Quite a few people ask me how to design a Trombe wall without doing full thermal simulations.
A Trombe wall is a massive sensor wall which operates on the basis of the greenhouse effect and which accumulates more or less solar energy depending on its composition (raw earth, concrete, etc.).
It was developed for heating homes by the French engineer Félix Trombe in Odeillo-Font-Romeu in the 1960s.
Today, passive techniques that are much more efficient than the Trombe wall exist to enhance solar gain, but this system is still very popular among certain self-builders.
In theory, it allows for heating savings of around 40%, which depend enormously on the local solar resource and the quality of the sunshine.
Based on his experiments, Félix Trombe proposed a simple sizing rule for very sunny climates.
The rule is as follows: you must provide 1 m2 of collector in the south for 10 m3 to heat.
Many passive solar houses from the 1970s were designed based on this formula, without it being invalidated.
Sources: F. Trombe, J.-L. Tricaud, B. Sésolis.
Image: C. Gaillard, picture of the Trombe house in Odeillo-Font-Romeu.