All the materials and components that we combine into our homes have been manufactured and the processes involved from growing or mining, through all the manufacturing processes down to delivery and installation all use energy. The combined total of all that energy (Produced by burning fossil fuels) is called the CARBON FOOTPRINT. If you were to build your home from natural materials with minimal processing and sourced locally to your home-site the amount of energy required, and therefore, your carbon footprint, would be minimal.
The other extreme would be to use large amounts of material with high levels of energy input such as aluminium and steel which involve mining with heavy equipment, transport of ore over long distances, high energy input to convert to the finished product and long delivery distances from centralised manufacturing plants (As well as further processing into the fittings and products we finally install in our homes).
You can clearly see that there is a vast difference in these two scenarios and the resultant carbon footprint from each approach.
It must, however, be borne in mind that the efficiency of materials, the quantities employed, their expected lifespan and their reusability/recycle-ability at the end of their life should be considered when selecting construction systems and components.
The amount of aluminium in our homes is very small and the amount of high strength steel can be minimal in comparison with the energy input to process and transport heavy weight materials around the globe or to remote sites.
Karl Marx’s – “Less is more” – brings this into sharp focus and should be the starting point of all our home design and selection processes.
There are a number of definitions of carbon footprint. Some restrict the definition to energy in creation of product as above. However this may not be the whole picture as the energy use over the lifetime of a building, which can far exceed the amount consumed in its construction, can be dramatically reduced if better systems and materials possibly with higher carbon footprints are used in the initial creation. This overall consideration is discussed under Life Cycle Analysis.