National Grid USA Service Company. Impact Evaluation Of 2006 Design2000plus Custom Comprehensive Projects. Final Report

Transcription

1 National Grid USA Service Company Impact Evaluation Of 2006 Design2000plus Custom Comprehensive Projects Final Report July 11, 2010 Submitted to: National Grid USA Service Corporation Waltham, MA Submitted by: L&S Energy Services Clifton Park, NY

2 TABLE OF CONTENTS 1 Introduction Measurement and Evaluation Approach Site Reports Page i

3 1 Introduction OVERVIEW National Grid provide technical and financial assistance through the Energy Initiative and Design 2000plus programs to commercial and industrial customers for equipment and building energy efficiency improvements. Custom projects in these programs are customer- and site-specific and are justified as cost-effective using estimates of the projected energy and demand savings. Savings are estimated by comparing the proposed energy efficient equipment to the energy consumption of the existing equipment for retrofit projects or by comparing the proposed equipment to a baseline efficiency for new construction or time-of-replacement projects. This report presents the results of an impact evaluation performed by L&S Energy Services (L&S) of two Custom Comprehensive projects completed in 2006 under the Design 2000plus program. The report is organized into three sections. This introduction presents an overview of the impact evaluation and summarizes results, conclusions and recommendations applicable to this and future evaluations. Section 2 contains a more detailed presentation of data collection methods, instrumentation, and modeling tools used for the evaluation. Finally, the individual site reports are presented in Section 3. OBJECTIVE The objective of the impact evaluation is to provide verification or re-estimation of energy and demand savings for Custom Comprehensive projects for which incentives were paid in Custom Comprehensive projects are multi-measure installations in new buildings or major renovations where savings are usually calculated using building simulations to capture interactive effects. L&S determined annual energy savings, summer coincident peak demand savings (diversified), winter coincident peak demand savings (diversified), and percent on-peak energy savings. Energy and demand savings were quantified for a sample of two sites so that National Grid can set appropriate financial incentive levels and eligibility criteria for future years, accurately predict energy and demand savings accomplished through the rebate programs, and demonstrate savings to regulators and other interested parties. DESCRIPTION OF SAMPLE PROJECTS National Grid selected a sample of two Custom Comprehensive projects for the impact evaluation out of a population of five 2006 projects. These sites are designated by their Design 2000plus application numbers throughout this report. Application # is a 220,000 square foot, three-story office building in Attleboro, Massachusetts. Application # is a 128,470 square foot academic building with an attached student residential building on a university campus in the suburban Boston area. Tables 1-1 and 1-2 list the energy conservation measures included in each project along with tracking estimates of annual energy and diversified demand savings. The total savings shown at the bottom of each table consider interaction between all of the individual measures. Page 1

4 Table 1-1: Tracking Estimates of Annual Energy and Demand Savings for Measures Implemented at Design2000plus Application # Demand Savings (kw) Annual Energy Savings Savings Percent ECM Description of Measure Summer (kwh) On-Peak 1 Enhanced Lighting Controls ,492 2 Daylighting Controls ,036 3 Optimized Lighting Fixtures , Static Pressure Reset for Rooftop Units Occupancy-based Controls for Terminal Units , ,414 6 VFDs for Hot Water Pumps ,653 All Total Interactive Savings ,676 78% 1. Interactive Savings will not equal sum of individual non-interacted results Table 1-2: Tracking Estimates of Annual Energy and Demand Savings for Measures Implemented at Design2000plus Application # Demand Savings (kw) Annual Energy Savings Savings Percent ECM Description of Measure Summer (kwh) On-Peak 1 2 Upgrade EMS Programming for Air Handling Units Occupancy-based Controls in Music Building , ,600 3 Window Upgrade ,280 4 Premium Efficiency 325-ton Chiller ,760 5 Cooling Tower Fan with VFD , Upgrade Chiller and Tower EMS Programming Demand Control Ventilation in Music Building Variable volume CHW System in Residence Hall , , ,690 All Total Interactive Savings ,015 32% 1. Interactive Savings will not equal sum of individual non-interacted results Page 2

