The best replacement for window is portable air conditioner.

The best alternatives to window are rated as following:
★★★★★  portable air conditioner
★★★★  aisle
★★★  linux
★★  bow window
★★  aisle seat
★  portable air conditioners
★  tab
★  bay window
★  document
★  viewport
★  isle
★  double hung window
★  isle seat
★  split ac
★  new construction
★  aisle long flight
★  wall air conditioner
★  window
★  wall air conditioners
★  door
★  central air conditioning
★  mirror
  central air
  aile seat
  aisle seat better
  new construction window
  split air conditioner
  aile
  page
  no window pmag
  no window
  sash replacement
  vinyl window
  pericardiocentesis
  single hung
  page wpf
  replacement
  unix
  linus
  single hung window
  double hung
  aisle with baby
  vertigo
  modeless
  therapeutic index
  disturbia

Your alternative for window is not listed? Suggest!
Speaking about window, one probably shouldn't forget about sill.

Other search terms related to window and their ratings are:
★★★★★ sill
★★★ seat
★ transom
door
You have in mind a companion for window and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of window in all years. Click on graph for more.
window
portable air conditioner
aisle