Refurbishment Scenario to Shift Nearly Net ZEBs Toward Net ZEB Target: An Italian Case Study - Nearly Zero Energy Building Refurbishment - page 233

Table 3 Annual electricity balance of the LH

Balance Metric Nearly net ZEB Net ZEB (refurbishment)

Energy load MWh 25.6 22.8

Energy generation MWh 24.7 38.3

Net energy MWh -0.9 15.5

Fig. 3 Energy balance of the
LH and effects of the retrofit

Energy balance

40

35

Generation -side
refurbishment

30

Leaf House

25

Starting point

Load -side refurbishment

20

20 25 30 35 40

DEMAND [MWh]

Further, the retrofit scenario would involve a surplus of 15.5 MWh/y, which
would be entirely exported to the grid(E net, LH [ 0), shifting the LH from the
nearly Net ZEB condition to the target of Net ZEB, in terms of energy measured at
the end-use level. In Fig. 3 , such a shift is clearly showed.
The above technical solutions aim at reducing the annual energy loads of the
LH and to increase the energy generation. However, they require extra materials
and components, thus increasing the embodied energy of the building. Then, the
life cycle approach in the energy and environmental assessment of the foreseen
retrofit options is necessary to avoid shifting environmental burdens from one step
of the life cycle to another. In the following sections, the authors apply the life
cycle approach to assess the ecoprofile of the LH, taking into account two different
building scenarios:

• Nearly Net ZEB, which represents the building as it was designed and built
(Baseline scenario).
• Net ZEB, which represents the refurbished LH according to the above set of
energy saving options (Refurbishment scenario).

Further, in order to get a deeper description of the energy performance of the
retrofit actions and to compare the different alternatives, the energy payback time
(EPT) and the emission payback time (EPT) are calculated (Ardente et al. 2011 ).