Data Collection & Analysis Flashcards
7 cards from real EMP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Data Collection & Analysis flashcards as text
What is the term for the phenomenon where energy consumption continues to decline after an energy efficiency project is complete due to behavioral and operational changes?
Answer: Post-installation persistence
Persistence refers to how well energy savings are maintained over time, which can be influenced by ongoing operational practices and equipment maintenance.
Which data collection method is most appropriate for quickly assessing plug load energy consumption across an office floor?
Answer: Portable plug-in energy monitors (kill-a-watt meters)
Plug-in energy monitors measure individual device consumption without electrical work and are ideal for rapid office plug load surveys.
In a Sankey diagram used for energy analysis, what do the widths of the flow arrows represent?
Answer: Magnitude of energy flow
In a Sankey diagram, arrow width is proportional to the quantity of energy flowing through that pathway, making losses visually prominent.
An energy manager wants to identify if a chiller's performance has degraded over time. Which analysis approach is most appropriate?
Answer: Tracking COP (Coefficient of Performance) against load and ambient temperature over time
Plotting COP as a function of load and ambient conditions over time reveals gradual performance degradation that would be masked in simple utility bill comparisons.
What type of error occurs when an energy meter systematically reads 5% higher than actual consumption due to a calibration offset?
Answer: Systematic (bias) error
A consistent, directional offset in readings is a systematic error (bias), distinguishable from random error by its predictable direction and magnitude.
Which approach best accounts for production output variation when normalizing industrial energy data?
Answer: Multivariate regression using production units as an independent variable
In industrial facilities, production rate drives energy use; including production units as a regression variable isolates efficiency changes from output variation.
What is the minimum recommended data length for establishing a statistically valid energy baseline according to ASHRAE Guideline 14?
Answer: 12 months
ASHRAE Guideline 14 recommends at least 12 months of pre-retrofit data to capture seasonal variation and ensure a representative baseline.