AEE Certified Energy Manager (CEM) - CEM Exam Practice Test
In a chilled water thermal energy storage system, chilled water is stored at 4°C and used for supply water.
Chilled water return is 14°C. Calculate the storage capacity required to hold 50 GJ of thermal cooling. (The specific heat of water (C) is 4.2 kJ/kg-°C. Assume no system losses.)
Chilled water return is 14°C. Calculate the storage capacity required to hold 50 GJ of thermal cooling. (The specific heat of water (C) is 4.2 kJ/kg-°C. Assume no system losses.)
Correct Answer: B
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Which type of lighting control technique operates in "manual on" and "auto-off mode, and can be used in situations where there is brief occupancy that do not need lights on?
Correct Answer: A
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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?
Correct Answer: E
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How does an enthalpy-based economizer control operate?
Correct Answer: C
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The set point for the chiller supply water temperature is varied as a function of the thermal demand for space cooling. What do you call this control strategy?
Correct Answer: D
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Using an interest rate of 15%, an energy project has a net-present value (NPV) of $3,500. Which statement is true about the project's internal rate of return (IRR)?
Correct Answer: B
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The primary advantage of predictive maintenance over preventive maintenance in building energy systems, is that predictive maintenance:
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Correct Answer: C
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Which motor parameter is the most difficult to measure with precision?
Correct Answer: E
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A controller has a signal output that can range from 4 to 20 mA (milli-amperes). The controller regulates the output temperature from a three-way mixing valve from 5°C to 15°C. What is the control gain?
Correct Answer: E
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