Case Study-Morrissey Engineering-Omaha, NE
Engineering Firm's New Corporate Headquarters Teams with Electric Submeters to Optimize Building Performance
Combination of high-efficiency design and submetered data helped MEI's Omaha headquarters become Nebraska's first LEED Platinum-certified facility under the LEED for New Construction rating system.
When the time came for Morrissey Engineering, Inc. (www.morrisseyengineering.com), a successful Omaha-based engineering consulting firm, to design its own corporate headquarters, management knew that the structure would have to demonstrate superior energy performance while also showcasing MEI's broad-based sustainable design capabilities. To that end, a talented team from Sinclair Hille Architects (design concept), Holland Basham Architects (architect of record) and Meyers Carlisle Leapley (general contractor) joined forces with MEI's own highly capable engineering staff who provided the mechanical, electrical and technology design services.
Nebraska's First LEED Platinum Facility
Referred to as the 4940 Building-after MEI's Omaha street address-the structure recently became the first facility in Nebraska to achieve LEED Platinum certification (see table 1) established by the U.S. Green Building Council (USGBC) and verified by the Green Building Certification Institute (GBCI). The LEED green building certification program is the nationally accepted benchmark for all design, construction and operation of green buildings. As a state-of-the-art corporate headquarters, the all-electric 15,580-square-foot building features recycling stations, bike storage, showers with changing rooms and preferred parking for fuel-efficient vehicles and carpools.
Other sustainable design features include low-flow plumbing fixtures, daylight harvesting, occupant-sensing lighting control, a wind turbine for renewable energy production, reflective roofing and parking lot paving materials that reduce heat absorption. In addition to extensive use of recycled building materials and the recycling of rainwater through an on-site pond for irrigation, the building's energy-reducing components have helped MEI trim its utility bill by some 40 percent compared to a minimally code-compliant baseline structure, achieving in the process:
- 40% lower CO2 emissions
- Over 45% of total energy usage from renewable sources
- 6% of total building energy provided by on-site wind turbine
- 46% lower potable water use
Green Meters Facilitate Green Building Initiatives
Building commissioning and LEED certification are based in large part on accurate and reliable energy data. Submeter manufacturers like E-Mon have responded to the green challenge by developing next-generation hardware and software tools that specifically address the needs of sustainable facilities by providing functionality that helps users measure and verify compliance with LEED, EPACT, Renewable Energy, Demand Response and other major energy initiatives. Certified to ANSO C12.1 & C12.16 national accuracy standard, new-generation green meters offer a number of important features for new construction or retrofit applications, including:
- Scrolling LCD display of kilowatt (kWh) usage
- kWh in dollars
- Current demand load (kW)
- Cost per hour, based on current load
- Estimated CO2 emissions in pounds based on DoE standards
- Estimated hourly CO2 emissions based on current load
- Net metering, including utility-delivered vs. user-received power and net usage
- Compatibility with pulse-output utility meters, including water, gas, BTU, steam, etc.
MEI Submeters Measure & Verify Energy Use for LEED Certification
For the energy monitoring function required for Morrissey's LEED-NC Platinum certification, a network of seven Green Class E-Mon D-Mon submeters were installed to measure and verify the applicable certification points shown above.
Installed in the facility's mezzanine-level electrical closet, the three-phase meters accept raw energy data from lighting, mechanical and plug loads throughout the facility. The meter data from these key loads is continuously transmitted over the RS-485 network to an E-Mon Interval Data Recorder (IDR). The IDR stores the data in 15-minute intervals and communicates with E-Mon Energy, the facility's PC-based energy intelligence software.
In operation, E-Mon Energy software lets management read and monitor energy consumption (kWh) and demand (kW) via on-site or off-site non-dedicated computers. Graphs and energy data profiles are generated for demand analysis, load profiling and energy management functions, including itemized electrical bills for departmental allocation or even tenant billing if desired.
According to Andrew Lang, MEI's lead electrical engineer on the project, the system encountered no major challenges during installation and has been running for more than a year. Early in its operational life, the submetering system provide its mettle by identifying a potentially costly problem before it actually became one.
Submetering the twelve commercial spaces on the ground floor proved less challenging than metering the residential floors above. "The entire building had finished drywall ceilings with limited access for cabling," said project manager Reiss, who explained that the 200A split-core current sensors were installed in an existing junction box in the hallway just outside each apartment. 'We were able to pull cables from all the current sensors down to the MMUs. All the new cabling came through the corridors, then down the electrical riser closet to the basement." The hinged construction of the low-voltage (0-2V) output split-core current sensors allowed the electricians to install them non-invasively around the electrical feeds being monitored, thus eliminating the need to shut down the load and resulting in a safer, faster install.
In the basement, an Ethernet cable was run a few feet from the MMUs to the building's engineering office where a desktop PC running E-Mon Energy software is used to analyze the meter data and output monthly owner billing statements.
Costly Problem Revealed by meters
Shortly after occupying the building, Morrissey was notified by its local electric utility that the 4940 Building's demand level had surprisingly exceeded its 50 kilowatt (kW) winter demand cap. If it happened again, MEI would be placed on "demand billing" status, which came with an automatic 10% rate hike.
Alarmed by the potential increase, Morrissey Engineering profiled the 4940 Building's electrical usage patterns using E-Mon Energy software. Analysis of the facility's load profiles quickly revealed the culprit, described by Lang as "coincident power demand during morning warm-up from the night set-back condition." During off hours, MEI's Building Management System (BMS) reduces temperature settings when the building is unoccupied. In the morning, heating equipment starts up to make the facility comfortable before the occupants arrive. The demand spike was caused by all of the ground source heat pumps (GSHP) running full bore at the same time, along with the perimeter baseboard heating system. These combined power draws added greatly to the overall load and created higher than anticipated demand for electrical power. E-Mon Energy's data visualization capability showed power during warm-up to be three times higher than normal daytime operation. Andrew Lang stated that "the biggest thing for us was getting this information."
As a corrective measure, Morrissey programmed its BMS to lock out perimeter baseboard heating during morning warm-up, and also scheduled the ground-source heat pumps to start earlier and to operate sequentially, thus minimizing demand during this peak period. To further reduce its demand profile, the building management system can stage each heat pump to cycle off during periods of peak demand. Interior temperatures typically don't vary that quickly over short time periods, so any variations go unnoticed by the occupants. Morrissey Engineering can also monitor building performance via individual metering of the mechanical systems, lighting, plug load and wind turbine to ensure that all systems are running at peak efficiency.
Bottom Line Considerations
The recent operational history of the 4940 Building illustrates the benefits of combining an efficient facility design with the use of submeter data to optimize building performance. As exemplified by MEI's state-of-the-art corporate headquarters, balancing aesthetics and functionality through the complementary integration of architecture and engineering best practices can product striking results. From an operational standpoint, submeter data helped MEI identify further energy savings opportunities and lower cost by understanding and controlling its electrical load profile-key factors in the 4940 Building's LEED platinum certification and ranking among the top 10 percent of energy-efficient facilities in the country, according to the EPA's Energy Star program.
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