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# Energy Savings Calculations for Existing Building Commissioning

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Engineers Angela Vreeland and Gustav Brändström demonstrate common traps and tricks in dealing with trend data, along with detailed calculations that can be applied to a variety of energy saving measures.

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### Energy Savings Calculations for Existing Building Commissioning

1. 1. Welcome to the Webinar onEnergy Saving Calculations forExisting Building Commissioning We’ll start the presentation shortly. Hover your cursor at the top of your screen to access the WebEx menu bar and open your Chat window. We will end with an open discussion, but feel free to ask clarifying or technical support questions during the presentation through your Chat window.Gustav Brändström, PEAngela Vreeland, PEFebruary 19, 2013
2. 2. Energy Saving Calculations forExisting Building CommissioningGustav Brändström, PEAngela Vreeland, PEFebruary 19, 2013
3. 3. Agenda Agenda  Introduction  Why use spreadsheet calculations?  Trending and Trend Data  TMY and Bin Data  Top Energy Saving Measures in EBCx  AHU Measure  Optimize Airside Economizer  Pump Measure  Install VFD on Hot Water Pump  Wrap-up  QuestionsPage 3
4. 4. Introduction Why Use Spreadsheet Calculations?  Customizable for any application  Can be based on actual building operation  Applicable to multiple scenarios with little modification  TRAP: Do not double count savings! Remember to include interactions between findings and equipment.  Scheduling > Controls changes > Retrofits  Central system > Major equipment > Terminal equipmentPage 4
5. 5. Introduction Why Use Spreadsheet Calculations?  Most 3rd party tools apply to specific scenarios  “Square peg in round hole”  All inputs must be re-entered for each case  Energy modeling is not economical for analysis of individual equipment  Time-consuming  Not intent of modeling softwarePage 5
6. 6. Introduction Trending and Trend Data  Trending – brief overview  The process of capturing time series data on equipment operation  Data is exported from a Building Automation System (BAS) or data loggers for spreadsheet analysis  Data set-up, collection, processing, and analysis are time consuming  Allows us to understand how the equipment operates See the Innovation Exchange’s Webinar on Trending titled: Using Building Automation Systems as a Cx ToolPage 6
7. 7. Introduction Trending and Trend Data  Why use trend data?  Trend data allows you to identify operational issues you wouldn’t find otherwise.  Functional performance tests and other tools can’t capture all modes of operation  Trend data allows you to more accurately calculate savingsPage 7
8. 8. Introduction TMY and Bin Data  Energy savings calculations are based on OAT  Typical Meteorological Year Weather Data  Normalized weather  Covers at least 15 year timeframe  Average and typical, not average  “Major” cities only  Get from NREL  http://www.nrel.gov/rredc/solar_data.html  Bin Data  Grouped or “binned” data  Increments vary depending on system characteristics  Outdoor temperature is typically put in 5 F bins  Used in most spreadsheet calculationsPage 8
9. 9. Introduction TMY and Bin Data  TRICK: AVERAGEIFS() and COUNTIFS() in Excel  These functions make creating bins out of data super easy!!  AVERAGEIFS() - Average value of a range, given criteria  COUNTIFS() - Number of occurrences in a range, given criteria OAT Bins Avg OAT (F) Hours Hours ON 60 65 63.7 3 1.5 65 70 68.5 2.25 0.75 70 75 72.4 3.25 1.25 75 80 77.8 2 1.25 80 85 82.5 8.25 5.75 85 90 85.8 1.25 1.25 =AVERAGEIFS(Avg Range, CriteriaRange1, Criteria1, CriteriaRange2,Criteria2, …) =AVERAGEIFS(OAT Column, OAT Column,">="&BinLL, OAT Column,"<"&BinUL)Page 9
10. 10. Agenda Agenda  Introduction  Why use spreadsheet calculations?  Trending and Trend Data  TMY and Bin Data  Top Energy Saving Measures in EBCx  AHU Measure  Optimize Airside Economizer  Pump Measure  Install VFD on Hot Water Pump  Wrap-up  QuestionsPage 10
11. 11. AHU Measure Top Energy Saving Measures in EBCx Key Measure Mix % of Total Savings Revise control sequence 21% Reduce equipment runtime 15% Optimize airside economizer 12% Add/optimize SAT reset 8% Add VFD to pump 6% Reduce coil leakage 4% Reduce/reset DSP setpoint 4% Add/optimize optimum start/stop 3% Add/optimize CWST reset 2% Source: A Study on Energy Savings and Measure Cost Effectiveness ofPage 11 EBCx, PECI, 2009
12. 12. AHU Measure Optimize Airside Economizer  Four most common high limit control strategies  Fixed Drybulb Temperature- OAT  Differential Drybulb Temperature- OAT vs RAT  Fixed Enthalpy- OAh Enthalpy is calculated from drybulb temperature and humidity  Differential Enthalpy- OAh vs RAhPage 12 ???
