Duct Leakage Percentage Calculator
System leakage from fan flow versus the sum of grille airflows.
US homes average 20โ30% duct leakage โ often the single biggest HVAC energy hole. Mastic, not cloth 'duct tape', is the fix.
Formula
Duct Leakage Percentage Calculator is a free duct leakage for HVAC designers, technicians and energy auditors โ instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Duct Leakage Percentage Calculator
System leakage from fan flow versus the sum of grille airflows. The calculation implements leak % = (Q_fan โ ฮฃQ_grilles)/Q_fan (SMACNA leakage classes; ENERGY STAR duct sealing). US homes average 20โ30% duct leakage โ often the single biggest HVAC energy hole. Mastic, not cloth 'duct tape', is the fix.
How to use Duct Leakage Percentage Calculator
- 1Enter Fan/AHU delivered flow in L/s.
- 2Enter Sum of all grille flows in L/s.
- 3Read Leakage, Leakage percentage instantly โ no submit button needed.
- 4Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Duct Leakage Percentage Calculator?
- โImplements the standard formula โ leak % = (Q_fan โ ฮฃQ_grilles)/Q_fan
- โReference cited on-page: SMACNA leakage classes; ENERGY STAR duct sealing
- โOne-click SI โ Imperial toggle โ values convert in place, physics stays in SI
- โBuilt-in engineering verdict flags out-of-range results instantly
- โRuns entirely in your browser โ nothing uploaded, free forever
Frequently asked questions
What formula does the Duct Leakage Percentage Calculator use?+
It computes leak % = (Q_fan โ ฮฃQ_grilles)/Q_fan, per SMACNA leakage classes; ENERGY STAR duct sealing. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
US homes average 20โ30% duct leakage โ often the single biggest HVAC energy hole. Mastic, not cloth 'duct tape', is the fix.
Is this based on ASHRAE methods?+
The calculations follow the standard ASHRAE/ISHRAE formulations cited under the result, simplified where industry practice does the same. For permit-grade design, confirm with the full code procedure.
Is the Duct Leakage Percentage Calculator free to use?+
Yes โ completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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