5 All of the measures were originally evaluated in Technical Assistance (TA) studies completed by program technical assistance providers in The TA providers estimated energy and demand savings using the equest hourly building energy simulation program. Each measure was screened individually for costeffectiveness, then the recommended measures were combined and compared to the baseline building to determine final comprehensive savings. EVALUATION APPROACH The evaluation effort relied on site inspection of the measures, building operation staff interviews, spot power measurements, field monitoring, energy management and control system (EMCS) trend data, and data analysis to true up equest building energy simulation models developed by the Technical Assistance provider. L&S engineers performed the initial field work at both sites during the summer of The primary objective of this effort was to obtain sufficient data to adjust key simulation input variables. Data loggers were installed on key systems affected by the energy conservation measures. Battery-powered time-of-use (TOU) data loggers were deployed to verify lighting and motor operating schedules if not available from other sources. Power meters or current recording data loggers were installed to capture load variations on specific motor and chiller applications. These data loggers were reserved for variable load applications on systems with the highest portion of project savings. Data collection occurred for a sufficient period of time to capture a range in loading conditions given the project schedule so that seasonal variations could be observed. In addition to the monitored data, the building energy management and control system (EMCS) was used as a source of data on system operation. EMCS trend data on specific points selected by L&S was setup and collected by the customers and subsequently reviewed by L&S to reveal how systems operate over time and help true up the equest model. The model developed by the TA provider with all measures implemented was modified by L&S, as necessary, to reflect conditions observed in the field and calibrated to reflect the metered and monitored data. The primary means of calibration was to true up the model so that the predicted energy use or operational performance of the system affected by the measure approximates actual characteristics over the selected monitoring period. This approach provides the most reasonable estimate of simulated performance and energy use for the system and, therefore, a best estimate of energy savings for the individual measures and the comprehensive project. Since calibrating the entire building model to actual energy use was of secondary importance, observation of building systems outside of those affected by the measures was limited. We believe this approach is more valid than calibrating the entire building to actual energy use since it focuses on the measure. Once calibration was achieved, savings were determined for each measure individually and for all of the measures combined. The baseline equest model for each measure was simulated so that all of the other measures were implemented. This approach provides interactive savings for the individual measures and, therefore, the best estimate of actual savings for each measure. A building baseline model with no energy conservation measures was developed and compared to the final calibrated model with all measures implemented to provide total project (i.e., comprehensive) savings. Savings results were determined for four savings parameters: annual energy, annual energy saved during on-peak period, and summer and winter demand savings during the summer and winter peak periods, respectively. The peak periods used to determine evaluated demand savings are consistent with the onpeak demand periods defined by ISO New England. Summer on-peak demand reduction is the average demand reduction over all hours between 1 PM and 5 PM on non-holiday weekdays in June, July and Page 3

