Most conversations about IECC 2021 metering focus on electrical submetering. But the code also requires monitoring of all nonelectrical energy supplied to the building—including natural gas, chilled water, hot water, and steam. This post explains the full scope of Sections C405.12 and C405.13, details the specific metering equipment needed for each nonelectrical energy type, walks through how subcircuit electrical monitoring and nonelectrical metering work together, and demonstrates how Emergent Metering’s PowerRadar platform serves as the single unified front end that ties everything together.
The Full Scope of C405.12 and C405.13: Electrical and Nonelectrical Monitoring
The 2021 IECC addresses energy monitoring in two parallel sections that together mandate a comprehensive, whole-building view of energy consumption. Section C405.12 covers electrical energy monitoring—the end-use submetering of HVAC, lighting, plug loads, and process loads that we detailed in Blog Post 1. Section C405.13 extends the same monitoring principles to every nonelectrical energy source that serves the building.
For nonelectrical energy, the code requires submeters or other measurement devices to collect energy consumption data for each end-use category. This includes natural gas consumed by boilers, furnaces, domestic hot water heaters, kitchen equipment, and any other gas-fired appliance. It includes thermal energy delivered through chilled water and hot water distribution systems. It includes steam energy where buildings are served by district steam or on-site steam generation. And it includes any other nonelectrical energy source that contributes to the building’s operation.
The data acquisition requirements for nonelectrical energy mirror those for electrical energy: data must be stored for a minimum of 36 months, the system must provide hourly, daily, monthly, and annual logged data, and a graphical reporting mechanism must be permanently installed and accessible to building operations personnel. For natural gas specifically, the system must either accept interval data from submeters or provide the ability to manually enter gas utility bills into the reporting system.
HVAC and water heating equipment serving only an individual dwelling unit is exempt from end-use submetering. End-use submetering is also not required for fire pumps, stairwell pressurization fans, or emergency-only systems. Individual tenant spaces under 2,500 square feet with dedicated source meters are exempt as well.
States Where Whole-Building Monitoring Applies
Every state that has adopted the 2021 IECC for commercial buildings triggers both the electrical (C405.12) and nonelectrical (C405.13) monitoring requirements. This includes Connecticut, New Jersey, Hawaii, Virginia, Louisiana, Colorado, Massachusetts, Vermont, Maine, Utah, Florida (8th Edition), and Pennsylvania, as well as major Texas cities including Austin, Dallas, Houston, San Antonio, El Paso, and Killeen.
Colorado adds a particularly important layer. The state requires the 2021 IECC as a minimum, but also mandates electric-ready and solar-ready provisions. After July 1, 2026, any Colorado jurisdiction updating its building code must adopt the Low Energy and Carbon Code based on the 2024 IECC. Building owners in Colorado should plan metering infrastructure today that can accommodate renewable energy production monitoring alongside current code requirements for consumption monitoring.
California’s Title 24 Part 6 imposes even more comprehensive submetering requirements that exceed ASHRAE 90.1 in several areas. Commercial buildings must install Energy Data Display Systems that track total building consumption and disaggregate usage by end-use category including HVAC, lighting, receptacles, process loads, and other large loads. EV charging stations require separate metering. The standard mandates 15-minute measurement intervals with hourly, daily, monthly, and annual reporting. Tenants must have access to their consumption data. While California uses its own code rather than the IECC, the monitoring requirements are functionally equivalent and often more stringent.
Metering Each Energy Type: Equipment, Installation, and Integration
Natural Gas Metering
Natural gas is the second-largest energy source in most commercial buildings, used primarily for space heating (boilers, furnaces, rooftop unit gas heat sections), domestic hot water generation, and commercial cooking. The code requires metering of gas consumption at the end-use level—meaning you need to know how much gas the boiler consumes separately from how much the kitchen uses, not just the total building gas consumption.
Emergent Metering carries two primary natural gas metering technologies. The Sierra Instruments BoilerTrak 620S is a thermal mass flow meter designed specifically for boiler fuel gas measurement. It inserts directly into the gas pipe and measures mass flow rate with no moving parts and no pressure drop, providing both instantaneous flow rate and totalized consumption. The Sage Metering Model 51 is a thermal mass insertion meter suited for larger gas mains and process applications, measuring flow from the point of insertion through the pipe’s cross-section.
Both meters provide pulse output and analog (4–20mA) signals for integration. Pulse output connects to the Obvius/Leviton AcquiSuite’s pulse input module (A8911-23 High Density Pulse Module, which accepts up to 23 pulse inputs) or to the Gen 4+ Bridge’s pulse interface. Once connected, natural gas consumption data appears in PowerRadar alongside electrical data—in the same dashboards, the same reports, the same 36-month data archive. Users configure the gas meter’s pulse scaling factor (cubic feet or therms per pulse) in PowerRadar, and the platform automatically converts raw pulses into engineering units for display and reporting.
Chilled Water and Heating Water (BTU) Metering
Buildings with central chilled water plants, district cooling connections, or hot water heating systems require thermal energy (BTU) metering to capture the nonelectrical energy delivered through these distribution systems. BTU metering measures two things simultaneously: the volumetric flow rate of the water through the pipe, and the temperature differential between the supply and return lines. The thermal energy is calculated as the product of flow rate, temperature differential, and the specific heat of water.
Emergent Metering’s EES-301 Ultrasonic Thermal Energy (BTU) Meter ($3,000–$3,100) uses clamp-on ultrasonic transducers that attach to the outside of the pipe—no pipe cutting, no system shutdown, no process interruption. The meter supports pipe sizes from 1 inch to 48 inches and includes clamp-on temperature sensors that measure the supply and return water temperatures through the pipe wall. For PVC piping, which has lower thermal conductivity than metal pipe, Emergent can provide insertion-style temperature sensors that require a temperature well to be installed in the pipe for accurate measurement.
