There is a curtain.
Behind it is a number.
The number is wrong.

One room with every calculator in it

The world has built dozens of carbon calculators for buildings. Each was built by a different organisation — sometimes a government agency, sometimes an industry association, sometimes a software company. Each calculator uses a slightly different set of rules. Each one stops counting carbon at a slightly different point.

If you ask the wood industry's calculator about a wooden building, it gives a low number. If you ask the concrete industry's calculator about a concrete building, it gives a different low number. Both calculators are technically correct under their own rules. Neither one tells you the full story.

This site puts every calculator, every standard, and every country's rule in one room, side by side. It also publishes a recomputation of well-known buildings under a wider set of rules — the same rules other industries already have to follow. The recomputed numbers are larger. They are also more honest.

The framework underlying the recomputations is called Divergent Resource Logic, or DRL. The name comes from a simple observation: the rules that apply to a tree and to a rock are different. Same extraction. Same processing. Same downstream effects. Different rules. That divergence is what this site exists to make visible.

How far different materials are counted

Every life cycle assessment has a boundary. The boundary is the line where counting stops. The chart below shows how far each common construction material gets counted under standard rules. A bar that goes from 0 to 100 means cradle-to-grave — every emission, from extraction through to final disposal. A shorter bar means counting stops earlier.

The chart is schematic — exact percentages vary by standard and study. The shape is not in dispute. Aluminium gets a recovery credit (Module D) and is counted to the gram. Steel is similar. Concrete includes carbonation re-uptake at end-of-life. Timber, alone among major construction materials, both starts late (skips soil and forest dynamics) and ends early (skips most end-of-life methane).

The three pieces missing from timber's bar

The shaded extension on the timber bar above represents three specific carbon flows that other materials' bars include but timber's does not:

1. Soil carbon. About half a tree — by mass and by carbon content — is underground. Roots, soil fungi, the organic layer in the topsoil. When a forest is clear-felled, much of this carbon oxidises and leaves the soil over the following decade. Peer-reviewed meta-analyses put the loss at roughly 11% of soil organic carbon in the top 30 cm. It is not in any standard wood LCA.
2. End-of-life methane. When timber is buried in landfill at the end of a building's life — which most of it is, in the U.S. and Canada — the wood decomposes anaerobically and releases methane. Methane is 27.9 times more potent than CO₂ over a hundred years. Standard wood LCAs assume preferred end-of-life scenarios; reality often differs.
3. Foregone sequestration. If a tree had not been felled, it would have kept growing — and the science is now clear that large trees keep adding mass faster than small trees. Stephenson and colleagues confirmed this in Nature in 2014 across 403 species. The carbon a forest would have stored, had it not been harvested, is the largest of the three missing pieces and the most contested.

Add those three lines and the timber bar gets longer. The wooden building's carbon number gets bigger. Sometimes a lot bigger. That is the entire arithmetic of DRL.

The boundary did not move by accident

The standards that govern building life cycle assessment — EN 15978 in Europe, ISO 14040/44 globally, the various national standards built on top — all share the same treatment of biogenic carbon. The treatment is called the carbon-neutral convention. It says: sequestration in growing wood is reported as a negative emission at production stage; the same amount is then reported as a positive emission at end of life. The net is zero. By convention. Regardless of what actually happens to the carbon.

This is a methodological choice. It was made decades ago when the science of soil carbon and forest dynamics was less developed. It has not been revisited as the science has caught up. The bodies that maintain the standards — the European Committee for Standardization, the International Organization for Standardization, the major wood-industry research consortia — have all participated in the development of mass timber building codes and life cycle assessment methodology in the same period, often in the same working groups.

None of that is a secret. All of it is in published meeting records, industry-funded grant programmes, and lobbying disclosures.

