Industrial electricity costs in Mexico rose 33% between December 2018 and August 2024, on INEGI data reported by Alto Nivel on 16 September 2024. That is the reason plant managers are being pitched energy audits. It is not a reason to buy one blind.
Two things decide whether an audit pays for itself at a Mexican site, and neither appears in a generic savings pitch. The first is which line of the CFE invoice each recommended measure actually moves, because the medium-voltage industrial tariff bills capacity and distribution on kilowatts and energy on kilowatt hours in three separate time windows. The second is the measurement a load center already owes CRE under the Código de Red, which overlaps heavily with the instrumentation an audit needs.
This piece sets out what an audit can move on a Mexican bill, which obligations genuinely attach to a plant and which do not, and what the deliverable has to contain before a finance director should release capital against it.
What an audit can and cannot move on a Mexican bill
CRE approved the tariff schedules for basic supply in Acuerdo A/058/2017 on 23 November 2017. Under the GDMTH schedule a medium-voltage plant pays a capacity charge and a distribution charge on kilowatts, plus energy charges on kilowatt hours split into punta, intermedio and base periods. Only the supplier operation charge is a fixed monthly amount. Transmisión, operación del CENACE and servicios conexos no incluidos en el MEM are billed on kilowatt hours as well, so they move with consumption in every period.
That structure decides the value of every measure an auditor proposes. Trimming consumption in the base window moves the cheapest energy rate plus the per kilowatt hour components that ride on every kilowatt hour, and it leaves the two kilowatt charges alone. Shifting the same load out of the punta window moves the most expensive energy rate, and if the site's coincident peak falls with it, the capacity and distribution charges fall as well. Two measures that save identical kilowatt hours can therefore differ by a wide margin in pesos.
So the first question to put to any auditor is narrow. For each measure, which charge on the invoice does it reduce, and by how much. An audit that answers only in kilowatt hours has done half the work. Interval data is what makes that answer possible, which is why sub-metering usually precedes a useful audit rather than following one.
The measurement you already owe
CRE issued the Código de Red as Resolución RES/151/2016, published in the Diario Oficial de la Federación on 8 April 2016, and reissued it as Resolución RES/550/2021, published in the DOF on 31 December 2021 and in force since 1 January 2022. It binds Centros de Carga connected at media tensión, above 1 kV and up to 35 kV, and at alta tensión, 35 kV and above. It applies regardless of contracted demand and regardless of supply scheme.
At media tensión the requirements cover voltage variation, transient voltage, frequency variation, short circuit, protections, control systems, information exchange and current imbalance. At alta tensión the list adds power factor, current harmonic distortion and voltage flicker. The studies behind those requirements must use Class A measurement instruments under NMX-J-610/4-3-ANCE or IEC 61000-4-30. Load centers already connected on 8 April 2016 had until 9 April 2019 to comply.
Two points get misreported often enough to be worth stating plainly. CRE holds the compliance and sanction authority here, not CENACE, which operates the system and the market. And CRE does not authorize or certify inspectors for these studies. A load center may run them itself or engage a specialized firm.
The practical consequence is a scoping decision. Power quality logging for the Código de Red and load logging for an energy audit put similar instruments on similar points for a similar number of days. Buying them as one mobilization is cheaper than buying them twice. Our note on grid code obligations that apply to load centers covers the requirement in full.
What the clean energy rules actually require of you
Plants are frequently told they face penalties for missing Mexico's clean energy targets. On basic supply that is not correct. Under the Lineamientos que establecen los criterios para el otorgamiento de Certificados de Energías Limpias, published in the DOF on 31 October 2014, the parties required to hold CELs are the Entidades Responsables de Carga. Those are the Suministradores de Servicios Básicos, the Suministradores de Servicios Calificados, Usuarios Calificados participating in the market, end users under abasto aislado, and the holders of legacy interconnection contracts.
A factory buying basic supply from CFE is not itself an obligated party. Its supplier carries the obligation, and the cost reaches the plant inside the tariff. The position changes if the plant migrates to qualified supply, because the obligation then sits with the plant. That is a reason to model the CEL cost before migrating, not a reason to commission an audit.
