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

Archive for August 2015

Bremen’s Café Ambiente

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Bremen and its musicians

Bremen and its musicians

A donkey, a dog, a cat and a rooster decide to go to Bremen to make a living as musicians. They chance upon a robbers’ house, deep in the forest, and make such a racket with their “music” that they scare the robbers away. They stay in the house happily ever after. They never make it to Bremen.

That’s pretty much all I knew about Bremen before going there on a day trip from Hamburg.

Bremen is a very pretty city with a core of intact medieval buildings. My guidebook mentioned Café Ambiente as something to visit if interested in renewable energy. They serve beer; we went.

Even in Germany, there used to be women’s groups advocating for the prohibition of alcohol. The building that now houses Café Ambiente was built in 1929 as a home for the movement. A terrasse was added in 1957 (so guests could enjoy their coffee outdoors in summer). But the place fell on hard times as abstinence didn’t fit with post-war Germany and the city bought the place in 1984. In its gorgeous setting on the river shore, the renamed Café Ambiente is known locally as a “literature café” because of its readings by famous authors.


Starting in 1997, the Ministry of the Environment of Bremen chose this café for an energy concept project – a showcase for energy management in the hospitality sector. The change most obvious to customers are the solar cells on the terrasse’s glass roof (also called winter-garden). These produce a nice dappled shade effect, and, of course, a fair bit of power: nine kilowatts during sunny periods. But retrofitting a building that has historical significance isn’t easy: according to the website PV Database,

The PV-System is nicely integrated into the double glazed roof construction of the winter-garden. In total 159 semitransparent PV-Modules are used with a light transmission rate of 45% each. Due to the round shape of the winter-garden it was necessary to produce 20 different size and shapes of PV-modules. The custom made glass-glass PV-modules encapsulate 7270 polycrystalline cells with a total power output of 9,5kWp. The estimated energy output is 5000 kWh per year.

But the €930,000 renos weren’t just about the solar deck; the structure was also fully insulated to modern (German) standards, and that includes all the glass in the covered terrasse.

The kitchen underwent a complete overhaul. Restaurant kitchens have huge energy demands for cooking and refrigeration, which can account to half of a restaurant’s energy bill. The first and obvious step was to fully separate the cold (coolers and freezers) and hot areas (ovens, grills, etc) of the kitchen without impeding the chefs’ movements. In the hot area Café Ambiente is equipped with a pizza oven, a steamer, two ovens, a hot plate and a grill, all using natural gas. These new appliances are state-of-the-art energy efficient, of course; but what makes the real difference is the induction fume hood, which is coupled with a heat exchanger for heat recovery.

The solar cells integrated into the glass roof

The solar cells integrated into the glass roof

In the seating area of a restaurant fresh air must be constantly brought in, so that there are no stagnant odors, to a rate of at least 15 air changes per hour. (To picture what that means in terms of energy needs, imagine completely replacing all the warm air in a room with cold air from outside – and doing that fifteen times every hour.) The kitchen itself produces smells, smoke and heat and requires a lot of fresh air, 30 to 50 air changes per hour.

This is where the heat exchanger comes in: the incoming cold air from outdoors is heated by the exhaust, so as to recover as much heat as possible. This is now a common feature of energy-efficient PassivHaus but is far less common in restaurants, given the size of the heat exchanger required. To ensure that the ventilation rate reflects how busy the restaurant is, an indoor air CO2 meter is used, so that only as much fresh air as needed is brought in (the more people inside, the higher the CO2). As a result the heating energy required to keep the restaurant warm is reduced by between 50 and 80%; think of it as recycling the heat from the ovens to keep the rooms warm.

Heat exchangers are also used to reduce the energy needed to heat the water for washing and dishwashing, which is stored in two separate tanks, again for saving energy. Add to that energy efficient lighting, and the overall yearly savings in avoided CO2 emissions are about 30 tonnes per year.

Every chef's dream...

Every chef’s dream…

Which may not seem like a lot, overall; the EPA uses a figure of 4.7 tonnes of CO2 per year for one average car. Still, here is one single restaurant that has managed to reduce its emissions to the equivalent of six fewer cars.

More details and many photos can be found in the brochure entitled “Environmentally-friendly gastronomy” (Umweltfreundliche Gastronomie, in German only), which also describe the energy upgrades of Café Sand across the Weser River; or on the site of the State of Bremen’s electricity company, Energie-Konsens (also in German only, alas).

Written by enviropaul

August 29, 2015 at 12:42 am

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

Written by enviropaul

August 21, 2015 at 11:59 am

The streets of Hamburg

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Now settled in Germany, ensconced in a nice little appartment for a few months – time to get back to blogging. I have pledged to document German environmental success stories.

