Passive Solar Indirect Gain

Indirect solar gains such as Trombe walls and Barra walls allow heat from a southern facing wall heat adjacent rooms.

The indirect gains heats a thermal mass which then conducts the heat later in the house.

In the summer time by opening a window in the adjacent room the hot air is drawn up and out bring cool air into the room.

A variation of the Trombe wall is a Barra wall which is used to hear the wall floor and ceiling using the thermo siphon effect.

The heat is released at night time and is a very efficient use of the sun gain.

It is however expensive as it require thermal mass in the ceiling space

Trombe walls are useful where you need to use walls on the south side of a house instead of a window.