Does the orientation of rammed earth walls affect thermal performance?

Orientation Considerations

When constructing rammed earth walls, the orientation of the wall relative to the sun is crucial for optimal thermal performance. In general, walls should be oriented to face north in the northern hemisphere to minimize direct solar radiation. However, in desert and arid climates, south-facing walls can be beneficial if properly designed to capture winter sun while reducing summer heat gain. A 30° angle from the south-facing wall has been shown to be an effective compromise, allowing for winter sun exposure while minimizing summer heat gain.

Thermal Mass and Cooling

Rammed earth walls are renowned for their high thermal mass, which enables them to absorb and release heat slowly. This property is particularly beneficial in desert and arid climates, where extreme temperature fluctuations can occur. By designing walls with a thermal mass of at least 100 kg/m², builders can harness the natural cooling effect of the earth, reducing the need for mechanical air conditioning. In such climates, walls with a high thermal mass can lower indoor temperatures by up to 3°C compared to walls with a lower thermal mass.

Formwork and Soil Mix

The formwork used to construct rammed earth walls can also impact their thermal performance. A well-designed formwork system can ensure a smooth, uniform surface finish, which is essential for optimal thermal transfer. Additionally, the soil mix used in rammed earth construction can affect the wall’s thermal mass and durability. A mix with a high proportion of clay and a low sand content has been shown to produce walls with improved thermal performance and structural integrity.