Tim Ellingson, P.E. — May 2015
Hotel Ivy was battling excessive chilled water usage, especially during winter months. As a result building owner Heartland Realty Investors, Inc., approached CEE for assistance. After review of initial issues CEE recommended its Existing Building Commissioning Services (EBCx) to comprehensively identify savings opportunities.
CEE’s Engineering Services studied Hotel Ivy’s systems from September 2014 to January 2015, collecting continuous trend data on all available mechanical equipment in the building. Project scope was complex since some hotel central systems also served separately owned condos. Where possible, CEE maintained focus on the lodging, restaurant, spa/fitness, conference center, and garage functions of the site. In addition to mechanical system focus, CEE also leveraged its One-Stop Efficiency Shop® program to identify significant internal and external lighting retrofit opportunities.
Attention was also given to the site’s free-cooling system, which was originally intended to reduce chilled water consumption during the heating season. CEE identified that controls were malfunctioning and overridden, resulting in limited free-cooling potential and excessive chilled water consumption.
Results indicate the potential to save up to $77,000 annually with a simple payback under 3 years. The property could significantly reduce its energy use and related costs by preventing simultaneous heating and cooling and implementing variable airflow for the basement through third floors. Opportunity also exists in the hotel-operated kitchen space through exhaust hood demand-controlled ventilation. Additional savings were found through optimizing existing control sequences and lighting retrofits throughout the facility.
CEE also championed a process to bring together ownership parties, the controls contractor, and NRG Energy Center Minneapolis, to document existing free-cooling system faults and recommendations to improve operation. With revised controls and the addition of NRG Minneapolis system instrumentation on the building automation system, operators will be able to gauge building load at a moment’s notice and take action.