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The streets of Hamburg: some numbers

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The bloc where our friends live, with an aerial view of the huge courtyard

The bloc where our friends Stephan and Anya live, with an aerial view of the huge courtyard

It’s one thing to say that the feel of Hamburgs’s streets is nice, as I did in my earlier post, but it’s another to quantify it. Here are a few numbers I’ve been able to gather.

Ottensen is a neighbourhood of about 3 km2, with a population density is about 11,300 inhabitants per square kilometer. In contrast, Vancouver as a whole has about half that, at 5,300, while the West End’s is double at 21,800. But there are no towers in Ottensen, only blocks with inner courtyards.

The courtyard of the appartment bloc of our friends Stephan and Anya, where we stayed one weekend, is fully enclosed and nobody can get in without a key. From what I could calculate from Google maps, the bloc occupied by the contiguous buildings has a surface area of about 3.5 hectare (a rectangle of 250 by 140 meters), and the courtyard represents about half of that. A rough count tells me that there are about 250 appartments, so maybe 500 people live there (that represents a density of 13,000 p/km2, so I can’t be too far off). How many kids per hectare of grassy courtyard, I’ve no idea, but we saw quite a few.

A view of the courtyard from the kitchen window of the apartment of our friends

A view of the courtyard from the kitchen window of the apartment of our friends

The nearest subway station, Bahrenfeld S-bahn, is 750 meters away (but there is a bus stop just around the corner). About 1.2 km in the other direction is the subway and main train station of Altona, including a stretch of 200 meters of pedestrian mall. And on the street that leads to that busy, successful pedestrian mall, I counted three small groceries and four cafes or bakeries, as well as a few other little retail shops, including a bike repair and rental. Not bad for a street that is considered residential, not commercial.

The latest stats (2008) show that commuters mostly walk (28%), bike (12%), or use transit (18%). Under one third (31%) use their cars; add to that 11% who get a ride. This is for the whole city, including the far flung areas; the core sees nearly half (46%) of commuters walking or biking.

As for the famous fake brick insulation applied to the outside walls: it is designed to create an additional insulating value of 0.25 W/m2K in the walls, and 1.4 for the windows. This compares to Vancouver’s code for Green Homes Program of 0.26 for walls (R22 in the old units) and 2.0 for windows. (The smaller the number, the better the insulation; pre-renovations, some of the old walls had a value ten times as large, meaning that ten times as much heat left through the walls beforehand. Details on the Hamburg’s climate initiatives can be found here, and examples of building retrofit, with cost information, here.) One design detail that impressed me: many of the old buildings had no balconies, but the upgraded ones do. The balconies are structurally independent from the building. This makes the retrofit easy, but it has another advantage, even in new construction: the thermal envelope is intact as a result. Balconies often act as fins in tower construction, meaning that the inside heat is lost to the outside through the structural steel beams that support them.

Vancouver’s program is great – but it applies to new buildings. Hamburg’s numbers are for old existing buildings; the requirements for new buildings are even more stringent. Despite having one of the more ambitious programs in BC, Vancouver Greenest City still has a ways to go to catch up to Hamburg Green Capital 2011. But there’s no reason we can’t get there.

The fake-brick insulation on the left, a full hand width.

The fake-brick insulation on the left, a full hand width.

An example of added balconies with little thermal bridging to the building itself

An example of added balconies with little thermal bridging to the building itself

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Written by enviropaul

August 21, 2015 at 11:59 am

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