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Windows - Inside Condensation

Water condensation on inside glass windows surfaces vs. outside temperature and inside temperature and humidity.

The influence of

  • outside temperature
  • inside air relative humidity (for inside air dry bulb temperature at 65 oF (18.3 oC))

on the condensation on inside surface of glass windows are indicated in the charts below:

Condensation on glass windows - inside surfaces

Windows - Overall Heat Transfer Coefficients U

  • Single glass window : U = 1.13 (Btu/ft 2 o F hr) =  6 ( W/m 2 o C )
  • Double sealed glass window : U = 0.58 (Btu/ft 2 o F hr) =  3 ( W/m 2 o C )

Example - Condensation temperature on a window surface

  • indoor relative humidity of 50%
  • window with single glass with U-value aprox. 6 (W/m 2 o C), 1.13 (Btu/ft 2 o F hr)

Based on the diagram above condensation on the inside of the glass starts when the outside air temperature is 6 o C (43 o F) .

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