Calculator Inputs
Example data table
Illustrative entries only. Replace values with verified data sources.
| Material | Density (kg/m³) | ECF (kgCO2e/kg) | Storage credit (kgCO2e/kg) | Typical transport factor |
|---|---|---|---|---|
| Hempcrete (hemp-lime) | 300 | -0.05 | 0.20 | 0.10 kgCO2e/ton-km |
| Cross-laminated timber (CLT) | 470 | 0.12 | 0.90 | 0.10 kgCO2e/ton-km |
| Biochar concrete additive | — | -0.80 | 1.20 | 0.10 kgCO2e/ton-km |
Formula used
Mass(kg) = Tonnes × 1000
Volume(m³) = Area(m²) × Thickness(m)
Storage credit = Mass × Storage
Transport = (Mass/1000) × km × Transport factor
End-of-life = Mass × EOL factor
How to use this calculator
- Add each material as a separate row.
- Select a quantity type and enter matching inputs.
- Provide density for m³ or m² entries.
- Enter ECF, storage, transport, and end-of-life factors.
- Press Calculate and review the summary above.
- Download CSV or PDF after results appear.
Lifecycle scope and boundary settings
Results change when you change the assessment boundary. This calculator separates embodied impacts, biogenic storage credit, transport emissions, and end‑of‑life factors, then combines them into one net figure. Keep the same scope across materials so comparisons remain fair. If one dataset reflects A1–A3 only while another includes A1–A5 plus C stages, rankings can reverse. Record which modules your factors represent and keep the boundary consistent across scenarios.
Interpreting ECF and storage credit values
ECF is entered in kgCO2e per kilogram and can be positive, zero, or negative. Negative values are plausible only when documented carbon uptake exceeds upstream process emissions. Storage credit represents carbon stored in the product and reduces net emissions. To manage uncertainty, run two cases: storage credit equals zero and storage credit equals the reported value. The difference highlights sensitivity to permanence assumptions and end‑of‑life treatment.
Transport sensitivity and distance planning
Transport emissions use ton‑kilometers: (mass/1000) × distance × transport factor. For example, 8,000 kg moved 120 km at 0.10 kgCO2e/ton‑km adds 96 kgCO2e. Heavy materials with modest embodied impacts can become carbon‑positive if haul distances are long. Use route distances, reflect mode where possible, and test distance bands such as 50, 100, and 200 km.
Cost and carbon performance together
Costs are estimated using unit cost per m³, per tonne, or per m², matching the quantity type you select. Reviewing cost beside net emissions helps identify low‑regret substitutions. Track net kgCO2e per m³ for volumetric elements and net kgCO2e per tonne for traded commodities. If two options are both carbon‑negative, prioritize reliable supply, local sourcing, and installation.
Using outputs for procurement documentation
CSV export provides row‑level mass, component emissions, and net results for audits and tender comparisons. The PDF summary highlights totals and key line items for quick stakeholder review. For procurement, store the factor source, transport assumption, and end‑of‑life pathway alongside each specification. When an EPD or mix design changes, rerun the same template and keep before‑and‑after exports for traceability.
FAQs
1) What makes a material carbon-negative in this calculator?
A material is carbon-negative when net emissions are below zero after combining embodied impacts, storage credit, transport emissions, and end-of-life emissions using your provided factors and quantities.
2) Can I calculate using tonnes instead of volume?
Yes. Choose the tonnes option, enter mass, and add factors per kilogram. Density becomes optional and is used only to estimate volume-based intensity metrics.
3) Why do I see carbon-positive results for a “green” material?
Long transport distances, high end-of-life impacts, or conservative storage assumptions can outweigh upstream benefits. Review the breakdown to identify the component driving the increase.
4) What if my ECF data uses a different boundary than my end-of-life factor?
Mixing boundaries can mislead comparisons. Align factors to the same modules, or run separate scenarios where you standardize scope across every material line item.
5) How accurate are the cost numbers?
Costs are estimates based on unit rates you provide. They are most useful for comparing alternatives under the same assumptions, not for producing a final bill of quantities.
6) What is the best way to share results with a team?
Use the CSV for full transparency and auditing, then share the PDF summary for fast review. Keep factor sources and assumptions with the exported files.