C a s a Z e r o E n e r g y
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The external walls are timber-framed panels with an inner insulation in wood fiber,
between two plywood slabs. A continuous layer of cork is outside of the panels to
guarantee the continuity of the external envelope and for totally eliminating thermal
bridges (Fig.4). With this constructive solution it was possible to build an envelope with
an excellent performance both in summer and in winter. The wall thermal transmittance
is 0,22 W/m
2
K the roof thermal transmittance is 0,21 W/m
2
K.
Integration with energy systems using alternative and clean sources
One relevant characteristic of the house is synthesized in its acronym “CasaZeroEnergy”.
This acronym comes from the fact that the house can be considered as a zero energy
building because it has very low energy consumption, it does not use any fossil fuel, its
energy demand is satisfied using renewable energy sources.
The house is an anticipation of the
EU directive 31/2010/CE
that requires the realization
of
near zero energy buildings
starting from 2020.
In particular the energy systems in the house are:
•
photovoltaic plant
of 14,6 kWh,
•
solar thermal panels
for DHW,
•
horizontal geothermal plant
with pump water-air heat.
The heat pump is integrated with a radiant floor heating. This is an innovative
heating/cooling system. It is based on the criterion that the radiant temperature is one of
the most important parameter in achieving the thermal wellbeing in an indoor space. The
water circulating in the floors in winter has a temperature around 33°C - 36°C similar to
the body temperature. In this way there are not important exchanges for radiation
between the body and the adjacent space. Therefore, the inhabitants, perceiving the
temperature of the air, will be in a wellbeing situation.
Instead, in summer, the cold water circulates in the pipes with a temperature around
16°C-20°C. Thus the floor temperature is around 20°C, causing a thermal interchange
for radiation between the floor and the human body. In this case the inhabitants will have
a fresh feeling and they will have a wellbeing situation.
Low energy consumption
The Laboratory of Building Design of the University of Trento (Italy) developed with a
mathematic model the prediction of the building behavior for what concern the energy
consumption. From this model, related to one year, the good behavior of the building,
both in summer and in winter condition, emerged.
The considered parameters as base for the estimation were:
•
building heated area = 378 sq.m
•
people present in the house = 4
•
DHW need = 75 l/person
In particular two different models were simulated. The first one was the model of the
house without the sunspace and the second one the model of the whole building,
considering the presence of the sunspace. In this way it was possible to estimate the
free energy gain coming from this passive solar system.
In this first case the house was modeled with only a thermal zone. The results of the
estimation are in Tab.1.
