Certified Energy Auditor Certification HVAC Systems and Controls 4

Question 1

What is the primary energy disadvantage of a constant volume reheat HVAC system?

Accepted Answer

Simultaneous heating and cooling waste energy

Answer

Constant volume reheat systems cool all air to a low temperature then reheat it for zones needing less cooling, wasting both cooling and heating energy.

Question 2

A building automation system (BAS) data point showing 'chiller plant delta-T' refers to:

Accepted Answer

Temperature difference between entering and leaving chilled water

Answer

Chilled water delta-T is the difference between the chilled water return temperature and supply temperature, which indicates how effectively the distribution system is transferring heat.

Question 3

What is the purpose of a cooling tower bypass valve in a chilled water plant?

Accepted Answer

Prevent freezing of cooling tower fill in cold weather

Answer

A bypass valve diverts warm condenser water around the cooling tower during cold weather to prevent the tower from freezing and to maintain minimum condenser water temperatures.

Question 4

When auditing a pneumatic control system for energy savings opportunities, the auditor should look for:

Accepted Answer

Opportunities to convert to direct digital controls (DDC)

Answer

Pneumatic controls are typically less precise and flexible than DDC systems; conversion to DDC often enables advanced strategies like optimal start, reset schedules, and better diagnostics.

Question 5

Which HVAC system type is generally most efficient for buildings with highly variable zone loads?

Accepted Answer

Variable air volume (VAV) with DDC controls

Answer

VAV systems with DDC controls modulate airflow to match zone loads, saving significant fan and conditioning energy compared to constant volume approaches.

Certified Energy Auditor Certification Practice Test

Certified Energy Auditor Certification Practice Test

Certified Energy Auditor Certification HVAC Systems and Controls 4