13. 13. AHU Measure Optimize Airside Economizer  Economizers malfunction frequently  Stuck outside damper  Outside air (OA) flow measuring station error  Temperature or humidity sensor out of calibrationPage 13
14. 14. AHU Measure Optimize Airside Economizer  Economizer control errors are common  Incorrect high and/or low limit setpoint  Incorrect minimum outside air setpoint  Lockout between economizer and mechanical cooling  Result in  A loss of “free cooling” opportunity  Increased cooling load  Increased heating loadPage 14
15. 15. AHU Measure Optimize Airside Economizer  How do we know if something is wrong?  Calculate the %OA where: OAT = Outside Air Temperature RAT = Return Air Temperature MAT = Mixed Air Temperature  Plot %OA against OAT and look at the patternPage 15
16. 16. - IDEAL PATTERN Economizer Lockout ~ 70°FPage 16
17. 17. AHU Measure Optimize Airside Economizer  Why should the high limit setpoint be ~70 F?  High limit of 71 F in MN was found to be ideal  Taylor Engineering Research  Best economizer control strategy is provided for each region  November 2010 ASHRAE Journal (Vol. 52, No. 11)  TRAP: Humidity Sensors are Error-Prone  Avoid enthalpy high limit control  Iowa Energy Center Research  http://www.iowaenergycenter.org/wp- content/uploads/2012/05/PTR_Humidity_Rev.pdfPage 17
18. 18. AHU Measure Optimize Airside Economizer Example  Finding (problem)  Economizer high limit lockout is 80 F  Measure (solution)  Change the lockout to 70 FPage 18
19. 19. - HIGH LIMIT TOO HIGH Lower the High Limit Setpoint: 80°F to 70°FPage 19
20. 20. AHU Measure Optimize Airside Economizer Example  Spreadsheet Calculation Layout  Reducing the high limit setpoint will lead to savings whenever the outside air damper is open more than it should be 1 2 3 A B C D E F G H I J K L Current Proposed OAT Dry OAT OA OA OA OA AHU On RAT Savings Bulb Bin Dry Bulb OA OA Flow Cooling Cooling OA OA Flow Cooling Cooling Energy Input Energy Input F F Hours F % CFM kBtus kWh % CFM kBtus kWh kWh 60/64 62.6 321 70.8 67.9% 9,840 0 0 67.9% 9,840 0 0 0 65/69 68.1 294 71.2 87.7% 12,712 0 0 87.7% 12,712 0 0 0 70/74 72.5 265 71.6 95.5% 13,847 3,400 340 10.0% 1,450 356 36 304 75/79 76.9 317 71.6 78.0% 11,307 20,534 2,053 10.0% 1,450 2,633 263 1790 80/84 82.1 284 72.6 18.2% 2,643 7,688 769 10.0% 1,450 4,218 422 347 85/89 87.8 152 72.0 10.0% 1,450 3,758 376 10.0% 1,450 3,758 376 0 90/94 91.9 54 73.0 10.0% 1,450 1,594 159 10.0% 1,450 1,594 159 0 2,442Page 20
21. 21. AHU Measure Optimize Airside Economizer Example 1 A B C D EColumn A- OAT Bins F G H I J K L Current ProposedOAT Dry OAT  5 F Bins OA OA OA OA AHU On RATBulb Bin Dry Bulb OA OA Flow Cooling Cooling OA OA Flow Cooling Cooling Energy Input Energy Input F F Hours F %Column B- Average OAT for Bin CFM kBtus% kWh CFM kBtus kWh 60/64 62.6 321 70.8  Obtain from 0TMY Data 67.9% 9,840 0 67.9% 9,840 0 0 65/69 68.1 294 71.2 87.7% 12,712 0 0 87.7% 12,712 0 0 70/74 72.5 265 71.6  Use AVERAGEIFS340 95.5% 13,847 3,400 10.0% 1,450 356 36 75/79 76.9 317 71.6 78.0% 11,307 20,534 2,053 10.0% 1,450 2,633 263 80/84 82.1 284 72.6 18.2% 2,643 7,688 769 10.0% 1,450 4,218 422 85/89 87.8 152 72.0 Column C- Total Hours the AHU operates 10.0% 1,450 3,758 376 10.0% 1,450 3,758 376 90/94 91.9 54 73.0 10.0% during Bin 1,450 1,594 159 10.0% 1,450 1,594 159  Obtain from trends of SF Status or VFD Speed and OAT  Use COUNTIFSPage 21