6 August. The winter on-peak demand reduction is the average demand reduction over all hours between 5 PM and 7 PM on non-holiday weekdays in December and January. The evaluation results for all individual ECM savings were developed differently than in the TA model (tracking estimates) and thus should not be exactly compared. The tracking analysis calculated individual ECM savings as the difference between the baseline model and the baseline plus the ECM, so the tracking savings represents savings gained by adding that ECM to the baseline case. The evaluation calculated the ECM savings as the difference between the package (all measures) model and the package minus the ECM, so that the evaluation savings represents the savings lost by removing that ECM from the package case. Because of the different methods, the evaluated ECM savings will be slightly less than the tracking savings for a given measure. Because different approaches were followed to evaluate each individual measure, the comparison of TA and evaluation savings by measure may not be on an equal basis. While evaluation savings for each measure are fully interactive, the TA measure savings may not be. However, for both the TA Study and evaluation comprehensive savings are the difference between the baseline building and the building with all measures implemented so the comprehensive results can be directly compared. EVALUATION RESULTS Tables 1-3 and 1-4 summarize evaluation annual energy and diversified peak demand savings for the two projects. The percent of the total annual energy savings that occur during the on-peak period as well as the ratio of evaluation to tracking estimates of savings are also shown. The ratio of savings estimates, or realization rate, is listed as a percentage. Individual measure savings and total comprehensive savings, which include interaction between all of the measures, are presented for each project. The site-specific results presented in this report will be used to calculate case-weighted realization rates for each of the four savings parameters for the entire Custom Comprehensive program population. These realization rates will be applied to all Custom Comprehensive sites that were paid incentives through the Design 2000plus program. For the office building site (Application #511077), evaluated annual energy savings for the entire project are 549,950 kwh, an increase of 80,274 kwh over the TA estimate of 469,676 kwh. The new estimate represents a 17% increase in savings over the TA estimate. This increase is seen even though the evaluated savings for ECM2 Daylighting Control are zero as the measure was not operational. The evaluation found that the hours of operations, and hence the predicted baseline system use, were greater than assumed in the TA model. This then offered more potential for the other ECMs (all but ECM2 that wasn t operational) to save energy. Page 4

7 Table 1-3: Energy and Peak Demand Savings for Application # Evaluated Savings Electric Savings % On-Peak Evaluated/Tracking Electric Savings % On-Peak ECM kw kw 1 65, % 176.7% 96.4% % 0.0% 0.0% 3 259, % 91.2% 104.9% 4 129, % 120.6% 113.0% 5 45, % N.A % 6 11, % % 77.8% Total Interacted 2 549, % % 111.2% 88.1% 151.7% 1. Tracking Estimate of Summer Savings was zero, so Evaluated/Tracking ratio could not be calculated 2. Interactive Savings will not equal sum of individual non-interacted results Total annual energy savings for the university building project (Application #511458) are 194,331 kwh, which is 73,774 kwh or 17.5% lower than the TA estimate of 268,105 kwh. The loss of energy savings comes from the building not being operated in the way proposed in the original TA study. The study included energy savings that relied on control strategies that were either never fully implemented or were over-ridden by building operators at some point after their installation and commissioning. Table 1-4: Energy and Peak Demand Savings for Application # Evaluated Savings Electric Savings % On-Peak Evaluated/Tracking Electric Savings % On-Peak ECM kw kw 1 22, % 39.2% 41.2% 2 5, % 25.6% 14.3% 3 6, % 20.9% N.A , % 70.6% N.A 1 5 2, % 37.1% N.A , % 258.1% N.A 1 7 5, % 93.5% % 8 15, % 54.8% N.A 1 Total Interacted 2 194, % % 207.2% 70.8% 121.7% 1. Tracking Estimate of Savings was zero, so Evaluated/Tracking ratio could not be calculated 2. Interactive Savings will not equal sum of individual non-interacted results Page 5

8 Table 1-5 compares total comprehensive savings for the two projects in the sample. For both sites combined, the evaluated energy savings are 0.9 % higher than tracking estimates 1. Summer and winter peak demand savings are 19% lower and 50.2% higher, respectively. Percent on-peak energy savings are 32.8% higher than tracking estimates. Specific reasons for discrepancies between evaluation and tracking estimates of savings for each individual measure are presented in the site reports included in the appendix. Table 1-5: Total Comprehensive Energy and Demand Savings for Sample Tracking Savings Evaluated Savings App. No. % Electric Energy On-Peak kw % Electric Energy On- Peak kw , % , % , % , % Total Combined 737, % , % App. No. Evaluated/Tracking % Electric Energy On- Peak kw % 111.2% 88.1% 151.7% % 207.2% 70.8% 121.7% Total Combined 100.9% 132.8% 81.0% 150.2% CONCLUSIONS AND RECOMMENDATIONS The total of the evaluated electric energy savings of the two sites are 100.9% of the corresponding sum of the tracking estimates. However, on an individual basis the evaluated electric savings at each site is roughly 17% different than the tracking estimate one higher and one lower. The summer and winter peak diversified kw savings show a greater differential. Both sites have evaluated summer demand savings lower than the tracking estimates. Interestingly both sites have evaluated winter demand savings greater than the tracking estimates. Much of the difference in the evaluated versus tracking estimates of savings can be attributed to differences between the assumptions regarding building operating characteristics used by the TA in the energy model and the actual building operation found in this evaluation. At one site the building operating hours were found to be longer than assumed by the TA, hence there was more equipment operation from which savings could be achieved. Note that this increase in electric energy savings would have been even greater if it wasn t for the lack of savings for one of the energy conservation measures installed at that site that was no longer operational. At the second site the evaluated energy savings were lower than the tracking estimates. This is due to the manner in which the building is currently being operated. Several building system control strategies were either over-ridden or changed by building personnel after occupancy of the building. 1 Comparisons between evaluation and tracking estimates of the sum of the savings for the two sites combined are not weighted to represent the population. Therefore, the realization rates presented in Table 1-4 do not represent results for the population of Custom Comprehensive projects. Page 6

