Energy efficiency of programming languages

Servers are taking an ever growing share of our electricity usage. Of course, they exist to run applications. And the energy consumption is, to a large degree, determined by the applications running on them. Ironically, servers turn electricical energy into thermal energy and thus contribute to global warming in a very concrete sense. When I look around, I don’t see a lot of discussion happening around the responsibility of application developers regarding energy usage and the impact this has on climate change.

Website tech update

It was time for several updates. This site is now hosted by Codeberg instead of GitHub, Edit: doesn’t work yet, so for now it’s still GitHub. created using Hugo instead of Jekyll, using a different template/theme. I’m also contributing a few additions to the Hugo theme.

Mit dem Mountainbike auf den Grünten? Nein.

Wer ins Oberallgäu fährt und eine Leidenschaft für das Radfahren mitbringt, wird vielleicht auf die Idee kommen, mit dem Mountainbike auf den Grünten, den “Wächter des Allgäus”, zu fahren. Spoiler: es macht keinen Sinn und ist gefährlich. Mir ging es auch so. Der Grünten ist ein alleinstehender, attraktiver Gipfel und mit 1738 m höher als viele andere Berge in der Umgebung. Außerdem gibt es (außer für Mitarbeiter_innen des Bayerischen Rundfunk) keine Bergbahn.

Gekommen, um zu bleiben: Gründe, jetzt das Fediverse zu betreten

Zuletzt aktualisiert am 22. Juli 2022 In meinem vorigen Beitrag Wir treffen uns im Fediverse habe ich über dezentrale soziale Netzwerke und das Fediverse geschrieben. Verglichen mit den großen, zentralisierten Vorbildern ist das Fediverse im Moment klein. listet noch nicht einmal 3 Mio Accounts. Etwa 500.000 davon waren innerhalb der letzten 30 Tage aktiv. Lohnt es sich da, Zeit zu investieren, sich ein Netzwerk aufzubauen und Tools zu testen? Oder sogar darüber zu reden und andere Menschen, die wir im Fediverse vermissen würden, zum Mitmachen zu überreden?

Wir treffen uns im Fediverse!

Der Jahreswechsel steht an, und damit drei Gründe, sich mit Alternativen für die zentralen sozialen Netzwerke zu befassen: Wir brauchen natürlich einen guten Vorsatz für das neue Jahr (oder eher für die ersten paar Wochen des neuen Jahrs) Wir haben vielleicht ein bisschen Urlaub und Zeit Die Bekanntwerdung des neusten Facebook-Skandals liegt erst wenige Tage zurück Die Facebooks und Twitters können nicht unsere Zukunft sein. Brauchst Du Gründe? Die Macht, die diese Konzerne konzentrieren, ist gefährlich.

ESP8266 publishing DHT temperature and humidity via Web Thing API

After reading through some of the Mozilla IoT examples, I got an ESP8266 to publish temperature and humidity values via the Web Thing API. Here is the code: Link

Zusammen braucht man weniger

Vom (Gedanken-)Experiment des Müllvermeidens zu einer hyperlokalen Tauschplattform für den täglichen Bedarf Language notice: this is a post about how to share resources between neighbours. As I am living in Germany and my neighbours speak German mostly, I feel like I have to write this in German. