Norddeutsche Landesbank am Friedrichswall Hannover_ Germany

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					Norddeutsche Landesbank
am Friedrichswall
Hannover, Germany
Behnisch, Behnisch & Partner

William Elsworthy
       The international competition for the Norddeutsche      Aegidietorplatz, a major traffic intersection and site of a
Landesbank in Hannover was won by the German firm of           theatre. South of the building are the 19th century suburbs.
Behnisch, Behnisch & Partner.          The interest in the     The Nord/LB is at an urban node, placed beside noisy
Behnisch proposal was the firm’s skill at bringing daylight    traffic arteries and looking out at the old city and the new
into the building, reducing energy use, and above all ensure   suburbs.
worker comfort. The Norddeutsche Landesbank (Nord/LB)
recognizes the integrated nature of working conditions,                Behnisch, Behnisch & Partner’s strategy for the
worker productivity, and morale.         Put simply, this      perimeter block and central tower was to create a building
relationship means that it is profitable to provide your       that is energy efficient, ensures worker comfort, and
workers with a comfortable environment. The Behnisch           responds to and engages the urban context.
proposal provided a building to house the Nord/LB that was
both   environmentally   responsible    and   economically             The climate control engineering firm for the project,
desirable. The Nord/LB building succeeds in its integration    Transsolar Energietechnik, set out two goals for the
of a number of green building technologies, and the            building’s efficiency.   “... to surpass the 1997 German
example it sets for the broad-based adoption of these          insulation regulations by 10%, and then to create
principles.                                                    environmentally sensitive measures at reasonable cost.”1
                                                               Peter Voit, the project engineer said that “because energy
       The bank complex, the agglomeration of 15 smaller       consumption for winter heating is comparatively low,
offices, lies at the south east corner of the old city.        attention was focussed on the reduction of costlier
Immediately to the building’s north lies the Friedrichswall,   environmental necessities – ventilation, cooling and
an orbital motorway that, like in many European centres,       lighting.”2
replaced the medieval city wall.     To the east lies the
       The Nord/LB uses an almost entirely passive                   needed, the energy they use is negligible. Such efficiency
ventilation system. Fresh air is supplied by shutter that            eliminated the need for a heat-recovery system”4.
open onto the courtyard.
       “Die Frischluft aus dem Innenhof wird unter dem Bau
       in die Doppelfassade geleitet. Dies wird damit
       begründet, dass die große Wasserfläche des
       Innenhofs und die begrünten Dächer der
       Betriebskantine für ein ausreichend gutes Mikroklima
       [The fresh air from the inner court is led under the
       building into the cavity facade. This is justified with the
       fact that the large water surface of the inner court and
       the green roofs of the cafeteria provide for a sufficiently
       good microclimate.]3
This microclimate provides the building with air that is
perhaps even cleaner and more refreshing that outside air,
or the air that would be provided using a conventional
mechanical system. Air is vented from the offices and
similar rooms through a suspended ceiling system to the
corridor, and from there to the large passive vents or
chimneys that exhaust air to the roof. Room occupants are
able to control the air flow with transom casement windows.
As the hot stale air rises out of the building, more cool fresh
air is drawn in from the courtyard below. This chimney
effect works particularly well when outdoor temperatures
are below 10/C, and “even when electrically driven fans are
       Cooling is achieved at the Nord/LB with a radiant
slab cooling system and a geothermal heat exchanger.
The concrete foundation piles (120 of them) are sunk
approximately 30 metres below ground and have water
pipes embedded in them. Water is pumped through the
piles to the building’s exposed concrete ceilings that have
polyethylene pipes cast into them. In the summer, glare
and solar gain are minimised by completely blocking or
reflecting light onto the ceilings using reflective louvres.
This lighting strategy combined with ambient and computer
equipment heat sources mean the ceiling slabs tend to heat
up during the summer days. Cold water (about 17/C) is
pumped through the pipes generally at night, adsorbing the      embedded cooling pipes cool fresh air that is taken in through
                                                                shutters on the building face and exhausted through chimneys
heat accumulated in the slab over the course of the day,
and cooling for the day ahead.5 In the winter, a heat pump              Daylighting, and thus the glazing systems used on
is used to warm up the water temperature from 6/C (to           the different faces of the Nord/LB are differently conceived.
about 25/C), and it is then pumped through the ceiling slab             “Je nach Himmelrichtung und dem Grad der
                                                                        Belästigung, wie sie zum Beispiel der Verkehrslärm mit
pipes to heat the building. “Exchange with a district heating           sich bringt...”
                                                                        [depending upon sky direction and the degree of the
system is also involved, while solar water heating,                     annoyance, for example with the traffic noise itself...]7.
photovoltaics, and fuel cells play minor and experimental
                                                                A system of operable thermal glazed windows and external
                                                                louvres was used.
The north and west are both next to noisy roads, and thus          is a major leap forward...It is now possible to replace
have an additional layer of glass to defend the offices the        traditional metal spacers with a high quality thermoplastic
from fumes and noise given off by the steady stream of             profile system.”10
passing cars. The sunshades are controlled both centrally
by computer and by controls within each room. The upper
slats function like a series of light shelves that reflect light
up and on to the ceiling to provide ambient lighting (and
passive heating in the winter). The lower slats reflect light
away form the building, to reduce solar gain and glare,
while still allowing the occupant to see outside. The louvres
are set off away from the building line to allow a layer of air    double skin along the Friedrichswall, glazed office partitions

