R01 · Machine room comparative building LCA
This page documents the in-house comparison calculation behind values marked [R01] on bauwen.de. It is a transparent working model, not an official QNG submission.
Comparison model
The construction variants use the same building geometry and use, an energetically equivalent envelope and effectively identical U-values. The initial model is a two-storey detached-house quantity typology with 167.19 m² NRF. It is used because it is small and transparent, not because it is proposed as a preferred housing type.
The detached house is an investigation model, not a model for what should be built.
Where the 38.33 tonnes go
The gap between the two functionally equivalent variants is 83.24 t CO₂e in A1–A3. In the static 50-year total, 44.91 t CO₂e remain. Most of the reduction comes from one block: C3+C4.
| Accounting block | Timber–straw | Massive | Effect on variant gap |
|---|---|---|---|
| A1–A3 | −5.24 t | +78.00 t | 83.24 t |
| Maintenance / replacement | 28.95 t | 30.53 t | +1.58 t |
| B6 static | 75.09 t | 75.09 t | 0.00 t |
| C3+C4 | 49.10 t | 9.18 t | −39.91 t |
| Total | 147.89 t | 192.80 t | 44.91 t |
83.24 + 1.58 − 39.91 = 44.91 t CO₂e.
The present A1–A3 gap is therefore reduced mainly by the modelled end of life of the biogenic variant. B6 does not change the gap in this setup.
Calculation and data state
The energy calculation for the uncooled residential building used DIN V 4108-6:2003-06 including corrigendum 1:2004-03 together with DIN V 4701-10:2003-08, a method permitted under §20(2) GEG until 31 December 2023. [Q09]
The LCA uses ÖKOBAUDAT 2020-II, 03 April 2020, i.e. EN 15804+A1-generation datasets. [Q10][Q11] The building assessment follows the life-cycle logic of DIN EN 15978 and the QNG rules used in the study, with a 50-year reference period. [Q04][Q12]
The ÖKOBAUDAT datasets used are not exactly the QNG calculation values required for an official QNG submission. They are more extensive, but for the values used here they can be regarded as broadly equivalent and identical in the decisive values. This comparison is an in-house calculation, not an official QNG submission. [Q13]
Next calculation states
- larger residential and other building typologies as quantity models;
- a separate current calculation state using EN 15804+A2 ÖKOBAUDAT data — without mixing A1 and A2 datasets; [Q14]
- explicit investigation of biogenic carbon / GWP-biogenic;
- comparison of conventions and time methods.
The historical A1 calculation remains available for reproducibility and will not be overwritten by an A2 update.