22. 22. AHU Measure Optimize Airside Economizer Example 1 A B C D EColumn D- Average RAT during JBin F G H I K L Current ProposedOAT Dry OAT  Obtain from trendsOA RAT and OAT OA of OA OA AHU On RATBulb Bin Dry Bulb  OA RAT vs OAT to see OA pattern OA Plot Flow Cooling Cooling overall OA Flow Cooling Cooling Energy Input Energy Input F F Hours F  % Use AVERAGEIFS- Filter for when AHU is ON CFM kBtus kWh % CFM kBtus kWh 60/64 62.6 321 70.8 67.9% 9,840 0 0 67.9% 9,840 0 0 65/69 68.1 294 71.2 87.7% 12,712 0 0 87.7% 12,712 0 0 70/74 72.5 265 71.6 95.5% 13,847 3,400 340 10.0% 1,450 356 36 75/79 76.9 317 71.6 78.0% 11,307 20,534 2,053 10.0% 1,450 2,633 263 80/84 82.1 284 72.6 18.2% 2,643 7,688 769 10.0% 1,450 4,218 422 85/89 87.8 152 72.0 10.0% 1,450 3,758 376 10.0% 1,450 3,758 376 90/94 91.9 54 73.0 10.0% 1,450 1,594 159 10.0% 1,450 1,594 159Page 22
23. 23. AHU Measure Optimize Airside Economizer Example  Spreadsheet Calculation Layout 1 2 3 A B C D E F G H I J K L Current Proposed OAT Dry OAT OA OA OA OA AHU On RAT Savings Bulb Bin Dry Bulb OA OA Flow Cooling Cooling OA OA Flow Cooling Cooling Energy Input Energy Input F F Hours F % CFM kBtus kWh % CFM kBtus kWh kWh 60/64 62.6 321 70.8 67.9% 9,840 0 0 67.9% 9,840 0 0 0 65/69 68.1 294 71.2 87.7% 12,712 0 0 87.7% 12,712 0 0 0 70/74 72.5 265 71.6 95.5% 13,847 3,400 340 10.0% 1,450 356 36 304 75/79 76.9 317 71.6 78.0% 11,307 20,534 2,053 10.0% 1,450 2,633 263 1790 80/84 82.1 284 72.6 18.2% 2,643 7,688 769 10.0% 1,450 4,218 422 347 85/89 87.8 152 72.0 10.0% 1,450 3,758 376 10.0% 1,450 3,758 376 0 90/94 91.9 54 73.0 10.0% 1,450 1,594 159 10.0% 1,450 1,594 159 0 2,442Page 23
24. 24. AHU Measure Optimize Airside Economizer Example 2 A E F G H Column E- Average %OA during Bin CurrentOAT Dry  Obtain from trends of MAT, RAT, and OA OABulb Bin OA OA Flow Cooling Cooling OAT Energy Input  Plot %OA vs OAT to see overall pattern F % CFM kBtus kWh  Use AVERAGEIFS- Filter for when AHU 60/64 67.9% 9,840 0 0 65/69 87.7% 12,712 0 0 is ON 70/74 95.5% 13,847 3,400 340 75/79 78.0% 11,307 20,534 2,053 80/84 18.2% 2,643 7,688 769 85/89 10.0% 1,450 3,758 376 90/94 10.0% 1,450 1,594 159Page 24
25. 25. AHU Measure Optimize Airside Economizer Example 2 A E F G H Column F- OA Flow CurrentOAT Dry  Calculated using equation below OA OABulb Bin OA OA Flow Cooling Cooling  SF Speed must be accounted for with Energy Input variable volume AHUs F % CFM kBtus kWh 60/64 67.9% 9,840 0 0 65/69 87.7% 12,712 0 0 70/74 95.5% 13,847 3,400 340 Column G- Cooling Energy 75/79 78.0% 11,307 20,534 2,053 80/84 18.2% 2,643 7,688 769  Energy required to cool OA 85/89 10.0% 1,450 3,758 376  Calculated using equation below 90/94 10.0% 1,450 1,594 159Page 25
