v6.1753.0
The IMO CII rating API is now listed wherever the API is described. /developers/, /developers/agents/, llms.txt and llms-full.txt list POST /v1/calculate/cii and the calculate_cii MCP tool. The counts move from seven calculation engines to eight and from twelve MCP tools to thirteen, checked against the live MCP server. The API card on IMO Carbon Intensity Indicator (CII): Calculator and Rating Rules and on the IMO CII Rating Obligation Checker (IMO CII Rating Obligation Checker) now shows a CII rating call: the ClassNK example ship, which the API rates D for 2026. Before, both pages showed a UK grid electricity lookup. Parity: Functions 1530 → 1531 (+1 gc_api_cta_pitch_cii in api-cta.php); hooks, shortcodes, CPTs, taxonomies, meta and constants unchanged. Files: inc/frontend/api-cta.php, inc/frontend/api-corpus-stats.php (engine and MCP tool registries), inc/frontend/api-surface.php, inc/frontend/llms-txt.php, scripts/check-php-parity.sh. Version: GC_VERSION 6.1752.1 → 6.1753.0.
v6.1752.1
Follow-up to v6.1752.0. The homepage still printed WordPress's global-styles CSS (about 15 KB). Since WordPress 6.9, classic themes queue it a second time in the footer and WordPress moves it into the <head>, so the v6.1752.0 removal ran too early. It now runs again straight after the footer queue. Parity: Hooks 409 → 410 (+1 add_action, wp_footer p2 in assets-enqueue.php); functions, filters, shortcodes, CPTs, taxonomies, meta and constants unchanged. Files: inc/frontend/assets-enqueue.php, scripts/check-php-parity.sh. Version: GC_VERSION 6.1752.0 → 6.1752.1.
v6.1752.0
Homepage clean-up. The homepage's WebPage schema now takes its name and description from the page's SEO title and meta description. It had kept the old "Carbon Accounting Calculators & Standards" name after the homepage moved API-first in September, so the schema and the <title> disagreed. Pages built on the homepage's own .gchome stylesheet (the homepage and its noindex staging copy) no longer print WordPress's block CSS, about 19 KB of inline CSS they never used. Full-page screenshots at 1440 and 390 px are identical with and without it. Parity: Hooks 408 → 409 (+1 add_action, wp_enqueue_scripts p9995 in assets-enqueue.php), Functions 1529 → 1530 (+1 gc_gchome_drop_block_css); filters, shortcodes, CPTs, taxonomies, meta and constants unchanged. Files: inc/schema/schema-helpers.php, inc/frontend/assets-enqueue.php, scripts/check-php-parity.sh. Version: GC_VERSION 6.1751.0 → 6.1752.0.
v6.1751.0
New calculation endpoint POST /calculate/cii: a ship's IMO Carbon Intensity Indicator and its A to E rating for every year from 2023 to 2030, from its type, deadweight or gross tonnage, distance sailed and fuel burned. It uses the same engine as the calculator on /standards/imo-cii/, with the optional G5 corrections (voyage adjustments, electrical and boiler consumption, reefers, ship-to-ship and shuttle tankers). Every parameter it uses is listed in the response with its MasterBrain key and IMO citation (resolution, table and page), and the response carries a receipt. Bad input is refused with a 400 or 422 that names the field, including unknown fields. The endpoint cannot be pinned with ?as_of=. It is also available in /calculate/batch as "cii". It goes live on the API when the gateway lists it. The calculator on /standards/imo-cii/ now reads its CII parameters from the MasterBrain (rows reporting.imo_cii.*, MasterBrain v2026.279) instead of the JSON file, and falls back to the JSON, with a log line, if a row is missing. Nothing on the page changes: 6,005 test ships give identical results and markup before and after. The ClassNK worked example and the MEPC.354(78) example are reproduced. Parity: Hooks 407 → 408 (+1 add_action, rest_api_init in rest-cii.php), Functions 1522 → 1529 (+7: gc_cii_mb_row, gc_cii_dd_covers, gc_cii_mb_overlay in sc-imo-cii.php; gc_cii_api_bad, gc_cii_api_num, gc_cii_api_param, gc_cii_endpoint in rest-cii.php); filters, shortcodes, CPTs, taxonomies, meta and constants unchanged. Files: inc/rest/rest-cii.php (new), inc/shortcodes/sc-imo-cii.php, imo-cii.js (the G5 deduction factor read from the data), inc/rest/rest-calc-batch.php, scripts/calc-golden-test.py (CII cases), scripts/check-php-parity.sh. Version: GC_VERSION 6.1750.1 → 6.1751.0.
