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AEE Certified Energy Auditor study materials
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AEE Certified Energy Auditor practice questions

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Question 1Developing an Energy Audit Strategy & Plan

An ASHRAE Level 1 energy audit is best described as:

  1. A walk-through survey identifying low-cost measures and overall energy use patterns Correct answer.
  2. A detailed survey that includes calibrated metering of every individual end use in the building
  3. A full engineering simulation calibrated to hourly interval data
  4. A commissioning investigation limited to verifying equipment nameplate ratings

Explanation

A Level 1 audit is the screening-level effort: a walk-through survey, review of utility bills, and identification of low-cost or no-cost measures with rough costs. It establishes the broad energy use picture rather than a metered end-use breakdown. Detailed metering and simulation belong to deeper audit levels.

Question 2Developing an Energy Audit Strategy & Plan

Which information set should be requested from the client before the audit site visit?

  1. Equipment vendor marketing brochures covering high-efficiency replacement products
  2. Manufacturer warranty certificates for the chillers
  3. A completed list of every energy conservation measure to be recommended
  4. Twelve months of utility bills, facility drawings and operating schedules Correct answer.

Explanation

Pre-site data collection centers on historical consumption and how the facility is physically arranged and operated. At least a full year of bills captures seasonality, and drawings plus schedules let the auditor plan the walk-through efficiently. Recommendations are an output of the audit, not an input.

Question 3Developing an Energy Audit Strategy & Plan

Defining the audit boundary primarily determines:

  1. The exact simple payback period that each recommended measure will achieve
  2. The calibration interval of the audit instruments
  3. Which facilities, systems and energy flows are inside the analysis Correct answer.
  4. The number of auditing staff that must be assigned to the site visit

Explanation

The boundary statement fixes what is counted and what is excluded, such as which buildings, processes, fuels, or tenant spaces fall within scope. Every later calculation of consumption, savings and cost depends on that definition. Staffing, calibration and payback results follow from the boundary rather than defining it.

Question 4Developing an Energy Audit Strategy & Plan

Energy use intensity (EUI) is calculated by dividing annual site energy consumption by:

  1. the gross floor area of the facility Correct answer.
  2. the number of hours the facility operates each year
  3. the total annual energy cost of the facility
  4. the peak electrical demand recorded during the year

Explanation

EUI expresses consumption per unit of floor area, which normalizes buildings of different sizes so they can be compared with peers or with the same building over time. The numerator must be converted to common units before dividing. Dividing by hours or demand produces different metrics entirely.

Question 5Developing an Energy Audit Strategy & Plan

Before removing panel covers or attaching instruments to energized equipment, the audit plan must include:

  1. A job hazard analysis and lockout/tagout with facility staff Correct answer.
  2. A copy of the facility's marketing plan
  3. A schedule for the next utility rate case filing
  4. A list of preferred equipment vendors for the planned replacements

Explanation

Energized work requires a documented hazard assessment and coordination with the facility's lockout/tagout and electrical safety program. This protects both the audit team and plant personnel and defines who authorizes any de-energization. Vendor lists, tariff schedules and marketing documents have no bearing on electrical safety.

Question 6Developing an Energy Audit Strategy & Plan

A facility's electricity use rose 8% while heating degree days rose 20% at the same site. To judge whether efficiency changed, the auditor should first:

  1. Conclude immediately that efficiency degraded because total consumption increased
  2. Compare only the summer months, when no heating occurs
  3. Regress consumption against weather before comparing the two years Correct answer.
  4. Assume the increase is entirely caused by new plug loads

Explanation

Consumption must be weather-normalized before year-over-year comparison, typically with a temperature regression fitted to monthly data. Only the consumption that remains above the weather-driven expectation signals a change in efficiency or operation. Drawing conclusions from raw totals attributes weather effects to the equipment.

