Page 108 - AIT0720_E-Paper

WOHNEN • LIVING INNERE WERTE • INNER VALUES

Schnittstellen zwischen alt und neu machen die Umnutzung des Bestandes sowohl innen als auch außen deutlich. • Intersections emphasize the conversion of the building stock inside as well as outside.

I t almost seems as if the Frieda Ottensen bunker wants to hide. It is situated behind original façade remains visible on the ground floor. To respond to the clients’ request
for an ecological energy supply, the heating demand is met by a heat pump operated
a row of stately houses from Wilhelminian time in a backyard of the popular Ham-
burg city district of Ottensen. Frieda – as the residents lovingly call their home – is with green power. A solar ice-storage tank serves as the seasonal energy storage for
surrounded by a district-typical structure of industrial and private backyards. In this operating the heat pump and offers the possibility of cooling the building during the
densely developed setting, even the concrete monolith constructed in 1942, which summer. The energy efficiency is additionally improved by the heat recovery from
formerly offered protection for up to 700 people, only stands out due to its impres- the exhaust air of the flats. The historic concrete outer walls were complemented on
sive height. Like numerous other buildings of this kind, for decades Frieda was also the inside with a structure tailored to the new function. A staircase with an elevator
exposed to decay and a long period of vacancy. The history of these buildings is far as well as weight-bearing walls and ceilings of non-plastered concrete link the total
too negatively afflicted, their external appearance is too sealed-off and forbidding. of seven storeys. Whereas, on the ground floor, there is space for car and bicycle par-
However, the urban location in one of Hamburg’s oldest districts makes Frieda ne- king, on the other six levels are flats measuring 44 to 127 square metres.
vertheless very attractive for a conversion. When the government decided to put the
high-rise bunker along Friedensallee on the market, some of the residents seized the Open, individually designed layouts
opportunity. To avoid watching random changes in front of their own homes, they
rounded up additional residents, friends and parents, founded a property-develop- For developing the sizes of the flats, flexibility was above all important. Some of the
ment association, made an offer and won the bid at the end of 2013. After a long residential units can be separated or combined and are able to react to the changing
planning period, with the help of the architect Björn Liese from Hamburg the con- life circumstances of the residents. A constancy regarding the group of residents com-
version began in 2016 with the goal of creating functional and flexible housing. Par- posed of renters and owners is thus achieved. The layouts of the flats are indivi-
ticularly important was not only to preserve the historic character of the building dually designed but they are all characterized by openness. Sufficient daylight is thus
but, above all, the development of a future-oriented energy concept. available even in the inside areas due to the depth of the bunker. The hallways si-
tuated in line with the windows can also be illuminated in this way. Thanks to the
A challenge: cutting open the concrete colossus incisions in the façade, new living space is produced which is located in the very
massive outer walls and is used in a variety of ways. French balconies, small loggias,
To make it possible to turn the high-rise bunker into a residential building, first the added balconies or the allocation to the interior are possible thanks to the differing
inside had to be completely gutted. Old storey ceilings and room divisions made way reveal depths of the window openings. That this construction project is shared by a
for a new building structure which was to be implemented in the empty shell. Par- collective is also reflected in the room programme. Areas such as the newly designed
allel to this, the massive façade with a depth of 110 centimetres on three sides of the roof terrace, the hobby room on the first floor or the backyard complement the pri-
building had to be cut open in order to allow daylight to penetrate the interior. The vate flats and are equally accessible for all the residents. Above all the roof terrace
heavy demolition- and conversion works were a major challenge due to the cramped of the building which noticeably towers over the surrounding development is com-
conditions of the backyard location and a not secured development. In coordination monly used and maintained and has thus become a highlight. Inside as well as on
with the residents, the construction burdens and neighbourly consents, the almost the outer skin, details become visible again and again in several spots which refer
impossible venture finally succeeded: It was possible to open up the façade of the to the original building. The building stock and the results of the conversion show in
concrete colossus. After the difficult demolition works followed the energetic impro- a variety of forms – in demolition traces and rough outer walls. The former bunker
vement of the building envelope. Starting with the first upper level, the bunker was thus remains perceptible and, after the conversion, now shows itself from a new,
given a thermally insulated façade with a mineral, grey coat of paint, whereas the open and friendly angle.

108 • AIT 7/8.2020