Stack Effect Calculator
Pressure difference from indoor-outdoor temperature.
Enter your values
ⓘ Live results
Results
- Stack pressure
- 0.111 in wc
- In Pa
- 27.65
- Direction
- Air rises and exits high, enters low
- Temperature difference
- 50 °F
Quick answer
Stack effect pressure rises with building height and the indoor-outdoor temperature difference.
ΔP = 0.0188 x h x (1/To - 1/Ti)
How to use the Stack Effect Calculator
- 1Measure height from the neutral pressure plane, usually mid-height of the building.
- 2Enter indoor and outdoor temperatures for the worst-case day.
- 3Use the result to size vestibules, shaft dampers and pressurisation fans.
Worked example
Using the values the calculator loads with:
Inputs
- Height above neutral plane30 ft
- Indoor temp70 °F
- Outdoor temp20 °F
Results
- Stack pressure0.111 in wc
- In Pa27.65
- DirectionAir rises and exits high, enters low
- Temperature difference50 °F
Frequently asked questions
Why does the top floor overheat?
Stack effect pushes warm air upward and out, drawing cold air in low — the top floor stays warmest.
Does it reverse in summer?
Yes, weakly, when indoor air is cooler than outdoor air.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.