Building Engineering HVAC and Building Mechanical Systems 3

Question 1

What is the function of a heat recovery ventilator (HRV) in a building's HVAC system?

Accepted Answer

To transfer heat between exhaust and fresh incoming air streams

Answer

An HRV transfers thermal energy from the warm exhaust air to the cool incoming fresh air, reducing heating or cooling energy needed to condition ventilation air.

Question 2

What ASHRAE standard sets minimum energy efficiency requirements for HVAC systems in commercial buildings?

Accepted Answer

ASHRAE 90.1

Answer

ASHRAE 90.1 establishes minimum energy efficiency standards for building envelopes, HVAC, lighting, and other systems in commercial facilities.

Question 3

What is chiller plant delta-T and why is it important?

Accepted Answer

The temperature difference between chilled water supply and return — larger delta-T means better efficiency

Answer

A larger chilled water delta-T allows more heat to be transported per gallon pumped, reducing pump energy and increasing overall plant efficiency.

Question 4

What type of expansion device is used in large commercial HVAC systems to meter refrigerant flow precisely?

Accepted Answer

Electronic expansion valve (EEV)

Answer

Electronic expansion valves use a stepper motor controlled by the system microprocessor to precisely regulate refrigerant flow across a wide range of operating conditions.

Question 5

What is the purpose of duct pressure testing in HVAC commissioning?

Accepted Answer

To verify ducts are airtight and not wasting conditioned air through leakage

Answer

Duct leakage testing quantifies air loss through duct seams and joints so corrections can be made before walls are closed, ensuring system delivers design airflow.

Building Engineering Practice Test

Building Engineering Practice Test

Building Engineering HVAC and Building Mechanical Systems 3