How electric submeters can help facility operator’s measure, verify, and report energy performance
Energy-efficiency retrofit projects require major planning, insight, and resources. The good news for facility operators — and electrical contractors — is that inexpensive submeters and energy intelligence software can provide the necessary energy data acquisition, analysis, and presentment that will ultimately prove their value through demonstrated energy savings and lower operating costs.
According to PlaNYC, New York City’s comprehensive road map to a “greener” municipal infrastructure, approximately 75% of the Big Apple’s current carbon footprint comes from buildings expected to occupy some 85% of city real estate through 2030. In response to these projections, the New York City Council adopted various high-impact energy conservation ordinances under the umbrella of the Greener, Greater Buildings Plan (GGBP). Signed into law by Mayor Michael R. Bloomberg in December 2009, the heart of the GGBP is four cutting-edge local laws (LLs) designed to reduce the city’s total carbon emissions by 30%, while saving $700 million in annual energy costs by 2030. These include:
- LL84/09 Benchmarking — By May 1, 2011, designated buildings will be required to annually benchmark their energy and water efficiency — and to publicly disclose that information on the Internet by Sept. 1, 2013.
- LL85/09 New York City Energy Code — Establishes a conservation code and closes a former loophole that excluded energy-efficiency improvements in upgrades impacting less than 50% of the building’s systems.
- LL87/09 Energy Audits and Retro-Commissioning — Every 10 years, designated buildings are required to pay for energy audits and retro-commission “tune-ups” of their boilers, furnaces, HVAC, electrical, lighting, and other building systems, starting in calendar year 2013.
- LL88/09 Lighting Upgrades and Submetering — Requires lighting system upgrades in specified non-residential and mixed-use building spaces, while also requiring electric submetering in defined commercial tenant spaces. Compliance filing deadline is Jan. 1, 2025.
At the forefront of municipal efforts to optimize the energy efficiency of its existing building stock, New York City’s vanguard GGBP — along with emerging measures in other jurisdictions around the country — not only illustrates the mounting pressure on facility managers to create and maintain high-performance buildings, but also underscores the rapidity with which such measures are becoming law.
Benchmarking Building Performance
As the first step in creating and maintaining an energy-efficient, high-performance building, the energy profile provides the basic informational building block for evaluating a facility’s energy savings potential. This information is also useful for determining baseline energy performance that can be used to benchmark one building’s performance characteristics against comparable properties. The time it takes to baseline the facility’s energy profile depends on a number of factors, including the level of project complexity, seasonal conditions, and more. It’s also important to note that a quickly obtained “snapshot” of facility energy use may not always provide the most accurate or comprehensive view of the facility’s typical energy profile. For example, an office building on a 24-hour cycle may require a much longer survey to determine what its typical energy profile looks like than a manufacturing process that cycles in an hour, thus requiring a much shorter period of time to characterize the load.
If a metering system is already installed, it is quite possible that all or most of the benchmark data is already available through “accountability” metering procedures in place at various points around the facility. For example, cost allocation — metering specific circuits, departments, or items of equipment to isolate and measure energy apart from the rest of the facility — can be an important tool for facility managers to identify major energy users as a first step in prioritizing and allocating dollars for energy retrofits, including lighting upgrades, control system improvements, and other efficiency upgrades.
As the retrofit progresses, it makes sense to keep the benchmarking metering system in place after the baseline period is completed in order to maintain consistency in measurement. The acquired data can also be used for building retro-commissioning and system fine-tuning, because it provides a 24/7 snapshot of performance that can verify whether or not system performance is within expected parameters.
Unfortunately, some energy retrofit projects never achieve their goals, primarily due to a lack of follow-through in measuring and verifying (M&V) the performance of the upgrades on a continuing basis. Because building performance naturally declines over time, it is necessary to continuously profile and periodically fine-tune equipment and systems to ensure that energy conservation program goals and payback expectations continue to be met. Calibration drift and manual overrides are just a few reasons why M&V needs to continue in the post-retrofit phase. Post-retrofit M&V also documents the extent to which efficiency is being lost, as well as provides insight into the true cost of retrofitting and maintaining energy-efficiency measures at peak efficiency, based on historical data — not calculations or projections.