Question 7Developing an Energy Audit Strategy & Plan

When interval meter data contains a multi-day gap, the auditor should:

  1. flag the gap, estimate with a documented method, and record uncertainty Correct answer.
  2. delete the month and report annual totals without it
  3. rely entirely on nameplate ratings to reconstruct the missing interval values
  4. fill the gap with the highest daily value to stay conservative

Explanation

Data gaps must be transparent: the location and length of the gap are recorded, the missing values are estimated by a stated rule such as interpolation from adjacent days, and the added uncertainty is carried into the results. This preserves the audit trail and lets reviewers judge the effect on conclusions. Silent deletion or arbitrary substitution undermines reproducibility.

Question 8Developing an Energy Audit Strategy & Plan

A site survey is scheduled during a period of typical production mainly because:

  1. equipment is easiest to access when it is shut down
  2. observed loads then reflect normal operating conditions Correct answer.
  3. utility bills are only available for those months
  4. staff are more likely to approve capital funding requests at that time

Explanation

Spot measurements and observed schedules are only meaningful if they represent ordinary operation. Surveying during atypical periods such as shutdowns or peak campaigns produces load data that will not match the billing history. Access to de-energized equipment is arranged separately through lockout procedures.

Question 9Developing an Energy Audit Strategy & Plan

For a campus with 40 identical rooftop units, a defensible metering sample uses:

  1. every unit, since sampling is never acceptable in energy audits
  2. random selection sized to meet a stated confidence level Correct answer.
  3. the three units nearest the maintenance office for convenience
  4. the newest units, because they are easiest to instrument

Explanation

Sampling is legitimate when the population is homogeneous and the sample size is tied to a stated confidence and precision target. Random or stratified selection avoids the bias introduced by convenience or condition-based choices. Extrapolation to the population must then be documented.

Question 10Developing an Energy Audit Strategy & Plan

When establishing a measurement and verification baseline, the baseline period should:

  1. cover only the single month with the highest energy consumption in the year
  2. start after the retrofit is installed
  3. be limited to one week of sub-metered data
  4. cover at least a full year so seasonal and operational variation is captured Correct answer.

Explanation

A baseline must represent the range of conditions the measure will be exposed to, which generally requires a full annual cycle including seasonal swings and production cycles. Shorter windows cannot support weather or production normalization. The baseline period by definition precedes the measure's installation.

Question 11Developing an Energy Audit Strategy & Plan

Under a limited capital budget, the most defensible screening sequence for energy conservation measures is to:

  1. Select measures only on the basis of the largest reported percentage savings
  2. Select measures only on the basis of the lowest total installed capital cost
  3. Rank by payback, then confirm long-lived measures with life-cycle cost Correct answer.
  4. Defer all measures until every end use is individually metered

Explanation

Simple payback is a fast first screen that respects capital constraints, but it ignores equipment life and therefore penalizes durable measures. Long-lived or capital-intensive options should then be tested with life-cycle cost or net present value. Selecting purely by cost or by headline percentage savings misallocates capital.

Question 12Developing an Energy Audit Strategy & Plan

An audit team assembled for a large industrial plant typically pairs an energy engineer with:

  1. a marketing coordinator able to promote the audit findings
  2. a commercial real estate agent who knows local property values
  3. an insurance adjuster able to price equipment losses
  4. a process specialist familiar with the production equipment Correct answer.

Explanation

In industrial settings, production equipment and process heat often dominate consumption, so engineering analysis must be informed by someone who understands how the process runs and where throughput losses occur. Pairing these skills lets the team separate process-driven load from support-system load. Property valuation, promotion and insurance pricing are outside the technical scope.

Question 13Developing an Energy Audit Strategy & Plan

Compared with a Level 1 audit, an ASHRAE Level 2 audit adds:

  1. a guarantee that the predicted savings will be achieved
  2. destructive testing of major equipment to verify its condition
  3. an end-use breakdown and cost analysis of each identified measure Correct answer.
  4. a full hourly whole-building simulation calibrated to interval data

Explanation

Level 2 moves from screening to quantification: consumption is disaggregated into end uses and each identified measure receives a savings and cost estimate suitable for budgeting. Whole-building calibrated simulation and destructive testing exceed Level 2 expectations. No audit level guarantees realized savings.

