Why was the Globe Theatre open air?

English playhouses developed from inn courtyards, the usual place for performances before the 16th century. These had galleries round the edges and were open in the middle. The open-air theatre was a very short-lived thing; even Shakespeare moved indoors towards the end of his life; the Blackfriars theatre was enclosed.

The principal advantage of the open theatre was light; daylight did the job perfectly. The move indoors was made possible by improvements in candle technology. Old-fashioned tallow candles gave nowhere near enough light; the new wax jobs did.

Wax candles, though, were expensive; prices at the Blackfriars were more than double those at the Globe. Hence the French saying, le je ne vaut pas la chandelle: the game (that is, the play) is not worth the candle.