Your CFE bill tells you how much the whole plant consumed last month. What it doesn't tell you is how much the production line consumed, how much the compressor area, how much the yard lighting, and how much that furnace nobody shuts off on the weekend. For operations management, that bill is a single aggregate number: useful for paying, useless for deciding. Electrical submetering exists precisely to break that number into pieces and put a cost on each part of the process.
This article is a practical guide for the industrial manager who already suspects where the energy is going but has no way to prove it. We explain what electrical submetering is, what you need to implement it, how it differs from the software that processes that data, and, above all, how it turns into real savings and not a pretty dashboard nobody uses. The underlying rule is simple: you can't optimize what you don't measure, and a single meter at the entrance measures almost nothing.
What is electrical submetering?
Electrical submetering is the measurement of consumption downstream of the CFE billing meter: installing internal meters by area, by production line, or by cost center to find out where each peso of your bill goes. It is a secondary, internal, and proprietary measurement; it does not substitute or replace the billing meter CFE uses to invoice you.
The distinction matters. The CFE meter —or the CENACE meter if you are in the Wholesale Electricity Market (MEM)— is the one that defines what you pay and has legal validity. Submetering bills nothing: it is your management instrument. It measures the same kilowatt-hours, but distributes them among the real consumers in your plant. Where the bill says "the plant consumed 180,000 kWh," submetering says "compressors 52,000, furnaces 41,000, production 38,000, HVAC 30,000, the rest 19,000." That breakdown is the raw material of any efficiency decision.
In practical terms, submetering is placing measurement points on the panels, feeders, or equipment you want to monitor, and connecting them to a system that records the data over time. It can be as narrow as measuring the three production lines, or as granular as measuring each critical motor. The scope is defined by your objective, not by the vendor's catalog.
Why measure consumption by cost center?
Because without allocation by cost center, any savings initiative is blind. When you know each area's consumption, you can assign real costs, hold each management accountable for its spending, and prioritize investments where they truly move the needle. An aggregate number allows none of that.
Think of the financial analogy: no finance department would accept an income statement with a single line that reads "expenses: X." It would want the breakdown by department, by project, by cost center. Industrial energy, which is usually one of a plant's three largest variable costs, is still managed in many companies as that single line. Submetering turns it into an energy income statement.
This enables three things the bill alone cannot give. First, cost allocation: if you make three products on three lines, you can charge each one its real energy consumption and know its true margin, not an invented proration. Second, accountability by area: when the plant manager sees that their zone spiked consumption 18% without production going up, there is a conversation to be had; without the data, there is only a pricier bill and zero culprits. Third, investment prioritization: if submetering reveals that compressors are 30% of consumption, you know exactly where to put the next peso of capital before buying solar panels or renegotiating the tariff.
That logic of measuring before acting is the same one an energy audit: what to measure applies in its data-gathering phase, and the one that underpins any serious program of energy KPIs for industry. Without submetering, those KPIs are calculated on plant-wide averages and lose almost all their diagnostic power.
What do you need to submeter?
You need four components: meters at each point of interest, current transformers that read large loads without manipulating the main cable, a communication network that brings the data to a single place, and software that stores and displays it. It is a system, not a standalone device.
You don't have to install everything on day one. A good rollout starts with the highest-consumption points —the ones you already suspect carry weight— and grows toward detail as the data justifies the next measurement point. This table summarizes the components and what each one is for.
| Component | What it does | Practical note |
|---|---|---|
| Submetering meter | Records kWh, kW of demand, voltage, current, and power factor at a point | The heart of the system; choose one that measures demand, not just energy |
| Current transformer (CT) | Reduces the feeder current to a signal the meter can read | Allows measuring large loads without cutting or intervening the main conductor |
| Communication network | Transports the data to the concentrator or server | Usually uses open industrial protocols; mind the compatibility |
| Acquisition software | Stores, charts, and reports the history of each point | This is where data becomes decisions; see the UDM section below |
| Concentrator or gateway | Gathers several meters and delivers them to the software | Reduces wiring and makes it easier to scale point by point |
Two field warnings. Installing the current transformers touches the energized panel, so it is planned and executed by qualified personnel, ideally with a scheduled shutdown of the circuit. And the choice of meter matters: one that only counts energy will tell you how much an area consumed, but one that also records demand in kW will tell you when it consumed it —data that is gold for how to control your peak demand, where the few-minute peak defines a charge you pay all month.
How does submetering differ from UDM?
Submetering is the hardware that generates the data; UDM is the software that manages it and gives it meaning. Submetering measures; Utility Data Management (UDM) audits, budgets, and reconciles. They don't compete: they are the two halves of the same information system.
It helps to see it as two layers. The physical layer —meters, current transformers, communication— produces a stream of raw measurements: so many kWh, so much demand, at such a point, at such an hour. On their own, those numbers are a sea of data with no conclusion. The management layer is the one that takes that stream, cross-references it with your CFE bill, your contract terms, and market prices, and answers business questions: are you paying what you agreed to? Which area deviated from budget? Is the cost per kWh of this line competitive?
