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15 How to Determine the Need for Retrocommissioning Ideally, a recommissioning plan is established as part of a new buildingâs original commission- ing process or an existing buildingâs retrocommissioning process. Recommissioning should be seen as part of the facilities O&M program. If recommissioning is not a normal practice, the decision to retrocommission may be triggered by a change in building use, the onset of operational issues, or the need to reduce facility operations costs. Such instigating factors may include: ⢠Performance failures discovered following initial construction and turnover ⢠Normal equipment and system deterioration that is not addressed by the normal O&M strategies ⢠Systematic problems in building operation, such as simultaneous heating and cooling ⢠Indoor air quality complaints ⢠High or increasing energy consumption profiles ⢠Malfunctioning equipment or sensors, such as inoperable dampers ⢠Control optimization issues, such as sub-optimal chilled water-supply temps ⢠Excessive equipment repair and replacement costs ⢠Traveler comfort complaints ⢠Employee complaints or high employee absenteeism ⢠Tenant requests during contract negotiations ⢠Frequent tenant turnover ⢠Operations team personnel turnover The Value Proposition for Retrocommissioning The value proposition for retrocommissioning and recommissioning stands on three key principles: ⢠Performance. Retrocommissioning yields performance improvements that enhance a facilityâs ability to support its intended mission in a safe, reliable, and cost-effective manner. Such benefits include reduced energy consumption, improved indoor air quality, and greater reliability of systems and equipment. ⢠Economics. Increased efficiency typically accompanies performance improvement in buildings with regard to energy and operations. Although increased energy efficiency is realized in lower utility bills, operational efficiency is seen in reduced system and equipment failures and fewer emergency maintenance calls. A 2004 study on commissioning published by Lawrence Berkeley National Laboratory analyzed the results from 224 buildings across 21 states, representing 30.4 million square feet, 73% of which were existing buildings that underwent retrocommission- ing. The study concluded that for existing buildings, the median savings was 15% of energy S E C T I O N 2 Getting Started with Retrocommissioning
16 Optimizing Airport Building Operations and Maintenance Through Retrocommissioning: A Whole-Systems Approach costs with a payback of 0.7 years (Mills et al. 2004). Besides the energy cost savings, prolonged equipment life will reduce whole-building lifecycle costs. ⢠Compliance and safety. Retrocommissioning and recommissioning help to ensure that systems and equipment operation remain in compliance with performance, safety, and other regulatory codes or standards. For airports, the potential value of retrocommissioning and recommissioning is amplified by the fact that airport facilities are complex and operate for extended hours, every day of the week. Airports are critical to the transportation system in the United States, which emphasizes the need for high reliability in building systems. Furthermore, at an airport the mechanical and electrical systems extend well beyond the typical commercial building envelope, and they are applied to support the unique mission of the airport. For example, mechanical HVAC systems provide cooling and heating to aircraft that are parked at gates, and electrical systems are used to provide ground power to the same aircraft. The operation of all building systems should be considered to optimize whole-building lifecycle costs. With so many systems in play, the potential for energy and operational savings identified through retrocommissioning and recommissioning is correspondingly large. How to Plan for Retrocommissioning Planning for retrocommissioning begins with project definition and goal setting. Goals for retrocommissioning should consider performance improvements, operating cost reduction, regulatory compliance, or improvements in facility reliability. Goals for the retrocommissioning process may be specific and quantifiable or may simply state the overall objectives outlined above, along with targets for quantifiable improvements (e.g., energy reduction goals or O&M cost management goals). Identifying appropriate buildings and building systems also is important. Although nearly all buildings can benefit from retrocommissioning, application of limited funding requires that airports prioritize candidate buildings. Given that the process is intended to reduce the lifecycle cost