Methodology

The atlas is a bottom-up, building-by-building embodied-carbon account of Germany's 19.4 million residential buildings. Each estimate is a representative value drawn from the pool of assemblies documented for buildings of the same type and age, aggregated to any spatial scale by floor-area-weighting. Full methodological detail lives in the accompanying paper and its supplementary material.

Life-cycle scope

The system boundary follows DIN EN 15978. The embodied global warming potential (GWP_A–C) covers:

Module	Stage	Description
A1–A3	Product stage	Raw-material supply, transport, and manufacturing of construction components
B4	Replacement	Periodic replacement of components over the building service life
C3–C4	End of life	Waste processing and disposal

Modules A4–A5 (construction process), B1–B3 (use-phase maintenance), B5–B7 (refurbishment, operational energy and water), and C1–C2 (deconstruction, transport to waste processing) are excluded because the underlying assembly database does not report them. Operational modules B6–B7 are excluded by definition as they are not embodied.

Functional unit

The functional unit is kg CO₂e per m² net floor area (NFA) per year, annualized over a reference study period of T = 50 years.

Life-cycle module decomposition

Each building's embodied carbon is resolved into three module groups that map onto the timing of the emissions:

Product stage (A1–A3) — released in full when the building is constructed, and already spent for the standing stock.
Replacement (B4) — recurring replacement of components over the building's service life.
End of life (C3–C4) — waste processing and disposal, incurred only when a building is demolished.

Each group is reported as a minimum–maximum bracket obtained by pairing each component with its lowest- and highest-impact representative construction. End-of-life therefore remains contingent on a decision that has not yet been taken: keeping a building in use defers it indefinitely.

Data sources

Dataset	Role	Reference
ETHOS.BUILDA	Building geometries and attributes for ~19.4M German residential records (location, footprint, height, net floor area, construction year, roof shape, size class)	Dabrock et al. (2024); Dabrock et al. (2025)
Meier-Dotzler	Component-level GWP intensities (gwp_A–C) for 1,154 German building assemblies, resolved by component type and building age class. Only the OldBuilding family (521 assemblies) is used.	Meier-Dotzler (2023)
TABULA	Residential building typology providing classification logic and geometric ratios (e.g. window-to-wall) used to harmonize ETHOS.BUILDA and Meier-Dotzler	EPISCOPE/TABULA

Sample coverage

All 19.4 million residential buildings in ETHOS.BUILDA are assessed, spanning every federal state. For 10 states the geometry rests on official 3D building models (LOD2); for the six remaining states, building heights are estimated from OpenStreetMap footprints via a machine-learning model (Dabrock et al., 2025).

Building stratification

Every building is assigned to a class key defined jointly by its size class and building age class (BAC):

Size class: Single-family House (SFH), Terraced House (TH), Multi-family House (MFH), Apartment Block (AB).
Building age class (BAC): 11 classes (BAC1–BAC11) following the TABULA period definitions, from the pre-1919 stock through 2016 onward.

Uncertainty

Each reported value is a representative estimate for a class of similar buildings, not an as-built measurement of a specific structure. The estimation model quantifies the resulting uncertainty and was cross-checked against an independent bottom-up case study. Full procedure and results are reported in the accompanying paper and its supplementary material.

Aggregation

Building-level results aggregate to any spatial unit G by floor-area-weighting:

{GWP}_{m^{2} a, G} = \frac{\sum_{i \in G} {GWP}_{i}}{T \cdot \sum_{i \in G} A_{NFA, i}}

where ${GWP}_{i}$ is a building's embodied carbon over its 50-year study period, $A_{NFA, i}$ its net floor area, and $T = 50$ years. This is mass-conserving, so the national total is preserved at every scale.

Citation

Kaufmann, V., Meier-Dotzler, C., Lang, W. & Zhu, B. (Work in Progress). Embodied carbon of Germany's residential stock and the emission cost of retrofitting it. Working paper, Technical University of Munich.