v6.1750.1
IMO CII ship lookup: a ship whose EU MRV report puts none of its CO₂ inside the EU ETS now reads "None of it was reported as falling within the EU ETS, so no allowances are due" instead of "0 t of it fell within the EU ETS … 0 allowances, about €0". That is 1,038 of the 17,880 ships with a 2025 report, mostly general cargo ships. No figure changes. Update schedule: booked a check for /standards/imo-cii/ (id imo-cii), due 7 December 2026, after the resumed IMO extraordinary session on the Net-Zero Framework (4 December 2026), and after every MEPC session and each new EU MRV year from then on. Files: imo-cii.js (one sentence), scripts/imocii/test-mrv.js (checks the new sentence), assets/data/update-schedule.json (one booked entry). Version: GC_VERSION 6.1750.0 → 6.1750.1.
v6.1750.0
New shortcode [gc_imo_cii] for the IMO Carbon Intensity Indicator page (/standards/imo-cii/, build plan row 143). Its calculator rates a ship A to E for any year from 2023 to 2030 from its type, capacity (DWT or GT), distance sailed and the fuel it burned, for all 13 ship types in IMO's G2 guidelines (MEPC.353(78)), using the reference lines, the reduction factors (MEPC.338(76), amended by MEPC.400(83): 5% for 2023 rising to 21.5% for 2030), the rating boundaries of G4 (MEPC.354(78)) and the carbon factors of MEPC.364(79). It shows the attained and required values, where the ship sits on the A–E bar, its rating every year to 2030 with the same voyages, and when it first drops to D or E. A ship rated D three years running or E once must add a corrective action plan to its SEEMP; the calculator says so when the reader enters the two years before. Optional inputs apply the G5 corrections (MEPC.355(78)): fuel and distance in safety or ice periods, fuel for reefers and cargo heating or discharge (or reefer-days, at 2.75 kW each), and the ship-to-ship and shuttle-tanker factors, plus an EEXI/EEDI correction factor. A what-if box shows the rating after a slower average speed (fuel power ∝ speed cubed, Fourth IMO GHG Study 2020) or a switch of part of the fuel to another fuel. For ships trading with Europe it estimates the EU ETS allowances due (Directive (EU) 2023/959: 40%, 70% then 100% phase-in, half of voyages to or from outside the EU) at an editable price, and the FuelEU Maritime GHG intensity, surplus or deficit and penalty (Regulation (EU) 2023/1805, Annex II default factors including methane slip). A fleet box rates many ships at once from pasted CSV and downloads the result. A ship lookup searches the EU MRV reports of about 24,000 ships, 2021 to 2025, by name or IMO number, and shows each year's verified CO₂ on EU voyages, the share inside the EU ETS, the allowances due (40% for 2024, 70% for 2025) and their cost at an editable price, and how the ship's CO₂ per tonne-mile ranks among ships of the same type reporting the same measure; a button carries the ship type into the calculator. Its data (scripts/imocii/build-mrv.py, from EMSA THETIS-MRV workbooks downloaded by hand) is uploaded to wp-content/uploads/gc-data/imo-cii/, not committed, and the lookup renders nothing if it is missing. The reference lines, reduction factors and fuel factors also render as tables, with CSV downloads (assets/data/imo-cii/, built by scripts/imocii/build-cii-data.py). Parity: Hooks 406 → 407 (+1 add_shortcode, gc_imo_cii), Functions 1493 → 1522 (+29, all in sc-imo-cii.php); add_shortcode 92 → 93; actions, filters, CPTs, taxonomies, meta and constants unchanged. New stylesheet imo-cii.css and script imo-cii.js, enqueued only on pages using the shortcode. Test scripts/imocii/test-cii.js checks the browser script against the server for 6,005 ships (every type, year, correction and EU input, bad inputs included) and reproduces ClassNK's published example (62,000 DWT bulk carrier, 60,045 nm, 17,447 t CO₂: attained 4.687, required 4.711 in 2023 to 4.413 in 2026, C to D in 2026) and the G4 worked example; scripts/imocii/test-mrv.js renders 2,266 ships from the MRV build and checks the allowances against the source columns. Version: GC_VERSION 6.1749.1 → 6.1750.0.
