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.

1. Welcome to the Webinar on
Energy Saving Calculations for
Existing 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, PE
Angela Vreeland, PE
February 19, 2013

2. Energy Saving Calculations for
Existing Building Commissioning
Gustav Brändström, PE
Angela Vreeland, PE
February 19, 2013

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
 Questions
Page 3

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 equipment
Page 4

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 software
Page 5

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 Tool
Page 6

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 savings
Page 7

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 calculations
Page 8

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. 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
 Questions
Page 10

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 of
Page 11 EBCx, PECI, 2009

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 RAh
Page 12 ???

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 calibration
Page 13

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 load
Page 14

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 pattern
Page 15

16. - IDEAL PATTERN
Economizer
Lockout ~ 70°F
Page 16

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.pdf
Page 17

18. AHU Measure
Optimize Airside Economizer Example
 Finding (problem)
 Economizer high limit lockout is 80 F
 Measure (solution)
 Change the lockout to 70 F
Page 18

19. - HIGH LIMIT TOO HIGH
Lower the High Limit Setpoint:
80°F to 70°F
Page 19

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
2,442
Page 20

21. AHU Measure
Optimize Airside Economizer Example
1
A B C D EColumn A- OAT Bins
F G H I J K L
Current Proposed
OAT Dry OAT  5 F Bins OA OA OA OA
AHU On RAT
Bulb 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 COUNTIFS
Page 21

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 Proposed
OAT Dry OAT  Obtain from trendsOA RAT and OAT
OA
of OA OA
AHU On RAT
Bulb 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 1,594 159
Page 22

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
2,442
Page 23

24. AHU Measure
Optimize Airside Economizer Example
2
A E F G H Column E- Average %OA during Bin
Current
OAT Dry
 Obtain from trends of MAT, RAT, and
OA OA
Bulb 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 1,594 159
Page 24

25. AHU Measure
Optimize Airside Economizer Example
2
A E F G H Column F- OA Flow
Current
OAT Dry
 Calculated using equation below
OA OA
Bulb 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 1,594 159
Page 25

26. AHU Measure
Optimize Airside Economizer Example
2
A E F G H Column H- Cooling Input
Current
OAT Dry
 Calculated using equation below
OA OA
Bulb 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 1,594 159
Page 26

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
2,442
Page 27

28. AHU Measure
Optimize Airside Economizer Example
3
A I J K L Columns I thru L
Proposed
OAT Dry
 Repeat the same analysis for
OA OA
Bulb 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 1,594 159
Page 28

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 implement
Page 29

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 better
Page 30

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
 Questions
Page 31

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 of
Page 32 EBCx, PECI, 2009

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 low
Page 33

34. TRICK: Plot HW dT vs OAT. Example of low temperature drop
Design Loop dT = 48°F
Page 34

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. TRICK: Plot # of AHUs heating vs OAT. Example of Low use of heating at the AHUs
Page 36

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 sensor
Page 37

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 172,895
Page 38

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 172,895
Page 39

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 172,895
Page 40

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 172,895
Page 41

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 172,895
Page 42

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 172,895
Page 43

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 172,895
Page 44

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 172,895
Page 45

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 172,895
Page 46

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 years
Page 47

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
 Questions
Page 48

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, 2009
Page 49

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.org
Page 50

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 development
Page 51

52. Questions?
Page 52

53. Energy Saving Calculations for
Existing Building Commissioning
Gustav Brändström, PE
Angela Vreeland, PE
February 19, 2013