What government has published about it

In the United States, three pieces of public record are sufficient to demonstrate the configuration without naming intent:

• On 23 April 2018, the U.S. Environmental Protection Agency issued a policy statement classifying forest biomass as carbon-neutral for the purpose of stationary-source emissions accounting. The statement itself notes, verbatim: "this statement of agency policy is not a scientific determination." The same day, the American Forest & Paper Association issued a press release characterising the EPA's classification as "reflecting long-standing scientific principles." Both documents are public.
• The U.S. Department of Agriculture's Forest Service has, since 2014, operated grant programmes — including the Wood Innovations Grant Program — that have funded mass timber demonstration projects, building-code research, and life cycle assessment methodology development. Congressional Research Service Report R47752 notes, verbatim: "It is not always clear what specific FS mission area or authority has supported each of these — and other — activities."
• The Softwood Lumber Board, a federally authorised industry checkoff programme, has co-funded WoodWorks (the wood-industry technical assistance organisation behind the Wood Calculator used in the T3 Minneapolis disclosures), with the Board's own published framing for the partnership being to "support, influence, convert" design professionals to wood specification.

None of those facts is contested. They are reproduced from the agencies' and organisations' own publications. The reader can decide what configuration they describe.

The CEO lifespan problem

One more structural observation, and then we move to the personal part. CEOs of forestry companies typically take their roles between ages 45 and 55 and serve, on average, about a decade. The decade in which soil organic carbon drops most steeply is the first one after harvest. The decades in which the end-of-life methane will eventually be released — for buildings constructed in the 2020s — are the 2070s and 2080s. No single person in the corporate chain experiences both ends of the consequence. The forest looks green from the road. The slash pile is behind the hill. Institutional amnesia is not a bug. It is a design feature of how the time horizons line up.

If a factory did this, the news would be on every channel

The thought experiment is short. Imagine a manufacturing facility that, every fifteen to thirty years, releases the same quantity of carbon and disturbs the same volume of soil that a single average industrial clear-cut releases. Now imagine a forestry operation doing the same thing. The two events are not in different regulatory universes by accident — they are in different regulatory universes because we chose to put them there.

The two events do similar things, at scale, to similar quantities of carbon and soil. They face entirely different regulatory consequences. That asymmetry is not natural. It was constructed.

It is starting to change. Slowly. In court.

The carbon-claims regime that has held since the 1990s is beginning to crack — first at the consumer-protection edge, where green-marketing claims are being tested by class-action lawyers, then upstream at the corporate-disclosure level, then upstream again at the methodology level. The construction industry is several years behind tobacco, pharmaceuticals, and fossil fuels on the same trajectory. Greenwashing lawsuits globally roughly doubled between 2020 and 2025, reaching approximately 2,700 active cases.

A small sampling, all from public dockets and press records:

The forestry and mass timber industries have not, as of the most recent public records, been a primary target of these cases. The Apple-style litigation is mostly concerned with carbon-offset quality. The next wave, already visible in the EU Green Claims Directive and in the SFI Competition Bureau filing, will press on the underlying carbon-accounting standards directly. The configuration DRL documents is the configuration those cases will eventually have to contend with.

Some doors

This is not an action page. We do not raise money, we do not lobby, we do not have a mailing list. But people sometimes ask what they can do after reading the recomputations on this site. Here are doors, not instructions.

Read more

Start with the Corrected Ledger — building-by-building recomputations of award-winning timber, concrete, and steel projects. Each page is around a fifteen-minute read. Each one carries a downloadable Reproduction Sheet so the math can be checked. Then the DRL Thesis Codex if you want the full scientific argument.

Support a conservation organisation

These groups are doing different parts of the work. None of them are affiliated with this site. Listed alphabetically, not by ranking.

File a public comment

U.S. federal agencies — including the EPA, USDA Forest Service, and SEC — accept public comment on proposed rules. Comments enter the docket and are part of the public record. If a proposed rule touches on forest carbon accounting, building LCA methodology, or climate disclosure, public comments are read by agency staff. regulations.gov is the entry point.

Use the calculator on your own building

If your organisation is involved in a building project — institutional, commercial, residential — and the project is making a carbon claim, the Corrected Ledger mini-calculators are reusable. The full Disclosure-Ready Calculator is in development; when it ships, every input on every building page will pre-populate it. The point is to make the recomputation easy enough that asking the question becomes routine.