Where does your house's carbon live?
The embodied carbon (A1–A5) of a single-family home, chapter by chapter of the bill of quantities. Bar length is each chapter's weight, colour answers who decides on it, and the whisker shows the range across the literature. Change the total or the m² to estimate your home's tonnes. (Chart labels in Spanish.)
We group structure together with the envelope as a single decision —the constructive system— because in a load-bearing wall (timber frame, CLT, structural clay block, rammed earth) the wall is the structure: choosing it governs around 60% of the embodied carbon. If your project uses a pillar/frame structure (concrete or steel), the structure is more tied to the structural calculation and the part the designer can freely choose narrows to the envelope (~28%). The chapter breakdown doesn't change; what changes is who decides.
Synthesis of ranges from 8 sources (WBCSD, INDICATE-Spain/GBCe, González-Vallejo et al., ISOSTATIKA, Build UP, Mercader et al., ARDITEC-BCCA, EcoHabitar). Central percentages are our own synthesis of the ranges, not a single measurement; the total (600 kg CO₂e/m²) is an editable assumption. The 'load-bearing wall' mode changes no percentage: it regroups who decides.
A home's embodied carbon, chapter by chapter
Breakdown of the embodied carbon (A1–A5) of a conventional single-family home across the bill-of-quantities chapters. Percentage of the total, with the min–central–max range from the literature, and its equivalent in kg CO₂e/m² on a 600 kg CO₂e/m² assumption. The 'who decides' column groups the structure within the constructive system. Ordered from highest to lowest footprint.
| Chapter | % min · central · max | kg CO₂e/m² | Who decides | The Descarboniza lever |
|---|---|---|---|---|
| Structure | 25 · 32 · 40% | 192 | Constructive system | Timber/light frame; short spans; lightened floors; low-clinker concrete |
| Façades | 12 · 16 · 20% | 96 | Constructive system | Rammed earth, adobe, CEB, straw; biobased insulation (cork, hemp); lime instead of cement |
| Foundations | 10 · 15 · 20% | 90 | Ground & foundations | Optimise geometry; blended cements; lime for soil improvement |
| Finishes | 8 · 10 · 15% | 60 | Interior & services | Lime mortars; exposed earth; durable finishes |
| Roof | 5 · 7 · 9% | 42 | Constructive system | Timber structure; reclaimed tiles; cork; green roof |
| Masonry & partitions | 5 · 7 · 9% | 42 | Interior & services | Lightweight partitions; straw/timber panels; flexible layout |
| Services | 5 · 6 · 10% | 36 | Interior & services | Passive design = less equipment; accessible, demountable services |
| External joinery & glazing | 3 · 5 · 6% | 30 | Constructive system | Certified local timber; durability (fewer replacements); recycled glass |
| Earthworks | 1 · 2 · 3% | 12 | Ground & foundations | Minimise excavation; reuse soil on site (rammed earth, CEB) |
| Constructive system (structure + envelope) | 45 · 60 · 75% | 360 | In a load-bearing wall (timber frame, CLT, structural clay block, rammed earth) a single decision governs this block. In a pillar structure, the structure (~32%) is tied to the calculation and only the envelope (~28%) is freely chosen. | |
| Ground & foundations | 11 · 17 · 23% | 102 | Set by the site and the structural calculation, not by material choice. | |
Bill-of-quantities chapters (BCCA/PEM) do not map one-to-one onto Level(s)/EN 15978 elements; the mapping is declared per row. Central percentages are our own synthesis of the ranges from 8 sources (F1–F8), not a single measurement. The total (600 kg CO₂e/m²) is a working assumption derived from INDICATE-Spain 2024. n/d = no data.