Question 14Developing an Energy Audit Strategy & Plan

Before deploying a portable power logger for a two-week measurement, the auditor should:

  1. record readings only when the plant is shut down
  2. rely on the accuracy statement printed in the manufacturer brochure
  3. verify current calibration and accuracy over the expected load range Correct answer.
  4. attach it to the largest motor in the plant first

Explanation

Measurement credibility depends on a current calibration certificate and on the instrument's accuracy being adequate at the loads actually expected, including low-load conditions where many loggers lose accuracy. Brochure specifications describe a new unit, not the specific instrument in hand. Shutdown-only readings would not represent operation.

Question 15Developing an Energy Audit Strategy & Plan

A change-point regression of monthly consumption against outdoor temperature gives an R-squared of 0.91, but the residuals show a systematic monthly pattern. The best interpretation is that:

  1. The data must be discarded and a different baseline year selected
  2. The residuals can be ignored because the goodness of fit is high
  3. An R-squared above 0.9 confirms the model is valid for savings verification
  4. The fit explains most variance, but the pattern suggests an omitted driver Correct answer.

Explanation

A high R-squared shows the model explains most of the variation, but structure in the residuals indicates the model form or variable set is incomplete, for example a missing production or occupancy term. Residual diagnostics, not the fit statistic alone, determine whether a baseline is suitable. The remedy is to refine the model, not to discard the data outright.

Question 16Developing an Energy Audit Strategy & Plan

Which practice most improves the credibility of an audit's reported savings estimate?

  1. propagating measurement uncertainty into a reported savings range Correct answer.
  2. rounding all inputs to the nearest whole number
  3. reporting a single point value with no qualification
  4. using nameplate ratings in place of metered data wherever possible

Explanation

Savings are a difference between two uncertain quantities, so the uncertainties in metered data, assumptions and operating hours should be combined and reported as a range. This tells decision makers how much confidence the estimate supports. Single point values and coarse rounding conceal rather than communicate that uncertainty.

Question 17Developing an Energy Audit Strategy & Plan

Metered end-use loads sum to only 82% of utility-billed consumption. The auditor should:

  1. accept the difference because audit tolerances are irrelevant
  2. scale every end-use load up so the totals match the utility meter exactly
  3. investigate unmeasured loads and losses until the gap is explained Correct answer.
  4. conclude that the utility meter is over-registering

Explanation

A closing energy balance is a basic quality check: unexplained differences usually point to unmeasured systems, distribution losses, or timing mismatches between meter periods. The auditor traces the gap until it falls within a stated tolerance or its cause is identified. Forcing a match by scaling hides the very findings the audit is meant to surface.

Question 18Developing an Energy Audit Strategy & Plan

The element that most makes an audit recommendation actionable is:

  1. a defined scope with savings, cost and stated assumptions Correct answer.
  2. a list of every possible technology in that equipment class
  3. a general statement that the equipment should be upgraded
  4. a reference to the manufacturer's efficiency rating only

Explanation

A decision maker needs to know exactly what will be installed, what it is expected to save, what it will cost, and what assumptions produced those numbers. That combination allows independent review and budget approval. General advice, exhaustive technology lists and single rating references give no basis for economic comparison.

Question 19Energy Use Analysis

Which metric expresses annual energy consumption per unit of plant output?

  1. Demand factor
  2. Power factor
  3. Energy intensity Correct answer.
  4. Load factor

Explanation

Energy intensity is total energy divided by a measure of output, such as tonnes produced, units assembled, floor area, or revenue, so it allows energy performance to be compared across periods, plants, or products. Load factor and demand factor describe the shape of the load, while power factor describes the relationship between real and apparent power.

