Concept of the ecological low-energy building at the technical college for engineering in Butzbach
The building has a usable area of approximately 350 m2.
It was designed using solar architecture and the already existing
buildings and vegetation were also taken into consideration. The building
has large window fronts towards the south, the southeast and the southwest
to harness the sun for lighting and heating purposes. The building's roof
slopes relatively steeply towards the north resulting in a smaller
building shell. Thus the thermal losses are held low on the building's
cold side. This effect is increased by the very small windows on the north
side. An interior corridor is located between the north and the south side,
which is only partly heated in winter. These measures give a positive A/V
ratio (surface of the outer shell divided by the interior volume).
As the building is intended not only for housing classrooms, but also for
practical study purposes, a lot of different building materials and
techniques were used. Appliances, like for example the air conditioning, are
not hidden away but can be seen in the classrooms and are accessible for measuring purposes.
Technology is permanently monitored and updated, so that the building goes
through a dynamic development and further generations of students can work
at it and learn from it.
classroom
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When choosing the building
materials attention was paid to the fact that they were ecologically
proven considering the existing market. Each supplier had to prove the
materials' harmlessness by safety data sheets. One aim was to show that
the construction principles can be used in building conventional one- and
two family houses and that no special building had been created here. The
timber-frame construction allows the owners to do interior work themselves;
this also was the case with the school building. Reasonable priced and
ecologically friendly new ways to build are possible here in
cooperation with maufactures of prefabricated buildings and building
societies. The building houses classrooms, an energy consulting centre and
an EDP room. The public energy consulting centre also offers information
events about low energy building.
The house was
built on a poured concrete foundation using timber-frame construction. The
timber is treated with natural colours. To achieve a good wind tightness the
different building elements are sealed by special sealing strips. The wooden
beams are connected using traditional mortise and tenon joints.
<<< Photo: timber frame construction (north
view)
The inner walls of the timber-frame construction are faced with glue-poor
OSB coarse wood chipboard. In the external area cement-poor
Heraklit-boards are attached to the north front which are covered with
ecologically friendly plaster. Inside the walls there is an 18 cm thick
insulation which consits of "Foamglass" as non flammable
material around the boiler room and hard and soft fibre boards in other
areas. The partition walls between classrooms and corridor inside the
building were also insulated with soft fibre boards.
A
particularly thick insulation was used for the roof area. One half of the
roof is insulated with 28 cm thick sheep wool, while cellulose insulating
materials were blown into the other half of the roof. The roof is designed
as ventilated/cold roof, i.e.following the sealed insulating layer an air
layer was built in, on which the actual roof membrane with the roof
planting was applied. The small lateral roofs are insulated with flax.
Photo: cross section of roof >>>
The walls of the sanitary facilities are made of light-weight precast sheets of pressed Perlite (Perlcon Board). The hollow walls seperating the sanitary area from the corridor are filled with Perlite insulation material. On the other side of the corridor there is a small conference room with an adjoining cloakroom. The different walls were made of substantial bricked lime sandstone and loam (soil) blocks.
The floors are likewise highly insulated. Each room has got a different floor structure, which can be seen through small glass windows set into the floor. The floor structure height amounts to 23 cm and uses materials such as Foamglass, soft and hard fibre boards and pourable insulation materials. These were sealed by flow cement or bitumen casting. When possible homegrown materials, like wood, were used for the floors. Where Terracotta was layed, low radiating material from Spain was chosen.
All different insulating materials used in the building can also be seen through windows set into the walls. Sensors allow the monitoring of the temperatures inside the insulation. Inside the roof insulation there are temperature sensors which are likewise connected to a central computer via an integrated unified data transmission system for buildings. This building instrumentation also controls all lighting and heating processes and additional alarm systems.
Photo: walls partly filled with insulation >>>
The walls inside the building were among other materials finished with plaster on the basis of cotton mixed with minerals for colour and design. Also pressed Perlite boards, loam (soil) boards, hemp and straw were used. In addition different plaster carriers are tested ranging from metal stretch band to linen, hemp and reed quilt.
