Balcony doors versus small high windows
A sliding door moves a lot of air, and a lot of sun. A small high window does neither well. Match the opening you have to intake, exhaust, and daytime shade.
Not every opening is the same hole in the wall.
A balcony door or sliding door is a tall sheet of glass. When it should be open, it is the best intake or exhaust you have. When it should be shut, it is a radiator if the sun hits it. A small high window is the opposite: weak airflow, less sun load, often too high for a floor fan on the sill.
Doors: shade by day, flush by night
- Exterior shutters, a screen, or a reflective blind on the door during Phase 1. Interior curtains are a poor second
- At night, the door is usually the opening to use, especially on the cooler façade
- A floor fan works well across a door track or just inside the opening. Standing fans sit back from the track
- Street-facing balcony doors pick up heat-island air and noise. Prefer them as exhaust if you also have a courtyard window
Sun plus a west balcony is a classic top-floor trap. Close and shade that door while UV is high: sunny-side windows.
Small and high windows
- They rarely make a through-draught on their own
- A floor fan on the sill is often impossible. Use a standing fan in the room, or treat them as the exhaust crack in a cross-vent setup
- They are still worth opening at night if they are your only openings. Weak flush beats no flush
- By day, even a small pane on the sunny side should be shaded. Glass is glass
Mix them on purpose
If you have a balcony door on the courtyard and a small window on the street, you already have a decent cross-vent pair: door wide for intake, small window cracked for exhaust. That is the same idea as courtyard versus street.
If you only have one small window, you are in single-sided territory. Patience and a fan: single-sided layouts.