Building LCA tools look similar and are not. The right choice depends on the job: producing a figure that survives certification, evidencing a funding application, steering a design before it is fixed, or sanity-checking a number in ten minutes. A tool that is excellent at one of these is often unremarkable at another — which is why feature-matrix comparisons mislead.
This guide is written by a team that builds one of these tools, so read the last section with that in mind. It is more useful to be straight about where Elementa does not fit than to claim it fits everywhere.
The short version
- Certification and compliance — you need verified data, EPD handling and standards coverage. This is where the established platforms are strong.
- Funding evidence (QNG, KfW) — you need output in the form the funding body accepts, which is a workflow question more than a calculation one.
- Early-phase decisions — you need speed and comparability across options, not precision on one option.
- Quick sanity checks — free calculators are genuinely fine, and paying for this job is a waste.
- Most teams eventually need two tools, because the early job and the certification job pull in opposite directions.
- Whatever you pick, check which database it uses. In Germany and Austria that question decides whether your figure reconciles with the assessment that follows.
What are the four jobs?
1. Producing a figure that survives certification
| Job | What matters | Tools positioned here |
|---|---|---|
| Certification | Verified data, EPD import, scheme coverage | One Click LCA; eLCA for BNB; eco2soft in Austria |
| Funding evidence (QNG, KfW) | Output in the accepted form | CAALA |
| Early design steering | Speed, whole-building, comparative | SCALE, One Click LCA Carbon Designer 3D, Elementa |
| Retain or replace | Existing and proposed compared | CARE Tool, Gebäude-Klimarechner, Elementa |
| Sanity check | Free and immediate | Ökobil, EcoTool, Grauer-Energie-Rechner |
The output is a document someone signs. What matters is verified product data, correct EN 15978 module handling, EPD import, and coverage of the certification scheme you are pursuing — DGNB, BREEAM, LEED, or the EPBD disclosure itself from 2028.
One Click LCA is the established platform here: cloud-based, BIM-integrated, broad standards and scheme coverage, and a large multilingual resource library. If your requirement is a certified assessment on a scheme it supports, it is the default for good reason.
Two regional alternatives belong here too. eLCA, from the German federal institute BBSR, is free, uses ÖKOBAUDAT and is BNB-conformant (BBSR, nachhaltigesbauen.de). In Austria, baubook eco2soft, developed by Energieinstitut Vorarlberg and IBO, calculates GWP, AP, PENRE and the OI3 indicator; it is free for up to three buildings with watermarked results and €120 per user per year for professional use (Energieinstitut Vorarlberg). For a job-by-job comparison, see One Click LCA alternatives.
2. Evidencing a funding application
Germany’s QNG standard and the KfW programmes attached to it have specific evidentiary requirements. The calculation matters, but so does producing it in the accepted form.
CAALA is strong in this territory and writes about it extensively — QNG-conformant Ökobilanz, energetic pre-dimensioning, and cost alongside carbon. If a German funding application is the deliverable, that focus is worth more than raw breadth.
3. Steering a design before it is fixed
Here the question is not “what is this building’s carbon?” but “which of these two buildings is lower, and roughly by how much?” That is a far easier question, and a different tool shape: fast, whole-building, tolerant of unknowns, comparative rather than absolute.
SCALE (Austria) works in this space, combining life-cycle GWP with circularity assessment from an early planning phase. One Click LCA’s Carbon Designer 3D starts from building type, floor area and storey count and generates quantities; it is an add-on requiring a Business licence or above (One Click LCA). Elementa is also here — more on that below. For the method behind any of them, see estimating embodied carbon at concept stage.
3a. Deciding what to keep in an existing building
A special case of early design, and the one with the largest carbon at stake. The CARE Tool (Architecture 2030 and partners, grant-funded) compares renovating with replacing, embodied and operational, at early design (caretool.org). The free Gebäude-Klimarechner (g-kr.online) compares renovation strategies with replacement construction and launched in 2026 as a beta for residential buildings (bau.bi). Elementa works element by element; see the retain-or-demolish worked example.
