Difficulty: Easy
Correct Answer: 22 °C DBT and 60% RH
Explanation:
Introduction / Context:
Comfort conditions define the target state for HVAC design. While exact preferences vary, guidelines (ASHRAE-like recommendations) identify a zone typically around 21–25 °C and 40–60% RH for sedentary activity and normal clothing.
Given Data / Assumptions:
Concept / Approach:
Excessively high RH (near saturation) impairs evaporative cooling from skin, while very low RH causes dryness. A mid-range RH around 60% with a DBT near 22 °C is widely cited as comfortable for many occupants.
Step-by-Step Solution:
Scan options for mid-range RH (40–60%) and moderate DBT (≈22–24 °C).22 °C, 60% RH falls squarely in common comfort zones.Options with 100% or 80% RH are outside typical comfort recommendations.
Verification / Alternative check:
Comfort charts place operative temperature with RH in a “comfort polygon,” in which 22 °C and 60% RH are acceptable for many conditions.
Why Other Options Are Wrong:
Common Pitfalls:
Assuming a single fixed point applies to all climates and clothing; real design uses comfort ranges and adaptive models.
Final Answer:
22 °C DBT and 60% RH
Discussion & Comments