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Recently rammed earth has become popular as a sustainable construction material. There are numerous benefits to the environment in using rammed earth compared to more modern alternatives of concrete and steel.
Sustainable rammed earth projects in the UK
Using rammed earth as a construction material greatly reduces the amount of CO2 released during the construction of the building.
The manufacture of cement requires the burning of limestone and produces CO2 as a waste product. Around 10% of global CO2 emissions are from the cement industry [1].
In using soil taken directly from the site, there is no transport requirement, directly reducing CO2 emissions and taking vehicles off the road.
1. The Guardian A cracking alternative to cement May 2006 article
The high thermal mass of rammed earth walls mean they act to naturally regualate the internal temperature of a building. If a rammed earth wall is designed into the heating system of a structure, the energy required to both heat and cool the building can be greatly reduced, which further reduces the CO2 emissions of the building.
Rammed earth naturally regualtes the internal relative humidity of the building, producing an improved air quality. This contrasts greatly with air conditioning systems, which act to dry the air in a building and contribute to harsh working and living environment.
Treloar et al 2000. Environmental assessment of rammed earth construction systems Structural Survey Article
Taylor & Luther 2003. Evaluating rammed earth walls: a case study Solar energy Article
Hall & Allinson, 2008. Assessing the Effects of Soil Grading on the Moisture Content-Dependent Thermal Conductivity of Stabilised Rammed Earth Materials. Applied Thermal Engineering.
Rammed earth is perfectly able to act as load bearing members within a structural system. We have particular expertise in the structural performance of rammed earth and have developed novel testing methods to aid understanding of the fundamental mechanisms governing the behaviour of rammed earth. The strength of dry, unstabilised rammed earth is close to 1MPa, but both the strength and stiffness of the material reduce greatly with increasing water content, and thus the building must be well designed in order to maximise the structural potential of the rammed earth.
The inherent recycleablility of rammed earth, and the reduction in CO2 emissions during the lifetime of the structure, the high thermal mass and thus low operating costs all mean that rammed earth has a much lower embodied energy than comparable building materials.