One solution, common on large Irish estates from the seventeenth century onward, was the icehouse: a purpose-built structure, usually partly or wholly underground, designed to store blocks of ice cut from frozen ponds or rivers during winter and insulated well enough to keep them solid through the warmer months. The demesne at Portumna, County Galway, contains one such structure, a quiet remnant of the domestic infrastructure that once supported life on a major landed estate.

Portumna Demesne was historically associated with the Burke family, Earls of Clanricarde, and the estate centred on Portumna Castle, a fortified house dating to the early seventeenth century. Icehouses on demesnes of this kind were working buildings, not ornamental ones. They were typically dug into a north-facing slope or banked with earth to maximise insulation, with a domed or vaulted chamber below ground level and a small access passage angled to reduce warm air exchange. Ice stored within could, in the right conditions, survive well into summer, serving the kitchens and cellars of the main house. The Portumna example sits within this broader tradition, though without more detailed notes it is difficult to say precisely when it was constructed or what form it takes.