CLIMATE DATA FROM ASHRAE

Primary step for Designing HVAC system is pulling weather data from ASHRAE!!

We need to take for warm-season temperature and humidity conditions are based on annual "percentiles" of 0.4, 1.0, and 2.0.

✅ ASHRAE Climate Design Conditions are based on 20 years of hourly weather data 

This ensures that design conditions are reliable, up-to-date, and reflect real-world climate trends.

ASHRAE publishes this data in percentile format. For example:

0.4% Dry Bulb: Temperature exceeded only ~35 hours/year

1.0% Dry Bulb: Exceeded ~88 hours/year

🎯 The 0.4% DB and WB values are commonly used in cooling design because they strike a balance between:

System reliability (handles nearly all hot conditions)

Cost efficiency (avoids oversizing for extreme outliers)

0.4% design temperature (from ASHRAE’s 20-year N20 data) is the standard choice for:

Offices, homes, commercial buildings

Data centers and hospitals (often 0.4% or even 0.1% for critical areas)

Designing for rare, critical-use applications with 20-year extremes.