26. 26. AHU Measure Optimize Airside Economizer Example 2 A E F G H Column H- Cooling Input CurrentOAT Dry  Calculated using equation below OA OABulb Bin OA OA Flow Cooling Cooling Energy Input F % CFM kBtus kWh 60/64 67.9% 9,840 0 0 65/69 87.7% 12,712 0 0 70/74 95.5% 13,847 3,400 340 75/79 78.0% 11,307 20,534 2,053 80/84 18.2% 2,643 7,688 769 85/89 10.0% 1,450 3,758 376 90/94 10.0% 1,450 1,594 159Page 26
27. 27. AHU Measure Optimize Airside Economizer Example  Spreadsheet Calculation Layout 1 2 3 A B C D E F G H I J K L Current Proposed OAT Dry OAT OA OA OA OA AHU On RAT Savings Bulb Bin Dry Bulb OA OA Flow Cooling Cooling OA OA Flow Cooling Cooling Energy Input Energy Input F F Hours F % CFM kBtus kWh % CFM kBtus kWh kWh 60/64 62.6 321 70.8 67.9% 9,840 0 0 67.9% 9,840 0 0 0 65/69 68.1 294 71.2 87.7% 12,712 0 0 87.7% 12,712 0 0 0 70/74 72.5 265 71.6 95.5% 13,847 3,400 340 10.0% 1,450 356 36 304 75/79 76.9 317 71.6 78.0% 11,307 20,534 2,053 10.0% 1,450 2,633 263 1790 80/84 82.1 284 72.6 18.2% 2,643 7,688 769 10.0% 1,450 4,218 422 347 85/89 87.8 152 72.0 10.0% 1,450 3,758 376 10.0% 1,450 3,758 376 0 90/94 91.9 54 73.0 10.0% 1,450 1,594 159 10.0% 1,450 1,594 159 0 2,442Page 27
28. 28. AHU Measure Optimize Airside Economizer Example 3 A I J K L Columns I thru L ProposedOAT Dry  Repeat the same analysis for OA OABulb Bin OA OA Flow Cooling Cooling Proposed Scenario Energy Input  Above 70 F, the %OA will drop to F % CFM kBtus kWh minimum position 60/64 67.9% 9,840 0 0 65/69 87.7% 12,712 0 0  Based on data at low OATs, the 70/74 10.0% 1,450 356 36 minimum %OA is 10% 75/79 10.0% 1,450 2,633 263 80/84 10.0% 1,450 4,218 422 85/89 10.0% 1,450 3,758 376 90/94 10.0% 1,450 1,594 159Page 28
29. 29. AHU Measure Optimize Airside Economizer Example A B C D E F G H I J K L Current Proposed OAT Dry OAT OA OA OA OA AHU On RAT Savings Bulb Bin Dry Bulb OA OA Flow Cooling Cooling OA OA Flow Cooling Cooling Energy Input Energy Input F F Hours F % CFM kBtus kWh % CFM kBtus kWh kWh 60/64 62.6 321 70.8 67.9% 9,840 0 0 67.9% 9,840 0 0 0 65/69 68.1 294 71.2 87.7% 12,712 0 0 87.7% 12,712 0 0 0 70/74 72.5 265 71.6 95.5% 13,847 3,400 340 10.0% 1,450 356 36 304 75/79 76.9 317 71.6 78.0% 11,307 20,534 2,053 10.0% 1,450 2,633 263 1790 80/84 82.1 284 72.6 18.2% 2,643 7,688 769 10.0% 1,450 4,218 422 347 85/89 87.8 152 72.0 10.0% 1,450 3,758 376 10.0% 1,450 3,758 376 0 90/94 91.9 54 73.0 10.0% 1,450 1,594 159 10.0% 1,450 1,594 159 0 2,442  Savings  2,442 kWh annually or \$170 at 7¢/kWh  ~10% of energy used to cool OA  No cost to implementPage 29
30. 30. AHU Measure Optimize Airside Economizer  Summary  Economizers malfunction often, but fixing them is typically very easy and cost-effective  Additional considerations….  Sometimes fixing the issue leads to more energy use  An AHU may economize at OATs as low as 20 or 30 F  The fewer sensors the economizer relies on, the betterPage 30
