Published 1 March 202814 min readLCI GenevaSIA 390/1 · 2032 · KBOBUpdated June 2026
Embodied energy in construction
For decades, a building's energy performance was measured solely by its operational consumption. Today, the energy embodied in materials — embodied energy — often accounts for 40 to 60% of the total environmental impact over the life cycle. This has become a central issue, and Geneva's legal framework now reflects it directly.
Embodied energy (or incorporated energy) refers to all the energy required to produce a building: raw material extraction, industrial processing, transport, on-site installation, maintenance, replacement over the building's life, then demolition and end-of-life treatment.
It is expressed in non-renewable primary energy — historically in MJ/m² of energy reference area (SRE), or in kWh/m²·an annualised over the building's standard service life (60 years per SIA 2032 technical guideline). But the indicator now used by Geneva's legal framework is not energy: it is the embodied carbon, i.e. the balance of greenhouse gas emissions expressed in kg CO₂-eq/m²·an.
A very well-insulated building consumes little operational energy — but if its walls are heavily reinforced concrete with synthetic foam insulation, its embodied energy can cancel out several years of operational savings.
40–60 %
of the total environmental impact over the life cycle (high-performance new building)
60 years
reference service life per SIA 2032 for the annualised calculation
~6–12
kg CO₂-eq/m²·an: embodied carbon range for construction (new build) — Geneva regulatory indicator
~500–900
MJ/m²·an: embodied energy range (primary energy) for a standard new building
Two indicators not to be confusedEmbodied energy measures a quantity of non-renewable primary energy (kWh or MJ/m²·an). Embodied carbon measures greenhouse gas emissions (kg CO₂-eq/m²·an). The two are related but distinct: a material can be energy-intensive without being very carbon-intensive, and vice versa. The decisive point in Geneva: the legal framework (LCI art. 117-118) regulates carbon — so compliance is measured in kg CO₂-eq/m²·an, not in MJ.
Embodied energy vs operational energy
Operational energy (heating, domestic hot water, ventilation, lighting) is the energy consumed during the building's life — this is what the HPE, Minergie® or Passivhaus labels measure. Embodied energy, by contrast, is "spent" even before the building is occupied. The more energy-efficient a building is in operation, the greater the relative share of embodied energy in its overall balance: the two now go hand in hand.
02 — Life cycle assessment
The building life cycle
Life Cycle Assessment (LCA) — or Analyse du Cycle de Vie (ACV) — is the standardised method for quantifying a building's environmental impact from "quarry to landfill". In Switzerland, the technical guideline SIA 2032 (life cycle inventory method) and the European standard EN 15978 structure the LCA into four main modules.
A
Production & construction
A1–A3: raw material extraction, product manufacturing A4: transport to site A5: installation and construction waste
B
Use
B1: impacts during use B2–B5: maintenance, repair, replacement B6–B7: operational energy and water use
Net benefits: material recycling, energy recovery, reuse. Wood stores carbon (negative D).
In practice, Geneva's regulatory calculation relies mainly on modules A1–A3 (material manufacturing) and B4 (replacements over the service life), which make up most of the embodied energy for a well-designed new building. Modules C and D are included in comprehensive approaches (SNBS, DGNB).
Component service life: a key factor
Embodied energy includes replacements over the service life (module B4). The structure (concrete, solid wood) lasts 80–100 years. The envelope (façades, roof) 30–50 years. Building services (mechanical ventilation, heat pump) 15–25 years. Insulation or a finish replaced twice over 60 years doubles its embodied energy impact — hence the importance of the intrinsic durability of the materials chosen.
03 — The footprint of materials
Not all materials are equal
Embodied energy varies considerably depending on the material. The Swiss database KBOB (Koordinationskonferenz der Bau- und Liegenschaftsorgane) publishes the reference values used in all regulatory calculations in Switzerland. The chart below compares the embodied energy of typical constructions per m² of gross floor area.
Construction embodied carbon (kg CO₂-eq/m²·an) shown as the primary value, embodied energy (MJ/m²·an) alongside. Indicative values, annualised over 60 years, modules A1–A5 + B4, per m² SRE. Orders of magnitude based on KBOB and SIA 2040 / 390-1 target values.