for facilities and improve long-term performance, the following considerations can be used to prioritize buildings for inclusion in the process: ⢠Buildings that experience the highest rate of critical failures or represent the greatest risk to operations from building deterioration or system failures. ⢠Buildings with the highest overall energy consumption or the highest energy intensity. (Also consider total energy cost per gross square foot.) ⢠Buildings with the highest number of occupant complaints or buildings that are known to operate poorly. ⢠Buildings in which automatic control of systems has been defeated over time to address opera- tional or occupant concerns. From an energy perspective, the acceptable simple payback period can provide some guidance in selecting buildings for retrocommissioning. Industry studies suggest that retrocommissioning provides an average 15% energy savings with a 3-year simple payback. The consensus in the industry is that this âaverageâ applies very reliably to any moderately complex building. With that information in mind, using an average overall cost of retrocommissioning, Table 3 provides some guidance in estimating the financial return from an investment in retro commissioning. When identifying systems to be included in a retrocommissioning process, given that the process is intended to be a holistic review of buildings, it is best to include all major systems in
Getting Started with Retrocommissioning 17 the processâmechanical, electrical, and envelope. If funding is limited, the selection of systems should be driven by the criteria noted above with a focus on including those systems that most directly impact the overall objectives of the program. The Cost of Retrocommissioning The cost of any effort to improve building operations through commissioning processes is entirely dependent on the scope of work established for the recommissioning or retrocommissioning effort. Before recommissioning, many airports need to first retrocommission their facilities. In this way, airport operations can establish an effective operational baseline that both meets the mission of the airport facilities and provides the optimum energy profile required to support the mission. This report will focus on the cost of retrocommissioning. Based on these costs, it is possible to predict the cost of follow-on recommissioning efforts. Limited but useful cost data are currently available in the literature for retrocommissioning. The largest sample data analysis for retrocommissioning costs has been reported in studies from Lawrence Berkley National Laboratories (LBNL), such as Building Commissioning, A Golden Opportunity for Reducing Energy Costs and Greenhouse Gases, published in July 2009 (Mills 2009). This study considered a total of 186 million square feet of building space. In reviewing the cost data reported, the cost for retrocommissioning ranges from $0.026 to $1.01 per square foot. The data pose a dilemma, however: the work provided by the lowest-cost effort and that provided by the highest-cost effort cannot reasonably be considered comparable. Analysis of retrocommissioning costs is further complicated by confusion about terminology. The term retrocommissioning has been applied to everything from energy studies that entail building sampling and energy modeling to intensive investigation and correction of building components and systems. For the purposes of ACRP Report 139, cost analysis focuses on retrocommissioning that is designed to address operational stability and reliability issues as well as energy optimization. This process may also identify capital improvements required to achieve a sufficient level of building system performance. The sample cost analysis provided in the following paragraphs provides guidanceâbased on the available literature (e.g., the LBNL study), on the authorsâ experience providing retro- commissioning services, and on the anecdotal experience of industry peersâfor addressing the cost of an intensive effort to identify and correct operational deficiencies that result in poor environmental control, poor occupant satisfaction, and higher energy costs. This discussion focuses on retrocommissioning programs whose objective, most simply stated, is to leave the building operating more effectively than when the effort began. Energy Cost ($/sq. ft.) Anticipated Energy Savings ($/sq. ft.) Acceptable Simple Payback (Years) Total Acceptable Investment ($/sq. ft.) $1.50 $0.225 3 $0.68 5 $1.13 7 $1.58 $2.00 $0.30 3 $0.90 5 $1.50 7 $2.10 $2.50 $0.375 3 $1.13 5 $1.88 7 $2.63 Table 3. Budgeting guidance for executing an energy efficiency project that meets simple payback criteria.
