All things environmental

Musings about the environment and all it touches, from education to city planning

Ottensen, or how to improve the environmental performance of a heritage district

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Ottensen's main street

Ottensen’s main street

Cities offer the best hope for tackling climate change. New dense developments with energy efficient buildings and short commutes with good public transit, such as Hamburg’s HafenCity, show how it can be done. That’s all well and good, but what about established neighbourhoods? Can their environmental performance be improved without destroying the character that makes them so compelling? I went for a walk in Ottensen to see how Hamburg’s climate initiatives apply in such cases.

Ottensen has the highest population density of all neighbourhoods in Hamburg. It survived the war relatively unscathed, so much of its housing stock, four-story appartments, predates the twentieth century. Until recently a working-class area, it is now highly desirable, with narrow winding streets that lead to the Elbe beach. But it has escaped the worse of gentrification, as it still has some affordable housing, a well integrated immigrant community, even graffiti. But the needs are clear: more housing, and a better environmental performance, is needed. How do you “improve” such an area without ruining it?

I took a look at Bergiusstrasse 24, a 10-appartment complex built in 1994, that the city promotes as a example. At over twenty years of age, the façade of brick building is fully covered in ivy and fits well in its surroundings; you wouldn’t know there’s anything special about this building. But its performance is remarkable: old as it is, it still requires no more than 41 kWh of energy per year per square meter of floor. This is 44% less than the adjacent buildings built during the same time period, and not even a quarter of what older buildings consume.

Bergiusstrasse

Bergiusstrasse.  Number 24 is the one with the ivy (and the “nuclear? no thank you” flags)

The building is heated with natural gas, but there are also 34 m2 of solar collectors on the roof, which supply all of the hot water needs during the summer. Also on the roof is a 20 m3 rainwater tank that provides water for toilet flushing and the communal laundry, leaving enough for the garden in the inner courtyard.

The building relies on think insulation to achieve its environmental performance; back in 1994, using a ventilation heat exchanger was considered a risky, newfangled approach. Instead, residents were asked to keep windows closed as much as possible during the winter; this originally created a huge controversy, to the extent that some of of the original community participants quit the project. As a Canadian, I did a double-take upon learning this, because this is second nature and the request seems so straightforward. But many Germans are used to sleeping with the windows partially open, to let in frische luft.

Resident Monika Bauer, an architect, says: “this turned out to be much ado about nothing. Sure, there are no tilting windows, and windows can’t remain open in winter; but that’s not to say that they can’t be opened to freshen up the air every now and then. I find that letting the thermostat control the temperature, leaving it alone, works best; the rooms are comfortable, and because of the insulation the walls feel warm.”

There are other examples of projects throughout the neighbourhood. Most put priority on housing needs, but renovations mean that better insulation can be incorporated along with the other features. For instance, Kastanienhof, a complex of old buildings on Grosse Rainstrasse 13, has been modernized so that the historic character (and the chestnut trees that give it its name) remains intact; but green roofs have been integrated to the complex.

The courtyard of Kastanienhof: can you tell that this has been renovated?

The courtyard of Kastanienhof: can you tell that this has just been renovated?

Many of these old complexes have an inner courtyard, often smallish and used for parking cars. This presents an opportunity, as in the case of Fette-Höfe, on Spritzenplatz 5. This is a group of old buildings, some with a lovely Jugendstil, or Art Nouveau, façade, facing a small square that hosted a farmer’s market when I visited. In this complex 23 new units were added to the inner court, along with two playgrounds, in 2013. All the new appartments are handicapped-accessible and can accommodate various needs, an important feature since Germany’s population is aging. The additions are a mixture of residential (2850 m2) and work environments (3100 m2), including the small Uli-Cami mosque. The city considers this sort of mix a key to sustainability: by mixing working and residential spaces, commuting is reduced and the mix contributes to the variety and liveability of the neighbourhood.

The roofs of the additions in the Fette-Höfe complex represent large flat surfaces, making it practical to incorporate green roofs in the form of terrasses accessible to the residents. Green roofs are key in such dense neighbourhoods; not only do they contribute to insulate the buildings, they also reduce air pollutants and, mostly, absorb excess rain. Old, dense neighbourhoods are particularly vulnerable to flooding following extreme storms, and pervious surfaces, such as green roofs, help.

farmer's market in front of Fette-Hoefe

Farmer’s market in front of Fette-Hoefe

But it’s not as if the neighbourhood has no green spaces. One of my favourite urban parks there is on Kemal-Altun-Platz, a 0.6 hectare multi-use park on the site of a former factory, Menck&Hambrock. The company used to make backhoes and excavators and had a large presence in Ottensen, with 2000 employees, so the park has an important heritage role. This is outlined in one of the landscaping details: the central play area is shaped like a set of cogwheels, and the park designers placed an old steam excavator near the entrance.

It’s a nice touch, but that’s not why the park is so appealing; rather, what is remarkable is how such a relatively small area can be such an efficient multi-use space. When I visited, there were toddlers playing in an area enclosed by wild-looking bushes, while older kids were helping themselves to a pile of old wood to build a bonfire, apparently unsupervised. There were kids running around and laughing, engaged in what to me look like a completely unstructured game of sorts. Somehow, there was a sense of unrestrained creative play and untamed nature that one would expect in the countryside, not in a small urban park. But despite that – the kids’ area occupies maybe just 150 square meters – the park has room for a playing field, a wall for graffiti, a separate dog area, and a liegewiese, a concept beloved of the Germans: a lawn intended specifically for sun-tanning or just plain lying around.

Does this have any lessons that would apply to Vancouver? At first glance, maybe not, because Vancouver lacks this type of dense, old and established neighbourhood. But then again, it brings to mind Gastown and Yaletown, or downtown New Westminster, or downtown Victoria, where this approach (green roofs and insulation retrofit, repurposed use of historical buildings, community-based decisions) could be adapted nicely.

Kids building a bonfire in Park

Kids building a bonfire in Kemal-Altun-Platz Park

Note: more details, and similar examples, can be found in city documents such as Future, Sustainable and Ecological (in German), Quality Housing Projects (in German), and Hamburg Green Spaces (in English, surprisingly), all downloadable as pdf.

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Written by enviropaul

October 9, 2015 at 7:17 am

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