31. 31. Agenda Agenda  Introduction  Why use spreadsheet calculations?  Trending and Trend Data  TMY and Bin Data  Top Energy Saving Measures in EBCx  AHU Measure  Optimize Airside Economizer  Pump Measure  Install VFD on Hot Water Pump  Wrap-up  QuestionsPage 31
32. 32. Pump Measure Top Energy Saving Measures in EBCx Key Measure Mix % of Total Savings Revise control sequence 21% Reduce equipment runtime 15% Optimize airside economizer 12% Add/optimize SAT reset 8% Add VFD to pump 6% Reduce coil leakage 4% Reduce/reset DSP setpoint 4% Add/optimize optimum start/stop 3% Add/optimize CWST reset 2% Source: A Study on Energy Savings and Measure Cost Effectiveness ofPage 32 EBCx, PECI, 2009
33. 33. Pump Measure Install VFD on Hot Water Pump  Constant volume pumping is common in existing buildings.  Hot water loops come in many variants; primary, primary/secondary, primary/tertiary, etc.  Energy savings from reducing the pump speed  Opportunities exist when the  drop in temperature is lowPage 33
34. 34. TRICK: Plot HW dT vs OAT. Example of low temperature drop Design Loop dT = 48°FPage 34
35. 35. Pump Measure Install VFD on Hot Water Pump  Constant volume pumping is common in existing buildings.  Hot water loops come in many variants; primary, primary/secondary, primary/tertiary, etc.  Energy savings from reducing the pump speed  Opportunities exist when the  drop in temperature is low, and/or  use in the AHUs are low.Page 35
36. 36. TRICK: Plot # of AHUs heating vs OAT. Example of Low use of heating at the AHUsPage 36
37. 37. Pump Measure Install VFD on Hot Water Pump  Example  Finding (problem)  Secondary Hot Water Loop Pump runs excessively  Measure (solution)  Install VFD on 40hp Pump, close off three way valves, and install differential pressure sensorPage 37
38. 38. Pump Measure Install VFD on Hot Water Pump  Calculation Layout 1 2 3 % of Total Flow %Req. Energy Use Bin 11.8% 11.3% 7.0% 13.1% 5.5% 15.6% 14.8% 20.9% Flow Current Proposed OAT Bin Hours AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-7 AHU-8 (min 30%) (kWh) (kWh) -20 -10 248 100% 59% 100% 63% 58% 64% 89% 77% 76% 6,994 4,061 -10 0 309 100% 62% 100% 63% 60% 55% 73% 66% 70% 8,714 4,328 0 10 436 100% 68% 100% 54% 62% 52% 68% 48% 65% 12,295 5,226 10 20 696 100% 48% 100% 44% 45% 40% 48% 36% 53% 19,627 5,600 20 30 1074 100% 27% 100% 28% 27% 31% 27% 15% 39% 30,287 4,622 30 40 1224 100% 18% 100% 0% 10% 20% 3% 8% 30% 34,517 3,107 40 50 1114 100% 8% 100% 0% 3% 14% 0% 7% 30% 31,415 2,827 50 60 1135 100% 0% 100% 0% 0% 9% 0% 3% 30% 32,007 2,881 60 70 1157 0% 0% 0% 0% 0% 0% 0% 0% 30% 32,627 2,936 208,483 35,588 Savings 172,895Page 38
