Tuesday, January 29, 2013

Trombe Wall

Trombe wall is defined as south facing mass wall (concrete, brick or masonry) that has the ability to absorb a lot of heat and is covered by a glazed surface (glass) that has a few inches gap between the pane of glass and the wall. Thermal mass gets the heat from sunlight and during night slowly releases it into the internal space through the upper vent in the wall. The function of glass is transferring short wave length radiation that heats the wall while stopping longer wave length radiation back out from the wall.



                                          
The function of Trombe wall can be better understood in these figures in which we can see two openings (vent) in the wall, one on top and the other in the bottom. In wintertime, the higher dense cold air near the floor enters the bottom opening and through the process of Trombe wall, it gets warmer and goes back to the inner space from the upper opening. The simple trick is that after the sun goes down, the hot wall will still keep heating air and exchanging that heat into the room. Once the wall gets cold, we need to stop the interaction of outside cold air with the inside air, therefore a one way flap is used on the bottom vent to prevent the reverse cooling cycle.


In summer we need to stop the Trombe wall heating inside. One way is using a proper roof overhang and shading trees. Another way is closing both vents; however we can take the advantages of another trick by making the Trombe wall act like a solar chimney. (how?)

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