18 Optimizing Airport Building Operations and Maintenance Through Retrocommissioning: A Whole-Systems Approach With these criteria in mind, the following information can be gleaned: The overall cost of retro commissioning averages $0.82 per square foot, including implementation. This average cost is based on a variety of facilities that range from simple offices, hotels, and elementary schools, to more complicated facilities such as hospitals and government complexes. Based on experience in the marketplace, retrocommissioning costs for any given building can be reasonably broken down by phases in the process. (A brief explanation of retrocommissioning project phases appears with this discussion; a more detailed examination is provided in Section 3.) The literature on this subject usually breaks the retrocommissioning process into three base phases: planning, investigation, and implementation. A fourth optional phase, monitoring and verification (M&V), also may be used. Typically, requests for proposals used by government agencies will also break the process into these phases. Based on these phases, some cost guidance can be provided (see Table 4). Phase Description Cost Range ($/gross sq. ft.) Planning Planning includes review of available documentation; preliminary site inspection; condition assessment of existing equipment and systems; baseline energy and performance analyses; preliminary evaluation of energy conservation opportunities; and investigation phase planning. $0.15 to $0.35 Investigation Detailed investigation of components and system, including control system testing, testing and balancing (TAB) survey and calibration, sensor and actuator calibration, implementation of âno costâ corrective measures, identification of both low-cost and medium- cost corrective actions and capital project opportunities for energy and performance enhancements, staff training, and retrocommissioning reporting. Professional fees $0.40 to $0.65 Quick-fix allowance (Note 1) $0.15 to $0.25 Implementation Implementation of low-cost and medium-cost corrective actions and commissioning of the implemented strategies; enhanced staff training; validation of capital projects not included in implementation phase. Professional fees $0.12 to $0.20 Corrective action cost allowance $0.15 to $0.50 Total professional fees Recommended allowance for corrective work $0.67 to $1.20 $0.15 to $0.50 (Note 2) Optional: Monitoring and Verification Phase Post-occupancy monitoring of implemented corrective actions; energy baseline verification and reporting; staff training reinforcement. $0.10 to $0.25 per sq. ft. (Note 3) Note 1: A quick-fix budget allowance should be included in a retrocommissioning budget to provide funds to correct component and systems deficiencies that prevent the retrocommissioning team from testing and evaluating systems. The allowance can be managed by the airport directly or by a qualified retrocommissioning provider based on airport approvals for expenditures. Note 2: Implementation costs are a function of the findings from the investigation phase and the budget available for implementation of recommendations. Generally, retrocommissioning has been found to deliver 15% energy savings annually with an average overall payback of 3.0 years. Thus, based on a âtypical buildingâ consuming approximately $2.00 per square foot energy cost, the allowable budget for this work would be approximately $0.90 per square foot (15% x $2.00/sq. ft. annually x 3 years = $0.90/sq. ft.). This analysis can be applied to a specific building by updating actual energy cost per square foot. Note 3: Alternatively, the Federal Energy Management Programâs M&V Guidelines Version 3.0 recommends a budget for M&V as 1â10% of the projected annual cost savings from the implemented measures. (Source: FEMP. [2008]. M&V Guidelines: Measurement & Verification for Federal Energy Projects, Version 3.0. U.S. Department of Energy, Energy Efficiency and Renewable Energy, Federal Energy Management Program. Available at http://www1.eere.energy.gov/femp/pdfs/mv_guidelines.pdf.) Table 4. Budgeting guidance for retrocommissioning, by phase.
Getting Started with Retrocommissioning 19 Frequency of Recommissioning The frequency of recommissioning will vary from system-to-system, building-to-building, airport-to-airport, and will depend on several factors, including: ⢠How critical is proper system performance to the airport or to the mission of the facility? ⢠How will the improper performance of a system affect the performance of other systems? ⢠How frequently are parts of the building renovated? ⢠How frequently does space usage change? ⢠What are the energy and operational cost impacts of improperly performing systems? ⢠How does system performance affect tenant satisfaction with the facility? For example, emergency generators are critical and tested monthly at most facilities, though used infrequently. Central plant, HVAC, and electrical systems will require monthly, quarterly, or annual testing frequency, depending on the criticality of the areas served, the age and condition of the equipment, and the diagnostic information available during normal operations. For airports, building systems are important to the airport operations. Airport facilities are functional spaces, providing the medium for airlines to serve travelers. Interruptions in facility operations that affect the airlineâs ability to meet traveler expectations will have financial impacts and user satisfaction issues. Energy costs for airport facilities also are significant. Achieving small improvements in energy efficiency can have a significant financial return.
