Tenant Energy Data: The Missing Layer for Landlords

Consider an illustrative commercial portfolio with 70 tenants. The portfolio and tenant count are hypothetical, but the underlying Irish data gap is real. SCSI’s green-lease guidance anticipates regular tenant-to-landlord environmental data sharing, potentially quarterly and in a landlord-required format.

Without common infrastructure, that process could mean someone sending 70 requests for electricity, gas or heating spreadsheets every quarter. The replies may arrive in different formats, cover different dates and use different meter names. Some may not arrive at all.

The landlord can see the energy used in receptions, corridors, lifts and shared plant. Much of what happens inside leased space sits behind tenant meters and supplier accounts that the landlord cannot see directly.

This is not primarily a spreadsheet problem. It is a recurring data-infrastructure problem across lease, organisational and metering boundaries.

A better system establishes the right to obtain the data, collects it consistently, records its quality and turns it into repeatable tenant, building and portfolio views. The objective is a dependable route from energy records to intensity, carbon and pathway reporting, without rebuilding the dataset every quarter.

The Quick Version

• Tenant-procured energy can create a significant blind spot in whole-building and portfolio reporting.
• SCSI identifies data sharing as a critical part of a green lease and provides illustrative provisions for regular tenant-to-landlord reporting.
• The useful data layer can combine electricity, gas or heat, submetering, floor area and carefully chosen operational context such as occupancy.
• Energy use intensity requires a clear energy boundary and floor-area convention. Carbon intensity also requires documented, version-controlled emissions factors.
• Occupancy can explain demand, but it is not part of the basic CRREM energy-use intensity formula.
• Start with one representative building, settle data rights and definitions, then automate the repeatable parts.
• Optim Energy can configure Optim EOS to support tenant, building and portfolio reporting, using suitable existing systems and additional hardware where required.

Why the Landlord’s Data Stops at the Lease Line

A multi-let building can have several energy boundaries at once. The landlord may buy electricity for common areas and central plant. Tenants may buy electricity or gas directly. Heating may be provided centrally and recovered through a service charge, or bought through a district-heating arrangement. Local submeters may separate floors, units, equipment or shared services.

Each source can be valid while the combined picture remains incomplete.

Monthly landlord invoices cannot explain tenant demand. A tenant spreadsheet may contain annual totals but no meter identifiers or interval profile. A building-management system may show plant operation without showing all the energy supplied to leased areas. Floor-area records can use different conventions across acquisitions. One portfolio number can therefore conceal missing tenants, overlapping meters and inconsistent denominators.

The reporting consequence matters. Under the GHG Protocol, tenant energy in downstream leased assets is often reported by a landlord in Scope 3 Category 13. The exact classification depends on the lease type and the landlord’s organisational and operational boundaries, so it should not be assumed for every portfolio (GHG Protocol Scope 3 Calculation Guidance).

Irish energy-audit guidance recognises the same practical divide. SEAI says landlords and tenants in multi-tenant buildings may need to agree which energy uses each controls, using utility bills, meters or submeters where available and documented estimates where reliable readings do not exist (SEAI Guide to Achieving Compliance with the Energy Auditing Compliance Scheme).

The operational consequence matters too. A landlord cannot manage whole-building performance confidently if a material share of consumption appears only once a year, arrives late or is estimated without explanation.

Green Leases Can Establish the Data Right

Technology cannot solve an authority problem. Before connecting an API or installing a submeter, the landlord needs a clear basis for collecting, using and sharing the information.

The Society of Chartered Surveyors Ireland addresses this directly in its 2025 information paper, Green Leases: A Best Practice Guide for Commercial Property Professionals. SCSI describes data sharing as a critical green-lease component and identifies electricity, gas, water, waste and refrigerant information as relevant. Its illustrative provisions cover regular tenant-to-landlord sharing, a landlord-required format, accurate tenant meters and landlord-installed submetering where reasonably required.