to flow behind them and up the building face. The operable
windows themselves are “TPS insulating glass”8 units.                      The offices and other rooms have fully glazed or
Scholl Glas GmbH, the parent company of GlasFicher                 glazed tops to allow daylight to pass from the offices into
GlasTechnik, the manufacturer of the glass9 used in the            the central corridors. “Though many workers had to adjust
Nord/LB notes: “GEWE-therm® noise control glass reduces            to the ‘fishbowl’ distractions and lack of privacy, the daylight
noise from the outside of buildings by up to 52 dB. Even           admitted was welcome from the start”11. Despite being
extreme noise levels can be effectively reduced.... GEWE-          open to the sky and to ambient daylight, and effort is made
therm® noise control glass also possesses excellent heat           to increase light level on the darker faces of the courtyard.
control properties, with K-values of up to 1.0 W/m”. They
elaborate on the advances in multiple-glazed unit                          “Aus diesem Grund wurden auf dem Büroblock am
                                                                           Friedrichswall Heliostaten installiert. Sie fahren
manufacture: “GEWE-therm® TPS (thermo plastic spacer)                      automatisch der Sonne nach und reflektieren das Licht, das
                dann über fest fixierte Spiegel vor der            into the building to reduce the need for energy consumption
                Gebäudekante in die Halle weitergeleitet wird”
       [For this reason on the office block at the                 and to provide a pleasant work place.
       Friedrichswall, ‘heliostaten’ were installed. They
       automatically follow the sun and reflect the light, which
       is then reflected by fixed mirrors projecting past the
       building edge, and then passed on] and reflected to the            Peter Voit, of Transsolar Energietechnik, set out
       courtyard’s dark corners and into the offices on the
                                                                   “ create environmentally sensitive measures at
       shaded faces.12
                                                                   reasonable cost.”1. It is perhaps too early to evaluate the
       The coordinated approach to daylighting makes the           long term running costs of the Nord/LB, but Transsolar
system used at the Nord/LB particularly effective. Christian       provides evidence from a number of other projects they
Bartenbach, founder of Bartenbach Lichtlabor, the                  engineered that suggest that the direct cost savings are
daylighting consultant “has never regarded light and its           great. “The integrated design concept used at the new
various effects from a physical angle alone but above all as       Gniebel administration building gave a cost-saving of about
a phenomenon to be explored by means of perceptual                 50% over the expected HVAC investment and enabled
psychology. By focussing on human perception he has                savings in the running costs of more than 60%”14. Excellent
reversed the conventional planning approach: rather than           daylighting and the allowance for individual modification of
starting with the luminaire, the ambience and the future use       light and ventilation, as Christian Bartenbach notes,
of a room are defined first. Only then does the actual             impacts on the psychology of the worker.            Worker
planning process begin, always taking into account the             contentment and productivity are the less-quantifiable
precepts of perceptual psychology. The result is a lighting        benefits of the environmentally sensitive lighting, cooling
design that fits the requirements of human beings, not vice        and ventilation systems.
versa.”13    The technologies described in the above
paragraphs are not seen individually as ends, but as an                   The interest in ensuring worker comfort does not end
organized and coordinated means to bring daylight deep             with the green technology. The architecture allows for
social interaction and the ease of use of the building.           eat lunch.     The sloping glass planes that enclose the
Generous public spaces like the cafeteria and its lake and        cafeteria (and the entrance foyer) indicate they are of
the planted roof terraces create a comfortable setting.           importance, and by extension that the employees are
          “Die Pausen und kleinen Besprechungszonen wurden        important to the Nord/LB.
          in Variationen offen in die großzügig aufgeweiteten
          Flurzonen integriert. Eine besondere Qualität haben
          die Büros, deren Flure sich zu den breiten Terrassen
          öffnen, die den Mitarbeitern zur Verfügung stehen.15”
          [Trace and small discussion zones were integrated in
          variations and generous expansions of corridor zones.
          The office corridors open onto broad terraces, which
          are at the disposal of the workers].
These areas, created by skewed massing and irregular
floor plates, create opportunities for discussion and
                                                                  tubular glass bridges   green roof and projecting corner of the
interaction and seem to function like decentralized                                       sloped glass cafeteria roof
lunch/tea rooms. The nodes also serve as locations for
single flights of stairs that provide short cuts between                  The Nord/LB building responds to its site context.

