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News, guides, and insights about BR18 climate documentation.
A45 vs. LCAbyg: Two tools — two different jobs
A45 and LCAbyg don't compete — they cover different parts of BR18. LCAbyg handles the full LCA (A1-D), A45 handles the construction process (A4-A5). See comparison table and the typical setup.
Invoice-based vs. sensor-based A4-A5 documentation
Comparison of two methods for A4-A5 data collection: invoice-based (no hardware, low cost, full BR18 coverage) vs. sensor-based (real-time data, high cost, partial coverage). BR18 does not require real-time measurement.
BR18 A4-A5: The Complete Guide to Climate Requirements for the Construction Process
Everything you need to know about A4-A5 requirements in BR18 — limits, documentation, calculation methods, responsibility distribution, and practical workflow from planning to occupancy permit.
Who is responsible for A4-A5 documentation?
Public-law responsibility, contract types, and contractual provisions — a practical overview of who bears responsibility for A4-A5 climate documentation under BR18, AB 18, and ABT 18.
The two separate CO₂ budgets in BR18
BR18 divides the climate calculation into two separate budgets: materials (A1-A3) and the construction process (A4-A5). You cannot borrow between them. Here's what it means in practice.
Practical guide to data collection on the construction site
Everything you need to collect for the A4-A5 calculation — from delivery notes and fuel receipts to weighing slips and electricity meter data. With checklist and subcontractor handling.
The 1-ton rule and de minimis thresholds in BR18 A4-A5
BR18 §297 exempts machines under 1 ton, water consumption, and consumables from the A4-A5 calculation. Here is the complete overview of exemptions and fixed rates.
Hidden CO₂ traps on the construction site
Construction waste accounts for 38% of the A4+A5 budget — and mixed waste is penalized harshly. Overview of BR18 Table 11's 15 fractions, energy traps from drying and site huts, and concrete reduction strategies.
Standard values vs. measured data: When can you use BR18's table values?
BR18 requires measured data for energy but allows choice for transport. Standard values are up to 70x higher than actual data. See when measurement is mandatory, when you can choose, and the recommended strategy.
A45 vs. LCAbyg vs. Excel: Comparison of A4-A5 tools
Objective comparison of the three realistic approaches to A4-A5 documentation: LCAbyg (free, full LCA), Excel (flexible, risky), and A45 (AI-driven, purpose-built). With comparison table.
Transitional rules 2025: When do the new A4-A5 requirements apply?
The cutoff date is the building permit application date — not the approval date. The 1,000 m² requirement is abolished. Unheated buildings over 50 m² are now covered. Here is the full overview.
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