Simulated Energy Savings Comparison Between Two Continuous Commissioning® Methods Applied to a Retrofitted Office Building

Abstract

Continuous Commissioning® (CC®) was performed on a 24,446 square foot institutional building used primarily to house offices and conference rooms. The building was constructed in 1950, and then had a complete Heating, Ventilating, and Air Conditioning (HVAC) retrofit in 2001 to include new equipment and Direct Digital Control (DDC). Following the retrofit, CC was carried out in this building, mainly implementing outside air temperature (OAT) based temperature and static pressure reset strategies. In 2008, a second round of CC was performed (and is still in progress), which has focused on incorporating demand based reset strategies in addition to the reset strategies already in place. This paper examines the advantages of demand based reset strategies used in conjunction with outside air based reset strategies, with this building serving as a case study. In a more general sense, the building also serves as a case study of the benefits of performing multiple rounds of CC in a facility over time. Predicted energy savings from the second round of CC over the first round were reported. Since the second round of CC was still in progress as of completion of this paper, savings were predicted using simulation models developed in Energy Plus, a commercial simulation software package. Actual savings achieved from CC will be determined and presented in a 2nd paper when sufficient post-CC data have been obtained. This paper also mentions two specific challenges that were encountered and addressed during the second round of CC, including: 1) control of terminal boxes with inline electric reheat, and 2) control of a constant speed multi-zone air handling unit with zone temperature control. Recommendations were made to optimize control relative to these and other issues, in order to improve comfort and energy efficiency in the facility.