e-News
Issue 78 January 2011
Measurement and Verification n Introduction n What is Measurement and Verification? n Uses of M&V in Energy Management Programs n Utility Incentive Programs n Performance Contracting n LEED for Existing Buildings n Use of Building Automation Systems for M&V Data Collection n Related Resources n Training Highlights n About e-News
Verifying what, exactly, and why? Introduction
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uildings are dynamic systems, with energy use driven by a significant number of variables that change with time, from the weather, to usage patterns, to the attributes of the structure itself and the installed equipment. The evaluation of energy savings due to improvements in a building will never be a simple task. Energy models can help in the effort, but models must always make assumptions that may not correlate well with the reality of a building’s actual energy use. This issue of e-News details the measurement and verification (M&V) process for analyzing energy savings created through the design and operation of efficient buildings, applications of M&V in Energy Management Programs for existing buildings, and discusses measurement and verification via Building Automation Systems.
What is Measurement and Verification? Measurement and verification is the process of determining the actual savings produced within a facility when an energy efficiency program is implemented. Energy savings are defined as the absence of energy use and therefore cannot be directly measured. To deal with that challenge, an approximation of energy savings is determined by comparing measured energy uses before and after a project is deployed. But the measured energy, alone, is not always enough to determine the actual savings. Conditions can change in a building between the before and after measurement periods – other than the efficiency improvement – that may require adjustments in the analysis of the measured data.
Figure 1 - M&V Comparison Process A key challenge of measurement and verification processes is determining what value the adjusted baseline should have (energy use absent the measured change), since it can no longer be directly observed. Energy Design Resources
Building modifications that are implemented to conserve energy or manage demand are commonly referred to as Energy Conservation Measures (ECM). ECMs may involve physical changes to facility equipment, revisions to operating and maintenance procedures, or changes to software. Behavioral modifications such as training for operations and maintenance staff or efficiency education of building occupants can also be considered energy conservation measures. The International Performance Measurement and Verification Protocol (IPMVP) was developed by the Efficiency Valuation Organization (EVO) to foster investment in energy efficiency and demand management projects around the world. IPMVP is a widely accept(continued on page 2)
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ed reference framework for M&V work; ASHRAE Guideline 14-2002, Measurement of Energy and Demand Savings, provides technical details complementary to IPMVP. An M&V process should include some or all of the following activities: 1. Installation of metering devices 2. Gathering and screening of data 3. Development of a computation method with acceptable accuracy 4. Computation of measured data 5. Reporting on analysis and conclusions 6. Third party verification
Uses of M&V in Energy Management Programs Three types of energy management programs will be discussed where M&V is essential for the success of the program:
Figure 2 - Measurement via Current Transducer
Utility Incentive Programs Many utilities offer incentive payments for customers who implement energy efficiency measures such as retrocommissioning programs. Retrocommissioning (RCx) focuses on improving the performance and efficiency of systems already installed in a facility. Through the analysis process, underperforming building systems are identified and adjustments are recommended to improve system efficiencies. Based on historical applications within PG&E’s program, RCx projects can generate average savings of 5-15% of total facility energy costs. Upgrades made as a part of the RCx process often pay for themselves in less than two years.
Power consumption at various time intervals and on sub-systems within a building can be measured through the use of current transducers (CTs) linked to dataloggers that will record the measurements. third-party vendors will work closely through a 3-stage process: 1. The facility owner grants access to billing data to establish a benchmark rating per the Energy Performance Rating System from the U.S. EPA or an equivalent energy rating system.
2. The utility’s representative and the assigned RCx provider will schedule on-site investigations and then identify problems and corresponding opportunities for energy savings. A report of recommended ECMs More on IPMVP is provided and includes prioritization of the ECMs, IPMVP is divided into three separated volumes and each of estimated project costs and incentives, energy cost them addresses different aspects of the M&V process. savings and payback periods.
Building operations staff, the sponsoring utility, and
IPMVP Volume I defines M&V and presents the fundamental principles of M&V. Volume I also contains a summary of common M&V design issues and lists other M&V resources. IPMVP Volume II provides a comprehensive approach to evaluating building indoor environmental quality issues. It also highlights good project design and implementation practices for maintaining acceptable indoor conditions. IPMVP Volume III provides complementary information on M&V methods associated with new building construction and with new renewable energy systems installed on existing facilities.
Energy Design Resources
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3. The facility owner and the utility project team will decide which ECMs should be implemented. Once the RCx provider confirms that ECM implementation is completed and savings calculations are verified (via either analysis or actual measurement), the utility pays the incentive to the owner.
Performance Contracting Under an energy savings performance contract, an energy service company (ESCO) guarantees that after ECMs are installed at a facility energy use will be reduced by a quantifiable amount. The ESCO will
e-News January 2011
Related Resources n International Performance Measurement
&Verification Protocol: Concepts and Options for Determining Energy and Water Savings Volume I http://www.nrel.gov/docs/fy02osti/31505. pdf n California Public Utilities Commission infor-
mation on measurement and verification http://www.cpuc.ca.gov/PUC/energy/ Energy+Efficiency/EM+and+V/ n Federal Energy Management Program
http://www1.eere.energy.gov/femp/index. html n Guidance on LEED credit for Measurement
and Verification http://www.buildinggreen.com/auth/productsByLeed.cfm?LEEDCreditID=17
finance the installation of the ECMs, receiving compensation from the facility owner as energy savings are confirmed through the M&V process. A recent study on ESCO projects showed that the median payback time for university projects, state and local government projects, and federal government projects were 6.8 years, 7.2 years and 8.5 years respectively. An ESCO will first perform an investment oriented energy audit that identifies ECMs and evaluates their potential. The ESCO will then propose a retrofit package that optimizes cost-effectiveness to save energy and help insure payback to the ESCO. Next, the facility owner will negotiate an energy performance contract with the ESCO. The contract should clearly define roles and responsibilities, outline technical and cost details, and explicitly state how savings will be determined, including any M&V specifications. Subsequently, payment is tied to measurement and verification of savings at regular intervals throughout the contract performance period.