v6.1749.1
Update schedule: booked a check for the new ASHRAE 62.1, 55 and 241 page (ASHRAE 62.1, 55 and 241: Ventilation, Comfort and Clean Air), due 31 Jan 2027 and every three months after. Why: the page's edition facts were checked by hand on 31 Oct 2026, ASHRAE 241's second public review closes on 23 Nov 2026, and the calculator's built-in Title 24 tables change only when California adopts a new Part 6. None of these can be re-read automatically, so a person reads the page through on this schedule. Files: assets/data/update-schedule.json (one booked entry, id ashrae-621). No code changed. Version: GC_VERSION 6.1749.0 → 6.1749.1 (data file only; nothing on any page renders differently). Also in this release: the editorial entry above, and Build Plan row 135 marked published (data/keywords/gc_build_plan.csv).
v6.1749.0
New shortcode [gc_ashrae621] for the ASHRAE 62.1, 55 and 241 standards page (build plan row 135). Its outdoor-air calculator takes one or more zones and gives the minimum outdoor air in cfm and L/s, per person and as air changes an hour, by two methods: California Title 24 Part 6 (2025), Section 120.1(c)3, with all 75 space types of Table 120.1-A built in (the larger of 15 cfm per person or the area rate, with the table's default occupant density as the floor), or ASHRAE 62.1's ventilation rate procedure with Rp, Ra and Ez typed in by the reader from their own copy of the standard. No ASHRAE table is reproduced. A unit serving several zones uses the simplified procedure for system ventilation efficiency (D and Ev) as printed in the 2025 California Mechanical Code, Section 403.5. Title 24's demand-controlled ventilation trigger (Section 120.1(d)3) is flagged per zone. For the same air it estimates indoor CO₂ once it levels off (NIST's per-person generation method, Persily 2017, with CDC NHANES 2021–2023 body mass by age and three activity levels), the cost and CO₂e of heating and cooling it (sensible heat only; NOAA 1991–2020 degree days, EIA commercial prices, EPA eGRID), and clean air changes an hour against CDC's aim of 5 or more. A second box checks thermal comfort under ASHRAE 55-2023: PMV and PPD, with the cooling effect of air movement above 0.1 m/s taken from the two-node SET model, and the adaptive model for naturally ventilated spaces. It is a port of the open-source pythermalcomfort library (MIT, UC Berkeley Center for the Built Environment) and matches its published test values, including PMV 4.51 at 41 °C, 2 m/s, 0.7 met, 2.1 clo. Title 24 Tables 120.1-A and 120.1-B and a CO₂-per-person table also render, with CSV downloads. Parity: Hooks 405 → 406 (+1 add_shortcode, gc_ashrae621), Functions 1459 → 1493 (+34, all in sc-ashrae-621.php); actions, filters, CPTs, taxonomies, meta and constants unchanged. New stylesheet and script; test scripts/ashrae621/test-621.js checks the browser script against the server for 6,601 ventilation and comfort cases and PMV against pythermalcomfort's own test values.
v6.1748.3
[gc_ashrae901] home-rule states that also have a statewide code (Nevada in DOE's September 2026 workbook) are now labelled as home rule in the states table and the lookup card. Why: the table showed Nevada's statewide code (2024 IECC and 90.1-2022) next to a DOE rating of 90.1-2016 with no explanation, and a "home rule" filter found 10 of DOE's 11 home-rule states. DOE's workbook defines home rule as codes adopted and enforced at the local level, sometimes above a statewide minimum, and rates those states from local codes covering 80% of population or permits; the table note now says that. Files: inc/shortcodes/sc-ashrae-901.php (gc_a901_states_html, gc_a901_lookup_card), ashrae-901.js (lookupCard). test-901: OK 5763 checks (JS = PHP). Parity: unchanged.
