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Figure 1: Quality of building envelope for Minergie-A buildings.
2.2 Net zero energy balance
The net zero energy balance includes space heating, domestic hot water, ventilation and
auxiliary services. The primary energy balance is based on Swiss national weighting
factors [EnDK 2009]. Only on-site production is taken into account. The quality of the
envelope, the type and efficiency of the heating, hot water and ventilation systems
determine the demand that has to be covered by renewable energy. The mean primary
energy demand of all buildings is 29 ± 8 kWh
ECH
/(m
2
a). Therefore, the actual level of the
net zero energy balance strongly depends on the building (fig. 2).
Nearly all buildings use a photovoltaic system (PV) to produce the required amount of
on-site energy. Table 1 shows average sizing values of the PV installation necessary to
meet the net zero energy balance of the Minergie-A buildings. Only three of the
considered buildings use the credit for the energy concept with wood and thermal solar
collectors.
Figure 2: Net zero energy balance for primary energy demand/generation of the Minergie-A buildings.
