LEED Gold Library Re-Commissioned to Save Energy

July 10, 2015 By Linda Hardesty

libraryRamsey County Library in Roseville, Minnesota is a 70,000 square foot facility constructed in 1993 with a major addition in 2010 that qualified the building for LEED Gold. The building’s heating, ventilation and air conditioning (HVAC) system is controlled by an advanced building automation system (BAS).

Ramsey County asked Uhl Company to conduct a re-commissioning study at the Library in 2013. The goal of this study was to review the building’s existing equipment and identify ways to make it run more efficiently and generate cost savings. The study included functional testing of major equipment and the use of analytics to identify seasonal energy conservation opportunities.

Uhl’s Roseville Library re-commissioning study identified many energy conservation opportunities in the facility and the county chose to implement most of them in a $13,300 project. Utility rebates of $7,673 from Xcel Energy helped cover the upfront costs of the project. Once implemented, the projects lowered natural gas use 5,038 therms and saved 54,420 kWh in electricity, for a utility cost reduction of $10,518. Overall, savings were 5 percent more than projected, and the payback period for the library was just over six months.

Energy efficiency enhancements Uhl implemented at the Library in Roseville included air handling unit (AHU) and roof top unit (RTU) run time improvements, demand ventilation adjustments, chiller compressor sequencing, RTU outside air CO2 control and economizer improvements, AHU discharge air and duct pressure resets, AHU economizer improvements, and adjusting library space temperature setpoints. The facility staff uses analytics to continually monitor building performance and is constantly commissioning the building’s operations to keep all systems optimized.

According to Uhl Company, even if a building was properly commissioned when it was built, changes in use and operations over time typically lead to diminished building performance. Re-commissioning is the process of making adjustments so that a building is once again properly calibrated to achieve optimal performance. Uhl says re-commissioning usually saves between 5-25 percent of building energy costs.

Based in Maple Grove, Minnesota, Uhl is a member firm of the InsideIQ Building Automation Alliance, an international alliance of independent building automation contractors.

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