Installing EV chargers is the easy part. Figuring out who pays for the electricity — and absorbing the demand-charge spike that charging creates — is where commercial and multi-tenant buildings get burned. Without submetering the chargers, EV energy disappears into the master bill and gets cross-subsidized by everyone else in the building.
The Cross-Subsidization Problem
When EV charging is not separately metered, its cost is buried in the building's total electricity bill and spread across all tenants or departments — including those who never plug in. That is unfair, hard to defend, and it removes any incentive for drivers to charge efficiently. Submetering each charging circuit is the only accurate way to assign EV energy to the people who use it — the same logic that drives multifamily common-area submetering.
Demand Charges — the Hidden Cost
Energy (kWh) is only half the bill. Commercial utility rates also include demand charges based on your peak kW within a billing period. EV charging draws large, sudden loads, so several vehicles charging at once can spike your facility peak and inflate demand charges far beyond the raw energy cost. This is frequently the single largest hidden cost of unmetered EV charging, and you cannot manage it if you cannot see it.
Why Submetering Is the Foundation
Submetering EV charging delivers three things at once: fair cost allocation (bill the right party for actual kWh), demand visibility (see when charging is driving your peak), and the data trail needed for benchmarking and incentive programs. ENERGY STAR's Portfolio Manager, for example, treats submetering of EV charging as the most accurate method of accounting for that load. Estimation is a liability; measurement is an asset.
Managing the Peak
Once you can see EV demand, you can manage it. Load management and staggered or scheduled charging spread the draw across time so fewer vehicles charge simultaneously at the peak. Some sites pair charging with battery storage to shave the spike. None of these strategies are possible without submeter data telling you when and how hard the chargers are pulling.
Allocation Models
With submeter data in hand, buildings allocate EV cost a few ways: direct billing of measured kWh to the driver or tenant, a blended rate that includes a share of demand charges, or a per-session fee calibrated to actual cost. The right model depends on your tenant mix and rate structure — but every defensible model starts from measured data, not estimates.
Specification Notes
Meter each EV charging circuit (or the dedicated EV panel) with a meter that captures both energy and demand, at an accuracy class appropriate to billing if you intend to invoice drivers. Confirm the meter can report interval data, since demand management depends on seeing the load over time, not just totals.
EV charging is a fast-growing load that, left unmetered, quietly inflates everyone's bill and your demand charges. Submeter the chargers, expose the peak, and you turn a hidden liability into a managed, fairly allocated cost.