An Insulating Concrete Form is a lightweight, expanded polystyrene form that interlocks with other ICFs to create a cast for exterior concrete walls. As the forms are installed they are connected with plastic ties, and rebar is placed across the empty spaced in the forms to reinforce the structure. Once the forms are all in place in the shape of the structure, the cavity is filled with concrete. The forms remain in place after the addition of concrete and the foam provides about four inches of thermal insulation for the 4-6 inch concrete walls of the building.
Rammed earth trombe wall built by the Design Build Bluff Organization
Rammed earth, also known as taipa (Portuguese), tapial (Spanish), pisé de terre or simply pisé (French), is a technique used in the building of walls using the raw materials of earth, chalk, lime and gravel. It is an ancient building method that has seen a revival in recent years as people seek more sustainablebuilding materials and natural building methods. Rammed earth walls are simple to construct, incombustible, thermally massive, very strong and hardwearing. Conversely they can be labour-intensive to construct without machinery (powered rammers), and if improperly protected or maintained they are susceptible to water damage. Traditionally, rammed earth buildings are found on every continent except Antarctica. From temperate and wet regions of north Europe  to semi dry deserts, mountain areas and the tropics. The availability of useful soil and building design for the local climatic conditions are the factors which favour its use.