That second layer is exactly what UDM does, which is why submetering is its best source of internal data. Without submetering, UDM works only with the aggregate bill and the billing meter; with submetering, it can bring reconciliation down to the level of each cost center. When the number of points grows, that management layer relies on energy management software for the CFO that automates reports and alerts. Submetering provides the sensors; the software provides the intelligence. You want both.
How does submetering turn into real savings?
It turns into savings when the data reveals consumption the aggregate bill hides: phantom loads operating without producing, demand peaks concentrated in one area, and low load factors that betray poorly sized equipment. Each finding is a concrete action with a peso saved behind it.
The pattern repeats plant after plant. Someone installs submetering expecting to confirm what they already knew, and the first month of data shows something no one had seen: a pumping system still running on Sunday, a furnace hitting peak demand right in the most expensive tariff hour, a compressor with leaks working twice as hard as needed. None of those problems appear on the CFE bill, because the bill only adds up. This table shows the typical findings and the action each one enables.
| Typical finding | What betrays it in submetering | Savings action |
|---|---|---|
| Phantom loads | Consumption in areas during non-production shifts or weekends | Schedule shutoffs, sequence startups, eliminate zombie equipment |
| Peak demand by area | A cost center concentrates demand in kW during expensive hours | Stagger startups of heavy equipment to flatten the peak |
| Low load factor | Lots of installed power with low average utilization | Resize motors, consolidate loads, review idle capacity |
| Poor power factor | One zone drags down the site's power factor | Local compensation with capacitors where the problem originates |
| Consumption drift | An area increases its kWh without its production rising | Maintenance, leak, or process adjustment in that specific zone |
The order of magnitude matters and is worth treating honestly: these savings vary enormously depending on the plant, the process, and how neglected the operation was. At sites with no prior management, it is not unusual to find, illustratively, between 5% and 15% of consumption that can be trimmed with operating discipline alone, without investing a single peso in new equipment. At already-optimized plants, the margin is smaller but the data still pays off: it detects deviations early, before they pile up on the bill. Any savings you claim after acting must be demonstrated with measurement and verification of savings (IPMVP), comparing measured consumption against a baseline; without that verification, savings are a belief, not a result.
How Enerlogix implements submetering
At Enerlogix, submetering is not an end, it is the first step of Plan 360 Management: measure first, decide with numbers, and execute only what pays for itself. Before proposing a single meter, we understand your process and your tariffs to define which cost centers are worth instrumenting; we don't fill the plant with sensors by default. Measurement follows the business question, not the other way around.
As an independent advisor, we don't sell or install hardware at a markup or lock you into a brand: we specify what is needed, supervise the installation with your personnel or contractor, and keep what truly matters, which is reading the data and turning it into decisions. We connect that submetering to the management layer —UDM— so that every measured kWh is reconciled against your bill and your contract, and we report to management in the language of cost, not engineering. Our only KPI is your verified net savings.
The result is that you stop arguing over the CFE bill as a black box and start managing energy the way you manage any other cost center: with numbers by area, clear owners, and investment priorities based on evidence.
Ready to find out where your bill really goes? Learn about the energy management service or request a free evaluation. We work with your real plant and your real consumption.
Frequently asked questions
It is the measurement of energy consumption downstream of the CFE billing meter, using internal meters installed by area, by production line, or by cost center. It serves to find out where each peso of your bill goes. It is a secondary, proprietary management measurement: it does not substitute or replace the billing meter CFE uses to invoice you, it only distributes that consumption among the real consumers in your plant.
Submetering is the hardware that generates the data: meters, current transformers, and communication that measure consumption by area. UDM, or Utility Data Management, is the software layer that takes that data, cross-references it with your bill and your contract, and turns it into audit, budget, and reconciliation. They don't compete: submetering measures and UDM gives it meaning. They are the two halves of the same information system.
Four components: meters at each point of interest, current transformers to read large loads without intervening the main conductor, a communication network that brings the data to a single place, and software that stores and displays it. You don't need to install everything on day one: it is best to start with the highest-consumption points and grow point by point as the data justifies the next. The current transformers are installed by qualified personnel.
It depends a lot on the plant, the process, and how neglected the operation was, so the figures are illustrative. At sites with no prior management it is not unusual to find between 5% and 15% of consumption that can be trimmed with operating discipline alone, without investing in new equipment, by detecting phantom loads, demand peaks by area, and low load factors. At already-optimized plants the margin is smaller, but the data still pays off because it detects deviations before they pile up on the bill.
No. Submetering is an internal management measurement that you install and administer; the CFE meter, or the CENACE meter if you are in the Wholesale Electricity Market, is the one with legal validity that defines what you pay. Submetering measures the same kilowatt-hours but distributes them among your plant's areas so you can allocate costs and make decisions. It is a control instrument, not a billing meter.
