Draft
STANDARD SAVINGS ESTIMATION PROTOCOL FOR
PUMP VFD
Submitted to
REGIONAL TECHNICAL FORUM
Submitted by
SBW CONSULTING, INC.
2820 Northup Way, Suite 230
Bellevue, WA 98004
January 28, 2011
Standard Savings Estimation Protocol - Fan VFD
TABLE OF CONTENTS
1. PURPOSE............................................................................................................ 1
2. DEFINITION
OF KEY TERMS ..................................................................................... 1
3. ELIGIBLE PROJECTS ............................................................................................... 1
4. REQUIRED KNOWLEDGE AND SKILLS OF PRACTITIONER ................................................... 1
5. REQUIRED COMMISSIONING .................................................................................... 2
6. DATA COLLECTION REQUIREMENTS ........................................................................... 2
6.1. Pump Motor Specifications................................................................................................ 2
6.2. Pump Operations ............................................................................................................... 2
6.3. Baseline Measurements .................................................................................................... 3
6.4. Post-Period Measurements ............................................................................................... 3
6.5. Typical Meterological Year (TMY) Weather Data .............................................................. 3
6.6. Inputs for Cost-Effectiveness Analysis ............................................................................... 3
7. PROVISIONAL DATA REQUIREMENTS ......................................................................... 4
8. SAVINGS ESTIMATION STEPS ................................................................................... 4
8.1. Prepare Trend Log Data ..................................................................................................... 4
8.2. Annualized Savings............................................................................................................. 5
8.3. Life Cycle Costs and Benefits ............................................................................................. 5
9. SAMPLING PROCEDURE .......................................................................................... 5
10. RELATIONSHIP TO OTHER PROTOCOLS AND GUIDELINES ............................................... 5
11. TYPICAL COST OF APPLYING THIS PROTOCOL ............................................................. 6
12. USER’S GUIDE TO PUMP VFD SAVINGS CALCULATOR .................................................. 6
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Standard Savings Estimation Protocol - Fan VFD
1. PURPOSE
This protocol establishes a method by which annual electrical energy savings (kWh) can be estimated for
a pump that has been upgraded by the addition of a Variable Frequency Drive (VFD). VFDs reduce
electric use by adjusting the pump motor’s speed to match the required load. Many pumps do not need
to run at full capacity all of the time, and VFDs are more efficient than other methods, such as throttling
valves, at regulating flow rates.
This protocol specifies minimum acceptable data collection requirements and the method by which
these data are to be used in computing savings for Pump VFD projects. Savings are computed using the
Excel workbook (to be developed) that accompanies this document to ensure standardized application
of the savings estimation methods.
2. DEFINITION OF KEY TERMS
Project. A project consists of one VFD installed to control a single pump. Modifications are made to
valves as needed throughout the distribution system to allow for flow variation in the post period.
Baseline. This modifier; as in baseline power refers to the period prior to the upgrade.
Post. This modifier; as in post power trend log, refers to the period after the pump VFD upgrade is
installed and fully commissioned.
Commissioning. This is the process of testing and adjustment required to ensure that the pump VFD is
operating according to its design intent.
3. ELIGIBLE PROJECTS
The following criteria define eligible projects.

Baseline flow must be constant. This excludes variable flow conditions such as pump cycling or twoway valves on equipment served by the pump.

Systems where pump flow varies with production level are excluded.

Pump must be directly driven by an electric motor. Diaphragm pumps driven by compressed air are
not allowed.

New construction projects are not eligible.

The cost of implementing this protocol must not make the project economically unattractive.
4. REQUIRED KNOWLEDGE AND SKILLS OF PRACTITIONER
The practitioner who has lead responsibility for applying this protocol must have a full understanding of
the following:
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Standard Savings Estimation Protocol - Fan VFD

Appropriate safety procedures for work involving pumps and the measurement equipment required
by this protocol

This protocol and the accompanying savings calculator.
The practitioner must also be able to successfully perform the following tasks:

Identify, by inspection and discussion with facility staff that the baseline flow is constant.

Identify the determinants of post period variations in flow: (1) outside air temperature or (2) facility
operations schedule.

Supervise a licensed electrician in installing sensors for true power measurements on the pump
motor and VFD.