v6.1748.2
Update schedule: booked a check for the new ASHRAE 90.1 page (ASHRAE 90.1: Editions, State Adoption and Savings), due 31 Jan 2027 and every three months after. Why: the page's 90.1-2025 facts (the edition is out, its new title, the lighting changes) were checked by hand on 31 Oct 2026. The weekly gc-ashrae901 job reloads DOE's state workbook and flags a new DOE determination by itself, but it cannot re-read ASHRAE's own pages, so a person reads the page text through on this schedule. Files: assets/data/update-schedule.json (one booked entry, id ashrae-901). No code changed. Parity: unchanged.
v6.1748.1
[gc_ashrae901] state lookup: the line under the edition now reads "equivalent, in DOE’s rating" (was "DOE rates the commercial code as", which read backwards under the edition on phones). PHP and JS changed together; test-901 parity unchanged. Why: on a phone the label wrapped under the edition, so the card read "90.1-2013 / DOE rates the commercial code as". The new wording reads in order and says the same thing: the edition is DOE's rating of the state code, not the code on the books (that line follows). Files: inc/shortcodes/sc-ashrae-901.php (gc_a901_lookup_card), ashrae-901.js (lookupCard). No data, hooks or styles changed. Parity: unchanged.
Sources: National Travel Survey 2025 — table NTS0901a (Annual mileage of cars by fuel type)
v6.1748.0
New shortcode [gc_ashrae901] for the ASHRAE 90.1 standards page (build plan row 134). It shows which 90.1 edition each state's commercial energy code matches, as rated by the US Department of Energy (DOE) in its September 2026 state workbook, with a state lookup and a 51-row table with a filter; every edition DOE has reviewed since 90.1-2004, with the date and Federal Register notice of its determination and the savings it found; and DOE's 16 prototype buildings under 90.1-2019 and 90.1-2022. A calculator estimates what building to 90.1-2022 is worth for a typical new building of a given type, size and state, compared with the state's current code or an older edition: kWh, therms, dollars a year at the state's commercial electricity and gas prices (EIA, MasterBrain v2026.277), and tonnes of CO₂e (EPA eGRID). Each building's electricity and gas use is split from DOE's own site and source energy figures; at DOE's national prices the split reproduces DOE's energy cost for all 16 buildings to within a cent per sq ft. The state data refreshes itself: a weekly job reloads DOE's workbook when DOE posts a new one. The dataset files (states, editions, prototypes) are downloadable as CSV. Parity: Hooks 404 → 405 (+1 add_shortcode, gc_ashrae901), Functions 1435 → 1459 (+24, all in sc-ashrae-901.php); actions, filters, CPTs, taxonomies, meta and constants unchanged. New stylesheet and script; test scripts/ashrae901/test-901.js checks the calculator in the browser script against the server (5,763 cases).
Editorial
/standards/imo-cii/ rewritten around a calculator (version 1.0 → 2.0.0). New title: IMO Carbon Intensity Indicator (CII): Calculator and Rating Rules. A calculator at the top rates a ship A to E for any year from 2023 to 2030, with IMO's corrections, a slower-speed or fuel-switch what-if, and EU ETS and FuelEU Maritime estimates; a fleet table rates many ships from pasted CSV; and a ship lookup shows the verified EU emissions, EU ETS allowances and peer rank of about 24,000 ships from the EU MRV reports, 2021 to 2025. New sections: SEEMP vs CII, how to improve a CII rating, a worked AER example (82,000 DWT bulk carrier, C in 2025, D from 2028), the reference-line table and how the calculator works; five new FAQs and one on looking up a ship. Corrected: the page said every cargo, cruise and passenger ship is rated; only the listed types are, and among passenger ships only ro-pax ships and cruise ships. The IMO Net-Zero Framework status now reads as it stands: draft approved April 2025, adoption adjourned for a year in October 2025 (57 to 49), no decision at MEPC 84, session to resume 4 December 2026 (it said adoption was targeted for a later 2026 session). Resolutions MEPC.336(76), MEPC.337(76) and MEPC.339(76) were described as the Annex VI amendment, the ship-type definitions and the verification rules; they are the 2021 G1, G2 and G4 guidelines, replaced in 2022, and the Annex VI amendment is MEPC.328(76). The cruise row no longer says "non-conventional propulsion", and high-speed ro-pax craft are listed. Added: MEPC.412(84) (May 2026), which keeps transport work as capacity times distance. The IMO CII Rating Obligation Checker (/tools/imo-cii-rating-obligation-checker/) now links to the calculator and carries the same two corrections (version 1.0.1). Title: IMO Carbon Intensity Indicator (CII): Calculator and Rating Rules. Affects: /standards/imo-cii/, /tools/imo-cii-rating-obligation-checker/