Three material levers stand out systematically: the structure (concrete vs wood), insulation (synthetic vs mineral vs bio-based) and the façade cladding (aluminium or zinc vs render or wood). Together, these three categories account for 60 to 70 % of a new building's embodied energy.
Wood: a carbon advantage
1 m³ of solid wood stores around 900 kg of CO₂ and requires 5 to 10 times less embodied energy than an equivalent volume of reinforced concrete. In module D, wood at end of life can be recovered for energy, returning part of the primary energy.
Steel: high performance, high energy
Steel is very strong for its mass — but its production energy is high (~20 GJ/t). Used in composite steel-concrete structures, it can double the structural embodied energy. Recycled steel (Electric Arc Furnace) reduces this impact by 60–75 %.
04 — Geneva's legal framework
LCI art. 117 & 118: what the law requires
The canton of Geneva has embedded, in its Loi sur les Constructions et les Installations (Buildings and Installations Act, LCI, RSG L 5 05), requirements that go beyond mere operational energy performance. Articles 117 and 118 form a complementary pair: one sets the rule for material selection, the other the method for measuring their carbon impact.
LCI · Art. 117Embodied carbon of materials — priority to reuse
Article 117 requires limiting the embodied carbon of construction materials, establishing a clear hierarchy:
Priority to reused materials — components recovered and reused
Failing that, use of recycled materials
Encouragement of low-embodied-energy materials (wood, bio-based, geo-sourced, local materials)
This is the legal framework for the "zero waste" approach and reuse on Geneva construction sites — the one applied from 2021 on the Carouge 87 renovation, the canton's first zero-waste site.
LCI · Art. 118Calculating embodied carbon — full life cycle
Article 118 defines how this footprint is measured: a balance of greenhouse gas emissions over the entire life cycle of the building, expressed in kg CO₂-eq/m²·an — material manufacturing, installation, operation, deconstruction. In practice:
The reference standard is SIA 390/1 "The Climate Path" (which replaced the SIA 2040 technical guideline); it sets limit and target emission values
The life cycle inventory calculation follows the method of the SIA 2032 technical guideline, based on values from KBOB
Not all cantonal quantitative thresholds have yet been set — the order of magnitude cited is ~5 kg CO₂-eq/m²·an for renovation (ref. SIA 2040 / 390-1)
Note: refer to the updated OCEN requirements and to standard SIA 390/1 for the applicable calculation values.
The calculation method by category — the keystone of the LCI
The carbon balance is not calculated material by material in a disorganised way, but by breaking the building down into major construction categories, each assessed using KBOB values and then summed. It is this breakdown by category that makes the approach practicable and comparable from one project to another:
In Geneva, the State, SIG and SSE have developed a dedicated tool for this calculation, long known as B2CB and replaced in 2025 by the platform "Bilan carbone chantier" (BCC, Construction Site Carbon Balance), made freely available to professionals.
And what about the HPE / THPE levels?
Contrary to a common misconception, the HPE and THPE levels are not defined by these articles of the LCI: they fall under the règlement d'exécution de la loi genevoise sur l'énergie (implementing regulation of the Geneva Energy Act, REn, art. 12B / 12C — LEn L 2 30) and concern the energy performance of operation. See the comparative guide to labels.
Weighing of interests: LEn (L 2 30) ↔ LCI — towards the primacy of carbon?
The two frameworks can come into tension. Aiming for a THPE level under the LEn drives down operational energy — more insulation, higher-performance glazing, more building services. Yet each of these additions carries a cost in embodied energy and embodied carbon, precisely what the LCI aims to limit. Beyond a certain point, the operational gain can be partly cancelled out by the additional construction carbon. Professional practice tends to consider that carbon logic (LCI) should take precedence over energy logic alone (LEn) when trade-offs arise — an orientation, however, that is not yet officially settled. Pending a formal framework, best practice is to optimise jointly both balances from the design stage, rather than maximising one at the expense of the other.
Coordination with the MoPEC
The canton of Geneva operates within the intercantonal framework of the Modèles de Prescriptions Énergétiques des Cantons (MoPEC, Cantonal Model Energy Regulations), whose 2025 revision progressively tightens requirements. Cantonal transposition via the LCI allows Geneva to go beyond the minimum baseline, notably by requiring LCA consideration from the design phase for projects of a certain scale (refer to the OCEN requirements in force for the applicable thresholds).