Install and operate a true power logger and obtain necessary trend logs from facility control
systems.
5. REQUIRED COMMISSIONING
This protocol may only be used for pumps that pass the following commissioning tests:

Review of installation documentation confirms that intended valve modifications have been made
throughout the distribution system.

Plot of VFD power during the post period confirms that the pump was responding to the control
signal at least 90% of the trend log (see 6.4). VFD power should change in response to changes in
facility operating modes and outside air temperature.
6. DATA COLLECTION REQUIREMENTS
The following data must be collected and entered into the savings calculator. The minimum acceptable
procedure for obtaining the data is specified.
6.1. Pump Motor Specifications

Pump Motor HP. Obtained from the motor name plate. Full load pump kW (computed by the
savings calculator) should not exceed 115% of pump motor nameplate HP times 0.746.
6.2. Pump Operations

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Determinants of Pump Speed. Obtained from facility operator. There are two possible
determinants: (1) outside air temperature or (2) facility operations schedule. In some cases, both
the outside air temperature and facility operation schedule are determinants of pump speed.
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Standard Savings Estimation Protocol - Fan VFD

Outside air temperature. The practitioner must determine how outside air temperatures (OAT)
affect pump operation. One of three types of OAT driven applications are possible: (1) cooling
driven (as in a chilled water pump), (2) heating driven (as in heating hot water pump), or (3) both
heating and cooling.

Facility Operations Schedule. Obtained from facility operator. Schedule may include daily, e.g.
nighttime setback, or seasonal variations in operating modes. If the pump has different operation
modes determined by the facility’s operations schedule, determine the periods for each mode
defined by hour of day, day of week and season.

Weather Station. If OAT is a significant determinant, identify the TMY (Typical Meteorological Year)
weather station which is closest to the project site.
6.3. Baseline Measurements

Pump Motor power. A one-time measurement of true RMS poly-phase power on the circuit
powering the pump motor.
6.4. Post-Period Measurements

Trend Log of VFD Power. A data logger is installed to measure 15-minute interval true RMS polyphase power on the circuit powering the VFD. If pump flow is determined by OAT, the period must
representative of temperatures relevant to the pump application (heating, cooling or both). If pump
flow is determined by facility operations schedule, the period must be representative of all
important modes of operation.

Trend Log of VFD Facility OAT. The facility’s control system is programmed to record OAT at 15minute intervals. This data must be collected for the same period as the VFD power trend log. This
data is required only if pump flow is determined by OAT. If OAT is not available from the facility’s
control system or appears unreliable, an OAT data recorder should be installed to create this trend
log.
6.5. Typical Meterological Year (TMY) Weather Data

TMY OAT. Typical Hourly OAT data for Pacific Northwest weather stations are contained in the
savings calculator to be used in estimating annual savings. Data from the station selected in 6.2 will
be used.
6.6. Inputs for Cost-Effectiveness Analysis
The following data need to be gathered to support the cost/benefit analysis feature of the calculator.

Project completion date.
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Standard Savings Estimation Protocol - Fan VFD

Measure cost. The initial cost of installing the new equipment, including all materials and labor
costs. This is the full cost of the VFD installation. This value must be supported by invoices or other
documentation.

Sector. Possible values are Agricultural, Industrial, and Commercial.
The following values are used in the cost-effectiveness calculation, but are pre-set in the calculator.

Electric shape. The calculator assigns an appropriate electric shape based on fan operation data
describe in section 6.2 and the profile of savings computed from the trend log data.

Periodic costs or savings. Any non-annual periodic costs associated with the measure, and the
associated time period. These are incremental costs of the efficient option over the costs of the
baseline. For a pump VFD, the calculator restricts this value to be zero.

O&M costs or savings. Annual O&M costs or savings associated with the measure. These are costs
or savings which occur with the efficient option that would not occur with the baseline option, i.e.
the costs associated with VFD maintenance. The calculator restricts this value to be zero.

Non-energy benefits. Annual non-energy related costs or savings associated with the measure. The
calculator restricts this value to be zero.

Measure life. Number of years the measure is expected to be in effect. For a pump VFD, the
calculator restricts this value to be 10 years.
7. PROVISIONAL DATA REQUIREMENTS
During the period that the RTF classifies this protocol as Provisional, the following data requirements
will be in force:

Trend baseline motor power. A data logger is installed to measure 15-minute interval true RMS
poly-phase power circuit powering the pump motor for a period of at least two weeks. This
measurement is used to confirm baseline flow is constant.
8. SAVINGS ESTIMATION STEPS
Savings are estimated using the savings calculator that accompanies this protocol (To be developed).
Savings are estimated as follows.
8.1. Prepare Trend Log Data

Data Synchronization. Start times for all trend log intervals are synchronized by moving each to the
closest standard interval start times of 0, 15, 30 and 45 minutes after the start of each hour.