Editorial
New standards page: /standards/ashrae-62-1/ covers three ASHRAE standards for the air inside buildings: 62.1 (minimum outdoor air for commercial buildings), 55 (thermal comfort) and 241 (clean air to control infection risk). It explains what each covers, the newest editions, and how 62.1 reaches law, through codes such as California's Title 24 Part 6 (2025 edition, in force from 1 January 2026). An outdoor-air calculator works out the minimum outdoor air for one or more zones, using either Title 24 Table 120.1-A (all 75 space types built in) or the reader's own 62.1 rates (Rp, Ra, Ez) from their copy of the standard; no ASHRAE table is reproduced. A unit serving several zones uses the system ventilation efficiency method as printed in the 2025 California Mechanical Code, Section 403.5. For the same air it gives the indoor CO₂ once it levels off (NIST per-person generation rates, Persily 2017), clean air changes an hour against CDC's aim of 5, and the yearly cost, therms and CO₂e of conditioning the air by state. A second calculator checks comfort under ASHRAE 55 (PMV and PPD, with the cooling effect of air movement, and the adaptive model), ported from the open-source pythermalcomfort library. Title 24 Tables 120.1-A and 120.1-B and a CO₂-per-person table download as CSV under CC BY 4.0. The page is booked on the update schedule (ashrae-621, due 31 January 2027). Links to the new page were added in the Related line of /standards/ashrae-90-1/ (version 1.0.1) and the related-pages lists of ASHRAE 90.4 Energy Standard for Data Centers and ASHRAE TC 9.9 Thermal Guidelines for Data Centers (each version 1.0.2). Title: ASHRAE 62.1, 55 and 241: Ventilation, Comfort and Clean Air. Affects: /standards/ashrae-62-1/, /standards/ashrae-90-1/, /standards/ashrae-90-4-data-centre-energy/, /standards/ashrae-tc-9-9-thermal-guidelines/
Sources: Natural Gas Navigator: Price of Natural Gas Sold to Commercial Consumers, annual, by state (2026)
Editorial
New standards page: /standards/ashrae-90-1/ covers ANSI/ASHRAE/IES Standard 90.1, the US energy standard for commercial buildings and apartment buildings over three storeys. It gives the newest edition (90.1-2025) and the newest DOE review (90.1-2022, determination of 6 March 2024, 89 FR 15983: 9.8% site, 9.4% source and 8.9% cost savings over 90.1-2019), how an edition reaches state law under 42 U.S.C. 6833, and what changed in 2022 (energy credits, on-site renewables, exterior lighting) and in 2025 (lighting, from Lighting Controls Academy). A state lookup and table show each state's commercial code and the 90.1 edition DOE rates it as, from DOE's state workbook (September 2026); an editions table lists every DOE determination since 90.1-2004 with its Federal Register citation and savings; and a calculator turns DOE's prototype buildings into kWh, therms, dollars and tonnes of CO₂e for a building type, size and state, priced with EIA commercial electricity and gas prices (MasterBrain v2026.277) and eGRID state grid factors. The data rebuilds weekly from DOE's files (job gc-ashrae901) and downloads as CSV under CC BY 4.0. The page is booked on the update schedule (ashrae-901, due 31 January 2027). Links to the new page were added on /standards/ashrae-90-4-data-centre-energy/ and /standards/ashrae-tc-9-9-thermal-guidelines/ (where they name Standard 90.1) and in the Related lines of NYC Local Law 97: Emissions Limits, Penalties and Deadlines and Boston BERDO: Emissions Standards, Payments and Deadlines; each is version 1.0.1. Title: ASHRAE 90.1: Editions, State Adoption and Savings. Affects: /standards/ashrae-90-1/, /standards/ashrae-90-4-data-centre-energy/, /standards/ashrae-tc-9-9-thermal-guidelines/, /standards/nyc-local-law-97/, /standards/boston-berdo/
Authored by Jeremiah Say. Verified by GreenCalculus Engineering.