1. What is Latent Cooling Load from Ventilation Air?

Definition: Latent cooling load from ventilation air in BTU/hr is the heat that results from an increase or decrease in the amount of moisture held by the air.

Purpose: It helps HVAC professionals determine the cooling capacity needed to remove moisture from ventilation air.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( QL \) — Latent cooling load (BTU/hr)
• \( CFM \) — Air ventilation rate (cubic feet per minute)
• \( W_o \) — Outside humidity ratio (%)
• \( W_i \) — Inside humidity ratio (%)

Explanation: The formula calculates the energy required to remove moisture from the ventilation air based on the humidity difference between outside and inside air.

3. Importance of Latent Cooling Load Calculation

Details: Proper calculation ensures adequate HVAC system sizing, energy efficiency, and comfortable indoor humidity levels.

4. Using the Calculator

Tips: Enter the air ventilation rate in CFM (±5%), outside and inside humidity ratios (%). All values must be ≥ 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the 0.68 constant in the formula?
A: It's a conversion factor that accounts for the heat of vaporization of water and unit conversions (60 min/hr × 0.075 lb/ft³ × 1076 BTU/lb).

Q2: How do I measure the humidity ratios?
A: Use a psychrometer or hygrometer to measure relative humidity, then convert to humidity ratio using psychrometric charts or calculators.

Q3: Why is the ventilation rate marked ±5%?
A: This accounts for typical measurement inaccuracies in airflow rates in HVAC systems.

Q4: What's a typical humidity ratio difference?
A: This varies by climate, but a common design difference might be 50-60% outside vs. 30-50% inside.

Q5: Does this include sensible cooling load?
A: No, this calculates only the latent (moisture-related) load. Sensible cooling load must be calculated separately.

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