Savings for Trended Period. For each interval, savings will be equal to baseline pump power minus
the trend long value for post VFD power.
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Standard Savings Estimation Protocol - Fan VFD
8.2. Annualized Savings

Average Savings by Trend Log Bin. For each operating mode, average kW usage by two degree
temperature bins, for all trend log intervals during operating hours, as defined by facility operations
schedules (Section 6.2).

Average Savings by TMY Bin. For each operating mode, TMY bin average savings equal trend log
average bin savings for each matching bin. Extrapolate average savings for TMY bins that do not
have trend log data. For heating savings, values are extrapolated by a best fit equation to the trend
log bins. Negative values will likely occur at temperatures greater than about 60F and should be set
to zero. For cooling savings, values are extrapolated by a best fit equation to the trend log bins.
Negative values will likely occur at temperatures less than about 60F and should be set to zero. No
bin value is allowed to exceed the rated pump motor kW.

Annual Savings. Sum the kWh values across all bins.
8.3. Life Cycle Costs and Benefits
The calculator contains a model called ProCost which computes life cycle costs and benefits. Inputs to
the model include the estimates of first-year savings and the cost-effectiveness input data described in
section 6. ProCost computes life cycle costs and benefits from the economic perspectives of the end
user, utility, and region. The calculator can be used to review these results.
9. SAMPLING PROCEDURE
No sampling is permitted by this protocol. Data collection and savings estimation is required for each
upgraded pump regardless of the number of such units that may be upgraded at a facility.
10. RELATIONSHIP TO OTHER PROTOCOLS AND GUIDELINES
The relationship between this protocol and other relevant protocols and guidelines is as follows:

International Performance Measurement and Verification Protocol – 2007 (IPMVP), Efficiency
Valuation Organization. This protocol is consistent with Option B - Retrofit Isolation: All Parameter
Measurement described in the IPMVP, as power and other key parameters are measured (pump
motor power, VFD %speed and OAT) in both the baseline and as-built cases.

M&V Guidelines: Measurement and Verification for Federal Energy Projects Version 3.0, U.S.
Department of Energy Federal Energy Management Program. The relevant part of this guideline
is Section 11.4 Variable Speed Motors. This guideline requires both baseline and post
measurements, which is consistent with this protocol.

Sampling Reference Guide, BPA. It is unlikely that more than 20 pump units would be upgraded as
part of any one project. It is difficult to obtain reliable sample estimates from populations this small,
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Standard Savings Estimation Protocol - Fan VFD
especially given the likely variation in savings between units. Therefore no sampling is allowed. This
is consistent with the BPA guide.

Regression Reference Guide, BPA. This protocol uses regression techniques to extrapolate savings to
temperatures beyond those observed in the trend logging period (for pump units whose speed is
primarily determined by OAT). The application of these regression techniques is consistent with the
BPA guide.
11. TYPICAL COST OF APPLYING THIS PROTOCOL
Shown below is an estimate of typical cost of applying this protocol for a single pump unit. Projects that
involve more than one pump unit at the same facility are likely to see lower cost per unit. Expense for
alternative measurements, allowed by this protocol, are not included in this estimate of typical cost.
Item
Quantity $ / Hour Rental Total Cost
Equipment
Power Meter
1
100
100
Power Logger
1
400
400
Labor
Practitioner
Travel
4
110
440
Scheduling
2
110
220
Facility Operator Interview
1
110
110
VFD Inspection
1
110
110
Electrical Measurements
1
110
110
Install/Remove Power Logger
4
110
440
Savings Estimate
4
110
440
Travel
4
90
360
Electrical Measurements
2
90
180
2
150
300
Electrician
Controls Specialist
Setup and Export Trend Logs
Total
$3,210
12. USER’S GUIDE TO PUMP VFD SAVINGS CALCULATOR
[To be developed once this protocol is finalized and savings calculator is developed. This Guide and the
Calculator are outside the scope of SBW’s current contract.]
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SBW Consulting, Inc.