CEM Certified Energy Manager (CEM) Question and Answers

A piece of equipment costs $250,000 to buy and install. The annual operating cost for the equipment is $50,000 per year. The equipment will last 15 years. After 15 years, the equipment will have no net salvage value. The annual interest rate is 10%. What is the present value of the life-cycle cost to own and operate the equipment? Use end-of-year annual cash flow analysis.

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?

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

At the end of a performance contract, who owns the equipment installed by the project?

A new energy-efficient boiler costs $60,890 to buy and install. The new energy-efficient boiler will save $15,400 per year and last for 20 years. What is the internal rate of return (IRR) of the project?

A 7 bar (gauge pressure) compressed air system has 5 leaks that are 3 mm in diameter and 3 leaks that are 6 mm in diameter. The compressed-air system is pressurized 8,760 hours per year. Electricity cost is $0.10/kWh. What is the annual cost of the leaks in the compressed air system?

Which of the following is NOT included in commissioning documentation?

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?

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

A heat pump water heater has an annual average coefficient of performance (COP) of 2.1 and heats water from 15°C to 50°C. Hot water use is 100 liters per day, 365 days/yr. The electricity cost is $0.10/kWh. What is the annual water heating cost? (The specific heat of water (C) is 4.2 kJ/kg-°C.)

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

An energy project implemented today saves $10,000 per year for the next 20 years. Using the 5% interest table, determine the total value of savings at the end of the 20th year?

For general indoor residential lighting applications, which light source can provide the most appropriate illumination with the highest efficacy?

Using a degree-day base of 18°C, calculate the number of cooling degree days (CDD) if the outside temperature is a uniform 25°C throughout the year (365 days/year).

A 50-kW induction motor (1,500 rpm synchronous speed) has a nameplate full-load rotational speed of 1,455 rpm. Field measurements show the actual rotational speed is 1,475 rpm. Using the slip method, calculate the partial load factor of the motor.

A 1OO-kW packaged engine-generate combined heat and power (CHP) system has the specifications listed below. The CHP equipment operates fully loaded for 8.000 h/yr. What isthe annual fuel cost for the ChP equipment?

CMP equipment specifications: Electrical output 100kw Electrical efficiency: 25% Thermal recovery efficiency: 50*6 Total CMP efficiency: 75%

Additional information: Fuel cost: S3.S0/GJ Electricity cost S0.06/kWh Previous water heating efficiency: 8046 Mot water usage: 75,700 liters/day (21 *C temperature rise)

[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]

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?

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)?

What term describes the difference between the control signal value and the set point?

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?

In a performance contract, which group has the greatest investment risk?

Electricity costs SO. 10 per kWh. if an electric water heater has an efficiency of 95*6. what is the equivalent price of natural gas per Gigajoule for a natural gas water heater? The natural gas water heater has an efficiency of 95*t based on lower-heating value.

[Natural gas has an energy content of 36.400 K|/m3 (higher-heating value) and 32-760 K/m3 (lower-heating value).]

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Which of the following is/are benefits of commissioning?

What is the best type of heat exchanger to recover and transfer latent heat energy from one air stream to another?

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?

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?

When should commissioning be included in the design and construction of a facility?

What type of heat transfer is reduced by adding insulation to the inside surface of a wall?

A compressed-air distribution system has one section that frequently has low pressure when demand for compressed air is high. How can you resolve the problem without increasing energy consumption?

Which electric rate tariff would best cost justify a thermal energy storage (TES) system?

Which of the following International Performance Measurement and Verification Protocol (IPMVP) options would you use to verify annual energy savings in a project that upgraded lighting in a large manufacturing plant?

Which of the following color temperatures looks more like daylight?

What is a common method to reduce the impact of voltage imbalance?

You are using a performance contract to finance the added cost of using more-efficient equipment in the construction of a new building. Which of the following International Performance Measurement and Verification Protocol (IPMVP) options would you use to verify annual energy savings?

According to the institute of Electrical and Electronic Engineers (IEEE) standard 519. "Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems." the maximum total harmonic distortion (THD) for general low voltage systems less than 600 votts) should be:

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