One Click LCA vs Tally vs EC3: Choosing Building LCA Software

Teams starting embodied-carbon work usually ask which LCA tool is “best”. It is the wrong question. One Click LCA, Tally and EC3 were built for different jobs — certification reporting, design-stage iteration inside Revit, and material procurement respectively. Choose by the question you need answered.

One Click LCA — the certification workhorse

A cloud platform with the broadest coverage of rating systems and regional methodologies. Its strength is compliance breadth: templates and pre-configured calculations for LEED, BREEAM, Green Star, Level(s), national regulations and RICS-style whole-life carbon reporting, backed by a very large global database of EPDs and generic datasets.

• Best for: certification submissions, international projects, full EN 15978 module coverage including B, C and D;
• Inputs: Revit and IFC imports, plus spreadsheet takeoffs — useful when there is no usable model;
• Watch out: it is a paid subscription, and specific capabilities are sold as separate modules. Confirm that the licence you buy actually covers the scheme you need — teams have been caught assuming a general subscription includes a particular certification workflow when that requires an add-on.

Tally — LCA inside the Revit model

Tally runs as a plug-in inside Autodesk Revit. You map Revit materials to LCA datasets and generate results directly from the live model, which makes it excellent for comparing design options while the design is still moving. Because it is tied to the model, results update as the model does.

• Best for: design-stage optioneering in Revit-based practices, particularly in North America;
• Strength: no re-entry of quantities — the model is the takeoff, so iteration is fast;
• Watch out: results are only as good as the Revit model's material mapping and modelling discipline. A schematic model with generic materials produces a schematic answer. Certification coverage is narrower than One Click LCA's.

EC3 — free, and built for procurement

The Embodied Carbon in Construction Calculator, from Building Transparency, is free to use and organised around a large database of digitised EPDs. Its purpose is different from the other two: it is designed to help teams compare and specify actual products, and to set procurement requirements such as maximum GWP limits for concrete mixes or steel.

• Best for: material selection, supplier comparison and writing carbon limits into specifications and bids;
• Strength: free, and it shows the real spread between suppliers for the same product — frequently the cheapest carbon saving available on a project;
• Watch out: its focus is upfront A1–A3 carbon. It is not a substitute for a full EN 15978 whole-building assessment covering the use and end-of-life stages.

Side by side

And for product-level work

None of the three is the right tool for building an EPD background report. That work is done in full LCA software such as SimaPro, GaBi or openLCA, where you control the process model, allocation and datasets at the level a verifier expects.

How to choose

• Chasing a certification credit? Start from the scheme's accepted tools and confirm your licence covers it;
• Comparing schemes and structures at concept? Whatever is fastest to iterate in — often Tally if you live in Revit;
• Buying concrete or steel? EC3, and write the resulting GWP limits into the specification;
• Publishing an EPD? Full LCA software, not a building tool.

Serious projects commonly use two: one for the design and certification model, and EC3 alongside it to drive supplier selection.

The takeaway

The tool matters far less than the scope discipline and data quality behind it. Pick by the decision you are making — certification, design iteration or purchasing — verify that your licence covers the specific scheme before committing, and remember that a free procurement tool used well at the right moment often saves more carbon than an expensive assessment produced too late to change anything.

This article is general guidance and reflects information available at the time of writing. Software capabilities, licensing structures, database coverage and accepted tools for each certification scheme change frequently — always confirm current details with the vendor and the scheme before purchasing.