Resources Numerical accuracy Calculation policy
Reads a person's own carbon-factor file, cost book or climate answer into the tables the carbon, cost and solar panes calculate from.
The numbers are the source's; this code converts units and cleans them. Factor and money cells have currency signs, spaces and every comma removed before they become 64-bit numbers. Monthly climate values are rounded to two decimals when stored. A request to a climate provider carries the location to three decimals of a degree, and answers are cached on a 0.1 degree grid.
Open item. Read a decimal comma in imported files, or refuse a cell whose only comma is followed by one or two digits, so that 1,5 is never read as 15.
5 calculations in 1 source file. The code is read from the released app when this page loads. It is the calculation people run, not a copy kept for this page.
Tests tools/bimcraft-test/datapacks-test.mjs
A cell such as '$1,250.00' as a number.
Currency signs, white space and every comma are removed, then Number() converts the rest. A thousands comma is handled; a decimal comma is not: '1,5' gives 15 and '0,25' gives 25.
const num = (v) => { const s = String(v ?? '').replace(/[$€£,\s]/g, ''); if (s === '') return null; const n = Number(s); return Number.isFinite(n) ? n : null; };A material's embodied-carbon factor in the unit the carbon pane works in.
A1-A3 factor = value × unit factor (1 for kg, m, m², m³ and items; 0.001 for tonnes)
One 64-bit multiplication; 0.001 is not exact in binary, so a per-tonne value can change in its last digit. A per-kilogram factor with no density takes the density of the matching material in the starter table, and the row's note says so.
export function carbonFromFile(text, opts = {}) {
const all = parseCsv(text);
if (all.length < 2) return { rows: [], errors: [{ line: 0, code: 'empty' }], columns: {} };
const head = all[0].cells.map((x) => x.trim());
const c = pickCols(head, opts.map, ['name', 'unit', 'gwp', 'density'], SYN);
if (c.name < 0 || c.gwp < 0) return { rows: [], errors: [{ line: all[0].line, code: 'header' }], columns: c };
// no unit column: read it from a header like "kgCO2e/kg" or "kgCO2e per m3"
const hu = /(?:\/|per)\s*(kg|t|tonne|m3|m³|m2|m²|m)\b/i.exec(head[c.gwp] || '');
const rows = [], errors = [], seen = new Set();
for (const r of all.slice(1, 5001)) {
const g = (i) => (i >= 0 ? unguard(String(r.cells[i] ?? '')) : '');
const u = unitOf(g(c.unit)) || (hu ? unitOf(hu[1]) : null) || (opts.unit ? unitOf(opts.unit) : null);
const gwp = num(g(c.gwp));
if (!g(c.name).trim() || gwp === null || !u) { errors.push({ line: r.line, code: !u ? 'unit' : 'value' }); continue; }
let id = slug(g(c.name)); for (let n = 2; seen.has(id); n++) id = slug(g(c.name)).slice(0, 44) + '-' + n; seen.add(id);
// a per-kg figure needs a density to meet the model's volumes: the file's, the caller's, else the starter table's for that name (said in the note)
let dens = num(g(c.density)) ?? opts.density ?? null, dnote = '';
if (u[0] === 'kg' && dens === null) { const m = matchRow(STARTER, { material: g(c.name), name: g(c.name) }); if (m) { dens = m.density; dnote = ' Density ' + m.density + ' kg/m³ from the starter table.'; } }
const cl = cleanRow({ id, match: [g(c.name)], classes: [], basis: u[0], density: dens, a1a3: gwp * u[1], source: opts.source || 'your file', checked: false, note: IMPORT_LABEL + dnote });
if (!cl.row) { errors.push({ line: r.line, code: cl.errors[0] }); continue; }
rows.push({ ...cl.row, origin: 'yours' });
}
return { rows, errors, columns: c };
}Twelve monthly values of daily sunlight on a horizontal surface and of air temperature.
ghi = value rounded to 0.01 kWh/m²/day; T = value rounded to 0.01 °C
A value outside 0 to 12 kWh/m²/day or −60 to 60 °C rejects the whole answer. What is kept is rounded to two decimals.
export function parseNasaPower(j) {
const p = j?.properties?.parameter, a = p?.ALLSKY_SFC_SW_DWN, t = p?.T2M;
if (!a || !t) return null;
const ghi = MONTHS.map((m) => Number(a[m])), tAmb = MONTHS.map((m) => Number(t[m]));
if (ghi.some((x) => !Number.isFinite(x) || x < 0 || x > 12) || tAmb.some((x) => !Number.isFinite(x) || x < -60 || x > 60)) return null; // NASA marks missing as -999
return { ghi: ghi.map(r2), tAmb: tAmb.map(r2), source: 'NASA POWER climatology (ALLSKY_SFC_SW_DWN kWh/m²/day, T2M daily-mean °C)' };
}Twelve monthly values of daily sunlight and air temperature, averaged over the years in the answer.
ghi = Σ H(h)_m ÷ years ÷ days in month; T = Σ T2m ÷ years; both rounded to 0.01
Monthly sums are averaged over the years in the answer and divided by the days in the month, with February as 28.25 days. A missing temperature makes that month NaN and the answer is rejected. The results are rounded to two decimals.
export function parsePvgis(j) {
const list = j?.outputs?.monthly;
if (!Array.isArray(list) || !list.length) return null;
const sum = new Array(12).fill(0), ts = new Array(12).fill(0), n = new Array(12).fill(0);
for (const e of list) {
const m = Number(e.month) - 1, h = Number(e['H(h)_m']), t = Number(e.T2m ?? e['T2m']);
if (!(m >= 0 && m < 12) || !Number.isFinite(h)) return null;
sum[m] += h; ts[m] += Number.isFinite(t) ? t : NaN; n[m]++;
}
if (n.some((x) => !x)) return null;
const ghi = sum.map((s, m) => r2(s / n[m] / DIM[m])), tAmb = ts.map((s, m) => r2(s / n[m]));
if (ghi.some((x) => x < 0 || x > 12) || tAmb.some((x) => !Number.isFinite(x))) return null;
return { ghi, tAmb, source: 'PVGIS MRcalc monthly (H(h)_m kWh/m²/month ÷ days, T2m °C)' };
}The latitude and longitude put into the request address.
latitude.toFixed(3), longitude.toFixed(3)
The request carries the position rounded to three decimals of a degree. A position outside ±90 and ±180 degrees gives no address.
const coord = (lat, lon) => (Number.isFinite(lat) && Number.isFinite(lon) && Math.abs(lat) <= 90 && Math.abs(lon) <= 180 ? [lat.toFixed(3), lon.toFixed(3)] : null);The arithmetic is 64-bit, but the method or the data sets the accuracy: a solver tolerance, a mesh, a step size, a datum shift, a table. The limit is stated where the result is shown.