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Energy Efficiency Flashcards

7 cards from real HVAC 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 flashcards as text

  1. What does ASHRAE Standard 90.1 primarily address?

    Answer: Energy efficiency requirements for commercial buildings

    ASHRAE 90.1 sets minimum energy efficiency requirements for the design and construction of commercial buildings and their HVAC systems.

  2. An HVAC technician notices condenser coil fins are bent and restricting airflow. What is the most likely energy impact?

    Answer: Increased condensing pressure and reduced system efficiency

    Restricted condenser airflow raises head pressure, forcing the compressor to work harder and reducing overall system efficiency.

  3. Which factor primarily determines the Energy Efficiency Ratio (EER) of a cooling system?

    Answer: Cooling capacity in BTU/h divided by power input in watts at a specific test condition

    EER is calculated at a fixed ARI test condition (95°F outdoor, 80°F/67°F indoor) as BTU/h of cooling divided by watts of electrical input.

  4. What is the role of thermal expansion valves (TXV) in maintaining efficiency?

    Answer: They maintain consistent superheat to maximize evaporator use without liquid slugging

    TXVs modulate refrigerant flow to maintain a set superheat, ensuring the evaporator is fully used without allowing liquid refrigerant into the compressor.

  5. Which building envelope feature most reduces HVAC cooling loads in hot climates?

    Answer: High-reflectance roofing (cool roof)

    Cool roofs reflect solar radiation, reducing roof surface temperatures and heat transfer into the building, directly lowering cooling loads.

  6. What is 'demand-controlled ventilation' (DCV)?

    Answer: A strategy that adjusts outdoor air intake based on occupancy, typically using CO2 sensors

    DCV uses CO2 or occupancy sensors to modulate outdoor air quantities, reducing unnecessary ventilation energy during low-occupancy periods.

  7. Why does a dirty air filter negatively impact HVAC energy efficiency?

    Answer: It increases static pressure drop, forcing the blower to work harder for the same airflow

    A clogged filter increases resistance in the air distribution system, increasing blower motor energy consumption and potentially reducing airflow and capacity.