HVAC Systems and Performance Flashcards
7 cards from real Certified Energy Auditor Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 HVAC Systems and Performance flashcards as text
What is the typical minimum outdoor air ventilation rate for office spaces per ASHRAE 62.1?
Answer: 5 cfm per person plus 0.06 cfm/ft²
ASHRAE 62.1 requires 5 cfm/person (Rp) plus 0.06 cfm/ft² (Ra) for general office spaces under the ventilation rate procedure.
A cooling tower's approach temperature is defined as what?
Answer: Difference between leaving water temperature and ambient wet-bulb temperature
Approach temperature is the difference between the cooling tower's leaving (cold) water temperature and the ambient wet-bulb temperature — a smaller approach indicates better tower performance.
What is 'demand-controlled ventilation' (DCV)?
Answer: Modulating outdoor air intake based on measured occupancy or CO2 levels
DCV uses CO2 sensors or occupancy data to adjust outdoor airflow rates dynamically, providing required ventilation only when spaces are occupied.
An energy auditor measures a chiller's kW/ton as 0.55. A newer model offers 0.48 kW/ton. If annual chiller run-hours are 2,000 and the facility has 400 tons of cooling, what is the annual kWh savings?
Answer: 56,000 kWh
Savings = (0.55 – 0.48) kW/ton × 400 tons × 2,000 hr = 0.07 × 400 × 2,000 = 56,000 kWh.
What is the purpose of a building's static pressure control in a VAV system?
Answer: Maintain duct static pressure at a setpoint to ensure terminal boxes can deliver required airflow
Duct static pressure control ensures enough pressure is available at the most remote VAV terminal so it can open and deliver design airflow.
Which refrigerant replacement is commonly used as a low-global-warming-potential (GWP) alternative to R-410A in air conditioning?
Answer: R-32 or R-454B
R-32 (GWP ~675) and R-454B (GWP ~467) are leading low-GWP alternatives to R-410A (GWP 2,088) for air conditioning applications.
In a heat pump system, the reversing valve is used to do what?
Answer: Switch refrigerant flow direction to change between heating and cooling modes
The reversing (four-way) valve redirects refrigerant flow so the indoor coil acts as a condenser in heating mode and an evaporator in cooling mode.