The definition of net zero energy buildings in the energy performance building performance directive only includes operating energy quantities and related CO2 emissions. Embodied energy and other emissions are not taken into account. Figure 1 shows the paradox of the net zero energy buildings and figure 2 the relationship between embodied energy and life cycle energy.
A life- cycle perspective is needed to evaluate and quantify resource use and environmental impact of building and, hence, to identify sustainable solutions for new and energy refurbishment of buildings.
Figure 1. The paradox of NZEB [ESCI]
Figure 2. Embodied/Life Cycle Energy
[Prakash et al.]