In this rough calculation it is to be calculated how much drying wet laundry can lead the house to cool down. The motivation for the calculation is that a family member thought that the apartment is feeling significantly colder, whenever laundry was left for drying.

The following assumptions are made for this:

• 2 L = 2 kg of water from the laundry [1]
• Initial temperature: 20° C
• Apartment size: 100 m³
• Heating water, humidity, change properties neglected by changing temperature: All properties constant at initial conditions
• Heat of vaporization of water 2257 kJ / kg and 40.8 kJ / mol [2]
• Heat capacity of air: 1005 kJ / (kg * K) [3]
• Density air: 1.25 kg / m³[3]

This results in correspondingly 2 kg * 2257 kJ / kg = 4'514 kJ Energy needed to dry the laundry, providing cooling. For the cooling of 100 m³ * 1.25 kg / m³ = 125 kg air , this energy leads to an approximate temperature difference of 4514 kJ / (125 kg * 1005 kJ / (kg * K)) = 0.0359 K per cubic meter of air.

Thus it can be estimated that the cooling with this Apartment size and uniform heat distribution would not be noticeably. Without heat distribution, meaning when cooling a single cubic meter, however, the resulting 3.6 K cooling would probably be very noticeable.

Sources

1. https://www.welt.de/kmpkt/article158861840/Das-ist-der-schlimmste-Fehler-beim-Waeschetrocknen.html
2. https://en.wikipedia.org/wiki/Properties_of_water
3. https://en.wikipedia.org/wiki/Properties_of_water

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