During an inspection, what does a 'whirlybird' refer to?

A 'whirlybird' refers to a type of roof ventilation system that is designed to improve air circulation in buildings. It is typically a turbine ventilator that spins using wind power to draw hot air out of the attic or roof space, helping to reduce heat buildup and improve energy efficiency within the structure. This type of ventilation is particularly beneficial in regions with warm climates, where maintaining a cooler interior can lead to greater comfort and energy savings.

The other options do not accurately describe a whirlybird's function. Plumbing fixtures involve various installations for water control, decorative roof features do not serve a functional purpose in ventilation, and roofing material brands do not relate to ventilation systems at all. Thus, identifying a whirlybird specifically as a type of roof ventilation system is essential for understanding its role in home inspections.