Civil Engineering Reference
In-Depth Information
can be chosen: centralised or decentralised. Additionally, there is a possibility to
make provision for night cooling. For the cases studied, both kinds of solutions
were used.
For Schwanenstadt, a decentralised solution was chosen throughout the whole
building, and the same type of heat recovery unit was installed everywhere. This
unit is based on a plate heat exchanger with an 85 % nominal rate of heat recovery.
The unit hangs under the ceiling and is placed directly towards the exterior wall
allowing short ducts. When necessary, two units are placed in the same room.
Toilets have their own systems, while the sports hall has openings in relation to the
windows. There is provision for night cooling through natural ventilation.
The three other schools use centralised ventilation systems. For Zams-
Schönwies, to minimise the concrete perforation, the fresh air is distributed though
horizontal ducts in the cellar, and further through vertical ducts up through the
floors. Each duct serves two classrooms on two different stories. A water-based fin
radiator in front of the vent provides additional heat when needed. To limit costs,
the exhaust air is extracted through visible horizontal duct work below the ceiling,
collected on each floor and taken down to the cellar in the existing stairwell space.
For Zams-Schönwies and Sonderschule 6, the incoming air is preheated by an
underground heat exchanger. For Sonderschule 4, the ventilation system is par-
tially hidden.
5.4.2 Light
Lighting is an important source of electricity consumption, and concerns about this
consumption are part of the passive house concept. A first step in low-energy
design is to improve the use of daylight and then to implement control systems to
reduce the time when artificial light is used. The PHPP has an extended style sheet
to assess the need for electricity for lighting for different zones of the buildings
taking into account the access to day light. In the four schools, different actions
have been taken to increase the use of daylight. Skylights have been added in all
the buildings, especially above stairwells. In Sonderschule 6, new internal glazing
distributes the light deep in the building. Except in Zams-Schönwies where budget
limitation limited this option, the schools have new low-energy fixtures and
control systems. Lighting is closely related to solar protection, shading and glare.
5.4.3 Shading
All the windows exposed to direct sunlight are equipped with external movable
shading, screens for Sondeschule 6, and venetian blinds for the others. An inter-
esting solution was chosen for Sonderschule 4 (Fig.
3
) and Schwanenstadt; the
upper part of the blinds lets more light in when the lower portion of these blinds is
fully shaded, allowing more daylight into the room. All systems are automatically
driven with possibility for local override.
