This pipe in the roof space is meant to be connected to the extractor vent serving the bathroom of this modern house. The bathroom has no window for ventilation so the steamy air from the bathroom is being vented into the attic where it will remain creating a significant condensation risk. A connecting tube needs to be fitted so the moisture laden air is vented to the exterior of the building.
The control of condensation involves maintaining surface temperatures above the dew point (the humidity related temperature at which water vapour turns into moisture), and the provision of adequate thermal insulation and proper ventilation. Unfortunately, the modern emphasis on draught proofing reduces ventilation in dwellings, increasing the risk of condensation.
Adequate heating and ventilation will help to keep condensation to a minimum. The control of condensation can be significantly improved by installing extractor ventilators in bathroom and kitchen areas with ducts arranged to disperse the humid air to the outside. This will help to remove water vapour at source. The extractors should be operated whenever these rooms are in use.