39. 39. Pump Measure Install VFD on Hot Water Pump  Calculation of OAT bins 1 % of Total Flow %Req. Energy Use Bin 11.8% 11.3% 7.0% 13.1% 5.5% 15.6% 14.8% 20.9% Flow Current Proposed OAT Bin Hours AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-7 AHU-8 (min 30%) (kWh) (kWh) -20 -10 248 100% 59% 100% 63% 58% 64% 89% 77% 76% 6,994 4,061 -10 0 309 100% 62% 100% 63% 60% 55% 73% 66% 70% 8,714 4,328 0 10 436 100% 68% 100% 54% 62% 52% 68% 48% 65% 12,295 5,226 10 20 696 100% 48% 100% 44% 45% 40% 48% 36% 53% 19,627 5,600 20 30 1074 100% 27% 100% 28% 27% 31% 27% 15% 39% 30,287 4,622 30 40 1224 100% 18% 100% 0% 10% 20% 3% 8% 30% 34,517 3,107 40 50 1114 100% 8% 100% 0% 3% 14% 0% 7% 30% 31,415 2,827 50 60 1135 100% 0% 100% 0% 0% 9% 0% 3% 30% 32,007 2,881 60 70 1157 0% 0% 0% 0% 0% 0% 0% 0% 30% 32,627 2,936 208,483 35,588 Savings 172,895Page 39
40. 40. Pump Measure Install VFD on Hot Water Pump  Calculation of AHU heating use  % of total loop flow through each AHU 2 % of Total Flow %Req. Energy Use Bin 11.8% 11.3% 7.0% 13.1% 5.5% 15.6% 14.8% 20.9% Flow Current Proposed OAT Bin Hours AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-7 AHU-8 (min 30%) (kWh) (kWh) -20 -10 248 100% 59% 100% 63% 58% 64% 89% 77% 76% 6,994 4,061 -10 0 309 100% 62% 100% 63% 60% 55% 73% 66% 70% 8,714 4,328 0 10 436 100% 68% 100% 54% 62% 52% 68% 48% 65% 12,295 5,226 10 20 696 100% 48% 100% 44% 45% 40% 48% 36% 53% 19,627 5,600 20 30 1074 100% 27% 100% 28% 27% 31% 27% 15% 39% 30,287 4,622 30 40 1224 100% 18% 100% 0% 10% 20% 3% 8% 30% 34,517 3,107 40 50 1114 100% 8% 100% 0% 3% 14% 0% 7% 30% 31,415 2,827 50 60 1135 100% 0% 100% 0% 0% 9% 0% 3% 30% 32,007 2,881 60 70 1157 0% 0% 0% 0% 0% 0% 0% 0% 30% 32,627 2,936 208,483 35,588 Savings 172,895Page 40
41. 41. Pump Measure Install VFD on Hot Water Pump  Calculation of AHU heating use  TRAP: Do not assume linear load  TRICK: AVERAGEIFS() 2 % of Total Flow %Req. Energy Use Bin 11.8% 11.3% 7.0% 13.1% 5.5% 15.6% 14.8% 20.9% Flow Current Proposed OAT Bin Hours AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-7 AHU-8 (min 30%) (kWh) (kWh) -20 -10 248 100% 59% 100% 63% 58% 64% 89% 77% 76% 6,994 4,061 -10 0 309 100% 62% 100% 63% 60% 55% 73% 66% 70% 8,714 4,328 0 10 436 100% 68% 100% 54% 62% 52% 68% 48% 65% 12,295 5,226 10 20 696 100% 48% 100% 44% 45% 40% 48% 36% 53% 19,627 5,600 20 30 1074 100% 27% 100% 28% 27% 31% 27% 15% 39% 30,287 4,622 30 40 1224 100% 18% 100% 0% 10% 20% 3% 8% 30% 34,517 3,107 40 50 1114 100% 8% 100% 0% 3% 14% 0% 7% 30% 31,415 2,827 50 60 1135 100% 0% 100% 0% 0% 9% 0% 3% 30% 32,007 2,881 60 70 1157 0% 0% 0% 0% 0% 0% 0% 0% 30% 32,627 2,936 208,483 35,588 Savings 172,895Page 41
42. 42. Pump Measure Install VFD on Hot Water Pump  Calculation of AHU heating use – Three-way valves 2 % of Total Flow %Req. Energy Use Bin 11.8% 11.3% 7.0% 13.1% 5.5% 15.6% 14.8% 20.9% Flow Current Proposed OAT Bin Hours AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-7 AHU-8 (min 30%) (kWh) (kWh) -20 -10 248 100% 59% 100% 63% 58% 64% 89% 77% 76% 6,994 4,061 -10 0 309 100% 62% 100% 63% 60% 55% 73% 66% 70% 8,714 4,328 0 10 436 100% 68% 100% 54% 62% 52% 68% 48% 65% 12,295 5,226 10 20 696 100% 48% 100% 44% 45% 40% 48% 36% 53% 19,627 5,600 20 30 1074 100% 27% 100% 28% 27% 31% 27% 15% 39% 30,287 4,622 30 40 1224 100% 18% 100% 0% 10% 20% 3% 8% 30% 34,517 3,107 40 50 1114 100% 8% 100% 0% 3% 14% 0% 7% 30% 31,415 2,827 50 60 1135 100% 0% 100% 0% 0% 9% 0% 3% 30% 32,007 2,881 60 70 1157 0% 0% 0% 0% 0% 0% 0% 0% 30% 32,627 2,936 208,483 35,588 Savings 172,895Page 42
