University of California, Irvine is using smart, web-based electrical sub-meters to capture actionable energy-use data at the building, zone and room level to identify opportunities for decreasing operating expenses and carbon footprint. To get the necessary resolution of detail, low-cost load monitoring devices are retrofitted to the electrical panels in research labs and other energy intensive facilities across campus and connect to a server via TCP/IP. When combined with energy management system (EMS) data from other systems, the sub-meters help provide continuous commissioning of building performance.
In addition to using sub metering and building EMS, UC Irvine has installed centralized demand-controlled ventilation (CDCV) in lab buildings throughout campus. The system monitors and increases ventilation rates when indoor air quality is beyond the acceptable delta. In addition, the system trends indoor air quality, zone-level delivery rates, occupancy, and fume hood sash position to provide a more sophisticated level of monitoring and commissioning of building HVAC use.
While LEED™, Energy Star, and Labs21 benchmarks look at total building load as it is captured at the utility meter, these metrics reveal very little about what phenomena is specifically contributing to energy consumption within the building and where the opportunities for improvement are.
“You could have a piece of equipment that’s driving energy use up because it’s in front of a thermostat or you could have a small energy-intensive data center. In that case you might have a really efficient building that performs poorly from a total watts per-square-foot perspective, or it could be the other way around,” says Matt Gudorf, campus energy manager at UC Irvine.
To accurately identify the root-causes for energy use, UC Irvine installed smart sub-meters in the electrical panels of three research buildings as a pilot project. The sub-meters capture specific load data and transmit it to a secure central server for detailed analysis using customized dashboards. Based on the success of the pilot, UC Irvine is now rolling the system out to other buildings across campus.
“The kind of actionable information that leads to savings is really found at the floor and zone levels. That’s where you want to be able to drill down and get to detailed information. Sub-metering allows you to isolate specific things like lighting load, HVAC, or plug load and break it out by room, floor, or zone to really understand what’s going on,” says Gudorf.
Smart Continuous Commissioning
UC Irvine is now able to conduct continuous commissioning of facilities by compiling data from EMS, CDCV, and electrical sub-meters into customized graphic dashboards that make it possible to quickly pinpoint opportunities for reducing costs and energy consumption, as well as validate the success of energy saving upgrades and other initiatives.
The budget-friendly sub-meters consist of a simple screen-less circuit board and a series of up to 12 clamp-on CTs that attach directly to electrical panels. The boards are also connected to the network via TCP/IP. Since all data is handled entirely online there are no meters to read in the field, and no software to install on individual computers.
Energy use data is compiled with graphic dashboarding tools that allow for easy analysis of facility performance. Once occupancy and utilization baselines are established, specific zones, floors, and rooms can be monitored 24/7 based on relevant metrics.
While the sub-meters mount neatly on the wall next to designated electrical panels, UC Irvine also has a portable briefcase-based system—still under development by a vendor—that is used to spot-check individual facilities and troubleshoot issues on an as-needed basis without the cost of installing a committed unit.
Case Study in Continuous Commissioning
The University recently had an opportunity to conduct a case study comparing two nearly identical research buildings—one finished in 2001 and re-commissioned in 2010 after receiving a series of energy upgrades, the other built in 2010 and certified LEED® Platinum.
Using watts per square foot as the metric, the new LEED Platinum research center, Gross Hall, was found to perform better than the older research facility, Hewitt Hall, by a significant difference of two watts per square foot.
Comparing them to other labs across the country using the Labs21 benchmark, the energy retrofits done to Hewitt Hall achieved the average for performance at the same type of research laboratories in the same climate, while Gross Hall beat the best currently benchmarked building by 18 percent.
Although Gross Hall performs extremely well when measured on a watts per square foot basis across the entire building, the ability to monitor plug loads at the zone level allowed UC Irvine to capture valuable peak demand savings by pinpointing a 60 kilowatt spike happening when an autoclave was turned on during peak-demand time.
“If you pay a peak demand charge of $10 per KW, it may have just cost you $600 to run that autoclave. So we set up a best-practice rule stating that the autoclave should only be run before 9 AM or after 5 PM. Now we’re no longer creating this huge peak-demand charge that wasn’t really necessary,” says Gudorf.
In another case, monitoring energy and HVAC loads of specific zones revealed a lab that was running at full air-flow during the day but then would suddenly drop off at night.
“The change was so sharp we knew something was going on. But it’s hard to see what’s really happening in a situation like this from an
Business Case for Sub-Metering
While creating a smart continuous commissioning system using electrical sub-meters and CDCV data requires a slightly higher initial investment, it results in documented energy savings over the long term by delivering monitoring capabilities and strategic analysis that can’t be achieved through traditional commissioning efforts.
“Commissioning is great, but its effectiveness falls off over time and then you have to re-commission, which requires additional investment. When you put in the necessary sub-metering, dashboarding, and personnel to monitor things you have a bigger initial investment but you don’t experience the performance fall-off. And the ongoing savings compound quickly, whether it’s by changing the hours an autoclave runs, or by moving a hotplate away from the thermostat. These are the kinds of things continuous commissioning helps you find every single day,” says Gudorf.
Outliers and Solutions
Combining energy-use data from the building, zone, and room level with information pulled from utility meters and EMS makes it possible to identify performance issues so they can be better managed. But according to Gudorf, it all starts with establishing the right metrics.
“Once you’ve established key operational metrics—whether it’s watts per square foot, kilowatt hours per widget produced, whatever—you determine what sub-metering and dashboarding you need to get that information at the floor and zone level,” he says.
Then it becomes a matter of doing the data analysis to make sure facilities are performing as expected or beating their designated benchmarks.
“You’re basically graphing large amounts of information and looking for the outliers. Then you go out and deal with them on a case by case basis with the ultimate goal of reducing your energy costs and carbon footprint. You have to drill down a little bit to do the analysis, but it’s now becoming very easy and very cost effective to do these things,” says Gudorf.
By Johnathon Allen
This report is based on a presentation by Gudorf at the Tradeline Lean Facility Lifecycle Conference in March, 2012.