Assessment of Load and Energy Reduction Techniques (ALERT) Retrocommissioning Case Study of Two National Renewable Energy Laboratory (NREL) Sites

Portland Energy Conservation Incorporated (PECI) in conjunction with the National Renewable Energy Laboratory (NREL) staff performed an Assessment of Load and Energy Reduction Techniques (ALERT) retrocommissioning evaluation on several buildings located at the South Table Mountain site and National Wind Technology Center site located in Golden, Colorado. The retrocommissioning process involved a coordinated effort between PECI and NREL staff and was completed in November of 2002. Retrocommissioning (RCx), or existing building commissioning, is an event in the life of a building that applies a systematic investigation process for improving and optimizing a building’s energy-using equipment such as the HVAC and other mechanical equipment, lighting equipment, and related controls. The investigation phase for this project identified 33 findings. This paper gives an overview of the project and discusses a few of the operations and maintenance (O&M) findings as well as capital improvement recommendations that have the greatest potential for energy savings. An update on the progress of implementation will also be discussed. The combined measures recommended for implementation result in an estimated total annual savings of 572,444 kWh, 54,114 therms, and a total utility cost savings of $44,040, which correspond to a 7.0% reduction in annual energy usage and 4.4% reduction in annual utility costs. With the measures already implemented, and those in the process thus far, the total estimated savings are 231,924 kWh, 51,550 therms, and $28,920 annual energy savings. Implementation costs were estimated at $56,380, which would result in a 1.9 year average payback. It cost approximately $0.09 per square foot to perform the ALERT RCx assessment. Of the 33 measures identified, energy savings were not calculated for 14 of them due to insufficient data at the time or they are very general and difficult to estimate. Most of the measures focus on O&M improvements, and many of these measures have been implemented, or under evaluation for implementation. It is not unreasonable to assume that the measures under evaluation, if selected for implementation, could account for an additional 1% energy and cost savings. INTRODUCTION This report presents the draft results of the ALERT RCx evaluation performed on several of the NREL buildings located at the South Table Mountain (STM) site and the National Wind Technology Center (NWTC) site, located in Golden, Colorado. This ALERT RCx evaluation was completed as part of the ALERT program funded by the Department of Energy through the Federal Energy Management Program (FEMP). PECI and NREL staff completed the retrocommissioning study as the ALERT team. The NREL facilities staff personnel are very energy conscious and have already implemented many energy conservation measures over the years. Prior to performing the ALERT RCx study in 2002, NREL staff performed an in-house energy audits in 1996 and 2000 to achieve energy savings on measures with a less than 10-year payback. The measures implemented from the 1996 study and those selected for implementation from the 2000 study are listed in Appendix A. Their knowledge and expertise have greatly improved the ALERT team’s ability to identify the savings opportunities outlined in this study. The ALERT evaluation program was established by the Federal Energy Management Program (FEMP) and designed to identify energy-savings measures in existing buildings. ALERT teams focus on noto low-cost measures by working with site personnel to perform energy use assessments. The process involves assessing operational energy efficiency measures, finding public benefit funds for the proposed measures, and working with on-site personnel to develop an implementation plan. Retrocommissioning is an excellent way to obtain energy savings through low cost improvements that optimize building systems to operate efficiently and effectively. NREL continually evaluates and implements cost effective energy conservation measures as a normal course of ESL-IC-03-10-10 Proceedings of the Third International Conference for Enhanced Building Operations, Berkeley, California, October 13-15, 2003 business. For this project, retrocommissioning created significant energy savings beyond the measures implemented by facility staff. For example, prior to the ALERT RCx study, NREL staff implemented 10 O&M and capital improvement measures identified in the 1996 study and selected additional measures from the 2000 study for implementation, which resulted in an estimated annual energy savings of $115,315, with an average payback of 4.1 years. After implementing just four of the O&M measures from the ALERT RCx study, the owners will see an estimated additional $22,610 per year in energy savings. The retrocommissioning process also identifies potential capital improvements that can be made at the facility to further reduce energy usage and utility costs. Often, the savings associated with the low cost improvements can be used to “buy down” the implementation costs associated with the capitalintensive measures and make the overall package more economically viable. The ALERT team was specifically asked to evaluate potential capital improvements on this project as well as all low cost improvements. METHODOLOGY Commissioning of existing buildings, or “retrocommissioning”, is a systematic process applied to existing buildings to identify and implement operational and maintenance (O&M) improvements and to ensure building system functionality. The primary goal of retrocommissioning is to optimize equipment and system operation to function together efficiently and effectively, although retrocommissioning may also recommend capital improvements. The three fundamental procedures are discussed in detail below. o Investigation and data collection o Analysis of data o Implementation of recommendations BASELINE FACILITY DESCRIPTIONS The following buildings were evaluated for energy saving measures: o STM – Field Test Laboratory Building (FTLB): 117,800 SF. Consists of laboratory spaces and office spaces. o STM – Solar Energy Research Facility (SERF): 117,200 SF. Consists of laboratory spaces and office spaces. o STM – Shipping & Receiving: 13,500 SF. o STM – Visitor Center: 5,000 SF o NWTC – Building 251: 21,700 SF. Primarily an office facility with small computer room. o NWTC – Data Sheds: total square footage unknown o NWTC – Trailers: total square footage unknown Investigation and Data Collection The retrocommissioning process begins by collecting and evaluating data pertaining to facility equipment and current operation. The primary tasks for this project are outlined below. Documentation Review. The investigative process consists of first obtaining as much building documentation as possible to allow the ALERT team to become familiar with the building and its systems. For this project, all control drawings and utility billing data for the past three years were provided. Control drawings and original sequence of operations were reviewed prior to visiting the site. Initial Site Assessment. The next step was to conduct an initial site assessment. The initial site assessment consisted of spending five days total in selected buildings at the STM and NWTC sites during July 2002 interviewing staff, reviewing control sequences and equipment operating schedules programmed into the central building automation system (BAS), inspecting and testing equipment, and performing an analysis of the site-gathered data. The assessment identified several significant findings, as well as identifying areas for monitoring and testing Manual Testing. Some systems were manually tested to determine system operation. For example, pre-filters were removed from a rooftop air handling unit to determine the pressure drop associated with the filters and evaluate the energy savings associated with permanently removing the pre-filters from the air stream. Trend Analysis. Additional data points were programmed into the BAS for trend collection. This trend data helped identify energy conservation opportunities and develop energy savings calculations. For example, trending compressor operation and outside air temperature for a rooftop HVAC unit at the NWTC site allowed a correlation to be developed between energy use and outside air temperature. ESL-IC-03-10-10 Proceedings of the Third International Conference for Enhanced Building Operations, Berkeley, California, October 13-15, 2003 Analysis of Data The ALERT team then analyzed the site interview, trend, monitored, and manual test data, and written documentation. From this work, the team formulated findings and developed estimates for the associated energy savings and costs to implement . The results are presented below. Energy Use Analysis. At the time of the ALERT RCx study, all of the buildings located at both the STM site and NWTC site were connected to one central electrical meter at each site, which made it difficult to determine the actual energy used by individual buildings. Several of the larger buildings located at each site were evaluated for energy conservation opportunities several years ago, with savings estimates based on DOE2 simulations. The ALERT team used the previously developed end use breakdowns to gage the reasonableness of the savings calculations, but a detailed end use breakdown for all buildings was not performed. Table 1 outlines the total energy usage for each site for 2001. Table 1. 2001 Site Energy Usage