Heat Loss Calculator

Quick estimate based on area and insulation level

Floor Area (sq ft)

Ceiling Height (ft)

Insulation Level

Design Temp Difference (F)

Window Area (% of wall)

Calculate heat loss for a specific building component

Component Area (sq ft)

R-Value of Component

Temperature Difference (F)

Formula

Q = U x A x DeltaT | U = 1/R | Q_total = Q_walls + Q_windows + Q_ceiling + Q_floor + Q_infiltration

What is design temperature difference?

It is the difference between your desired indoor temperature (typically 70F) and the coldest expected outdoor temperature for your location.

How does insulation affect heat loss?

Better insulation (higher R-value) dramatically reduces heat loss. Doubling the R-value cuts heat loss through that component in half.

Why is infiltration included?

Air infiltration through cracks and openings can account for 25-40% of total heat loss in older homes.

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