The distinguishing question to ask any tool in this category: how long does it take to get a first whole-building number? If the answer is measured in days, it will not be used at concept stage, whatever it claims.
4. Sanity-checking a number
Sometimes you want to know whether 400 kg CO₂e/m² is plausible. Free tools do this well — Ökobil, EcoTool, and Freiburg’s Grauer-Energie-Rechner among them. Paying for this job is a waste, and no one should be sold a platform to answer it.
The question most comparisons skip: which database?
A carbon figure is the product of a quantity and an emission factor. The factor comes from a database, and which database is not a detail in DACH.
ÖKOBAUDAT is the German federal construction-material database, free, EN 15804 conformant, and what German certification and funding routes expect. Austrian practice additionally draws on baubook. Tools built for the German market work against these.
Tools built elsewhere often use other datasets — the UK’s ICE database is common and perfectly respectable, but a figure derived from it will not reconcile line-by-line with an ÖKOBAUDAT-based assessment. That is not a quality problem. It is a comparability problem, and it surfaces late, when someone tries to match two numbers that were never going to match.
Ask the question early: which database, and does it match the one my certifier will use?
Where does Elementa fit — and where does it not?
Elementa is a pre-assessment tool: an indicative whole-building figure on Elementa’s seven building systems, for the product stage (EN 15978 modules A1–A3), at concept stage, with circularity pathways for existing fabric and indicative assembly costs from a versioned 2026 Austrian reference of expert estimates (±15–25 % for most rates; not tender prices).
It is a good fit if you are choosing between structural systems, deciding whether to retain or demolish, or need a defensible early number before anyone will fund a full assessment.
It is the wrong tool if you need a certified assessment, a QNG submission, or BIM-integrated workflow on a live model. It does not do those, and it says so plainly — an indicative figure cannot be the value disclosed on an energy performance certificate.
Being straight about the database: Elementa prices each layer from an ÖKOBAUDAT generic dataset (EN 15804+A2, modules A1–A3) pinned to that layer. It proposes the dataset that fits the project’s location first, generic before product-specific, and asks you when several fit equally. A layer with no dataset pinned stays unpriced and is left out of totals rather than given a default figure. Earlier versions used the ICE database; that has been removed. Working from ÖKOBAUDAT means the early figure draws on the database German certification routes expect, but it is still an indicative pre-assessment of the product stage, not a QNG or DGNB submission — the certified assessment will typically replace generic datasets with product EPDs.
How should you choose, in practice?
- Name the deliverable. A certificate, a funding submission, a design decision, or a sanity check. Everything follows from this.
- Check the database against your certification route, before anything else.
- Time the first result. For early-phase work, a tool that takes days will not get used.
- Assume you will need two. The early-phase tool and the certification tool are different products, and the handover between them matters more than either tool’s feature list.
- Distinguish estimate from assessment in writing — in board papers, tenders and marketing. This is a governance question from 2028 onward, when the figure lands on a certificate.
Frequently asked questions
Can one tool cover the whole project? Some try. In practice the early-phase job rewards speed and tolerance of unknowns, while certification rewards precision and verified data. Most teams end up with two and should plan the handover deliberately.
Is free software good enough? Price isn’t the question; provenance is. eLCA is free and BNB-conformant on ÖKOBAUDAT. A free sanity-check calculator isn’t built for a certificate. What you need for a certified figure is auditable data provenance and correct module handling, whoever pays for the tool.
Does the tool decide compliance? No. From 2028 the EPBD requires a life-cycle GWP calculated to EN 15978 and disclosed on the EPC. The tool supports that; it does not confer it.
How much does the database really change the number? Less than the quantities do. A different database moves the figure by a margin that matters at certification and rarely changes a design decision — but it does decide whether two assessments reconcile.
Where this leaves you
The honest summary is that these tools are not competing for one job; they are serving four. The mistake is not choosing the wrong tool, it is not naming the job first.
Early figures are indicative and directional. They inform decisions; they do not replace a verified life-cycle assessment or an energy performance certificate.
This guide describes tools as at August 2026, from publicly available information. Products change; verify current capability with each vendor. Elementa is our own product and is described in the same terms as the others, including where it does not fit.