Understanding Submetering and Its Role in Energy Accountability

A building's main utility meter can tell an owner how much electricity the entire property consumes, but it does not always show who is using that energy or where it is being consumed.

That is where energy submetering becomes useful.

A submeter measures energy consumption for a specific area, tenant, floor, system, or piece of equipment. Instead of seeing only total building consumption, owners and managers can gain a more detailed picture of how electricity is being used.

For NYC commercial buildings, submetering also has a direct regulatory connection. Local Law 88 requires certain covered buildings to install electrical submeters for covered tenant spaces and provide monthly energy statements.

What Is Energy Submetering?

A submeter is a measurement device installed downstream of a building's primary utility meter within its internal electrical distribution panels.

While the main utility meter records aggregate property power:

Submeters provide granular, isolated consumption data:

Depending on the system design, submeters can also measure electricity used by specific building systems, equipment banks, or dedicated end uses. This creates a much more detailed picture of energy consumption throughout the facility.

Main Utility Meter vs. Submeter

Understanding the operational division between primary utility meters and internal submeters is foundational for energy management.

Neither meter replaces the other. The main meter provides the property's overall consumption baseline, while submeters add the crucial layer of diagnostic granularity.

Why Submetering Improves Energy Accountability

One major problem in multi-tenant buildings is that occupants may not directly see how much energy they consume. In unmetered commercial leases, electricity is often billed on a flat square-footage basis (prorated rent), meaning tenants who waste energy bear no direct financial penalty, while conservative tenants subsidize wasteful neighbors.

Consider three commercial tenants occupying identical floor plates:

• Tenant A (Professional Services): 20,000 kWh/month — standard office schedule
• Tenant B (Consulting Firm): 8,000 kWh/month — hybrid workforce, efficient controls
• Tenant C (Media / Trading Firm): 35,000 kWh/month — high server density, 24/7 operations

Without individual measurement, the owner sees only a lump-sum monthly total. With submetering, unusually high consumption becomes transparent immediately. This creates true energy accountability because tenants pay for what they actually use and can monitor their own consumption trends.

NYC regulatory studies have specifically demonstrated that receiving regular energy statements encourages non-residential commercial tenants to curtail unnecessary after-hours loads and reduce electricity use by 10% to 20%.

How Submetering Supports Tenant Energy Statements

Under NYC's LL88 mandates, covered tenant spaces must have electrical submetering installed, and building owners must provide monthly statements to each tenant or subtenant detailing measured electricity and applicable charges.

A simplified monthly tenant statement includes:

The exact format and billing methodology must comply with New York Public Service Commission (PSC) regulations and lease agreements.

Which NYC Buildings Are Covered by LL88?

NYC Department of Buildings (DOB) guidance identifies covered buildings under Local Law 88 (incorporated into NYC Administrative Code § 28-311) as:

• A single commercial building exceeding 25,000 gross square feet
• Two or more commercial buildings on the same tax lot that together exceed 100,000 gross square feet
• Two or more commercial condominium buildings governed by the same board that together exceed 100,000 gross square feet

How Submetering Helps Find Energy Waste

Submetering is indispensable because total consumption does not explain the cause of consumption.

Suppose a building's overall monthly electricity bill suddenly spikes by 18%:

Without submeters, building engineers would spend days testing mechanical rooms. With submetering, interval data instantly pinpoints the source:

Facility teams can immediately inspect Tenant C's floor to identify common culprits:

• Override thermostats running supplementary DX units continuously over weekends
• Failed occupancy sensors leaving hundreds of fluorescent or LED fixtures illuminated overnight
• Unmonitored server closet supplemental cooling systems operating simultaneously
• Heavy commercial kitchen or refrigeration defrost heaters stuck on active cycle
• High plug-load anomalies from unauthorized high-draw appliances

Submetering and Energy Benchmarking (LL84 vs. LL88)

Submetering and whole-building benchmarking serve distinct but complementary roles in NYC building management:

Combining both compliance frameworks provides building owners with the high-level compliance score and the surgical engineering data required to lower Local Law 97 carbon emissions.

Submetering Different Building MEP Loads

Submetering does not have to stop at tenant demarcations. Forward-thinking property operators instrument major mechanical, electrical, and plumbing infrastructure to monitor critical facility loads:

Breaking down consumption into operational buckets allows engineering teams to benchmark chiller efficiency (kW/ton), track common-area lighting runtimes, and prevent EV charging banks from creating unexpected peak coincident demand charges.

Submetering and Building Automation Systems (BAS)

Modern digital submeters utilize open communication protocols (such as BACnet MS/TP, BACnet IP, or Modbus) to stream real-time data directly into Building Automation Systems (BAS) or cloud energy management software.

A fully integrated submetering network enables:

When an unexpected consumption anomaly occurs outside normal business hours, the system can automatically send notifications to building engineers to investigate before thousands of dollars in wasted electricity are billed.

Measurement & Verification (M&V) for Efficiency Projects

Submetering provides concrete verification when proving that an energy-efficiency capital upgrade delivered its anticipated return on investment (ROI).

Consider a floor undergoing an LED lighting and smart occupancy sensor retrofit:

• Pre-Retrofit Submetered Baseline: 25,000 kWh/month on lighting panel LP-4
• Post-Retrofit Measured Performance: 15,000 kWh/month on lighting panel LP-4
• Verified Energy Reduction: 10,000 kWh/month (40% measured savings)

Without a dedicated submeter, those lighting savings would be obscured by seasonal chiller fluctuations or tenant computer loads on the main utility bill.

Common Submetering Mistakes to Avoid

NYC LL88 Reporting Requirements & Penalties

To demonstrate compliance with Local Law 88, covered building owners must file an official compliance report with the NYC Department of Buildings. The filing requires:

• A comprehensive list of all covered commercial tenant spaces within the property
• Professional attestation (stamped by a Registered Architect or Professional Engineer) certifying that the required submeters have been correctly installed and commissioned
• A sample monthly electricity statement meeting NYC Administrative Code standards

Energy Accountability & Submetering Checklist

Conclusion

Energy submetering gives building owners and tenants an accurate, actionable view of electricity consumption. Instead of seeing only a single macro utility bill, owners can isolate exactly how much power individual tenant spaces, lighting risers, and central MEP systems consume.

That visibility fosters real energy accountability, eliminates cross-tenant subsidization, uncovers operational waste, and delivers verified measurement for energy retrofits.

For NYC commercial properties, submetering also satisfies compliance obligations under Local Law 88. However, the greatest long-term payoff extends beyond avoiding fines: by transforming raw power data into tenant accountability, submetering becomes an indispensable tool in decarbonizing commercial real estate and meeting Local Law 97 emissions targets.

Frequently Asked Questions