43. 43. Pump Measure Install VFD on Hot Water Pump  Calculation of total heating use  TRAP: Do not assume 30% minimum flow (as I did) 2 % of Total Flow %Req. Energy Use Bin 11.8% 11.3% 7.0% 13.1% 5.5% 15.6% 14.8% 20.9% Flow Current Proposed OAT Bin Hours AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-7 AHU-8 (min 30%) (kWh) (kWh) -20 -10 248 100% 59% 100% 63% 58% 64% 89% 77% 76% 6,994 4,061 -10 0 309 100% 62% 100% 63% 60% 55% 73% 66% 70% 8,714 4,328 0 10 436 100% 68% 100% 54% 62% 52% 68% 48% 65% 12,295 5,226 10 20 696 100% 48% 100% 44% 45% 40% 48% 36% 53% 19,627 5,600 20 30 1074 100% 27% 100% 28% 27% 31% 27% 15% 39% 30,287 4,622 30 40 1224 100% 18% 100% 0% 10% 20% 3% 8% 30% 34,517 3,107 40 50 1114 100% 8% 100% 0% 3% 14% 0% 7% 30% 31,415 2,827 50 60 1135 100% 0% 100% 0% 0% 9% 0% 3% 30% 32,007 2,881 60 70 1157 0% 0% 0% 0% 0% 0% 0% 0% 30% 32,627 2,936 208,483 35,588 Savings 172,895Page 43
44. 44. Pump Measure Install VFD on Hot Water Pump  Calculation of total heating use 3 % of Total Flow %Req. Energy Use Bin 11.8% 11.3% 7.0% 13.1% 5.5% 15.6% 14.8% 20.9% Flow Current Proposed OAT Bin Hours AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-7 AHU-8 (min 30%) (kWh) (kWh) -20 -10 248 100% 59% 100% 63% 58% 64% 89% 77% 76% 6,994 4,061 -10 0 309 100% 62% 100% 63% 60% 55% 73% 66% 70% 8,714 4,328 0 10 436 100% 68% 100% 54% 62% 52% 68% 48% 65% 12,295 5,226 10 20 696 100% 48% 100% 44% 45% 40% 48% 36% 53% 19,627 5,600 20 30 1074 100% 27% 100% 28% 27% 31% 27% 15% 39% 30,287 4,622 30 40 1224 100% 18% 100% 0% 10% 20% 3% 8% 30% 34,517 3,107 40 50 1114 100% 8% 100% 0% 3% 14% 0% 7% 30% 31,415 2,827 50 60 1135 100% 0% 100% 0% 0% 9% 0% 3% 30% 32,007 2,881 60 70 1157 0% 0% 0% 0% 0% 0% 0% 0% 30% 32,627 2,936 208,483 35,588 Savings 172,895Page 44
45. 45. Pump Measure Install VFD on Hot Water Pump  Calculation of current (100% flow) vs proposed pump energy use 3 % of Total Flow %Req. Energy Use Bin 11.8% 11.3% 7.0% 13.1% 5.5% 15.6% 14.8% 20.9% Flow Current Proposed OAT Bin Hours AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-7 AHU-8 (min 30%) (kWh) (kWh) -20 -10 248 100% 59% 100% 63% 58% 64% 89% 77% 76% 6,994 4,061 -10 0 309 100% 62% 100% 63% 60% 55% 73% 66% 70% 8,714 4,328 0 10 436 100% 68% 100% 54% 62% 52% 68% 48% 65% 12,295 5,226 10 20 696 100% 48% 100% 44% 45% 40% 48% 36% 53% 19,627 5,600 20 30 1074 100% 27% 100% 28% 27% 31% 27% 15% 39% 30,287 4,622 30 40 1224 100% 18% 100% 0% 10% 20% 3% 8% 30% 34,517 3,107 40 50 1114 100% 8% 100% 0% 3% 14% 0% 7% 30% 31,415 2,827 50 60 1135 100% 0% 100% 0% 0% 9% 0% 3% 30% 32,007 2,881 60 70 1157 0% 0% 0% 0% 0% 0% 0% 0% 30% 32,627 2,936 208,483 35,588 Savings 172,895Page 45
