Tenant submetering and cost allocation
A meter per tenancy, the landlord incomer above them, and a dated map from meter to tenant that survives a change of occupier.
- Measure
- The landlord incomer, each tenancy, the common services, and the water, gas or heat that is allocated
- Rule
- Metrology and billing rules are national, so check them before a reading becomes an invoice
- Sensors
- ZEM-65, Class 0.5S to IEC 62053-22 with its CTs ZEM-63 datasheet (PDF, opens in a new tab)
- On site
- One Gateway per building, up to 250 wireless devices ZGW-20 datasheet (PDF, opens in a new tab)
Hardware for commercial tenant submetering
One electrical meter per tenancy and per common service, plus an interface for each non-electrical meter that is being allocated.
Each tenancy feed, the common services and the landlord incomer
- Choose the CT rating per feed: 120 A split-core, or 300 A, 1 kA and 3 kA Rogowski coils
Class 0.5S to IEC 62053-22 for the meter and its CTs together, CAT III at 480 V
Collects every submeter, keeps the readings and exports them to the billing process
If water or gas is allocated
Water and gas meters with a pulse output, where those are allocated too
Pulses down to 10 ms wide, up to 40 Hz, inputs to 35 V DC
If heat or cooling is allocated
Heat meters on a shared heating or cooling system
ZPC-20 and ZHM-21 share one enclosure with different terminals inside, so the ordering code is what you specify.
What each meter has to represent
Every meter stands for one boundary in the lease. Write down which one, and the date the mapping starts.
| Position | What it tells you | Reference | Sensor |
|---|---|---|---|
| Landlord incomer | The total the allocation has to reconcile against | Matching periods on both sides of the comparison | ZEM-65 (on this page), incomer |
| Tenancy feed | One tenancy's electrical consumption, at its lease boundary | CT direction and ratio confirmed against a known load ZEM-63 datasheet (PDF, opens in a new tab) | ZEM-65 (on this page), one per tenancy |
| Common services | Lifts, lighting and plant that are shared and then apportioned | Named in the lease as a landlord or shared cost | ZEM-65 (on this page), one per service |
| Water, gas or heat | The non-electrical consumption that is also allocated | Pulse weight or meter record written down, with its starting total ZPC-2X datasheet (PDF, opens in a new tab) | ZPC-20 (on this page) |
Date the map, do not overwrite it. When a tenancy changes hands, the new mapping starts on a date. The old readings keep the old owner.
Metering is not billing. The allocation rule, standing charges, taxes and the dispute process live in the billing system, not in the meter.
Energy cost allocation records in Edge
Edge keeps the measured record. The commercial calculation happens downstream, from data that can be shown to a tenant.
- Readings stay per meter
- The Gateway keeps each submeter's own cumulative total and interval data, so an allocation can always be traced back to a meter.
- The remainder is visible
- A calculated sensor subtracts the sum of the tenancies from the incomer, so unmetered load and losses are a number rather than a rounding.
- A quiet meter is reported
- A no-data rule fires when a submeter stops reporting, before a tenant is billed from a gap.
- Exported, not locked in
- Interval data leaves over MQTT, HTTP or a file export to whatever produces the invoices.
Commissioning checks
Do these before the first allocated invoice.
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Every channel names a real meter
Walk the boards and match each Edge point to the meter's position, its serial number and the tenancy it feeds.
Pass when every point has a photograph, a position and a dated tenancy.
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Direction and ratio are right
Switch a known load in one tenancy and watch its meter and the incomer.
Pass when the tenancy meter rises, the sign is positive, and the incomer rises by about the same amount.
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The building reconciles
Add the tenancies and the common services for one full period and compare with the incomer.
Pass when the difference is explained by named unmetered load and losses, and recorded.
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A tenancy change is handled
Change a mapping with a start date, then read a report that spans the change.
Pass when the earlier consumption still belongs to the earlier occupier.
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The local rules are confirmed
Ask the responsible professional which metrology, billing and privacy rules apply in this jurisdiction.
Pass when the answer is written down beside the measurement plan.
What monitoring does not replace
EpiSensor monitoring data is not automatically approved for tenant billing in every jurisdiction.
- Legal metrology. Whether a submeter's reading can be billed depends on national rules and on the meter's approval.
- The allocation rule itself, including standing charges, taxes and how disputes are handled.
- A shared service that the lease apportions by area or headcount: that is a contractual calculation, not a measurement.
- The lease. Where a meter's boundary and the lease boundary differ, the lease wins.
Sources and related guides
Sources
- WELMEC guides for measuring instruments (opens in a new tab) WELMEC. European legal-metrology guidance. National implementation decides whether a submeter's reading may be billed.
- ZEM-63 Wireless 3-Phase Electricity Monitor datasheet (opens in a new tab) EpiSensor. Specifications, ranges and ordering codes.
Related
- Multi-site energy monitoring Application guide One Gateway per site, the same point names and intervals everywhere, and a portfolio view that keeps working when a site loses its connection.
- Transformer and distribution board monitoring Application guide Meter the incomer first, then the feeders that explain a decision. How to pick CTs, keep phase detail, and reconcile the board against its parent.
- Current transformer ratio and burden calculator Engineering tool Work out a CT's secondary current and check its rated burden covers the meter and the lead loop.
- Pulse meter scaling and capacity calculator Engineering tool Convert pulse counts to energy and check pulse rate, pulse width and counter capacity.
Reviewed by EpiSensor Engineering on . Revision 4.
Map every meter to the tenancy it bills
We will map meters to tenancies, count the hardware, and show where the allocation has to reconcile.