05 — Calculation tools
SIA 2032, KBOB and software
Calculating embodied energy rests on three complementary pillars: a methodological standard (SIA 2032), a database of material values (KBOB), and software tools that combine the two.
Swiss standard
SIA 390/1 — The Climate Path
Standard on "greenhouse gas and energy emissions balance in buildings" (2025 edition, replacing the SIA 2040 technical guideline). Sets limit and target values in kg CO₂-eq/m²·an. This is the standard referenced by Geneva's LCI (art. 118).
Swiss technical guideline
SIA 2032 — Embodied Energy of Buildings
Technical guideline describing the life cycle inventory method: LCA modules to include, standard component service lives, presentation rules. It is the "calculation specification" applied to establish the balance required by SIA 390/1.
Geneva cantonal tool
Bilan carbone chantier (BCC, Construction Site Carbon Balance)
Platform developed by the State of Geneva, SIG and SSE (formerly B2CB, renewed in 2025). Calculates a building's GHG emissions by construction category, over the full life cycle. Free and open to professionals — the reference tool for LCI compliance in Geneva.
Swiss database
KBOB — Life Cycle Inventory Data
Database maintained by Swiss public sector building owners. Provides values for non-renewable primary energy (EPNR), total embodied energy and GWP (kgCO₂eq) for all common construction materials.
Online software (Austria)
eco2soft
Building life cycle assessment calculation tool developed in Austria (baubook, with Energieinstitut Vorarlberg and IBO). Relatively simple interface, suited to standard-sized residential and commercial projects; to be combined with KBOB values for Swiss use.
European software
One Click LCA
Multi-standard cloud platform (EN 15978, SIA 2032, DGNB…). Supports international databases (ecoinvent, KBOB, ICE). Suited to complex projects, DGNB certifications and RE2020 compliance reports.
Preliminary sizing tool
Lesosai / PHPP
Lesosai includes an embodied energy module (modules A–C) alongside the regulatory thermal calculation. PHPP (Passivhaus) focuses on operation — to be combined with eco2soft or One Click LCA for embodied energy.
European database
ecoinvent
The world's leading LCA reference database, managed by a non-profit association based in Zurich. Highly detailed, used as a back-end by most professional software. Accessed via subscription or built into partner tools.
When to calculate?
Embodied energy is ideally calculated in two stages: a preliminary estimate at the preliminary design phase (APD) to guide structure and envelope choices — when 80 % of decisions are still open — then a detailed calculation at the execution phase for the certification file or LCI compliance. A late calculation (after construction) allows verification but no longer optimisation.
06 — Reduction strategies
How to reduce embodied energy
Unlike operational energy, embodied energy cannot be offset after the fact: it is committed at the time of construction. Structuring decisions must therefore be made upstream, from the earliest sketches.
Bio-based and geo-sourced materials
Solid wood (CLT, glulam), cellulose fibre, hemp, straw, rammed earth, raw earth bricks: these materials have embodied energy 3 to 10 times lower than their conventional equivalents. Wood also stores atmospheric carbon (sink effect). Local geo-sourced materials (stone, earth) eliminate transport energy.
Reuse and the circular economy
Reusing an existing beam or a concrete slab eliminates almost all of the manufacturing embodied energy — only transport and refurbishment are counted. Structural reuse (floors, framing, façades) is one of the most powerful levers, still underused in French-speaking Switzerland but growing fast.
Compactness and structural optimisation
Less material means less embodied energy. A compact form reduces envelope surface area. A structure sized precisely (accurate structural calculation, optimised sections) avoids over-consumption of concrete or steel. The principle of "building lean" is the first embodied-energy move, even before the choice of materials.
Durability and ease of disassembly
A durable material is replaced only once over 60 years instead of two or three — proportionally reducing its B4 impact. Moreover, a "demountable" design (mechanical fixings rather than adhesives, reversible assemblies) enables future reuse of components: this is circular architecture in practice.
