C-BOA Tl Validatin f Energy Estimatin Methds February 21, 2012 1 f 7
Table f Cntents Summary... 3 Recmmendatin... 3 Evaluatin Apprach... 3 Technical Advisry Grup Oversight... 3 Prject Specificatins... 3 Engineering Review during Develpment... 3 Dcumentatin f As-Built Energy Calculatins... 4 Final Tl Testing and Cmparisns... 4 1.1.1 Air-Handling Example... 5 1.1.2 Central Plant Example... 6 2 f 7
Summary This reprt summarizes hw the annual energy calculated by the new C-BOA Tl (Custm Building Optimizatin Analysis Tl) were validated thrugh a rigrus develpment and testing prcess. It als includes the utcmes frm the cmparisn f C-BOA results t the energy estimated by ther appraches. The cnclusins will help Califrnia utilities gain cnfidence in using the C-BOA Tl fr estimating energy as part f utility retrcmmissining prgrams in Califrnia. Recmmendatin Based n the results f this analysis, which are detailed in the bdy f this reprt, we are cmfrtable with the prduced by the C-BOA Tl and recmmend its use in Califrnia s utility retrcmmissining prgrams. We suggest using the C-BOA Tl in cncert with the BOA Tl the BOA Tl wuld be used fr lwer measures (<75,000 and <5,000 therms), and the C-BOA Tl wuld be used fr higher measures. Evaluatin Apprach The energy estimated by the C-BOA Tl have been validated thrugh a rigrus prcess. This prcess included engaging a technical advisry grup frm industry, develping detailed technical specificatins fr the tl, nging engineering review and testing during develpment, dcumentatin f as-built calculatin appraches, and final tl testing and result cmparisns t ther calculatin methds. Each f these steps is discussed belw. Technical Advisry Grup Oversight At the beginning f the prject, a Technical Advisry Grup (TAG) was assembled. This grup f utility prgram managers and cmmissining prviders prvided guidance and review f ur verall prject, including the technical appraches utilized, thrughut the develpment prcess. The TAG advised the develpment team n technical issues such as the methd used t calculate peak demand, as well as technical issues related t the calculatin methdlgy used fr each ECM. Prject Specificatins Early in the prject, AEC and PECI wrked tgether t develp detailed specificatins fr the verall tl and fr the calculatin methdlgy related t each ECM. These specificatins were als reviewed by the TAG. General requirements included details n the bjectives, tl capabilities, the apprach used t accunt fr measure interactins, hw energy and peak demand are calculated, as well as required reprts and utputs. The technical specificatins als included a sectin fr each energy cnservatin measure (ECM). The bjectives, the required inputs, the calculatin methdlgies, and any assumptins and limitatins related t the ECM are included in the prject specificatins. Engineering Review during Develpment AEC cnducted the tl develpment and PECI managed the prject and prvided technical versight with assistance frm Eatn. During this develpment prcess, the calculatin apprach used fr each measure was reviewed multiple times by engineers at AEC, PECI, and Eatn. AEC engineers created a spreadsheet demnstrating the methdlgy that was t be used fr a specific ECM. This methd, which may have been revised since the tl specificatin, was reviewed by PECI and then cded int the tl t apply these calculatins t each f the weather bins. Since the calculatins within the tl are written in Visual Basic, it is nt easy t review the 3 f 7
calculatin methd by reviewing this cde directly. Instead, the engineers at PECI and Eatn cnducted multiple tests n each calculatin t ensure 1) the spreadsheet methdlgy was crrect, and 2) the results prduced by the tl matched the spreadsheet results. The testing and evaluatin prcess identified multiple issues. Each issue was dcumented and tracked until reslved. Fr issues that had an impact n the energy r demand estimates, the reslutin included revisin t the tl fllwed by anther review t cnfirm that the changes were successfully implemented. Dcumentatin f As-Built Energy Calculatins The calculatin appraches are detailed in the Help file assciated with the C-BOA Tl. The Help file is an executable file that can be pened directly r pened frm within the C-BOA Tl. Final Tl Testing and Cmparisns Fr the final testing phase, the C-BOA Tl was used t calculate energy fr sme example prjects and then thse were cmpared t the estimated by ther cmmn calculatin methds. There are inherent limitatins in this apprach since this evaluates ne estimate t anther estimate, neither f which may be cnsidered 100% accurate. Measured data was nt available t cnduct this cmparisn. T prvide additinal cmparisn data, we utilized the results frm the Califrnia utility retrcmmissining prgrams frm 2006 t 2009 t establish an expected range f values fr each f the ECMs. The prgram data fr affected measures, which included