levels.     The glass tubes that criss-cross the courtyard        The decision by Behnisch, Behnisch & Partner to create a

provide routes through the building that allow the worker to      six-storey perimeter block was made to match the scale of

be freed from the ordinary constraints of a large perimeter       the neighbouring buildings. Likewise, the placement of the

block and core system. The cafeteria occupies the primary         entrance was a response to its surroundings. Since the

position in the courtyard. It projects out from the base of       Friedrichswall is so noisy, and the Aegidietorplatz is such

the tower and opens onto the water basin in the courtyard,        an important urban node “the main approach from the north

reminding the worker of the environmental measures taken          east was defined by cutting away the lower two levels of the

by the building and providing delightful decks on which to        perimeter building in favour of a broad diagonal promenade
                                                                  leading to the main entrance.”16
view across the courtyard to the main entrance. view looking back to
the Aegidietorplatz

This cut also creates a visual connection to the semi-private                 The Nord/LB building in Hannover is a winning
courtyard from the Aegidietorplatz and the theatre situated            project.   It successfully implements environmentally
on it, and fosters the idea of an open architecture that the           sensitive measures in a holistic way that more than satisfies
Nord/LB would no doubt like to apply to public thought                 the demanding German building regulations, reduces
about its banking practices. The 17 storey tower with the              energy consumption, and ensures worker comfort. This is
20 metre reflective glass sculpture that adorns it gives the           done a reasonable cost, and creates substantial operating
tower a beacon like quality.          “The structure’s multiple        cost savings. The building projects an image of openness
orientations were intended as a way of connecting it with its          and addresses the various districts that surround it. The
surroundings, so that the Nord/LB wouldn’t seem like it was            entire scheme, including the added expense of the green
turning it back on anyone.”17                                          technology, provides demonstrable gains to the Nord/LB
                                                                       and serves to create a positive image for the company.

1. Architectural Record. February 2003. “High-Tech Tools Give German Engineers Low-Tech Solutions”. Sarah Hart.
Page 128

2. Sarah Hart, page 128

3. Bauwelt. July 5 2002. “Die Norddeutsche Landesbank”. Sebastian Redecke. Page 29 [Translated with OCR and
Google language tools]

4. Sarah Hart, page 128

5. Sarah Hart, page 128

6. Architectural Review. August 2002. “Constructive Urbanity”. Peter Blundell Jones. Page 43

7. Redecke, page 29 [Translated with OCR and Google language tools]

8. “Architecture: Norddeutsche Landesbank” Scholl Glas GmbH.

9. “Norddeutsche Landesbank am Friedrichswall” Architectural Record Construction.

10. “Insulating Glass”. Scholl Glas GmbH.

11. Architectural Record. February 2003. “Norddeutsche Landesbank”. Tracy Metz. Page 137

12. Redecke, page 26 [Translated with OCR and Google language tools]

13. “Perceptual Psychology” Bartenbach Lichtlabor GmbH.
14. “Cost Savings” Transsolar Energietechnik.

15. Redecke, page 27 [Translated with OCR and Google language tools]

16. Jones, page 43

17. Metz, page 125