That does not mean every existing landlord already has a right to every dataset. SCSI notes that legacy leases may lack provisions requiring cooperation. It suggests staged adoption through new leases and renewals, while voluntary sharing can begin sooner.

A workable data clause or side agreement should settle more than frequency. It should establish:

• which utilities, meters and leased areas are in scope;
• whether readings, invoices, interval files or calculated totals are required;
• the reporting period, format and submission date;
• who may access the information and for what purpose;
• how missing, estimated or corrected data will be handled;
• who pays for new metering, integration and maintenance; and
• how the arrangement will be reviewed when systems or reporting duties change.

The SCSI clauses are illustrative rather than legal advice. Each property and lease needs appropriate professional review. The important infrastructure lesson is simple: data rights and technical connections must be designed together.

Build a Source-to-Report Data Layer

The required architecture is less glamorous than a new sustainability dashboard. It is also more useful.

Input	What it contributes	What must be controlled
Electricity	Whole-site, tenant, circuit or equipment consumption	Meter identity, interval, units, gaps and overlaps
Gas and heat	Combustion or supplied-heat consumption	Calorific basis, meter interface, supplier factors and boundaries
Submetering	Separation of tenants, floors, shared plant or major loads	Mapping, calibration, maintenance and billing status
Floor area	Denominator for comparable intensity metrics	Area convention, exclusions and effective dates
Occupancy and space use	Context for demand, vacancy and operating patterns	Purpose, privacy, granularity and retention
Lease and tenancy records	Assignment of data to the right reporting entity and period	Unit changes, voids, confidentiality and access rights

Some data can come from suitable existing meters, BMS interfaces, tenant systems or supplier exports. Where a reliable signal does not exist, Optim Energy can supply and integrate Optim Energy hardware for metering, occupancy, temperature, radiator control and building-state monitoring as part of an agreed deployment.

The word “automatic” needs care. A connector can automate collection only after access, compatibility, naming, units and responsibility have been resolved. A scheduled import of an unidentified spreadsheet is still an unidentified spreadsheet.

Each record should retain its source, meter, period, unit and quality status. Corrections should not erase the earlier value without an audit trail. Estimated data should remain visibly estimated. Access should follow the agreed landlord, managing-agent and tenant roles.

That foundation is what makes reporting repeatable.

From kWh/m² to Carbon and Pathway Reporting

The calculation chain looks simple:

energy records → kWh/m² → kgCO₂e/m² → pathway comparison → tenant, building and portfolio reporting

The difficult part is making every arrow explicit.

1. Define whole-building energy

For a complete view, combine the relevant landlord-procured and tenant-procured energy for a consistent 12-month period. Document exclusions, missing intervals and estimates. Avoid adding a landlord main meter to tenant submeters if the latter are already contained within the main-meter total.

2. Choose the correct floor area

Energy use intensity divides annual energy by an appropriate floor area. The selected convention must be consistent across assets and over time. Indoor parking, external areas, mixed uses and material changes to leased space need deliberate treatment.

3. Apply documented emissions factors

Carbon intensity requires each energy source to be multiplied by the corresponding emissions factor before the results are combined and divided by floor area. The factor source, geography, year, unit and version should be retained with the result.

This matters because apparently similar factors may cover different gases or system boundaries. For example, SEAI’s current conversion-factor tables label their energy factors as CO₂ and explain important boundaries around upstream emissions. A complete kgCO₂e method must use factors appropriate to the reporting purpose rather than relabelling a CO₂-only result.

4. Compare with a defined pathway

CRREM’s May 2026 Assessment Guide requires whole-building operational energy, including tenant-procured energy, an appropriate floor area, property type, country and all relevant energy sources. It compares energy use and carbon intensity separately with country and property-type pathways and identifies potential misalignment years.

Occupancy can help explain why a building performed as it did. It does not enter CRREM’s basic energy-use intensity formula. Estimated or gap-filled energy can be used, but its status and method should be disclosed. Mixed-use assets also need an appropriate blended treatment.

