Question

The inside surface temperature of a window in a house is 5°C. The dry-bulb temperature of air in the house is 20 °C, and the pressure is 101.325 kPa. What is the maximum relative humidity allowable in the house if no condensation is to form on the window?

Answer 1

maximum relative humidity = 38%

Step-by-step explanation:

You can obtain this information from a Psycrometric chart like the one attached.

On the bottom axys you enter with the dry-bulb temperature of the room, 20°C. On the vertical axys on the right you have the dew point, wich is the temperature at which the moisture will condensate. In this case you are looking for the relative humidity that will condensate at 5°C so intersecting the 20°C and the 5°C horizontal line you get the maximum relative humidity = 38% (red point on the chart attached)