Meter Dashboards for Energy M&V Visualization
A valuable tool in the energy retrofit process is the ability to provide real-time information of the building’s resource use. To that end, Internet-based meter dashboards that typically provide a series of gauges, graphs, and live display values of important energy metrics within the facility are gaining momentum across the building landscape.
While the responsibility for the building’s resources rests primarily on management, the occupants are now being drawn into the equation by means of dashboards that keep everyone in the organization up to speed on the status of the facility’s energy initiatives. Educating building occupants on measures they can take to be more energy efficient can actually reduce the resource consumption within a building, and proper education on sustainability efforts can ensure those efforts continue into the future.
Although the data is often simplified and presented in summary form, it’s still helpful for facility managers and building owners to review this data, mainly because the information is so easy to access. Many dashboards are presented on a touch screen, located in a building’s main lobby, for example, as well as through the organization’s Intranet or Internet for the public to:
- View resource use in hourly, daily, weekly, monthly, or yearly increments.
- Compare historical data with current consumption patterns.
- Translate savings into monetary results.
- Visualize what sustainable efforts are in place.
- Show how being efficient saves money/tax dollars and helps the environment.
By importing data from electric submeters and other metering devices into Web-based communications, interval data may be cost-effectively collected, analyzed, and displayed in near real-time. Typical displays may include:
- Automobile-style gauges showing how energy is being consumed on a real-time basis.
- 24-hour load profiles for power, chilled water, steam, or other building systems.
- Historical comparisons of current usage versus previous time periods under similar conditions (time, day of week, temperature).
- Automated carbon footprint calculations, showing CO2, SO2, and NoX.
- Tenant- or consumer-level information about energy use and efficiency efforts.
As New York City’s “Greener, Greater Buildings Plan” and similar measures illustrate, dramatic changes are underway in the facility world — driven not only by the need to save more energy and cut operating costs today, but also by the desire to plan for tomorrow’s needs. In terms of energy-efficiency upgrades, what used to be considered merely “desirable” is now becoming law in many jurisdictions around the country. With the commercial/industrial new construction market stagnant in most areas, the emerging opportunity for most contractors will be to supply the expertise and solutions needed to retrofit the nation’s existing building stock to current and future energy performance levels. The old energy adage, “You can’t manage what you don’t measure,” was never truer than in today’s increasingly energy-minded facility environment.
Millstein is president and CEO of E-Mon, Langhorne, Pa. He can be reached at: firstname.lastname@example.org.
SIDEBAR: Submeter Basics
First introduced in the early 1980s, submeters are metering devices with monitoring capability that are installed on the facility side of the master meter to provide any or all of the following:
- Usage analysis and peak demand identification;
- Time-of-use metering of electricity, gas, water, steam, BTUs, and other energy sources;
- Cost allocation for tenant billing;
- Measurement, verification, and benchmarking for energy initiatives, including LEED Energy & Atmosphere (EA) and Water Efficiency (WE) credits;
- Load comparisons;
- Threshold alarming and notification;
- Multi-site load aggregation and real-time historical monitoring of energy consumption patterns for negotiating lower energy rates and more.
Of the three main submeter types, the first two — feed-through and current transformer (CT)-based — are socket-type meters. CT-style socket meters are used with loads of 400A and above. In commercial applications, they may be specified but will take up a lot of space in the electrical room due to the need for CT cabinets and meter bases. The extra space requirement cuts into the available rental space, which is undesirable in the commercial marketplace. Another major disadvantage in many jurisdictions is the fact that socket meters are not UL-listed. The third type is the solid-state electronic submeter, a non-socket device that provides clear advantages over the previous two.