Energy Efficiency & Conservation Techniques Flashcards
7 cards from real NABCEP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Energy Efficiency & Conservation Techniques flashcards as text
The 'negawatt' concept in demand-side management refers to:
Answer: A unit of electrical power capacity saved through efficiency or conservation
A negawatt represents one megawatt of power that has been saved through efficiency improvements, treated as equivalent to a megawatt of new generation capacity.
Which climate-responsive design strategy uses high-mass exterior walls that absorb daytime solar heat and re-radiate it into living spaces at night?
Answer: Trombe wall
A Trombe wall is a south-facing masonry or concrete wall with glazing that absorbs solar heat during the day and releases it indoors in the evening.
An energy model predicts a building's annual energy use. Which input change would most directly reduce predicted heating energy in a cold climate?
Answer: Improving window U-factor from 0.45 to 0.22
Halving the window U-factor dramatically reduces conductive heat loss through the windows, which is a major heating load driver in cold climates.
Which energy efficiency measure typically has the shortest simple payback in residential buildings?
Answer: Air sealing accessible penetrations (attic, basement)
Air sealing is low-cost and labor-light, often yielding 10–30% heating/cooling savings with paybacks of 1–3 years, outperforming capital-intensive measures.
A peak demand charge on a commercial utility bill is based on:
Answer: The highest average power demand measured during any 15- or 30-minute interval in the billing period
Demand charges are assessed based on the single highest demand interval (often 15 minutes) in the month, incentivizing load leveling and peak reduction strategies.
Which energy storage strategy is best suited for shifting residential air conditioning load from peak afternoon hours to overnight low-rate periods?
Answer: Ice storage thermal energy storage (TES)
Ice storage systems freeze water overnight during off-peak hours and melt the ice during the day to provide cooling, reducing peak electrical demand.
In whole-building energy performance rating systems like ENERGY STAR for commercial buildings, the score is based on:
Answer: Percentile ranking compared to similar buildings nationally using CBECS data
ENERGY STAR scores rank a building's EUI against its peer group from the Commercial Buildings Energy Consumption Survey (CBECS); a score of 75 or higher qualifies for certification.