Construction}})\ \text{tCO}_2\text{e}$	Core metric for planning statutory submissions (e.g. London Plan Policy SI 2, GLA WLCA).
Upfront Carbon Intensity	$\frac{\text{Total Upfront Carbon } (kgCO_2e)}{\text{Gross Internal Area (GIA) } (m^2)}$	Normalized intensity metric enabling benchmarking against industry targets (e.g. LETI 2030, RIBA 2030).
Benchmark Rating Band ($A$ to $G$)	$A\ (<300),\ B\ (<450),\ C\ (<600),\ D\ (<800),\ E\ (<1000),\ F\ (<1200),\ G\ (\ge 1200)$	Standardized rating band indicating design carbon efficiency relative to UK building benchmarks.
Total Whole Life Carbon ($A–C$)	$\sum (A1\text{-}A5 + B1\text{-}B5_{\text{In-Use}} + C1\text{-}C4_{\text{End-of-Life}})\ \text{tCO}_2\text{e}$	Comprehensive 60-year building lifecycle impact assessment.
Data Quality & Scope Audit	Matched elements vs. Unlinked materials vs. Excluded Scope	Data maturity indicator validating statutory reliability before submission.

RICS NRM Elemental Decomposition & Material Contributions

The secondary analytics tier breaks down embodied carbon across RICS New Rules of Measurement (NRM) building elements and material families:

RICS NRM Elemental Summary & Material Contributors

1. NRM Elemental Summary

Categorizes carbon emissions across statutory RICS NRM element groups:

NRM 1: Substructure: Foundations, basement excavations, ground-bearing slabs, retaining walls.
NRM 2: Superstructure: Structural frames, upper floors, roof structures, external walls, internal partitions, windows, and doorsets.
NRM 3: Internal Finishes: Wall finishes, floor finishes, ceiling finishes.
NRM 4: Services: Mechanical, electrical, and public health installations.
NRM 5: External Works: Landscaping, site boundary fencing, drainage, and paving.

2. Top Material Contributors

Identifies the primary carbon drivers across material classifications (e.g. Ready-Mix Concrete, Structural Steel, Glass, Timber, Masonry):

Ranks materials by total upfront carbon impact ($\text{tCO}_2\text{e}$).
Displays percentage contribution to the overall building footprint.
Highlights target areas for specification optimization and low-carbon EPD substitutions.

Carbon Breakdown Structure (CBS) Hierarchical Cards

The lower section presents the interactive Carbon Breakdown Structure (CBS) grouping cards:

Carbon Breakdown Structure Cards

CBS Card Controls & Indicators:

Group Hierarchy Selector: Switch between grouping by Category, EC Class, or RICS NRM.
Expand / Collapse All: Toggle all group cards simultaneously for rapid review.
Group Metrics Header:
- Element Count: Total physical elements contained within the group.
- Solid Volume & Mass: Reconciled physical volume ($m^3$) and calculated material mass ($\text{tonnes}$).
- Upfront Carbon ($A1–A5$): Combined upfront embodied carbon ($\text{tCO}_2\text{e}$).
- Net Whole Life ($A–C$): Total cradle-to-grave embodied carbon ($\text{tCO}_2\text{e}$).
- Data Quality Tag: Visual indicator showing resolution source (e.g. EC3 Live EPD, ICE Benchmark, Unlinked).

Dynamic Multi-Property Sub-Grouping

Within each expanded CBS group card, users can dynamically sub-group elements by any discovered BIM property:

CBS Subgrouping Toolbar

Quick Property Buttons: Instant sub-grouping by Category, EC Class, Material, Thickness, Manufacturer, or System.
Nested Subgroup Cards: Displays sub-aggregations of volume, mass, and carbon for each discrete property value.
Paginated Elements Table: Deep inspection table listing individual element instances with their ECInstanceId, resolved material, solid volume, density, and upfront carbon contribution.

Element Quick Inspection & Drawer Integration

Selecting any element row opens the Carbon Inspector Drawer:

Carbon Inspector Drawer

Inspection Drawer Capabilities:

Element Identity: ECInstanceId, User Label, Category, and ECClass.
Material Binding: Resolved material name, data quality tier, standard density ($kg/m^3$), and EPD reference.
Mass Properties QTO: Reconciled net volume, author quantity, and reconciliation status (COMPUTED_SOLID vs BOUNDING_BOX).
Lifecycle Modules Breakdown: Full tabular breakdown of $A1–A3, A4, A5, B1–B5, C1–C4$, and Module $D$.
Direct Actions:
- Zoom & Highlight in 3D: Focus the 3D viewport on the selected asset.
- Override Material / EPD: Open the live EC3 search dialog to assign a specific EPD.
- Exclude from Scope: Mark the element as non-embodied carbon scope ($0\ kgCO_2e$).