Why portables lose
A window AC keeps its hot parts outside. A portable unit keeps everything in the room and vents heat out through a hose. Single-hose models use room air to cool their condenser and blow it outside, which pulls hot outdoor air back in through every gap in the house. The hose itself also radiates heat back into the room.
Under Department of Energy rules, portable ACs are rated by Seasonally Adjusted Cooling Capacity (SACC), which accounts for these losses. A portable’s SACC is often far below the big BTU number on the box, so compare SACC to a window unit’s BTU.
If you need a portable
- Choose a dual-hose or hose-in-hose design, like the Midea Duo.
- Keep the hose as short and straight as possible, and insulate it if you can.
- Seal the window kit with foam.
When a portable makes sense
- Casement or sliding windows that won’t hold a window unit.
- Building rules that ban window units.
- A room you only need to cool for a few weeks a year.