critical view of trombe walls

A trombe wall is a thick concrete wall with a layer of glass, able to absorb and store large amounts of solar heat.

Its goal is to heat - or to cool - the rooms close to the wall.

Be aware anyway. Trombe walls are not useful except in very special conditions and climates, very difficult to find.

Trombe walls vs. common  masonry walls

Thermal Mass Strategies Passive HeatingThe role of a trombe wall does not differ much from that of common concrete floors and interior walls in passive solar strategies. Likewise trombe walls, these floors and interior walls can also be uses do store heat gains during the hotter parts of the day (see image at right).

Trombe walls are intended to lower indoor temperatures in the summer, during the hotter parts of the day (by storing heat gains during these parts) and to raise indoor temperatures during the evening and night, by slowly releasing the heat they have stored, in climates with fresh nights.

trombe walls Design

A typical trombe wall is 5 to 15 inch/10 to 40 cm thick, and has a sheet of metal foil glued to its outside surface and also a layer of glass over it. The foil should be dark, to absorb most of the infrared energy…

The glass is of high transmission type, and should be placed some inches above the black foil (0.75-2 inches/2-5 com), in order to create a small airspace, to maximize heat generation. For details on the architectural design of trombe walls, see this EERE PDF here.

Critical view

There are simple and less inexpensive alternatives to trombe walls.

Trombe walls will not work in climates where the weather stays cold for weeks at a time. And they do not make sense in hot climates, either.

Since trombe walls are uninsulated, they are an anomaly in modern buildings, with high levels of insulation in their envelope. They contradict everything an energy efficient home is. It's impossible to control their very negative impacts on the home's comfort. Overheating and huge energy loss will be unavoidable, in multiple weather conditions.

There are other alternatives that can work with far less problems. As mentioned earlier, concrete floors, conveniently designed, combining with properly sized windows, can store and release heat gains in heating and cooling strategies, without the negative impact of trombe walls.

Sunrooms are also an alternative. They can provide large amounts of heat and be part of passive solar strategies; they can cause overheating and they have to be properly designed and insulated, but the problems that may come from them are easier to fix.

And there is also natural cooling strategies, based on chimney walls, turbine vents, or natural ventilation strategies that can work in a few hot climates, without being an headache. See: Natural cooling methods

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trombe wallImage (from EERE): a trombe wall (at left, yellow) radiating heat generated by the winter sun; notice that the wall is protected from the summer sun by overhangs - something that will not be enough to prevent overheating problems (or huge problems of heat loss, in the heating season).

 

 

 

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