Occupant Behaviour

The occupants of the building create a significant amount of water vapour. Therefore, the air inside in a building typically has a higher moisture content than the external atmosphere.

Approximate Amount of Water Vapour from Occupant Behaviour

Occupant behaviourEstimated Amount of Water Released (per 2.5 inhabitants)
Cooking (unventilated)3.0 L / day.
Baths / Showers1.5 L/day. 
Clothes Washing0.5 L/ day.
Clothes drying (unvented)5.0 L/ load.
Dishwashing1.0 L / day.
Portable gas heaterup to 1.6 litres per 1kg of gas burned.
Breathing  (average)3 litres per day.
Breathing asleep (per hour) (average)50 ml.
Perspiration 0.5 litre per day.
Pot PlantsThe same amount as the input
(optional caption)


Bathing and showering, cooking, heating, indoor laundries, and unvented clothes drying are the most obvious sources of water; respiration, perspiration, indoor plants, and pets also produce moisture.

Areas for moisture-generating activities should be well ventilated and the entire building should be mechanically ventilated to outside the structure. Proposed changes to NZBC G4/AS1 will require venting to the outside of appliances such as showers, baths, and cooktops.


Clause Number: 
Revision Category: 
4 - Clause Inserted
Revision Detail: 

Newly created clause, combining new information with some from revised "Managing Water Vapout at the Source" (renamed Sources of Internal Moisture).