In Philippine architecture, the ventanilla is a small window or opening below a larger window's casement, created—often reaching the level of the floor—to allow either additional air into a room during hot days or some air during hot nights when the main window's panes are drawn.^[1][2][3] It also allows for more light to strike the floor.^[4]

The ventanilla is often used on upper floor windows, as in the bahay na bato. As the lower part of a composite window, its larger upper part is typically a window with sliding capiz shell-paned panels. The ventanilla is just under this upper large window's sill and is typically made with sliding panel-covers behind balusters or grills.^[5][3]

Bobby Mañosa's traditional methods for his design of the Coconut Palace is considered as displaying a fine example of how ventanillas can be applied in modern Philippine architecture.^[5]

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  An opened grilled ventanilla below a capiz shell window of the convent of Saints Peter and Paul Parish Church in Calasiao, Pangasinan.
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  The Rizal Shrine—a reproduction of the original two-storey, Spanish-colonial style house in Calamba, Laguna where José Rizal was born and grew up in—has four ventanillas at its main structure's front and two at each of its sides.
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  Side view of the wooden ventanilla balusters of the Kapitan Moy Residence.
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  Opened ventanillas at the Bahay Nakpil-Bautista, boasting their lyre-shaped grilles.
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  The large front windows of Apolinario Mabini's bahay kubo house augmented by ventanillas.
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  Ventanillas of Casa Manila.
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  Juan Luna's painting Tampuhan depicts a couple beside a large ventanilla.

• Media related to Ventanillas in the Philippines at Wikimedia Commons