A landlord data layer should therefore prepare consistent, traceable inputs for a CRREM assessment or another defined net-zero pathway. It should not present a pathway comparison as a certification, or imply that software output replaces professional review. Commercial use of proprietary pathway data must also follow the relevant licensing terms.

What Changes for a 70-Tenant Portfolio

Consider an illustrative portfolio with 70 tenants. This is a process example, not a customer case study or savings claim.

Before the data layer, the sustainability team maintains a contact list and sends a quarterly request. Staff reconcile tenant names with units, convert files, chase gaps and copy totals into a reporting workbook. When an asset is sold, a lease changes or a figure is corrected, the audit trail depends on email history and individual knowledge.

After implementation, the workflow becomes controlled:

1. Each building, tenancy, meter and floor-area record has a stable identifier.
2. Compatible data sources feed the platform on an agreed schedule.
3. Tenants use a defined fallback submission route where direct integration is unavailable.
4. Validation rules flag missing periods, unexpected units, duplicate coverage and abnormal changes.
5. Energy and carbon methods are applied consistently with their source versions recorded.
6. Authorised users can move from portfolio totals to a building, tenant or meter without rebuilding the calculation.
7. The team spends its time resolving real exceptions rather than formatting 70 spreadsheets.

The benefit is not the removal of every manual task. Someone still owns data quality, tenant engagement, methodology and exceptions. The value lies in making those responsibilities visible and repeatable.

Start With One Building, Not the Whole Portfolio

A useful pilot is designed to expose the awkward parts early.

Choose a representative multi-let building with a meaningful tenant-data gap, a cooperative property team and enough existing information to establish a baseline. Then:

1. Map the boundary. List landlord and tenant meters, energy sources, spaces and reporting responsibilities.
2. Review authority. Confirm what the leases, tenant agreements and internal governance permit.
3. Test the sources. Check interfaces, file formats, identifiers, intervals and historical coverage.
4. Define the methods. Agree floor area, emissions factors, estimation rules and pathway version before calculating outputs.
5. Fill only material gaps. Add suitable meters, gateways or anonymous operational sensing where the decision justifies them.
6. Run one reporting cycle. Produce tenant, building and portfolio views, then record every exception and manual intervention.
7. Standardise what worked. Turn the verified pattern into a repeatable deployment template, while retaining site-specific checks.

This approach is consistent with good interval-meter analysis: start with a trustworthy measurement boundary, then add detail where it answers a real question. It also supports the broader asset planning needed as European building-performance requirements evolve.

Where Optim EOS Fits

Optim EOS is Optim Energy’s building-performance platform and BEMS. Optim Energy can configure it around the landlord’s reporting boundary, suitable existing systems and the operational questions in scope.

For tenant carbon-data infrastructure, that can include:

• compatible electricity, gas, heat and submeter data;
• Optim Energy meters, sensors, gateways and controllers where existing signals are insufficient;
• tenancy, building and portfolio structures;
• floor-area and methodology records;
• configured kWh/m² and kgCO₂e/m² calculations;
• tenant, building and portfolio reporting; and
• comparison with an agreed net-zero pathway, with CRREM-ready data where required.

Each deployment still depends on technical compatibility, operating authority, data rights and the agreed methodology. Optim EOS can retain the readings, factors, boundaries and outputs used in a reporting process. It does not grant lease rights, certify a carbon inventory or guarantee alignment with a pathway.

Summary

Tenant energy reporting sounds administrative because the visible symptom is a stream of emails and spreadsheets. The underlying problem is strategic: a landlord cannot manage or report whole-building performance consistently without a dependable view of energy used inside leased space.

Green-lease provisions can establish the right and responsibility to share data. Metering and integrations can provide the readings. A governed data layer can preserve their meaning, quality and history. Only then do kWh/m², kgCO₂e/m² and pathway comparisons become repeatable portfolio information rather than a quarterly reconstruction exercise.

For a large landlord, fixing that unglamorous layer can be one of the most valuable steps in the entire carbon-reporting process.