CEM HVAC and Building Envelope 3

Question 1

What is the purpose of demand-controlled ventilation (DCV) in commercial buildings?

Accepted Answer

Modulate outdoor air intake based on CO2 or occupancy sensors

Answer

DCV reduces outdoor air ventilation when spaces are less occupied, cutting heating and cooling energy while maintaining acceptable indoor air quality.

Question 2

Which of the following best describes 'thermal bridging' in a wall assembly?

Accepted Answer

A highly conductive element that bypasses insulation layers

Answer

Thermal bridges are elements like metal studs or fasteners that conduct heat more easily than surrounding insulation, reducing the effective R-value of the assembly.

Question 3

What is the Integrated Part Load Value (IPLV) used to evaluate?

Accepted Answer

Chiller efficiency across a range of part-load operating conditions

Answer

IPLV is a weighted average efficiency metric for chillers that accounts for the fact that they rarely operate at full load, providing a more realistic performance comparison.

Question 4

In a cooling load calculation, which load component accounts for heat from occupants, lighting, and equipment?

Accepted Answer

Internal heat gains

Answer

Internal heat gains are heat generated inside the conditioned space by people, lighting, and plug loads, all of which must be removed by the cooling system.

Question 5

What does an air-side economizer's 'high-limit shutoff' control?

Accepted Answer

Outdoor air temperature or enthalpy threshold above which economizing is disabled

Answer

The high-limit shutoff closes the outdoor air damper to minimum position when outdoor conditions (temperature or enthalpy) exceed a threshold where free cooling is no longer beneficial.

(CEM) Certified Emergency Manager Practice Test

(CEM) Certified Emergency Manager Practice Test

CEM HVAC and Building Envelope 3