The building has a controlled forced ventilation. Pipes with a diameter of 30 cm were buried in the ground. In summer the fresh air flowing in the pipes is cooled by the surrounding ground and in winter it is preheated. The already preheated fresh air passes a cross flow heat exchanger which uses the warm exhaust air that leaves the building for a further increase in temperature. In winter additional heating is provided by a gas fired boiler using caloific value technology and conventional radiators in the classrooms. The heating system is structured in such a way that single rooms can be disconnected. An electrostatic filter is used for cleaning the air that is sucked into the building. It keeps even pollen away from the interior.
Photo: Pipes for air conditioning
buried in the
ground
The windows have fixed glazing
for which glass with U-values of 1.1 W/m2 or better was selected. The
windows are set into timber frames. The sealing to the building consits of an
ecologically friendly cork foam insulation. Energetically seen a PVC window
framework is superior to the timber frames, but in case of fire however dioxins
and furans are set free. For demonstration purposes some double glazed windows
have electrically operated blinds between their panes for shading. In summer
trees that already existed provide natural shading of the building's southeast
and southwest front. These are supplemented by vine louse and
flour-rope-resistant vines which carry their ripe fruits in early autumn and
throw off their leaves soon after this. Different systems of transparent thermal
insulation which pass on the heat to either solid material such as loam,
limestone, wood, cork or directly to the classroom air can also be found on
these fronts of the building. For the first time in Germany a new system of
transparent thermal insulation that uses a honeycomb cardboard structure was
installed.
electrically operated blinds
wall with transparent thermal
insulation
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The heating system is supported by a solar thermal system. The special feature of this system is that it is emptied automatically respectively filled automatically in cases of extreme heat or cold. A future student's project will be the usage of an old heating oil tank for long-term solar hot water storage. In combination with a heat pump the heat stored in the tank can be used in winter to contribute to space heating.
From the outset an extensive roof planting with the possibility of rain water use was taken into account. The entire roof consists of three different vegetations levels. It was assumed that about a third of the annual rain fall stays on the roof and so an only 5.8 m3 holing concrete cistern was installed for the relatively large roof. The waste water of part of the toilets will be fed to a reed bed water purification installation where it is filtered ecologically and fed back to the toilet system later on. The evaporating water of the pond will be topped up from a cistern, so that only in extremely dry periods drinking water must be used for partly refilling the pond. The sanitary installations have additional flush-free urinals and compost toilets that seperate fluid and solid waste automatically.
A 1 kW grid connected PV system is installed on a frame in the large pond on the south side of the building. The pond's water surface serves at the same time to reflect sunlight into the building and to increase the light intensity on the PV modules. A front photovoltaic system using polycrystalline cells is, among other things, integrated into the building's large glass front. The cells are melted into high quality glass. Due to the fact that the cell's distance is relatively high sufficient light is let into the building's interior. These front PV systems demonstrate that vertically installed PV modules can be used to produce power and to construct an interesting front at the same time.
A 4 m2 large mirror is
installed on the main school building, which tracks the sun in a 20 second
rhythm up to the year 2040, using a special software. This mirror reflects the
sunbeams onto 4 further mirrors situated opposite the low energy building. In the
winter months two of these mirrors reflect the sunlight onto a soil block and a
lime-sandstone wall inside the building, which have a different thickness for
testing purposes. These walls store heat that is slowly passed on to the house's
interior. In summer these mirrors can be turned away to avoid additional heating
of the building. In the sun-rich time the mirrors can be turned towards the PV
panels. Two further mirrors reflect light into the building in summer and winter
to reduce artificial lighting. If necessary these mirrors can also be
turned away and are then directed onto the front PV modules.
light into building
The building hasn't got a cellar
of its own to keep building costs low. A small seperate "natural"
cellar was built in another location on the campus. It is soil-covered and
constructed out of lime-sandstone and without further insulation. The capillary
effect causes humidity to penetrate the stone. The water's evaporation produces
the desired cooling effect in summer. In winter the soil keeps the cold away, so
that the average annual cellar temperature is between 13° C and 15°C, which in
turn is ideal for storage.This funcion oriented cellar is superior to the
usually over-heated cellars of common houses.
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The
ecologically friendly state of the art low-energy house in Butzbach is only
approx. 15 % more expensive than a house which is built using conventional
building techniques. Based on today's energy prices the additional costs will
have amortized in approx. 20 years. Since today's house pay off times are
substantially higher than this, the building is not only ecologically friendly
but also economical. The long term rise of energy prices and the possible mass
production of timber frame buildings will make such buildings superior to
traditional buildings.