Question 20Energy Use Analysis

Load factor over a billing period is defined as:

  1. Average demand divided by peak demand in the same period Correct answer.
  2. Energy consumed divided by the connected load in kW
  3. Peak demand divided by average demand in the same period
  4. Connected load divided by the highest metered demand

Explanation

Load factor equals average demand over a period divided by the peak demand in that same period, so it always lies between zero and one. A high load factor means demand is steady and the capacity represented by the peak is well utilized.

Question 21Energy Use Analysis

Which term describes the portion of a facility's energy use that continues even when production is zero?

  1. Seasonal load
  2. Process load
  3. Peak-shaving load
  4. Baseload Correct answer.

Explanation

Baseload is the energy consumed regardless of production activity, for example lighting, standby power, idling equipment, and HVAC in unoccupied areas. It is commonly estimated as the intercept of a regression of energy use against production.

Question 22Energy Use Analysis

A day has a mean outdoor temperature of 50 degrees F. Using a 65 degrees F balance point, what are the heating degree days for that day?

  1. 0 HDD
  2. 15 HDD Correct answer.
  3. 50 HDD
  4. 115 HDD

Explanation

Heating degree days are calculated as the balance-point temperature minus the mean daily temperature whenever the mean falls below the balance point, and zero otherwise. Here 65 minus 50 gives 15 HDD for the day.

Question 23Energy Use Analysis

One kilowatt-hour of electrical energy is equivalent to approximately how many Btu?

  1. 341 Btu
  2. 1,000 Btu
  3. 3,412 Btu Correct answer.
  4. 10,000 Btu

Explanation

The standard conversion is 1 kWh = 3.412 kBtu, or about 3,412 Btu. This factor is used to place electricity on the same energy basis as fuels when constructing an energy balance.

Question 24Energy Use Analysis

A facility has an average electrical demand of 350 kW and a peak demand of 1,000 kW over the same month. What is its load factor?

  1. 65%
  2. 286%
  3. 28.6%
  4. 35% Correct answer.

Explanation

Load factor is average demand divided by peak demand, so 350 divided by 1,000 equals 0.35, or 35%. A value in this range indicates that demand is peaky and that there may be room to improve utilization.

Question 25Energy Use Analysis

A plant consumes 4,800,000 kWh per year and produces 24,000 units of product. What is its energy intensity?

  1. 20 kWh per unit
  2. 50 kWh per unit
  3. 2,000 kWh per unit
  4. 200 kWh per unit Correct answer.

Explanation

Energy intensity is annual energy divided by annual output, so 4,800,000 kWh divided by 24,000 units equals 200 kWh per unit. This ratio is the basis for tracking whether energy use is rising faster or slower than production.

Question 26Energy Use Analysis

In a least-squares regression of monthly energy use against monthly heating degree days, the intercept of the fitted line represents:

  1. The average monthly energy use over the year
  2. The energy use per heating degree day
  3. The weather-independent energy use Correct answer.
  4. The goodness of fit of the regression

Explanation

For a model of the form energy = a + b times HDD, the slope b is the weather-dependent use per degree day and the intercept a is the use that occurs when HDD is zero. The intercept therefore estimates the weather-independent, or baseload, component for a period of that length.

Question 27Energy Use Analysis

A monthly electric bill shows 200,000 kWh of consumption, a billing demand of 500 kW, an energy charge of $0.05 per kWh, and a demand charge of $12 per kW. What is the average cost per kWh?

  1. $0.05 per kWh
  2. $0.0625 per kWh
  3. $0.08 per kWh Correct answer.
  4. $0.12 per kWh

Explanation

The energy charge is 200,000 times $0.05 = $10,000 and the demand charge is 500 times $12 = $6,000, giving a total of $16,000. Dividing by 200,000 kWh gives an average of $0.08 per kWh, which is higher than the energy rate alone.

Question 28Energy Use Analysis

A regression model of monthly energy use has a coefficient of determination of 0.92. What does this indicate?