9 Differences between tracking and evaluated savings can be explained mostly by the availability of monitored data for the impact evaluation and a better understanding of how the installed systems are actually operated and controlled. Data collected on the systems affected by the measures allowed for calibration of the equest models at the system level. For example, input power to fan motors on variable air volume systems installed under the program were monitored for the evaluation. Also, continuous chiller power monitoring was collected. Data collected on these systems were used to true up the as-built equest models to reflect actual conditions observed in the field. The system-level calibration approach provided a best estimate of savings for each measure and the comprehensive projects. The TA provider developed their energy savings analysis based on assumed operating schedules based on customer-provided information and typical equipment performance. The TA providers did not have actual building data for use in developing their equest energy models. Instead, they typically relied on design data for specific measures for model inputs as well as customer interviews; hence differences in savings estimates are to be expected. Also, in some cases system operation changed from when the TA Study was completed and the evaluation performed. The following process-related recommendations should be considered by National Grid to improve future estimates of savings for the Custom Comprehensive end-use and to help ensure that the estimated savings are realized for completed projects: 1. Enhanced commissioning and training would enable building operators to gain an improved understanding of the energy-related impacts of altering equipment control strategies and operation. 2. Tracking savings estimates should be adjusted based on the results of commissioning or if the commissioning identifies equipment and systems that were not implemented as proposed (or anticipated by the TA analysis). This would reduce the changes in savings values that are made during the evaluation process. 3. Continue to foster open dialog between the program applicant (and their team) and the TA provider. This will enable the TA provider to obtain as accurate as possible an understanding of the building design and anticipated building operation. 4. Retain and provide to evaluator all program documents including design drawings and specifications, submittals, model zoning diagrams, analysis spreadsheets, etc. as this would enable the evaluator to have enhanced documentation over just the TA analysis report and current program documents. The more thorough and comprehensive the documentation, the better the evaluator can calculate the evaluated savings. Page 7

