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1 Measurement and Verification of Energy Savings © Copyright Econoler Training Center, 2015
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Measurement and Verification of
Energy Savings
© Copyright Econoler Training Center, 2015
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TRAINING AGENDA
Measurement and Verification
Module 1: M&V and M&V protocol
Module 2: Main concepts associated with M&V activities
Module 3: Option A
Module 4: Option B
Module 5: Planning and reporting and practical
considerations
Module 6: Example: Option A – lighting
Module 7: Example: Option B – pump
Module 8: M&V activities of MC staff
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Module 6
Option A – Lighting Retrofit
Objective:
Discuss key M&V issues in relation to a lighting
retrofit project using Option A
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OPTION A: RETROFIT ISOLATION
Consider design of an M&V plan for a lighting retrofit using
Option A: “Key parameter measurement”
› Key Parameter: Lighting fixture power
- Sample measurement before and after the retrofit
› Non-key Parameter: Hours of operation - Assumption of lights’ hours of operation
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The hours of operation are ASSUMED, even though the hours of operation in the baseline are logged.
Light fixtures manufacturer supplies power data which are not field-measured. IPMVP treats such power data as ASSUMED.
To be IPMVP-compliant, the lighting power must be measured.
› The manufacturer data mustn’t be used as the key parameter.
OPTION A: RETROFIT ISOLATION
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MEASUREMENT BOUNDARY &
INTERACTIVE EFFECTS
Interactive effects
New higher efficiency
fixture
Boundary
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MEASUREMENT BOUNDARY &
INTERACTIVE EFFECTS
What parameters affect energy use within the boundary?
› Lamp efficiency improvement
› Hours of operation
› A proportion of lamps burned out (baseline period)
What interactive energy effects occur outside the boundary?
› Less cooling
› More heating
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BASELINE DETERMINATION
It is dificult to make direct measurements in the electrical panel because the lines supplying the lighting fixtures also supply other pieces of equipment.
The parameters required to establish the lighting consumption are:
› Number of lights by type and wattage
› Sample by type, wattage and location
› Power of the sampled lights
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SAMPLING METHODOLOGY
1. Select a homogeneous population
› If there are two different types of units in the population, they should be grouped and sampled separately.
› In this case, only one type of fixture with the same light bulbs and ballast type / arrangement;
BASELINE DETERMINATION
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SAMPLING METHODOLOGY
2. Determine the level of precision and confidence
desired
› Precision refers to the error bounds around the true estimate
› Confidence refers to the probability that the estimate will fall in the range of precision.
› Conventional approach: 90% confidence level and ±10% precision.
BASELINE DETERMINATION
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SAMPLING METHODOLOGY
3. Decide on the level of disaggregation
› Establish whether the confidence and precision level criteria should be applied to the measurement of all components, or to various subgroups of components.
› In this case, only one component
BASELINE DETERMINATION
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SAMPLING METHODOLOGY
4. Calculate the initial sample size
n0 is the initial estimate of the required sample size, before
sampling begins
cv is the coefficient of variance, defined as the standard deviation
of the readings divided by the mean. Until the actual mean and
standard deviation of the population are estimated from actual
samples, 0.5 may be used as an initial estimate for cv.
e is the desired level of precision.
z is the standard normal distribution value, with an infinite number
of readings, and for the desired confidence level.
BASELINE DETERMINATION
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SAMPLING METHODOLOGY
4. Calculate the initial sample size
› With a 90% confidence level with 10% precision, and a cv of 0.5:
No = 67
BASELINE DETERMINATION
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SAMPLING METHODOLOGY
5. Make sample readings
› Calculate and report actual Cv and precision.
BASELINE DETERMINATION
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SAMPLING METHODOLOGY
6. Finalize the sample size
› Because the initial sample size (number of readings) is determined using an assumed cv, it is critical to remember that the actual cv of the population being sampled may be different.
BASELINE DETERMINATION
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› Measure at randomly selected light switches
› Measure for 1 second before and 1 second after retrofit
Data point Sensor/meter
Power of the sampled lights Power meter
MEASUREMENT
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The general equation for calculating savings is:
Savings = ( Baseline Period Measured Parameter – Reporting-Period
Measured parameter) * Estimated Value ± Interactive Effects
The energy saving calculation for a lighting fixture is:
Savings = ( Baseline Period Power – Reporting-Period Power) *
Hours of Operation± Interactive Effects
TYPES OF SAVINGS
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› 100 hrs/month of operation in the savings reporting period, based on a measurement in the baseline
› 5% of lamps/ballasts are burned out at any time
› Cooling demand reduction is assumed to be about 3% of the savings from the reduction in fixture wattage;
ASSUMPTIONS
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Baseline Post-retrofit
Number of fixtures 2,000 1,950
No. of Fixtures in Sample 73 30
Measured average power per sample
fixture
185.6 W 103.4 W
MEASUREMENT AND SAMPLE SIZE
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Total Fixture Load (kW) =
Measured Average Power * Total Number of Fixtures *
Percentage of Operational Fixtures
Baseline total load (kW) =
185.6 Watts /1000 Watts / kilo Watt * 2000 fixtures * 95 % operational
Baseline total load (kW) = 352.6 kW
Post-retrofit load (kW) = 103.4 W/1000 * 1950 * 0.95
Post-retrofit load (kW) = 191.5 kW
SAVINGS CALCULATION
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Load Reduction
Load Reduction = 352.6 – 191.5 = 161.1 kW
Interactive Effects – Reduction of Cooling Load
Interactive Effects (kW) = 161.1 * 0.03 = 32.2 kW
SAVINGS CALCULATION
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Monthly Consumption Savings
Monthly Consumption Savings =
(Load Reduction + Reduction of Cooling Load) * Estimated
Hours of Operation
Monthly Consumption Savings =
(161.1 + 32.2) * 100 = 19,330 kWh/month
SAVINGS CALCULATION