The EES-401 Ultrasonic Energy (BTU) Meter ($3,450–$3,550) provides higher precision measurement for applications where billing-grade accuracy is required, such as district energy metering or tenant chilled water allocation. Both models provide Modbus RTU output for direct connection to Obvius/Leviton AcquiSuite hubs, Honeywell JACE controllers, or the Gen 4+ Bridge’s Modbus port. Data flows into PowerRadar as thermal energy (BTU, ton-hours, or kWh-thermal) and is displayed alongside electrical energy data in the unified platform.
For buildings with multiple chilled water or hot water loops—primary/secondary pumping systems, multiple air handling unit coils, or tenant-level thermal energy distribution—multiple BTU meters can be installed to disaggregate thermal energy by end use. PowerRadar’s device group feature aggregates thermal energy data the same way it aggregates electrical data, allowing engineers to create end-use groups like “HVAC Heating,” “HVAC Cooling,” “Domestic Hot Water,” and “Process Heating.”
Steam Metering
Buildings served by district steam (common in cities like New York, Philadelphia, Boston, and Hartford) or with on-site steam boilers require steam mass flow metering. Steam is more difficult to meter than water because it is compressible and its density varies with pressure and temperature. Accurate steam metering requires measurement of both mass flow rate and pressure or temperature to determine the energy content.
Emergent carries the Sage Metering Model 51 Thermal Mass Insertion Meter ($3,500) for steam applications. This meter uses a heated sensor element to directly measure mass flow rate, providing accurate readings for both saturated and superheated steam without the need for separate pressure and temperature compensation. The insertion design allows installation on existing steam mains without cutting the pipe—only a hot tap connection is required.
Steam meter data integrates into PowerRadar through the same Modbus or pulse pathways as other non-electric meters, with energy values displayed in BTU, therms, or pounds of steam as appropriate for the application.
Domestic Water Metering
While the 2021 IECC’s primary metering requirements focus on energy, water metering is increasingly required by municipal ordinances, green building certifications (LEED, WELL, Green Globes), and Building Performance Standards. Emergent Metering’s water metering product line provides the same non-invasive installation and unified platform integration as the energy meters.
The EES-101 Ultrasonic Water Sub-Meter ($2,600–$2,800) uses clamp-on transducers for pipe sizes from 1 to 48 inches, providing flow rate and totalized volume without any pipe penetration. The EES-201 High-Precision Ultrasonic Water Flow Sub-Meter ($2,980–$3,080) adds billing-grade accuracy for applications like tenant water billing or irrigation monitoring. For smaller pipe sizes in residential and light commercial applications, Emergent carries a full line of in-line water meters from Master Meter and M&E, ranging from 5/8-inch residential meters ($64–$200) to 2-inch commercial meters ($680–$1,280).
All water meters integrate into PowerRadar through pulse output, with flow volumes displayed in gallons, cubic feet, or liters alongside energy data.
Compressed Air and Nitrogen Metering
Compressed air is often called the “fourth utility” in industrial and light manufacturing buildings, and it is one of the most expensive forms of energy when measured per unit of useful work. Leaks in compressed air systems waste an estimated 20–30 percent of compressor output in typical facilities. The 2021 IECC categorizes compressed air as a process load, and monitoring its production and distribution reveals efficiency opportunities that can reduce total building energy consumption significantly.
Emergent carries compressed air flow meters from VP Instruments (VPFlowScope In-line and Probe models, $2,000–$3,500), IFM (SD series thermal flow sensors, $1,200–$1,400), and Keyence (FD-G ultrasonic series, $1,500–$5,000). These meters measure flow rate in CFM (cubic feet per minute) or SCFM (standard cubic feet per minute), along with pressure and temperature, enabling calculation of energy content and identification of leaks through pressure drop analysis.
All compressed air meter data flows into PowerRadar through Modbus, pulse, or analog integration, completing the whole-building energy picture that the 2021 IECC envisions.
The Unified Front End: PowerRadar Ties Everything Together
The most important practical requirement of the 2021 IECC’s monitoring mandate is that all energy data—electric, gas, water, steam, thermal—must be accessible through a single, permanent reporting mechanism within the building. Building operators should not need to log into five different systems to understand their building’s energy performance.
PowerRadar serves as this unified front end. Electric subcircuit data from Panoramic Power wireless sensors and Leviton S7100 BCMs arrives via the Gen 4+ Bridge. Nonelectrical energy data from gas meters, BTU meters, steam meters, water meters, and compressed air meters arrives through Modbus connections to the bridge or through Obvius/Leviton AcquiSuite data hubs. All data is stored in the cloud for 36+ months with hourly, daily, monthly, and annual reporting in graphical format—exactly what the code requires.
PowerRadar’s Energy Flow (Sankey diagram) visualization ties the whole picture together in a single image: total building energy enters from the left, splits into electrical and nonelectrical streams, further divides into end-use categories (HVAC, Lighting, Plug Loads, Process, Heating, Cooling, Hot Water), and flows down to individual pieces of equipment on the right. The width of each stream represents its share of total energy consumption. A building operator can glance at this diagram and immediately understand where energy is being consumed and where the largest savings opportunities exist.
For building owners with multiple properties, PowerRadar’s account dashboard provides a portfolio-level view across all sites. Managers can compare energy intensity across buildings, identify underperformers, and drill down into any site for detailed subcircuit analysis. Automated reports can be scheduled for weekly or monthly delivery to ownership, property management, and engineering teams, providing consistent energy performance documentation without manual effort.