  1. 92% of the metered data points were usable in the fit
  2. About 92% of the variation in energy use is explained by the model Correct answer.
  3. Energy use rises by 92% for each unit change in the independent variable
  4. The model's predictions are within 92% of the metered values

Explanation

The coefficient of determination measures the fraction of the variance in the dependent variable that the regression explains, so 0.92 means the model accounts for about 92% of the observed variation. It says nothing directly about the size of individual residuals or the number of data points.

Question 29Energy Use Analysis

A facility has a total connected load of 2,400 kW and a measured peak demand of 960 kW. What is its demand factor?

  1. 0.25
  2. 0.40 Correct answer.
  3. 0.60
  4. 2.5

Explanation

Demand factor is peak demand divided by total connected load, so 960 divided by 2,400 equals 0.40. It expresses how much of the installed equipment capacity is actually drawn on at the time of the system peak.

Question 30Energy Use Analysis

What does the area under a load duration curve represent?

  1. The peak demand in the period
  2. The average demand in the period
  3. The facility connected load
  4. Energy use over the period Correct answer.

Explanation

A load duration curve sorts load levels from highest to lowest across a period, so the area beneath it is load multiplied by time, which equals energy. The highest point of the curve is the peak demand and the mean height is the average demand.

Question 31Energy Use Analysis

Submetering of a plant's major end uses accounts for 84% of the electricity measured by the main utility meter over the same period. What is the most appropriate next step?

  1. Investigate the gap by checking unmetered loads and meter accuracy Correct answer.
  2. Conclude that the main utility meter is over-registering
  3. Treat the gap as distribution loss and take no further action
  4. Scale the submetered values upward pro rata to match the total

Explanation

An end-use breakdown that does not close to the metered total signals unmetered loads, instrument error, or mismatched time periods, and each of these can change the conclusions of the analysis. The gap should be quantified and explained before results are reported.

Question 32Energy Use Analysis

Three production lines have individual peak demands of 600 kW, 500 kW, and 400 kW, yet the facility meter never exceeds 1,100 kW. Which explanation is correct?

  1. The utility meter is under-registering the true facility peak demand
  2. A shared transformer halves the measured demand of each line
  3. The facility load factor must exceed 1.0 during peak periods
  4. Non-coincident peaks: the line maxima occur at different times Correct answer.

Explanation

Individual loads seldom reach their maxima at the same instant, so the facility peak is less than the arithmetic sum of the individual peaks. This non-coincidence is the basis for the diversity factors used when estimating combined loads.

Question 33Energy Use Analysis

A plant's monthly energy use depends both on production volume, which varies widely, and on outdoor temperature. Which analysis best normalizes energy use for comparison between periods?

  1. Degree-day regression alone, with production volume left out
  2. A simple ratio using the single highest-production month as the base
  3. Multiple regression using production volume and heating degree days Correct answer.
  4. The average of the last three years of total annual consumption

Explanation

When two variables jointly drive energy use, a multiple regression including both separates their effects and allows consumption to be adjusted to a common set of production and weather conditions. A single-variable model leaves one driver confounded with the other and can bias the normalized result.

Question 34Energy Use Analysis

A load-shifting project reduces a facility's monthly peak demand from 1,200 kW to 950 kW while total kWh consumption is unchanged. With a demand charge of $14 per kW per month, what are the annual demand-charge savings?

  1. $42,000 Correct answer.
  2. $14,000
  3. $3,500
  4. $0, because kWh consumption is unchanged

Explanation

Demand charges are billed per kW of monthly peak regardless of energy consumed, so the saving is 250 kW times $14 per kW times 12 months, which equals $42,000. Energy charges are unaffected because the kilowatt-hour total did not change.

Question 35Energy Use Analysis

How many data points are recorded by a meter that logs at 15-minute intervals over a 30-day period?

  1. 1,440
  2. 2,880 Correct answer.
  3. 720
  4. 43,200

Explanation

A 15-minute interval gives four readings per hour and 96 readings per day. Multiplying 96 by 30 days gives 2,880 intervals, assuming no missing data.