Why Hamburg? Dinah, of course. I’ve been coming here with her visiting family and friends, and gradually I have to come to discover that the nice European lifestyle that enthralls tourists is also something that holds hope for the environment (yes, sitting at a patio, beer in hand, I do think serious thoughts sometimes). And Hamburg is a case in point. So let’s start with Dinah’s story, then.

Griegstrasse in Ottensen, where Dinah grew up.

Griegstrasse in Ottensen, where Dinah grew up.

The Ottensen area of Hamburg is where Dinah grew up, in one of the typical appartment blocs that make up the urban landscape here. Most of these blocs have an inner courtyard, usually with an expanse of grass and trees, and they are large enough for an army of kids to run around. Now a long-term Vancouver resident, Dinah finds it hard to understand why people insist that they need a house in the suburbs to raise their kids. Her experience was just the opposite. She remembers playing outside in the yard, unsupervised, even at a young age. There would always be someone around, other kids, somebody’s mother or Oma, somebody to keep an eye on things. And no stranger could enter the inner courtyard unnoticed.

She also remembers walking everywhere, to school, to parks, even to the nearby beach on the Elbe river (with her Oma, that). Walking everywhere was made possible by the density of the neighbourhood; there were many well-attended parks, schools, and shops nearby precisely because the population density created by these appartments made such amenities practical. For that matter, the ground floor of the appartment blocks themselves often had shops like a dentist’s office, a jewelry, or the obiquitous bakery. This mix of retail and residential gives an open, welcoming feeling to the streets, adding to the density of amenities and contributing to community safety through Jane Jacobs’ vaunted “eyes on the street”.

For Dinah it was a bit of a letdown to land in a Canadian suburb (DDO, now part of Montreal) as a nine year old. Sure, there was a nice little park behind the bungalow; but there was nowhere to walk to. Everything of potential interest was just too far; and few of the adults walked anywhere, for that matter. As for transit, forget it.

A few weeks ago we spent a weekend at some friends’ place, who happen to live in the Ottensen neighbourhood where she grew up. Going for my morning coffee, I notice that this is still a walking neighbourhood, even if the streets are now lined with parked BMWs or Opels. One Monday morning around 8am, I count three pedestrians and two cyclists for every car I encounter. People here walk or cycle more than in Vancouver; it is just more practical to do so. There’s always a bus or train station nearby. As a result, only 31% of commuters use their car – that, for the whole city, not just the centre. From a climate change standpoint, this is one of the great advantages of density: far fewer emissions per capita for transportation.

We talked to a woman renting an appartment in Dinah’s old building. She said it was extensively renovated two years ago: insulation and new energy efficient windows were installed, as well as balconies, through Hamburg’s climate initiatives. She said that it made a big change in comfort; and in winter, she barely needs to heat the place once or twice a week. And the insulation was added from the outside; the tenants could stay in their appartments during the renovations. You need to look closely to notice the renos: the insulation has a faux-red brick pattern, so as to fit with the existing architecture of the city.

Preserving a large bank of affordable rental housing has also been a priority for the city (about 30% of all housing stock in the city has a form low rent, whether co-ops or city-owned; about one third of the new build appartments have subsidized rent), and in many cases the appartments targeted for energy efficiency retrofit are the ones with rent control. The city government has made it clear that energy efficiency programs cannot be at the expense of its poorer residents.

The other thing about the neighbourhood is that it feels right. It dawns on me that part of the appeal of European cities is not just the historical aspect

Walking down an ordinary street in Ottensen

Walking down an ordinary street in Ottensen

of the old buildings; it is the proportions. These buildings are all four stories tall, and the treed streets are wide but not overly so. Art historians tell us that landscapes are about prospect and refuge: we are hard-wired to want to see what’s coming, but we also want a sense of shelter and protection. The proportions of these streets seem to hit just the right harmony between prospect and refuge, what we call human-scaled. Commercial Street is one of my favourite Vancouver street, and now I realize it’s because it has the same proportions.

Are there lessons for Vancouver here? The Hamburg mid-rise appartments with inner courtyards could be a model for liveable, high-density development; and it is clear that such complexes can be highly energy efficient. And these buildings lend themselves very well to affordable housing programs (I’ll leave that for another post).

When Dinah was growing up, her Opa would go to the basement to fetch the coal needed for heat and hot water; daily showers were unheard of. Then, as the “German miracle” reached everyone, the building saw its first set of renovations, with central heating and hot water, eventually connecting to the more efficient district heating. And now, with this latest round of renovations, it barely requires any energy, and the tenants are comfy. Germans seem to welcome change, and government leadership. Vancouverites, well…

Written by enviropaul

August 21, 2015 at 9:36 am