A plant whose average power factor in a billing period falls below 90% pays a surcharge on its CFE invoice. The formula, set by the Secretaría de Hacienda y Crédito Público in the acuerdo published in the DOF on 31 October 2000, is 3/5 x ((90 / FP) - 1) x 100, applied to the amount of the invoice. At a power factor of 0.85 that is 3.5% of the whole bill. At 0.70 it is 17.1%. The surcharge is capped at 120%. The bonus for running above 90% is capped at 2.5%.

That is one line on a CFE invoice, and it answers to reactive compensation and to how the plant runs its motors. It does not answer to how many kilowatt hours the plant consumes. It is the clearest illustration of what an efficiency program really does. It does not reduce the bill as a single quantity. It moves three separate charge blocks by three different mechanisms, and a kilowatt hour saved in the wrong period moves almost nothing.

What follows is how a Mexican industrial site should read those three blocks, what an efficiency study measures against each of them, what the plant has to hand over before the work can start, and how long it takes.

The three blocks on a GDMTH invoice

A load above 25 kW per month taken at medium voltage with hourly metering sits on GDMTH, the tariff CRE set out in the schedules published in the DOF on 28 January 2022. The invoice is built from three things. Energy is priced separately in the punta, intermedio and base periods. Demand is billed in kW against the highest demand recorded in the billing period. The power factor adjustment is then applied as a percentage of the invoice total.

Each block responds to a different class of measure. Compressed air leak repair, lighting retrofits and process scheduling move the energy block, and how much they move it depends on which period the load sits in. Shifting a batch process out of punta moves the energy block without changing total consumption at all. Billed demand moves only if the measure lowers the peak, which is a question of sequencing and interlocks rather than of efficiency. Reactive compensation moves the third block and nothing else.

This is why a percentage of consumption is not a percentage of the invoice. A measure that cuts base period kilowatt hours by a fifth leaves billed demand and the power factor adjustment untouched. The invoice falls by less than a fifth, and by how much less depends entirely on the split between the three blocks on that site's own bill. No one can tell you that split without reading your meter data.

What the power factor line is worth

The SHCP formula is arithmetic, so a plant manager can price this line without any outside help. Take the average power factor printed on the last invoice and read across.

The asymmetry is the point. Correcting a bad power factor is worth several percent of every invoice. Correcting an already good one is worth at most 2.5%, and that is the statutory ceiling. A site sitting at 0.88 has very little to gain from capacitors under the CFE tariff alone. Our note on power factor and the risks it carries goes through how the average is computed across a billing period.

The tariff is not the only rule in play. CRE reissued the Código de Red as RES/550/2021, published in the DOF on 31 December 2021 and in force from 1 January 2022, replacing RES/151/2016. It requires load centers to hold a power factor between 0.95 lagging and 1.0, measured in five minute intervals rather than averaged across the month. That requirement is not enforceable until 8 April 2026. A plant clearing the CFE test at 0.91 on a monthly average can still be outside the band for hours at a time, and it has a fixed date by which to close the gap. Our summary of what the Código de Red requires covers the rest of the obligations.

Some plants are already required to measure

The disposiciones administrativas de carácter general published in the DOF on 15 November 2018 set the criteria for a Usuario de Patrón de Alto Consumo. A site crosses the threshold if it consumes more than 45 GWh of electricity a year, or more than 100,000 barriles equivalentes de petróleo of fuel a year excluding transport fuel. Forty-five GWh a year is an average load of about 5.1 MW, so this catches large steel, cement, glass, chemical and automotive operations rather than a single assembly plant.

A UPAC has to report to CONUEE each year between 1 March and 30 June, covering production, imports and exports, consumption by energy carrier, and the efficiency measures it has put in place together with their energetic and economic results. If a company is already assembling that submission, the measurement work behind an efficiency study is half done, and the two exercises should be run on the same data rather than separately.

What a 12 week study covers

Mexico Energy Partners scopes an industrial energy efficiency study at 12 weeks, of which three days are spent on site. Those are the firm's own scope figures and they describe a typical engagement rather than a contractual commitment. The 12 weeks are not 12 weeks of analysis. Most of the elapsed time is logging.

The sequence runs roughly as follows. Interval metering goes on the main incomer and on the largest motors, compressors and chillers. The loggers stay in place long enough to cover a full production cycle, including a weekend and a shift changeover, because a study that only sees a Tuesday will misread the peak. The three days on site cover the compressed air system, the boiler and steam distribution, the chilled water loop, the main switchgear and the metering points. Analysis then reconciles the logged data against twelve months of CFE invoices, so that every proposed measure can be priced against the tariff the site actually pays.

The clock starts when the metering is installed, not when the proposal is signed. That is the single most common reason these projects slip.

What the plant has to supply

Nothing can be scoped without four items. Twelve consecutive CFE invoices, including the demand and power factor figures on each. The single line diagram. A list of motors, compressors and chillers with nameplate ratings and duty. The production schedule by shift, including planned shutdowns. A site that cannot produce the motor list usually discovers that fact during the audit, which is itself a finding.

The deliverable is a measure list. Each measure carries a capital cost, an effect stated separately in kilowatt hours by time band and in kilowatts of peak demand, and a payback calculated on that site's own tariff rather than on a national average. The same measure returns a different payback on two sites in different regions, because the demand charge differs.

We do not publish a savings percentage for this work. A range with no baseline, no period and no sample behind it cannot be used to build a capital request, and a number quoted before anyone has read your meter data is a guess. The reasons a plant commissions the work in the first place are set out in our list of reasons to commission an energy audit.

Timing against the capital cycle

The 12 week study is only the first leg. Add supplier quotation, procurement and installation, and a measure identified in a study that reports in April is realistically commissioned in the following financial year. A study that starts after the budget is drafted produces a measure list with nowhere to go.

The Código de Red band gives one hard date to plan against. Reactive compensation work that has to be in place by 8 April 2026 needs its capital request submitted in a budget round well before that, and the measurement that justifies it earlier still. Everything else can be sequenced. That one cannot.

Have us scope the study on your plant

Send twelve months of CFE invoices, the single line diagram, the motor, compressor and chiller list, and the production schedule. Mexico Energy Partners returns a scoped study proposal setting out the measurement plan, the on-site dates and the list of deliverables. No commitment to a measure or to a saving is made at that stage, because none can honestly be made before the metering has run. Our energy efficiency service page describes the wider scope of work.

Sources

• Secretaría de Hacienda y Crédito Público, Acuerdo que modifica las disposiciones complementarias a las tarifas para suministro y venta de energía eléctrica, published in the DOF on 31 October 2000. Power factor surcharge and bonus formulas and their 120% and 2.5% caps.
• CRE, tariff schedules for CFE Suministro Básico defining GDMTH and the punta, intermedio and base periods, published in the DOF on 28 January 2022.
• CRE, RES/550/2021, Código de Red, published in the DOF on 31 December 2021 and in force from 1 January 2022, replacing RES/151/2016 of 8 April 2016. Power factor band of 0.95 lagging to 1.0 in five minute intervals, enforceable from 8 April 2026.
• Disposiciones administrativas de carácter general que establecen los criterios para determinar cuándo un usuario cuenta con un patrón de alto consumo de energía, published in the DOF on 15 November 2018. UPAC thresholds and the CONUEE reporting window.
• Mexico Energy Partners, scope of work for industrial energy efficiency studies, December 2023. The 12 week duration and the three days on site, described as typical rather than contractual.