Local sourcing and short supply chains
Transport generally accounts for 5 to 15 % of embodied energy (module A4). Favouring certified regional timber (FSC/PEFC), insulation manufactured in Switzerland or neighbouring France, and local aggregates reduces this impact while supporting local supply chains — an argument increasingly valued in Geneva's public tenders.
07 — Labels and embodied energy
Which labels include embodied energy?
Only certain labels go beyond operational energy performance to include embodied energy and the carbon balance of materials. The table below summarises the main certifications available in French-speaking Switzerland and neighbouring France.
Label
Embodied energy required
Standard / method
Remark
Minergie®-ECO
✓ Yes
SIA 2032 + KBOB
The complementary ECO module requires an embodied energy calculation and health/materials criteria
Passivhaus Classic/Plus/Premium
— No (Classic) ◐ Partial (Plus/Premium)
PHPP (renewable energy)
Passivhaus Plus/Premium includes renewable energy generation but not materials LCA as standard
SNBS
✓ Yes — required
SIA 2032 + ecoinvent
"Construction materials" criterion with a maximum GWP and embodied energy threshold; mandatory for reference Geneva public buildings
DGNB
✓ Yes — central
EN 15978 + ÖKOBAUDAT / KBOB
Full LCA (A–D) weighted into the overall score. One of the most demanding systems on this criterion.
Minergie® Standard
— No
—
Operational energy only. The Minergie + ECO combination is needed to include embodied energy.
HPE / THPE (Geneva)
◐ via LCI art. 117–118
SIA 390/1 / KBOB
HPE/THPE (REn art. 12B/12C — LEn L 2 30) cover only operational energy. The embodied carbon of materials falls under LCI art. 117–118, which apply regardless of the target level.
RE2020 (France)
✓ Yes — Ic construction
E+C– / regulatory LCA
Ic construction indicator (kgCO₂eq/m²·an) with a decreasing threshold per regulatory milestones 2022–2031
◐ = partial or incentive-based coverage. — = not required by the base standard.
RE2020: a pioneer on the materials carbon balance
The French RE2020 regulation, in force since January 2022, is one of the first national regulations to make a regulatory LCA mandatory for all new buildings. Its Ic construction indicator caps the CO₂ emissions of materials, with thresholds tightening in 2025, 2028 and then 2031, strongly encouraging timber structures and bio-based materials.
08 — Key questions
What clients ask
Is embodied energy mandatory in Geneva?
Yes, progressively. LCI art. 117 requires limiting the embodied carbon of materials — with priority to reuse, then to recycled materials — and art. 118 defines the method: a balance of greenhouse gas emissions over the entire life cycle. Quantitative thresholds have not yet been set by regulation, but the direction is clear. For public buildings and projects of a certain scale, a formal LCA is expected. Integrating this criterion from the design stage is both a progressively binding legal requirement and good professional practice.
Does building with wood cost more?
Timber construction often carries a 3 to 8 % cost premium on the structural shell compared with conventional concrete — but this figure is shrinking as the supply chain industrialises and thanks to site-level gains (speed, dry installation). Over the whole-life cost (LCC), wood is often competitive, notably through reduced construction waste and the preserved value of components at end of life.
Can concrete be kept while still reducing embodied energy?
Yes, several levers exist: low-clinker concrete (cement substituted with fly ash or blast furnace slag, up to –40 % of CO₂), recycled concrete for certain applications, optimised structural sections, and offsetting through the choice of bio-based insulation and low-embodied-energy finishes. An optimised concrete structure can come down to ~400 MJ/m²·an, close to a standard timber building.
At what project phase should this be addressed?
Embodied energy is essentially "won" or "lost" during the preliminary studies (EP) and preliminary design (APD) phases. A quick estimate based on a massing and a construction system is enough to guide the major choices. Waiting until the execution file to think about it means it is no longer possible to act on the decisions that really matter.
How can embodied energy be integrated into an architecture competition?
An increasing number of competitions in Geneva and Vaud include an embodied energy / carbon balance criterion in their brief. A schematic per-m² estimate (volumetric ratio based on the intended construction system) is enough at competition stage to position the project. KBOB values by construction system allow a quick comparison between variants without detailed modelling.
The embodied energy of your project, in concrete terms?
Preliminary LCA estimate, material choices, reuse, LCI art. 117–118 compliance — let's talk about it from the sketch phase.