Embodied Energy of a Home
Typical home, over 60 year life - has 10% embodied energy of materials and 8-10 times more than that in energy use . 60 years is short, so we should be talking about more like 100 year life.
Thus, the embodied energy of materials is much smaller than energy used. If we offset this with PV, we can reduce the carbon footprint of homes to negative - by producing the world's first replicable negative carbon footprint house. This means it produces surplus energy for other uses, such as producing hydrogen fuel for cars.
BHAG - To create the first house in the world that produces fuel for the family car in 10 years. This means that weanifacture the electrolysis, sylyorage, and car.