Q&A
Q: What was the delta in actual usage from the meter vs the estimate for the full-panel system?
A: When extrapolated to one year, the metered energy use for the data center at the Salt Lake City courthouse was double the estimate —127,103 kWh/yr vs. 63,510 kWh.
Q: Are system subscription services the only way to go, or could similar systems be available without a "cloud" service model.
A: The pricing model for the wireless CTs has recently changed to eliminate ongoing subscription costs. An upfront hardware cost provides unlimited access to all of the sensor data.
Q: Is there a building size recommendation for these submetering systems?
A: No. Large pieces of equipment should be targeted for fault-detection and diagnostics or tenant overtime billing. For capturing energy conservation measures (ECMs), mid to large size buildings will be most cost-effective.
Q: How many of the ECMs could have been discovered by a traditional energy audit?
A: A data center professional who conducted an energy audit at the Salt Lake City Courthouse testbed said that in the past he did not have access to the level of data available from the submetering system.
Q: What is the lifespan of the wireless current transformers (CTs) and do you have to replace batteries?
A: The wireless CT lifespan is assumed to be 10 years. They are powered by the current through the wire and do not require batteries or ongoing maintenance.
Q: With these submetering systems are there alarming functionalities we can use when units are exceeding base loads and or normal operations?
A: Yes, submetering systems can provide fault-detection and diagnostic capabilities including alarming functionalities. This can be particularly beneficial to facilities without GSALink.
Q: Do you find inaccuracies with measuring loads controlled by VFDs?
A: We did not assess loads with VFDs but would not expect any issues with accuracy. Because VFDs typically provide higher power factor and can continuously ramp the motor drive this could lead to even better performance.
Q: Do we need to get pre-approval from IT before installing these systems and using 3rd party software?
A: Yes, all technologies that capture or utilize GSA data or interface with systems connected to GSA's network need to be cleared by GSA IT-Security. The submetering systems tested by GPG were approved for the pilot tests, however, depending on how they are implemented in a production environment, they may be subject to a full evaluation from GSA IT security, and require remediation prior to use. The complexity of the remediation will depend on where the submetering system's network-based components are hosted.
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