High Performing Buildings - Summer 2011 - (Page 60)

Ongoing Commissioning A two-year ongoing commissioning, measurement and verification process started two months after building occupancy in June 2008. Operating a high performance building requires good trending data and metering, so the first ongoing commissioning exercise focused on vetting the building’s measurement systems. This was followed by a seven-month cycle of ongoing systems commissioning that extended across late summer, fall, winter and early spring. System adjustments involved tinkering with the sequence of operations and equipment schedules, recalibrating equipment and making physical amendments to remedy system anomalies while maintaining comfort and efficiency. Closing the Performance Gap Due to a lack of post-occupancy commissioning and adjustments, many buildings do not perform as intended and they tend to drift even further from performance goals over time. However, Great River Energy demonstrates that a building can perform as intended and improve further. The work performed after occupancy incrementally brought the POst-COnstruCtiOn ChanGes PriOr tO the MeasureMent PeriOd meter indexing and function The building team discovered several of the building’s 46 meters were indexing incorrectly, and others were not functioning correctly. Although the meters were not included in the commissioning, the team studied the metered data, the total energy use and the shapes of the graphs. With this information, the team identified meters that produced unexpected results and troubleshot the problems. Perimeter Heat Pump operations data from the building automation system (BAs) indicated that the heat pumps serving the perimeter were not operating correctly. The building team discovered a problem with the interface between the packaged controls and the BAs. Correcting this interface improved control comfort in those zones and reduced energy use by preventing the overcooling that was occurring. Cold day lake loop flow increase on cold days, the heat pumps tended to trip out during morning warm-up. modifications to the pump operation increased the flow rate during cold periods, while maintaining lower flow rates at other times of the year. This optimization allows for successful operation during the heating season while minimizing pumping energy the remainder of the year. demand management Trending data illustrated a significant spike in electrical demand in the mornings. The annual peak demand occurred on cold winter mornings due to the overnight building temperature setback, which was selected to reduce energy consumption. rather than sacrifice energy savings gained from the night setback, the start-up schedule for the heat pumps was staggered to minimize peak demand. multiple iterative Adjustments multiple small, iterative adjustments to operating sequences, equipment schedules and equipment calibrations occurred during the 12 months prior to the measurement period. Power factor impacted by on-site Wind Turbine The wind turbine’s performance depends on wind resources, and requires a minimum wind speed to generate electricity, leading to volatile performance from month to month. since great river energy operates wind turbines as part of its generation portfolio, this volatility was expected. However, after several months of operation, the team determined that the turbine was partly responsible for the building’s lagging power factor, a measurement of a facility’s power efficiency. Capacitance was added to the turbine to improve its performance as part of the overall system. future refineMents expanding free Cooling Capacity great river energy continues to monitor building energy use and improve performance. As of spring 2011, the facilities team was in the final stages of installing free cooling capacity on some of the perimeter heat pumps. This was researched during the design phase, but not implemented because an analysis indicated a high first cost with extended payback. However, great river energy significantly improved the payback equation by performing much of the work themselves, and by only implementing this strategy on the south exposure, which needs more cooling due to passive solar heat gain. in minnesota, the cold climate makes the passive gain a net energy benefit for this building. more significantly, the measurement and verification process also revealed that the building can rely on far more free cooling hours from the lake than was originally anticipated. The design team modeled the lake performance conservatively because the amount of groundwater passing through the lake was not known. Three years of data indicate significant groundwater infiltration, providing cold lake temperatures capable of supporting free cooling between october and June. Turbine Blade Pitch The facilities team will review the turbine blade pitch and consider making adjustments based on the wind speed data collected from the turbine over the past 2.5 years. reduce exterior lighting security protocol will be reviewed to determine whether additional exterior lighting can be reduced after midnight. 60 HigH Performing Buildings summer 2011

Table of Contents for the Digital Edition of High Performing Buildings - Summer 2011

Commentary
Contents
Stanford University's Y2E2
The Christman Building
The Gettysburg National Military Park Museum and Visitor Center
Cannon Design Regional Offices, Power House
Great River Energy Headquarters
Letters
Products
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High Performing Buildings - Summer 2011