HVAC Energy Efficiency 2

Question 1

What does the term 'COP' stand for in HVAC system performance?

Accepted Answer

Coefficient of Performance

Answer

COP (Coefficient of Performance) is the ratio of useful heat or cooling energy output to the work energy input.

Question 2

A heat pump has a heating COP of 3.5. What does this mean?

Accepted Answer

It delivers 3.5 units of heat for every 1 unit of electrical energy consumed

Answer

A COP of 3.5 means the heat pump delivers 3.5 units of thermal energy for every 1 unit of electrical energy input.

Question 3

Which refrigerant property most directly impacts system energy efficiency?

Accepted Answer

Latent heat of vaporization

Answer

High latent heat of vaporization allows a refrigerant to absorb or release large amounts of heat during phase change, improving efficiency.

Question 4

What is the purpose of an economizer cycle in a commercial HVAC system?

Accepted Answer

To use outdoor air for free cooling when conditions allow

Answer

An economizer uses cool outdoor air directly for space cooling, reducing or eliminating compressor operation when outdoor conditions are favorable.

Question 5

What HVAC measure is most effective at reducing energy use in large commercial buildings during partial-load conditions?

Accepted Answer

Variable frequency drives (VFDs) on fans and pumps

Answer

VFDs reduce motor speed proportionally to load, cutting fan and pump energy consumption dramatically at partial loads.

HVAC Practice Test