How to
How to track environmental impact of a merch program
A prose guide — what data to request, which supplier to ask, how to convert the figure into an auditable line in the annual report — so a merch program across Mexico City, Monterrey and Guadalajara stops being a black box and becomes a verifiable piece of the ESG file.
Why most merch environmental reports do not survive an audit
The prose of a merch program's environmental report does not fail because of the numbers; it fails because of the genealogy of those numbers. A figure of 4.2 kg of CO₂ equivalent per t-shirt is only useful if the buyer can show where each gram came from: the fiber, the dye, the water, the electricity at the workshop, the truck that carried it to the logistics operator in Tlalnepantla, the flight if it crossed Laredo, and the last mile if it delivered to a home in Cumbres del Sol or in Bosques de las Lomas. Without that genealogy the report is a marketing assertion, not a compliance piece.
In Mexico the problem gets harder because the supply chain tends to be deep. A typical program lives across three tiers that rarely share a system: the cut-and-sew workshop in Iztapalapa or Tepeji del Río, the screen-printing or embroidery house in Texcoco or Tlaquepaque, and the logistics operator in Apodaca or San Luis Potosí. Each tier has its own accounting and none has a legal obligation to share consumption data unless the buyer requested it in writing at the start of the program. The report is assembled afterwards, from what could be reconstructed, and that is why the numbers are soft.
The second problem is the choice of standard. There are three serious frameworks for merch — the GHG Protocol with its scopes 1, 2 and 3, ISO 14067 for product carbon footprint, and PAS 2050 for product life-cycle assessment — and there is a market of automatic calculators that offer "figures" without auditable methodology. If the program's annual report will be read by a European customer who already reports under CSRD, or by a parent-company sustainability committee, the standard and the calculator must be the same as theirs, not whatever the cheapest supplier uses.
This guide is for the brand, sustainability or procurement team that has to assemble the next fiscal year's report and that prefers to do it right once. It covers the minimum data set requested from each tier, the prose of the seven steps to assemble the annual disclosure, and the antipatterns that make the figure incomparable across fiscal years or across business units. It does not discuss the report's narrative; only the prose of the document that holds the numbers.
The intended scale is a mid-market program: 1,500 to 15,000 units, one to three brands, between five and ten textile and non-textile SKUs, and at least two comparable annual cycles. The structure holds for smaller and larger programs; what changes is the amount of evidence requested per tier.
The report's prose in 7 steps
- System boundary and reporting scope. One page that defines what the report includes and what it leaves out. Program A: 8,200 units produced between January and December, delivered in six Mexican cities, includes production, packaging and last mile; end-of-life and end-user use are excluded. The boundary is what separates a credible figure from an inflated one.
- SKU inventory and physical units. A spreadsheet with each SKU, the quantity manufactured, the substrate with figures (combed cotton 180 g/m², recycled polyester rPET 280 g/m², kraft cardboard 300 g/m²), declared country of origin, and unit weight in grams. Without this inventory the intensity figures (kg of CO₂ per unit) cannot close.
- Supplier and energy disclosure. For each tier, a letter signed by the supplier with annual electricity consumption in kWh, source (CFE, solar panels, generator), natural gas consumption in m³ if applicable, and water consumption in m³ if the process requires it. The letter's prose must state the period covered and the calculation methodology, not only the number.
- Transport and distances. A table with each leg of the program: origin, destination, mode (truck, rail, air, sea), total weight transported in tonne-kilometres when available, and logistics provider. The prose distinguishes between contracted transport (the operator holds the figure) and subcontracted transport (the figure is estimated from weight × distance).
- Footprint calculation against an explicit standard. The report names the standard: GHG Protocol for scope 1 and 2, and a published emission-factor library (DEFRA 2024, EPA US, SEMARNAT when applicable). Figures are multiplied, not estimated "by eye".
- Packaging, waste and partial end-of-life. One page with primary and secondary packaging (LDPE bag, kraft cardboard box, paper sticker), waste percentage reported by the workshop, and an indication of whether the program has any recovery, reuse or donation scheme for surplus. The prose does not need to close the life cycle, only declare what was measured and what was not.
- Auditable annual report and evidence archive. A PDF signed by the sustainability lead, with date, total figures, figures per SKU, methodology and a link to the evidence archive. The evidence is kept for at least five fiscal years to support internal and external audits.
Prose antipatterns that invalidate the figure
The first antipattern is the opaque calculator. If the report says "4.2 kg of CO₂ per unit" without naming the standard, the emission factor or the calculator supplier, the figure is a toast to the sun. The prose names the standard, the version of the factor and the cut-off date.
The second antipattern is the cheerful sum of scopes. Adding scope 1, 2 and 3 without distinguishing duplications inflates the figure and confuses the auditor. The prose separates the three, reports them separately, and only sums them when the methodology allows.
The third antipattern is the unweighted average. "The workshop's average electricity consumption was 12,000 kWh per month" without weighting per produced unit hides the fact that a low-inventory month biases the intensity. The prose requests the figure per produced unit, not the monthly figure.
The fourth antipattern is the transport that is ignored. Scope 3 accounts for 70% to 90% of a textile program's footprint; if the report does not include the leg from the port of Manzanillo or Lázaro Cárdenas to the national logistics operator, the figure is half a lie.
The fifth antipattern is raw material without traceability. If the fabric supplier declares "Mexican cotton" without a certificate of origin, the report's prose cannot claim either a short-transport footprint or improved agricultural practices. The prose requests the certificate or marks the fiber as "declared but not verified".
The sixth antipattern is the methodology change between fiscal years. If year one was calculated with DEFRA 2022 and year two with DEFRA 2024 without saying so, year-over-year comparison is broken. The prose declares the methodology of each fiscal year and keeps a comparable series.
The seventh antipattern is the missing signature and date. A PDF without a responsible signature is not a report, it is a draft. The prose closes the document with name, title, date and period covered.
Tools, templates and references
SKU inventory spreadsheet. A spreadsheet with SKU, quantity, substrate, declared country of origin, unit weight and responsible supplier. The spreadsheet is the backbone of the report; without it the intensity figures cannot close.
Supplier disclosure letter. A one-page template with energy, water, gas, waste and period-covered fields, plus the responsible party's signature. The letter is delivered at the start of the program, not when the auditor asks for it.
Auditable calculator. A spreadsheet or script with published and referenced emission factors, ideally based on the GHG Protocol and a public library such as DEFRA or EPA. The calculator records the cut-off date and the version of the factors.
Transport policy. One page with the modal-preference rule — truck before air when the calendar allows, freight consolidation before express shipments — and the logistics providers that comply with it. The policy enters the RFP and is reported in the sustainability document.
Annual report. A 6-to-12-page PDF with executive summary, methodology, figures per SKU, figures per scope, evidence disclosure, and the responsible party's signature. The report is published internally and, when the customer asks for it, shared with the buyer.
Evidence archive. A cloud folder with the supplier letters, electricity bills, certificates of origin, transport manifests and surplus-destruction certificates when applicable. The archive lives for at least five fiscal years.
Useful references. GHG Protocol Corporate Standard for scope 1, 2 and 3 accounting; ISO 14067:2018 for product carbon footprint; PAS 2050:2011 for life-cycle assessment; DEFRA Conversion Factors for Company Reporting (annual version); EPA Emission Factors Hub; SEMARNAT for Mexican environmental regulation; LGPGIR and its regulation for packaging waste.
Suggested schedule. Data collection from January 1 to 31, inventory validation from February 1 to 15, calculation and review from February 16 to March 31, report publication in April, permanent evidence archive. An annual cycle that is neither hurried nor late.