Sensible Heat Calculator
Sensible heat is the heat that causes a temperature change without a phase change. The equation Q_s = 1.08 × CFM × ΔT is fundamental to HVAC psychrometrics. The constant 1.08...
Formula
Source: Engineering Toolbox, ASHRAE Fundamentals | Last reviewed: June 8, 2026
Examples
0 BTU/hr
= 8640 BTU/hr
- cfm = 400
- delta_T = 20
400 CFM at 20°F ΔT = 8,640 BTU/hr sensible
0 BTU/hr
= 38880 BTU/hr
- cfm = 1200
- delta_T = 30
1,200 CFM heating 30°F = 38,880 BTU/hr
0 BTU/hr
= 32400 BTU/hr
- cfm = 2000
- delta_T = 15
2,000 CFM cooling 15°F = 32,400 BTU/hr
Where is this used?
Heating load calculations: sizing furnaces and heating coils.
Air handler specification: matching airflow to heating/cooling capacity.
Energy analysis: estimating annual heating and cooling energy consumption.
Frequently Asked Questions
Where does the 1.08 constant come from?
1.08 = 0.075 lb/ft³ (standard air density) × 0.24 BTU/lb-°F (specific heat of dry air) × 60 min/hr. At high altitude, air density is lower: at 5,000 ft, use ~0.90 instead of 1.08. For precise work, calculate the constant from actual air density and specific heat.
What is the difference between sensible and latent heat?
Sensible heat changes temperature (you can 'sense' it with a thermometer). Latent heat changes moisture content (humidity) without temperature change — it's the energy required to evaporate or condense water. Total heat = sensible + latent.
How does this relate to tons of cooling?
1 ton of cooling = 12,000 BTU/hr. If your sensible heat calculation gives 36,000 BTU/hr, that's 3 tons of sensible cooling. However, total cooling load also includes latent heat, so the actual tonnage required is typically 20-30% higher than the sensible-only calculation in humid climates.
Reviewed for accuracy
· Last reviewed: June 8, 2026
All calculations are for reference only. Always verify with manufacturer data and a qualified engineer for critical applications. Learn about our editorial process.