What is embodied Energy?
When we are talking about our design and material choices in a natural home, we often discuss the embodied energy. This can be defined as:
Embodied energy is the energy consumed by all of the processes associated with the production of a building, from the mining and processing of natural resources to manufacturing, transport and product delivery. Embodied energy does not include the operation and disposal of the building material, which would be considered in a life cycle approach. Embodied energy is the ‘upstream’ or ‘front-end’ component of the life cycle impact of a home.
Why does Embodied Energy Matter?
I once wrote to a well-known insulation manufacturer asking for their calculations on the embodied energy in their product. The reply came back that insulation doesn’t have an embodied energy because it saves you energy. Alarming no?
So if I build a house with the most energy intensive insulation available, and I mean really fill the house with the stuff, way over code. The fact that the building may cost the earth practically nothing to heat and cool over its lifetime… is massively overshadowed by the enormous energy debt the house is in to start with. Even if the house exists for 200 years it might never pay off its initial construction debt.
Others come to similar conclusions; in one study, A comprehensive assessment of the life cycle energy demand of passive houses, the authors concluded that a family living in a Passive House, a very high standard that demands a lot of insulation, will, over the life of the house, only use a tiny bit less energy than those who live in a conventional house.
Like this author, they conclude that the only way to seriously reduce our life cycle energy cost is to live in smaller apartments downtown, but that is another slideshow.
But when you look at the list of materials in the passive house they studied (on TreeHugger here) you see it is full of 135 cubic meters of polyurethane foam insulation, sixty cubic meters of concrete, clay brick cladding and clay tile roof. There is a seriously high amount of embodied energy and carbon in this house.
Read more in this great slideshow from Lloyd Alter @ treehugger –