Question 36Energy Use Analysis

In a twelve-month billing analysis, one bill covers only 18 days yet shows a much lower consumption total than the other months. How should this record be handled?

  1. Compare months on a per-day basis instead of raw totals Correct answer.
  2. Exclude that month from the analysis as an outlier
  3. Replace the value with the twelve-month average consumption
  4. Assume the meter was faulty and estimate the missing energy

Explanation

Billing periods vary in length, so raw monthly totals are not directly comparable and short cycles appear artificially low. Converting each period to an average daily consumption, or normalizing to a common period length, removes the distortion while retaining the data.

Question 37Data Collection & Analysis

How many Btu of thermal energy are equivalent to 1 kWh of electrical energy?

  1. 860 Btu
  2. 2,545 Btu
  3. 3,412 Btu Correct answer.
  4. 1,000 Btu

Explanation

One kilowatt-hour equals 3,600 kilojoules, and since 1 Btu equals about 1.055 kJ, the conversion gives 3,600 / 1.055 ≈ 3,412 Btu. This factor is the standard bridge between electrical and thermal units in energy auditing.

Question 38Data Collection & Analysis

An auditor needs to measure the oxygen and carbon monoxide concentrations in the flue gas of a gas-fired boiler. Which instrument is appropriate for this task?

  1. A rotating-vane anemometer
  2. A sling psychrometer
  3. A portable combustion analyzer Correct answer.
  4. A pyranometer

Explanation

A combustion analyzer draws a flue-gas sample through electrochemical or infrared cells that report O2, CO, and often stack temperature, from which excess air and efficiency are computed. Each of the other instruments measures a different physical quantity entirely.

Question 39Data Collection & Analysis

For a facility over a billing period, load factor is defined as:

  1. Average demand divided by peak demand Correct answer.
  2. Total consumption divided by peak demand
  3. Peak demand multiplied by the number of billing days
  4. Peak demand divided by average demand

Explanation

Load factor is the ratio of average demand to peak demand over the same period, expressed as a fraction or percentage. It indicates how fully the peak capacity is used and is always 1.0 or less.

Question 40Data Collection & Analysis

On a day when the mean outdoor temperature is 50°F, how many heating degree days accumulate against a 65°F balance point?

  1. 65 HDD
  2. 115 HDD
  3. 50 HDD
  4. 15 HDD Correct answer.

Explanation

Heating degree days equal the balance-point temperature minus the daily mean temperature when the mean is below the balance point. Here 65 − 50 = 15 HDD.

Question 41Data Collection & Analysis

What is the primary purpose of installing dedicated sub-meters on major plant systems?

  1. To allocate energy use and cost to specific end uses Correct answer.
  2. To raise the power factor of the facility
  3. To replace the utility revenue meter for billing
  4. To reduce voltage drop in the distribution feeders

Explanation

Sub-metering separates whole-building consumption into accountable end-use categories such as chillers, air handlers, and lighting. That disaggregation supports targeting, benchmarking, and verifying savings by system.

Question 42Data Collection & Analysis

Airflow is measured with an uncertainty of ±3% and the temperature rise across a heater with an uncertainty of ±4%. Treating the uncertainties as independent and random, what is the approximate uncertainty in the calculated heat output?

  1. ±7%
  2. ±5% Correct answer.
  3. ±3.5%
  4. ±1%

Explanation

Independent random uncertainties combine in quadrature, so the relative uncertainty is the square root of (0.03² + 0.04²), which equals 0.05, or ±5%. Simple addition is reserved for fully correlated worst-case errors.

Question 43Data Collection & Analysis

A preliminary sample of 40 interval readings has a standard deviation of 12 kW. To halve the standard error of the estimated mean, approximately how many readings are needed?

  1. 80
  2. 120
  3. 320
  4. 160 Correct answer.

