Lowering the embodied energy of constructions through reuse of building elements

Bearing in mind that an important goal of the building sector is to produce constructions with a low environmental impact, the embodied energy (EE) of their components, i.e. the energy acquired for all processes from extraction of raw materials up to the manufactory of building material or prefabricated construction elements, should be minimised. Studies on low consumption dwellings have shown that the production energy can account for 40-60% of the total energy. Current sorting and recycling techniques allow a reduction of the EE up to 50%. A single reuse of construction elements delivers an additional potential saving of 10-15% for typical construction materials. In anticipation of an inevitable end of use of constructions, this will require innovative design strategies, especially when multiple reuses are taken into consideration.

The 4Dimensional Design Strategy (4D), invented by H. HENDRICKX and H. VANWALLEGHEM includes this dynamic view on the built environment. 4D is a guide to design multiple construction systems, all compatible to each other, by which a variety of adaptable and reusable construction elements can be composed. In this paper the main principles of the 4D design strategy will be discussed and evaluated through a case study, i.e. a construction kit for temporary Flemish housing. Multiple reuses of its basic elements will drop the EE drastically. Both benefits and further difficulties are detailed.