46. 46. Pump Measure Install VFD on Hot Water Pump  Saves 172,895 kWh annually, or \$12,100 at 7¢/kWh. 83% of the current pump energy use saved! 3 % of Total Flow %Req. Energy Use Bin 11.8% 11.3% 7.0% 13.1% 5.5% 15.6% 14.8% 20.9% Flow Current Proposed OAT Bin Hours AHU-1 AHU-2 AHU-3 AHU-4 AHU-5 AHU-6 AHU-7 AHU-8 (min 30%) (kWh) (kWh) -20 -10 248 100% 59% 100% 63% 58% 64% 89% 77% 76% 6,994 4,061 -10 0 309 100% 62% 100% 63% 60% 55% 73% 66% 70% 8,714 4,328 0 10 436 100% 68% 100% 54% 62% 52% 68% 48% 65% 12,295 5,226 10 20 696 100% 48% 100% 44% 45% 40% 48% 36% 53% 19,627 5,600 20 30 1074 100% 27% 100% 28% 27% 31% 27% 15% 39% 30,287 4,622 30 40 1224 100% 18% 100% 0% 10% 20% 3% 8% 30% 34,517 3,107 40 50 1114 100% 8% 100% 0% 3% 14% 0% 7% 30% 31,415 2,827 50 60 1135 100% 0% 100% 0% 0% 9% 0% 3% 30% 32,007 2,881 60 70 1157 0% 0% 0% 0% 0% 0% 0% 0% 30% 32,627 2,936 208,483 35,588 Savings 172,895Page 46
47. 47. Pump Measure Install VFD on Hot Water Pump  Summary of Measure  Keep the pump running at as low of a speed as possible  TRICK: In conjunction with adding a VFD, look at the scheduling.  TRAP: If there are different modes of operation, account for them! (Morning Warm-up, freeze protection, etc.)  SAVE LOTS OF ENERGY!  Implementation cost \$29,000 (incl. commissioning)  Energy Savings \$12,100  Simple Payback 2.4 yearsPage 47
48. 48. Agenda Agenda  Introduction  Why use spreadsheet calculations?  Trending and Trend Data  TMY and Bin Data  Top Energy Saving Measures in EBCx  AHU Measure  Optimize Airside Economizer  Pump Measure  Install VFD on Hot Water Pump  Wrap-up  QuestionsPage 48
49. 49. Introduction Target High Energy Savings Measures Key Measure Mix % of Total Savings Revise control sequence 21% TRICKs Reduce equipment runtime 15% Focus on: • Large equipment (high Optimize airside economizer 12% horsepower, tonnage, etc) Add/optimize SAT reset 8% • Equipment that runs a lot Add VFD to pump 6% Reduce coil leakage 4% Do a test calculation: Reduce/reset DSP setpoint 4% • Estimate savings and costs Add/optimize optimum 3% • Is the payback reasonable? start/stop Add/optimize CWST reset 2% Source: A Study on Energy Savings and Measure Cost Effectiveness of EBCx, PECI, 2009Page 49
50. 50. Wrap-up Resources  California Commissioning Collaborative  www.cacx.org  Better Bricks  www.betterbricks.com  Taylor Engineering  www.taylor-engineering.com  Portland Energy Conservation, Inc - PECI  www.peci.orgPage 50
51. 51. Wrap-up Conclusion  Trending  Invaluable tool  Identify operational issues  Calculate accurate energy savings (and spreadsheets)  Spreadsheet Calculations  Straightforward  Flexible  Accurate  Worth the investment in developmentPage 51
52. 52. Questions?Page 52
53. 53. Energy Saving Calculations forExisting Building CommissioningGustav Brändström, PEAngela Vreeland, PEFebruary 19, 2013