A45 vs. LCAbyg vs. Excel: Comparison of A4-A5 tools

Today there are three realistic ways to handle A4-A5 documentation under BR18: LCAbyg, Excel, and A45. All three can in principle be used to arrive at a valid calculation — but they differ significantly in workflow, time investment, and error risk.

This comparison is based on how the tools handle A4-A5 specifically — not the broader LCA (A1-D), where LCAbyg has a completely different role.

There is currently no official standard format for A4-A5 reporting to the municipality. The municipality requires documentation of compliance with the limit value, but the format is not defined — what matters most is traceability from data source to calculation result.

LCAbyg is the free LCA tool developed by BUILD (Aalborg University) with support from the Danish Housing Authority. It is the most widely used tool for full LCA (A1-D) in Denmark and is broadly recognized by municipalities and consultants.

Strengths

• Free and publicly available.
• Covers the full LCA lifecycle (A1-A3, B4, B6, C3-C4).
• Recognized standard — municipalities and consultants know and trust LCAbyg.
• Large library of Danish product data.

Limitations for A4-A5

• A4 (transport) cannot be calculated inside LCAbyg. You need a separate Excel sheet for the transport calculations.
• A5 data (energy, waste) is entered manually via supplementary files — there is no automatic handling.
• No AI, no invoice scanning, no automatic data extraction.
• No continuous compliance tracking — you only see the total result after entering everything.

Funding

The Danish Housing Authority withdrew its support for LCAbyg due to EU state aid rules. In 2026, LCAbyg is funded by foundations. From 2027, a new funding model must be established. This creates uncertainty about long-term development.

Excel is still the most common method for A4-A5 calculation in practice. It is the approach most contractors and consultants are familiar with — and it is free to start with.

Strengths

• No license or subscription.
• Full flexibility — you can build exactly the model you want.
• Everyone knows Excel.

Limitations

• Error risk: Formula errors, incorrect cell references, and manual typos are extremely common. One wrong formula can invalidate the entire calculation.
• No traceability: Who changed what, when? During spot checks, you cannot document changes.
• Coordination chaos: When three parties (main contractor, subcontractor, consultant) send Excel files back and forth, version conflicts arise. Coordination typically takes 1-2 weeks per data collection round.
• No real-time overview: You only see whether you comply with the limit once the spreadsheet is complete.
• Manual data entry: All data from invoices, weigh slips, and meter readings must be entered manually.

A45 is a SaaS platform built specifically for A4-A5 documentation under BR18. It is a newer tool that uses AI to automate data collection and calculation.

Strengths

• AI invoice scanning: Upload invoices, delivery notes, and fuel receipts. AI extracts materials, weight, distance, and fuel type automatically.
• Automatic BR18 calculation: Calculates according to Table 8, 10, and 11 without manual formulas.
• Method comparison: Compare measured data, standard values, and EPD per emission — automatically select the lowest result.
• Real-time compliance tracking: See continuously whether the project complies with the limit.
• Team collaboration: Invite contractors, subcontractors, consultants, and building owners to the same project.
• Coordination time: Typically reduces coordination from 1-2 weeks to hours.

Limitations

• Only covers A4-A5 — not the broader LCA (A1-A3, B4, B6, C3-C4). For that, you still need LCAbyg or similar.
• Requires a subscription (from 199 DKK/project/month).
• New on the market — shorter track record than LCAbyg.

The choice depends on your role and your project's complexity:

• Consultant with full LCA responsibility: You probably already have LCAbyg for A1-A3. For A4-A5, you can supplement with either Excel or A45. The question is whether the time savings justify the subscription.
• Contractor with A4-A5 documentation responsibility: A45 is designed for you. Upload invoices, get calculations, share with your consultant. No LCA expertise required.
• Small project with few materials: Excel may be sufficient if you have control of the formulas and are only coordinating with one party.
• Large project with many parties: The coordination savings from a shared tool (like A45) typically exceed the subscription cost many times over.

An important point: the three approaches are not mutually exclusive. Many projects use LCAbyg for A1-D and supplement with A45 or Excel for A4-A5. This is a completely normal and sensible division.