Summer Weatherization Tips: Part Ten
Cupolas serve to increase air circulation and interior lighting. They increase air circulation through a very basic process – warm air rises, so adding a pathway at the roof for that air to escape then creates upward airflow through the structure, pulling in cooler ground floor air. This process is also known as the Stack Effect. This airflow can also be created or enhanced with a whole house fan, but a cupola alone will create this airflow as a passive feature. Even without a breeze outside or a motorized fan, this airflow will continue. In winter, if the windows of the cupola close, then this airflow will stop, keeping heat within the structure.
Cupolas also serve other pragmatic functions – the first cupolas were minarets of mosques, from which muezzins called Muslim worshipers to prayer. In barns, they are used to add continuous airflow to haylofts, helping to dry hay. Larger cupolas with windows, such as the kinds found on Italianate buildings, are also known as belvederes or widow’s walks, which is commonly attributed to the wives of mariners who would watch for returning ships from the high vantage point.