AEE CEM Certified Energy Manager (CEM) Exam Practice Test

Which of the following is/are benefits of commissioning?

You can buy air compressor A for $15,000 or air compressor B for $6,000. Compressor A will cost $10,000 per year to operate. Compressor B will cost $11,500 per year to operate. If both air compressors have a 10-year life and your required return on investment is 12%, which air compressor has the lowest total life-cycle cost?

A facility replaces a natural gas heating system rated at 10,000 kJ/h and 80% efficiency with an electric heat pump rated at 10,000 kJ/h and a coefficient of performance (COP) of 2.3. Will this project also reduce the annual energy utilization index (EUI) for the facility?

Which heat recovery device listed below can be used to preheat boiler make-up water using the heat energy from skimming blowdown?

A fully-loaded heat pump unit delivers 36-kW thermal heating with a power draw of 12-kW electric. What is the coefficient of performance (COP) at full load?

What is the main cause of low power factor?

If the temperature difference across an external wall is 20°C and the heat flow across the wall is 2.5 Watts/m², calculate the insulation value of the wall (including inside and outside air films)?

A 75-kW induction motor operates at 80% partial load and 88% efficiency. A new high-efficiency 75-kW motor can be installed that will operate at 95% efficiency (also at 80% partial load). What is the reduction in electric power demand?

An energy-saving project costs $540,000. The project will have maintenance costs of $25,000 per year. The energy savings from the project are $160,000 per year. What is the simple payback of the project?

A cooling tower delivers 29°C water to a central chilled water plant. The cooling tower is capable of delivering water to the chilled-water plant with a 6°C approach temperature to the ambient wet bulb temperature. Using this information, what type of control strategy would you recommend be added to the cooling tower operation to save additional energy?

The temperature in an unconditioned mechanical room is found to typically be around 23°C warmer than ambient air. If the air intake of an air compressor located in the mechanical room is routed through a nearby wall so that ambient air is fed directly to the air compressor's intake, what impact can be expected on the air compressor's energy requirement?

Infiltration (inward air leakage) in a building is dependent on several factors. Which of the following is least likely to affect or influence infiltration in a building?

What is the definition of lamp life for a fluorescent lamp?

Which motor parameter is the most difficult to measure with precision?

An air-conditioning unit delivers 10,000 kJ/h (thermal cooling). The equipment uses single-phase electrical power at 220-volt and 5.25 amps with a power factor of 100%. Calculate the coefficient of performance (COP).

A hot-water boiler has a cut-in set point of 65°C on the hot water supply temperature and a differential set point of 10°C. What is the hot-water supply temperature that causes the boiler to turn off?

A compressed air system has a total volume of 247,500 liters. During a 30-minute break in production (air compressor system turned off and no production demand for compressed air), the system pressure drops from 7 bar, gauge (700 kPa, gauge) to 5 bar, gauge (500 kPa, gauge). Calculate the leakage rate in the compressed air system.

In a warehouse, lights are mounted 4 meters above the floor. This provides an average light level of 150 lux. To increase the light level without installing more lights or higher Wattage lights, you lower the light fixtures with pendants so that the lights are located 3.25 meters above the floor. Calculate the new average light level on the floor.

If outside air has a temperature of 30°C dry bulb and 20°C wet bulb, what is the dew point temperature?

What is the purpose of monitoring energy consumption?

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An air-conditioning system at full load is rated at 70-kW (thermal cooling) and has a coefficient of performance (COP) of 4.1. What is the electrical load at full load?

The International Performance Measurement and Verification Protocol (IPMVP) has how many categories (method options) to determine the performance of an energy- or water-consuming system?

A 25-kW motor, at full load, drives a centrifugal fan that produces 160,000 liters per second (l/s) of ventilation air. If the fan speed is reduced to a flow rate of 150,000 l/s, what is the new load on the motor?

A steam trap with a 6-mm orifice in an 0.8-MPa steam system has failed open. The steam system is pressurized8.760 hours/yr. The steam cost is $15.00 /GJ. Using thetable below, what is the annualcost of the vented steam through the failed steam trap? ignore any condensate return issues.

[The question from the previous image, which was about calculating the annual cost of heat loss through a wall, but had a discrepancy between the calculated cost and the provided answer choices]

Which type of single-phase alternating-current motor has the highest efficiency?

Using the lumen method, calculate the number of luminaires (fixtures) required to light a room to 200 lux. Each luminaire has 2 fluorescent lamps, 3,000 lumens per lamp. The room is 20 meters by 30 meters. The total light loss factor (LLF) is 0.70 and the luminaire coefficient of utilization (CU) is 0.80.

Exhaust gases from an industrial furnace flow through a heat-recovery steam generator, which generates medium-pressure steam. This steam is used in a steam turbine to generate shaft power driving a fan. Which type of combined heat and power (CHP) cycle does this process describe?

Which pump system listed below is most likely the best application for converting to variable-speed drive?

Which is the best application for variable-speed drives?

What is the Energy Use index (EUl) for a 4,000 m2 building that uses the following amountsof energy each year?

An office building is illuminated with T8 fluorescent lamps. Which of the following is the best schedule for group relamping (total replacement of all the T8 fluorescent lamps in the building)?

Which of the following controls can optimize the operation of lighting systems?

Which of the following statements best describe Demand Control Ventilation (DVC) in Building Automation Systems?

A 50-Hz alternating current (AC) induction motor has 3 pole pairs (6 poles). What is the synchronous speed of the motor?

Air is heated from 10°C (dry bulb temperature) and 80% relative humidity to 32°C (dry bulb temperature). What is the new relative humidity?

According to ISO 50001. when performing internal audits on the energy management system in an organization the internal auditor should do which of the following?

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A facility owner is considering installing a new chiller. The installed project cost will be $300,000. The annual savings from the energy-saving project will be $45,000 for the 20-year life of the chiller. If an energy-service company requires a minimum 20% return on investment (pre-tax), will the energy-service company agree to finance this project?

Which of the following best describes a dead band in controls?

Calculate the monthly electric bill for a customer that used 400 kW and 75,000 kwh during one month. Use the following declining block structure for a monthly bill:

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