almst 500 ECMs, prvides energy square, and cvered eight f the nine measures in the C-BOA tl. These values were utilized t ensure the results frm the mdeling tls bth C-BOA and the cmmn calculatin methds were reasnable. In sme cases the utility prgram data may result in lwer than expected square because the ECM may have nly affected a prtin f the facility, while the square data assumes that the ECM affected the entire square age f a building. Determining the precise scpe, including square age, f each f the utility prgram ECMs is utside the scpe f this effrt. The prgram data is shwn in Table 1. Table 1: Califrnia Retr-cmmissining Prjects 2006-2009 # Prjects Min f f Max f Min f f Max f Measure ECM-1: Optimized Ecnmizer Perfrmance 56 0 0.262 1.238 (0.016) 0.006 0.181 ECM-2: Optimize AHU scheduling 137 0 0.202 6.209 0 0.008 0.198 ECM-3: Reset Supply Air Temature 9 0 0.278 1.718 0 0.012 0.063 ECM-4: Reset Discharge Static Pressure Setpint 79 0 0.209 1.254 0 0.004 0.067 ECM-5: Add VFD n Supply Fan 59 (0.004) 0.168 1.370 (0.002) 0.001 0.013 ECM-6: Add VFD n Chilled Water Pump 96 (0.020) 0.253 2.366 0 0 0 4 f 7
# Prjects Min f f Max f Min f f Max f Measure ECM-7: Reset Chilled Water supply Temature 32 0 0.173 1.001 0 0 0 ECM-8: Reset Cndenser Water Temature 27 0 0.290 2.119 0 0 0 ECM-9: Add VFD t Cling Twer Fans 0 NA NA NA NA NA NA 1.1.1 Air-Handling Example The first prject example is based n a prject executed by Eatn in nrthern Califrnia, and included fur f the five measures that affect the air-side calculatins. The data frm the prject was used t estimate in the C-BOA Tl and als in a bin-based spreadsheet mdel utilized by Eatn. Fr the fifth measure, Add VFD n Supply Fan, a test scenari was evaluated. These results were cmpared t ne-anther, and als t the results frm the Califrnia RCx prgrams and are summarized in Figure 1 and in Figure 2: Estimated. The key bservatins frm these results are: The energy estimates frm Eatn s bin mdel and the C-BOA Tl are reasnable and within range f the expected values frm the Califrnia Prgram data fr all but ne ECM (SAT Reset). Overall energy fr the prject estimated by the C-BOA tl were lwer than the Eatn mdel r the Califrnia prgram data fr bth gas and electric, indicating estimates are cnservative. Sme variatins in the energy between the tw mdels exist, but are understandable and reasnable: ECM-2: The scheduling measure are within range, but the stacking rder f the ECMs is different between the tls. Eatn s tl evaluated scheduling last, which accunts fr the higher fr this ECM frm C-BOA Tl. Gas are lwer and mre cnservative in the C-BOA Tl. ECM-3: The SAT reset measure in the C-BOA Tl apprpriately applies a fan penalty, while the Eatn methd des nt. Althugh there is an increase in electricity usage, there are psitive cst due t reduced reheat energy. ECM-4: Reducing static pressure setpint des nt typically result in gas. The CA RCx prgrams shw gas, maybe because the airflw rate was als affected by the ECM fr certain instances. ECM-5: The Eatn tl utilized a different methdlgy (ASHRAE 90.1 Inlet Guide Vanes) as the baseline whereas C-BOA uses Englander and Nrfrd 1 analysis. Als, the Eatn apprach did nt include a VFD efficiency penalty in the calculatins, resulting in higher. 1 Englander, S.L. and Nrfrd, L.K. (1992) Measured Energy Cnsumptin f Variable-Air-Vlume Fans under Inlet Vane and Variable Speed Drive Cntrl, ASHRAE Transactins, 98 Part 2. 5 f 7
1.1.2 Central Plant Example The secnd prject example is based n a prject executed by Eatn in suthern Califrnia and includes all fur f ECMs included in the C-BOA Tl related t central cling plant systems. This prject data was used t estimate in the C-BOA Tl and in an equest mdel. These results were cmpared t ne-anther, and als t the results frm the Califrnia RCx prgrams, and are summarized in Figure 1 and in Figure 2: Estimated. The key bservatins frm these results are: The energy estimates frm Eatn s bin mdel and the C-BOA Tl are reasnable and within range f the expected values fr all ECMs. Overall energy fr the prject estimated by the C-BOA tl were slightly lwer, indicating cnservative estimates. Sme variatins in the energy between the tw mdels exist, but are understandable due t differences in the analysis techniques: The equest mdel utilizes 8,760 hurly data, whereas the C-BOA Tl analysis is based n bin data. The equest mdel des nt utilize a VFD efficiency penalty, which is included in C- BOA. The tw chiller plant mdels, which included multiple chillers, pumps and cling twers, have differences in the way the equipment is sequenced at part lad cnditins. EQuest includes a chilled water pumping penalty when resetting tematures, where the C-BOA Tl des nt. The C-BOA Tl assumes that the chilled water temature difference is the same in the baseline and prpsed cases. Figure 1: Estimated 6 f 7
7 f 7 Figure 2: Estimated