10 2 Measurement and Evaluation Approach OVERVIEW The evaluation effort relied on site inspection of the measures, building operation staff interviews, spot power measurements, limited field monitoring, energy management trend recording, and data analysis to true up equest building energy simulation models developed by the Technical Assistance provider. The model developed by the TA provider with all measures implemented was modified by L&S, as necessary, to reflect conditions observed in the field and calibrated to approximately +/- 20% of actual energy use first at the system level (i.e., to monitored energy use at the affected load such as a chiller). Savings were then determined for each measure individually and for all of the measures combined. The same baseline assumptions included in the Technical Assistance Study were used for the impact evaluation, unless observed/monitored building operating schedules necessitated making changes. ON-SITE SURVEY AND DATA COLLECTION L&S performed the initial field work at both sites during the summer of The primary objective of this effort was to obtain sufficient data to adjust key simulation input variables. For example, setpoints and operating schedules for HVAC equipment and systems were determined from monitored data, energy management and control system trending, or from staff interviews. Additionally, the sequence of operations for major equipment and systems were requested. Spot measurements of input power on motor loads relevant to the analysis were also obtained. Data loggers were installed on key systems affected by the energy conservation measures. Batterypowered time-of-use (TOU) data loggers were deployed to verify lighting operating schedules, to supplement data available from other sources (such as local controls or by staff interview). Power recording data loggers were installed to capture load variations on a dimming lighting system and chiller. These data loggers were reserved for variable load applications on systems with the highest portion of project savings. In addition, trend recording of data available from energy management systems was also used to provide actual equipment operation and status. The evaluation was guided by a measurement and evaluation plan that was developed for each site prior to commencing field work. The plan specified data requirements for each of the individual measures and was developed from program documentation provided to L&S including the program application, energy conservation report (i.e., Technical Assistance Study), Minimum Requirements Document (MRD) for each measure, commissioning reports, and other miscellaneous support documentation. The specific evaluation approaches defined in the work plan were refined during the site visit as required to account for actual field conditions and again after monitored data were analyzed along with supporting information gathered in the field. Evaluation priority was given to measures that provide a significant portion of the project savings. INSTRUMENTATION Table 2-1 lists the instrumentation used at the sites. Several types of data loggers were deployed to capture data on specific energy systems. Data points monitored by the loggers are defined in each of the individual site reports. All of the loggers are compact, non-intrusive, and easy to install and remove. They are described in more detail below. Page 8

11 Table 2-1. Instrumentation Specifications Instrument Make/Model Type Handheld Power Fluke Clamp-on power meter Meter Photo-Sensitive Dent Instruments / Smartlogger, time-of-use recorder Time-of-use Logger Smartlogger Power Recording Meter Dent Instruments / Elite Logger Three-phase power recording meter Photo-Sensitive Time-of-Use Logger: This logger is placed within a lighting fixture, with the built-in photocell facing the source of light. A magnetic or velcro strip is used to hold the logger in place in the fixture. The lighting logger has a sensitivity adjustment to eliminate daylighting and stray light interference. When the light fixture is turned on, the photocell detects light and the logger records an ON event. When the light fixture is turned off, the photocell detects no light and an OFF event is recorded. The logger records these changes in lighting status events with a time-stamp record that is stored in battery backed-up memory. To access the monitored data, the logger is connected to a portable computer via a cable and the data are downloaded to the computer. The raw data are converted to interval runtime through the manufacturer s proprietary software. Power Meter: This three phase recording power meter measures several parameters including amperage and true power over user defined intervals. Manufacturer s proprietary software is used to program the meter, display metered values, retrieve and, if desired, analyze the data. Data can be exported to spreadsheet applications for special analysis. equest BUILDING ENERGY SIMULATION PROGRAM equest is a freeware, complete, fully interactive, professional DOE-2.2 simulation environment based upon technology first developed for PowerDOE then enhanced for use in the current generation of Windows operating system versions. equest is a sophisticated, yet easy to use tool, which provides professional results quickly. equest was designed to allow users to perform detailed analysis without requiring extensive experience in DOE-2 modeling. This is accomplished by combining a building creation wizard, an energy efficiency measure (EEM) wizard and a graphical results display module plus the full DOE-2.2 program. Additionally, equest has a detailed building description interface mode that includes 2-D and 3-D display of building geometry (including CAD file import for point-and-click layout drawing), graphical display of HVAC equipment layout, and access to all DOE-2.2 input parameters and summary/hourly report data. The detailed interface also includes the capability to describe and perform parametric runs and the graphical display of results includes multi-run comparison graphics. 2 2 Description obtained from DOE2 website - Page 9

12 3 Site Reports The individual site reports are presented in Appendix A and B. Each site report details the measurement and evaluation approach, model calibration, data analysis, evaluation results, and comparisons of evaluation savings to tracking estimates. All supporting documentation, such as equest output reports and analysis summaries are included in the appendix of each report. Page 10