Explanation

The standard error of a mean equals the sample standard deviation divided by the square root of n. Halving the standard error therefore requires quadrupling the sample size, so 4 × 40 = 160 readings.

Question 44Data Collection & Analysis

A least-squares regression of monthly energy use against heating degree days yields a coefficient of determination (R²) of 0.86. This means that:

  1. The model's absolute error averages 0.86 kWh per month
  2. The slope is significant at the 86% confidence level
  3. 86% of the monthly bills were used to fit the model
  4. 86% of the variance in energy use is explained Correct answer.

Explanation

R² measures the proportion of the variability in the dependent variable that the regression model accounts for. A value of 0.86 means the weather-driven model explains 86% of the variation in monthly energy use, leaving 14% unexplained.

Question 45Data Collection & Analysis

A baseline model of monthly gas use versus heating degree days has a slope of 0.42 therms/HDD and an intercept of 120 therms. What does the intercept represent?

  1. The gas use per heating degree day
  2. The highest monthly gas use recorded in the baseline period
  3. The HDD value at which gas use becomes zero
  4. The weather-independent base gas use per month Correct answer.

Explanation

In a weather-normalized model the slope gives the weather-sensitive consumption per degree day, while the intercept is the modeled consumption when HDD is zero. It represents base loads such as service hot water and standby losses.

Question 46Data Collection & Analysis

A tariff bills demand at the greater of the current month's peak demand or 80% of the highest demand recorded in the previous 12 months. A facility peaked at 500 kW last July and its current month peak is 300 kW. What demand will be billed this month?

  1. 400 kW Correct answer.
  2. 300 kW
  3. 250 kW
  4. 500 kW

Explanation

The ratchet floor is 80% of the 12-month peak, or 0.80 × 500 = 400 kW. Because 400 kW exceeds the current peak of 300 kW, the facility is billed for 400 kW.

Question 47Data Collection & Analysis

A kWh meter is connected through 400:5 current transformers and 4:1 potential transformers. The meter register shows 350 kWh. What is the actual energy consumption?

  1. 112,000 kWh Correct answer.
  2. 350 kWh
  3. 1,400 kWh
  4. 28,000 kWh

Explanation

The meter multiplier is the product of the current-transformer ratio and the potential-transformer ratio: (400/5) × 4 = 80 × 4 = 320. Multiplying the register reading by the multiplier gives 350 × 320 = 112,000 kWh.

Question 48Data Collection & Analysis

Two wattmeters connected in a three-phase, three-wire circuit read 40 kW and 25 kW. What is the total real power drawn by the load?

  1. 65 kW Correct answer.
  2. 15 kW
  3. 32.5 kW
  4. 40 kW

Explanation

In the two-wattmeter method for a three-wire circuit, total real power is the algebraic sum of the two readings regardless of power factor or balance. Here 40 + 25 = 65 kW.

Question 49Data Collection & Analysis

Fifteen-minute interval data show a facility's monthly peak of 800 kW at 3:15 p.m., while the utility's system peak occurs at 5:00 p.m., when the facility is drawing 640 kW. For a demand charge based on the system peak, what demand is billed?

  1. 720 kW
  2. 640 kW Correct answer.
  3. 800 kW
  4. 160 kW

Explanation

Coincident demand is the facility's load at the moment the utility system peaks, which here is 640 kW. Interval data are required for this analysis because monthly billing totals alone cannot identify when the peak occurred.

Question 50Data Collection & Analysis

What is the main advantage of using utility billing data rather than portable metering for a screening-level analysis of a facility?

  1. Low cost, whole-facility, multi-year coverage Correct answer.
  2. It records end-use loads at 15-minute resolution
  3. It measures power factor at the service entrance
  4. It is unaffected by occupancy or weather changes

Explanation

Billing records are inexpensive and typically cover several years of whole-facility consumption and demand, which makes them well suited to screening and baseline development. Their coarse monthly resolution and lack of end-use detail are the trade-offs.