health and comfort of the inhabitants are the most important objectives
of a Passive House design. Excellent indoor air quality is indispensable.
But this can only be achieved if stale air is exchanged with fresh
outdoor air at regular intervals. This can definitely not be done
by just opening windows twice a day.
Ventilation will work accurately only if polluted air is removed
constantly out of kitchen, bathrooms, and all other room with significant
air pollution. Fresh air has to be supplied to the living room,
children’s room, sleeping rooms, and workrooms to substitute
the removed air.
The system will supply exactly as much fresh air as is needed for
comfort and for good indoor air quality; only outdoor air will be
supplied – no recirculated air. This will lead to a high level
of indoor air quality.
What has been discussed so far could be satisfied by using a simple
exhaust fan ventilation system, where the air is supplied through
direct vents in external walls. These vents allow fresh (cold) air
to enter the room at the required rate. However, for a Passive House,
the heat losses caused by such a system are much to high.
In Central Europe Passive
Houses will only work with highly efficient heat recovery. Heat
from the exhaust air is recovered and applied to the supply air
by a heat exchanger. The air flows are not mixed in the process.
State of the art ventilation systems may have heat recovery rates
of 75% to more than 95%. Of course this only works with counterflow
heat exchangers and very energy efficient ventilators (using so
called EC-motors with extraordinarily high efficiency). With this
technology the recovered heat is 8- to 15-times higher than the
more information about ventilation in a Passive House.
An additional opportunity to increase the efficiency of ventilation
systems is the use of earth buried ducts. The ground during winter
has a higher temperature than outdoor air, and during the summer
a lower temperature than outdoor air. Therefore it is possible to
preheat fresh air in an earth buried duct in winter, or to cool
it in summer. This can be done directly with air ducts in the ground,
or indirectly with brine circulating in earth buried pipes and heating
or cooling the air with a water-to-air heat exchanger.
In the exhibition,
Passive House ventilation systems can be seen: Heat recovery systems
of highest efficiency, quiet and suitable to be used in dwellings.
systems - the integration of the complete building services
in the ventilation system. This is possible in Passive Houses.
to Dylan Lamar for proof reading of the 1st edition
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