Rammed earth wall thickness for optimal thermal performance?

Optimal Wall Thickness for Thermal Performance

Rammed earth walls are well-suited for arid and desert climates due to their excellent thermal mass properties. Thermal mass is the ability of a material to absorb and release heat, helping to regulate the internal temperature of a building. In desert regions, where diurnal temperature fluctuations are extreme, a well-designed rammed earth wall can help keep the interior of a building cool during the day and warm at night.

A wall thickness of 4-6 inches (10-15 cm) is optimal for thermal performance. This thickness allows for a sufficient amount of thermal mass to be incorporated into the wall, while minimizing material waste and construction costs. Thicker walls may be more effective, but they also increase the amount of material required and the complexity of the construction process.

Formwork and Compaction Techniques

When building rammed earth walls, it’s essential to use proper formwork and compaction techniques to achieve the optimal wall thickness. A well-designed formwork system should be able to withstand the pressure of the compacted soil and provide a smooth, even surface for the final finish. Compaction techniques, such as hand tampering or using a mechanical compactor, should be used to achieve a density of at least 1.5 g/cm3 in the compacted soil.

Soil Mix and Thermal Mass

The soil mix used for rammed earth construction plays a critical role in determining the thermal mass properties of the wall. A mix with a high proportion of clay and silt will provide better thermal mass than a mix with a high proportion of sand. The mix should also be designed to withstand the local climate and weather conditions, with a mix of 10-20% clay, 40-50% silt, and 30-40% sand being a good starting point.