Above 45 GWh a year you already file with CONUEE
CONUEE's criteria for Usuarios de Patrón de Alto Consumo were published in the DOF on 15 November 2018. A user qualifies on annual electricity consumption above 45 GWh, or on fuel consumption above 100,000 barrels of oil equivalent excluding transport fuels. Sites that qualify report to CONUEE each year between 1 March and 30 June, covering consumption, fuel types and the efficiency measures they implemented with the results those produced.
Forty five GWh a year is close to a 5 MW average draw, so most single plants sit below it. For those that do not, the audit output is not an optional document. It is the evidence base for a filing the company already owes.
What to buy, and what the deliverable has to contain
ANSI/ASHRAE/ACCA Standard 211-2018, the Standard for Commercial Building Energy Audits, defines the procedures for Energy Audit Levels 1, 2 and 3. It was written for buildings rather than process load, but the level definitions are the common language auditors in Mexico quote when they price a scope. A Level 1 walkthrough with a bill review is useful for triage and cannot price a measure. A Level 2 survey adds field measurement and a cost and saving for each recommended measure. A Level 3 study adds the engineering analysis needed to underwrite capital-intensive work. For an industrial site being asked to approve equipment spend, Level 2 is the floor.
Whatever the level, the report should carry four things for every measure it recommends.
- Installed cost, with the date of the quotation behind it.
- Modeled annual saving in kilowatt hours and in pesos, with the tariff and billing period used.
- The invoice line the saving comes off, whether energy in a named window, capacity, distribution or the power factor adjustment.
- Simple payback, calculated per measure and not blended across the portfolio.
Two things should not be accepted. A single blended percentage for the whole site hides which measures pay and which do not. And a savings range quoted without the population behind it tells the reader nothing. Mexico Energy Partners does not publish a typical range in this note, because the engagement data that would support one has not been published. For the underlying case, see the reasons to commission an audit.
The emissions number, and how to state it
Any CO2 reduction from an electricity measure is displaced grid kilowatt hours multiplied by an emission factor. SEMARNAT publishes the Factor de Emisión del Sistema Eléctrico Nacional for the Registro Nacional de Emisiones, and the factor for 2023 is 0.438 tCO2e per MWh. Report the tonnage with the factor and its year attached, or nobody outside the company can check it.
Two limits are worth holding to. Electricity measures move scope 2 and leave process fuel alone, so a site that burns gas should not present a scope 2 reduction as a site-wide one. And an audit does not raise an ESG score. No rating provider derives a score from a single study, and claiming otherwise invites the question at the next investor meeting.
Get a scoped audit proposal for your site
MEP returns a scope, a fixed fee, the metering plan, the number of days on site, and the list of measures the audit will test. You supply twelve months of CFE invoices for every meter at the site, the connected load list or single line diagram, operating hours by shift, and details of the compressed air and chilled water plant. Send the form below and the scope and fee come back before any work starts.
Sources
- Alto Nivel, reporting INEGI data. Costo de la energía eléctrica para industrias aumentó 33% en el sexenio. 16 September 2024.
- Comisión Reguladora de Energía. Acuerdo A/058/2017, tarifas finales de suministro básico, including the GDMTH charge structure. 23 November 2017.
- Comisión Reguladora de Energía. Resolución RES/151/2016, Código de Red. Diario Oficial de la Federación, 8 April 2016.
- Comisión Reguladora de Energía. Resolución RES/550/2021, Código de Red, which reissued RES/151/2016. Diario Oficial de la Federación, 31 December 2021.
- Secretaría de Energía. Lineamientos que establecen los criterios para el otorgamiento de Certificados de Energías Limpias y los requisitos para su adquisición. Diario Oficial de la Federación, 31 October 2014.
- Comisión Nacional para el Uso Eficiente de la Energía. Criteria for Usuarios de Patrón de Alto Consumo. Diario Oficial de la Federación, 15 November 2018.
- ANSI, ASHRAE and ACCA. Standard 211-2018, Standard for Commercial Building Energy Audits. 2018.
- SEMARNAT. Factor de Emisión del Sistema Eléctrico Nacional 2023, 0.438 tCO2e per MWh.