Description:

New systems that integrate sensors and analytics are simplifying the submetering process and driving costs down. A full-panel submeter provides a compact data acquisition system that can monitor up to 42 separate circuits simultaneously. The system is typically mounted adjacent to the electrical panel and connected via metal conduit.

GSA's Green Proving Ground (GPG) program found that a new full-panel system was an effective solution for improving tenant billing practices and optimizing building operations via fault detection and diagnostics (FDD) and energy conservation measures (ECMs). A GPG testbed assessment found a one-year payback based on more accurate overtime tenant billing. Metered energy use was double the estimate.

Special Considerations

• High-accuracy current transformers (CTs) with a phase angle shift of <0.5° are necessary to support tenant billing.
• Size CTs to estimated power levels, as opposed to rated breaker values. An ammeter can estimate amperage draw.
• Tracing loads to individual circuits can be challenging due to inaccurate panel schedules, obscure naming conventions, or lack of circuit tracing. Tracing loads may be an expensive process in locations with many low-load receptacles. Define monitoring goals prior to deployment.
• A registered electrician is required to install the system. A spare breaker for the voltage tap will facilitate system installation.

See GSA’s Green Proving Ground for more details on the field demonstration findings.