LEED for Existing Buildings Measurement and verification can be a component of the LEED 2009 for Existing Buildings certification process. A number of Environmental and Atmosphere (EA) Credits consist of M&V-related activities, detailed below: 1. EA Credit 2.1: Document the operation of the major energy-using building systems and develop an energy performance optimization plan to achieve energy savings. 2. EA Credit 2.1: Conduct cost-benefit analysis for potential capital improvements that will provide energy savings. 3. EA Credit 2.2: Implement minor operational improvements and produce a capital plan for major retrofits or upgrades. 4. EA Credit 2.3: Regularly review and adjust building operation procedures to ensure optimal energy efficiency and system availability (minimize down time).
Limitations of M&V in LEED for New Construction M&V is used in LEED for New Construction as well. With LEED for New Construction, energy savings for a building are predicted by comparing two energy models – the proposed building and a baseline building with all ECMs removed. During verification of actual savings, utility bill data is compared to the energy consumption projections produced by the energy model of the proposed design, with some calibration added to the building model to match actual operating conditions. In turn, the calibration adjustments made to the proposed design model are then used to adjust the baseline energy model. As the evaluation of saving involves a two-step calibration process, the magnitude of uncertainties can in-
Energy Design Resources
crease, leading to a significant reduction in the accuracy of the resulting comparisons. This phenomenon was demonstrated in a study of a group of 18 LEED-certified buildings where the modeled energy use was compared to billed energy uses. When comparing the results for all 18 buildings, the mean value for actual consumption was only slightly lower than the mean value for modeled energy use. But when analyzed on a building by building basis, the variation between actual consumption and modeled energy use varied widely. This difference in modeled and observed results makes it difficult to measure and verify the energy savings that result from ECMs that are a part of a newly constructed building.
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5. EA Credit 3.1: Employ building automation system to control and monitor major building systems.
About e-News
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on’t miss future issues—to sign up for a free email subscription, please visit www.energydesignresources. com. Send letters to the editor, suggestions on topics for future issues, or other comments to enews@energydesignresources.com. Follow EDR on Twitter: http://twitter.com/ edrcalifornia. e-News is published by Energy Design Resources (www.energydesignresources.com), an online resource center for information on energy efficiency design practices in California. Savings By Design (www.savingsbydesign.com) offers design assistance and incentives to design teams and building owners in California to encourage high-performance nonresidential building design and construction.
6. EA Credit 3.2: Employ permanent system-level metering for capturing data on the energy consumption of major end-uses.
Use of Building Automation Systems for M&V Data Collection Most large, new commercial buildings are equipped with a Building Automation System (BAS). A BAS is primarily used to control HVAC equipment and may integrate other building systems, such as lighting controls.[5]A BAS is also capable of providing building operating data, such as loads, occupancy and equipment efficiency.[1] If targeted metering devices are also installed, a BAS can monitor energy consumption of specific enduses. The following factors should be considered before a data collection strategy is implemented that relies on a BAS: - BAS hardware and software should be capable of performing control functions and data collection simultaneously, without impeding system performance.
Energy Design Resources and Savings By Design are funded by California utility customers and administered by Pacific Gas and Electric Company, Sacramento Municipal Utility District, San Diego Gas and Electric, Southern California Edison and Southern California Gas Company, under the auspices of the California Public Utilities Commission.
- An interpreter program should be available if the trending data cannot be directly converted to energy consumption. - Metering devices should be installed in close proximity with the BAS communication network. - It can be relatively economical to install an additional sub-metering system if the number of metering spots is limited.
Training Highlights California utilities offer outstanding educational opportunities that focus on the design, construction and operation of energy-efficient buildings. Listed here are a few of the many upcoming classes and events; for complete schedules, visit each utility’s website.
http://www.pge.com/mybusiness/edusafety/training/pec/ classes/index.jsp?reqType=detail&ID=4749&db=PEC4749. csv&pageTitle=Class Details and Registration&postback=yes Demand Response - Calculating Load Reduction
Industrial Refrigeration Efficiency Upgrades Workshop
This class is designed for engineers who will be performing demand response audits or technical audits as part of integrated audits (energy efficiency and demand response), who require an understanding of demand response concepts, and who can benefit from practical methodologies for accurately calculating potential load reduction for a variety of measures.
This workshop will compare a typical plant with an efficient facility that demonstrates substantial energy savings. Instruction will touch on Title 24 (and Title 20) requirements and discuss opportunities for implementing energy efficiency measures that go beyond the code. Instruction will explore a recently constructed refrigeration plant that effectively integrates photovolatics, water efficiency, and other cuttingedge efficiency measures in pursuit of achieving net zero energy use.
March 31 (Thursday 8:00 am - 3:00 pm) - San Diego Energy Resource Center (SDERC) https://seminars.sdge.com/iebms/coe/coe_p1_all. aspx?cc=coe&oc=05
February 8 (Tuesday, 9:00 am to 12:30 pm) Vallejo--Blue Rock Springs February 10 (Thursday, 9:00 am to 12:30 pm) Bakersfield-Hodel’s
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