There was a time when residential air-conditioning meant either a whole-home central system forcing treated air through a network of interior ducts, or a cumbersome window unit. There were few, if any, other choices available. But now there is a wide range of options available to keep individual rooms comfortable during hot weather, from personal desktop units to energy-efficient heat-pumps. The smaller battery-operated units are truly portable, with most relying on an ice-water reservoir and a powerful fan. But, thanks to sophisticated designs, they can be surprisingly effective for a specific area, such as an individual workspace or a bedside table.

Freestanding portable units can cool an entire room, with many compact models taking up floorspace similar to a dehumidifier. For true operational efficiency, consider a heat pump unit for selected rooms, as they have the added capacity of providing low-cost heat on colder days. However, they require a permanent interior wall installation and a hose/power connection through an exterior wall to an outside fan unit.