CEM Concepts and Principles 5 ā Questions and Answers
Question 1: What does a 'load factor' of 50% on an electrical account indicate?
- The facility uses only 50% of its contracted energy capacity
- Average demand is 50% of peak demand over the billing period (Correct answer)
- 50% of the facility's load is from motors and mechanical equipment
- The power factor is 0.50 lagging on average
Correct answer: Average demand is 50% of peak demand over the billing period
Load factor is the ratio of average demand to peak demand; 50% means the facility used half of its peak capacity on average, indicating significant demand variability.
Question 2: Which of the following best describes 'energy benchmarking'?
- Setting a minimum acceptable equipment efficiency before purchase
- Comparing a facility's energy performance against similar buildings or historical data (Correct answer)
- Establishing a legal energy use limit for a regulated facility
- Testing equipment energy use under controlled laboratory conditions
Correct answer: Comparing a facility's energy performance against similar buildings or historical data
Benchmarking compares a facility's energy use intensity against peers or its own historical baseline to identify performance gaps and prioritize improvement efforts.
Question 3: In an energy balance, what does the term 'unaccounted-for energy' represent?
- Energy generated on-site that is not exported to the grid
- The difference between metered input energy and the sum of measured end uses (Correct answer)
- Energy consumed by tenants but billed to the landlord
- Standby losses from equipment that is switched off
Correct answer: The difference between metered input energy and the sum of measured end uses
Unaccounted-for energy is the gap between total metered input and the sum of all identified uses, often revealing losses due to leaks, theft, or metering errors.
Question 4: What is the primary advantage of using 'interval meter data' (15-minute intervals) over monthly utility bills for energy analysis?
- Interval data eliminates the need for sub-metering individual systems
- It reveals load profiles and demand patterns not visible in monthly totals (Correct answer)
- It automatically adjusts for weather variation in consumption data
- Monthly bills include demand charges that interval data does not capture
Correct answer: It reveals load profiles and demand patterns not visible in monthly totals
Interval data shows granular time-of-use patternsāpeaks, valleys, and anomaliesāenabling targeted demand management and operational optimization impossible with monthly data.
Question 5: The 'coefficient of performance' (COP) of a heat pump describes:
- The ratio of electrical input to mechanical work output
- The ratio of useful heat delivered to the energy input required (Correct answer)
- The percentage of rated capacity achieved at full load
- The annual heating output divided by annual fuel consumption
Correct answer: The ratio of useful heat delivered to the energy input required
COP is the ratio of useful thermal energy output to the electrical energy input; a COP of 3 means 3 units of heat are delivered for every 1 unit of electricity consumed.
Question 6: In energy project financing, what does an 'energy performance contract' (EPC) guarantee?
- A fixed utility rate for the duration of the contract
- That the energy savings will be sufficient to repay the project financing costs (Correct answer)
- That the installed equipment will operate without failure for 10 years
- A government grant covering 50% of project capital costs
Correct answer: That the energy savings will be sufficient to repay the project financing costs
Under an EPC, the energy service company (ESCO) guarantees that realized energy savings will cover all project and financing costs, transferring performance risk to the ESCO.
Question 7: Which organizational standard provides a framework for establishing, implementing, and maintaining an Energy Management System (EnMS)?
- ASHRAE 90.1
- ISO 50001 (Correct answer)
- IPMVP Option D
- ENERGY STAR Portfolio Manager
Correct answer: ISO 50001
ISO 50001 is the international standard that specifies requirements for an EnMS, enabling organizations to systematically improve energy performance using a Plan-Do-Check-Act approach.
CEM Concepts and Principles 5
What does a 'load factor' of 50% on an electrical account indicate?