alpbacher architekturgespräche 2003 - ATP

ground.The key categories are greenhouse effect, acidification, resource use and the warming effect
- four categories which are related to the use of fossil fuels. I would like to speak more of the energy
content of building materials. One thousand kilograms of timber use as much energy as ten kilograms
of aluminium (fig. 3).As you can see, with 1000KWH of thermal energy one could manufacture 500kg
of brick, 400kg of cement, 250kg of plastic, 60kg of steel or just 12kg of aluminium. One should be
careful about using such energy intensive building materials.Think of Otto Wagner who used aluminium
in the office of the Governor of the Sparkasse instead of a “more expensive” material.
Timber Construction as Resource-Saving New-Build
I will use a project of mine to illustrate the concept of ecological building materials in practice.The
Police Sports Club in Vienna is (almost) a new build project on the banks of the Danube (fig. 4, 5). Of
the previous inter war building we could only reuse the steps leading down to the river and the
foundations.The bowling alley from the previous building was roofed over and integrated into our
building. Here, you can see a two storey timber construction – one of Vienna’s biggest as the city
doesn’t have very many.The building is constructed of untreated larch and, in line with the concept
of low energy construction; natural building materials with a low energy use were used throughout.
Such materials are also easier to dispose of at the moment of demolition – as the timber is untreated
it can for example simply be burnt or reused.
The Material Concept versus the Resources concept: The basic energy statistics of buildings
are crucial.This table shows the general Austrian building stock (230 kWh/m 2 a); construction in line
with today’s regulations (115 kWh/m 2 a - in Austria we have the absurd situation – against which architects
organisations have fought for years - that we have nine different sets of building regulations); a
low-energy house (70 kWh/m 2 a), and a passive energy house (15 kWh/m 2 a) (fig. 6).
The quantity of energy that a building requires during its lifetime is many times that required for construction
and removal. For houses built in line with European standards (115 kWh/m 2 a) this figure is nine
times but for low energy houses (70 kWh/m 2 a) this is reduced to five times and with passive houses
(15 kWh/m 2 a) the energy use in construction and during an eighty year life are the same. A lifecycle
analysis of a passive energy house points to five times less energy use than a house built to the usual
building standards.These demonstrate both huge differences and a highly developed technology that is
yet to be fully implemented.When looking at primary energy input and life cycle analyses for a typical
new house we see that 8% of energy goes into construction, 2% into demolition and 90% into operating
the house across its 80 years life. For an energy saving house (which is a poor type of low energy
house, the figures are 16% for construction and demolition against 84% for operating, but with a passive
house the figures are 32% construction, 18% demolition and 50% operation.This is the most sensible
approach.We have even heard today of zero-energy houses with no net energy use (fig. 7).
I have brought a couple of publications.The 2002 World Congress of the UIA in Berlin had the title
“Resource Architecture” 1 Amongst the ten questions of the Congress manifesto was the question
“How can the ecological costs and global effects of the built environment be more recognised in the
economics of building”. One idea is to couple a building permit with a requirement to return a site
to its natural state, coupled with a financial guarantee covering the costs of this.This would in practice
mean putting 20% of the construction costs into trust for the next fifty or a hundred years.The
approach is of course far from reality but it is going in the right direction and would certainly be
cheaper than fighting expensive wars over energy or water.
Reconstruction rather than New-Build: New Build is a problem for the environment – especially
new building as we generally do it today. It is far more important to renew the existing building
stock.This diagram shows horizontally the lifespan of a building and vertically its value over time. (fig.
8). A building can be valued by its original worth and also by the measures required to keep it in
condition. Normally, a building will decay and, at a certain moment, be ripe for demolition. Of course
one can constantly invest but, in reality, investments are periodic (window replacement, façade and
roof renovation). After a certain time comes the question of whether the building still fulfils its use
and, if not, it should be renewed. Old buildings should, wherever possible, be retained.The most beautiful
works of architecture are often renovations of old buildings - Look at Palladio´s Market Hall in
Vicenza which is, in reality, a reused gothic building, or the many churches (such as Heiligenkreuz or
the Franziskanerkirche in Salzburg) which combine a Romanesque nave and gothic choir. Reconstruction
was for centuries the normal approach – right up to the point at which technology made
transport and demolition cheap.Today it is much cheaper to demolish and start again than to look at
creative ways of reusing old buildings.This is a cultural problem inherent to our building industry.The
target should be to reconstruct with environmental protection and added value in mind.The result
is often an interesting building which has the best of old and new. I refer also to the book “Modernising
old Buildings” which highlights examples of aesthetically and ecologically successful new buildings. 2
Here is a school reconstruction project in Vienna (fig. 9, 10). In this district there was no suitable site
for a new school.The project required a threefold increase in the useable area of the school plus the
construction of a new gymnasium. It was also important to us to keep the perfect proportions of the
old classrooms. We developed the basement as well as the street area in front of the school, under
which we built the library and music rooms. Good light is reflected off the facade of the school
buildings. Despite the high density we were able to create a modern school building with generous
well-lit rooms.All new elements were conceived as light and transparent in contrast with the existing
building. Here we see the building on props as high pressure concrete columns are laid.These formed
the foundations for the new building as well as creating the opportunity to reconstruct the basement
walls. Naturally we also developed the roofspace.The staircase had also to be appropriately underpinned
and extended both down and up. Here you also see how the old staircase was extended into
the roofspace. Such an approach is much more economical than demolition and also much easier to
realise in a dense urban area.There is also a cultural reinterpretation of the existing built stock.This
brings to an end my comments on reconstruction versus new build and on the resource concept for
building materials.
Resources for the Operation of Buildings: The second part of my talk will look at operating
resources. Bearing in mind global thinking regarding the disappearance of our natural resources, it is
especially important to address energy and water use in the operation of a building.
Water: If we start with the resource of water there are so many possibilities - from the targeted
use of drinking water to the use of “dirty” water for WCs and gardens etc.This could be filtered
rainwater from cisterns, water from groundwater wells or lightly recycled waste water.
Here is the housing project Osramgründe in Vienna’s Alterlaa, a 514 unit development where, for the
first time in the world, recycled “grey” water was used in a residential project (fig. 11, 12). As part of
a solar building concept the facades were positioned as far forwards as possible out of the shadow
of the Alterlaa apartment towers.A solar building concept can be either loss reducing (minimal transmission)
or gain-maximising (solar heating).These south-facing volumes are gain-maximising and the
east-west blocks, with a large glass roofed circulation, are loss-minimising.The orientation of the ninestorey
block has created a south-facing climatically interesting area which, from the very earliest wind
tunnel tests, could be seen to have a very positive effect.The ensemble is completed by four fourstorey
“villa” blocks and three kindergarten elements gathered around courtyards.The solar building
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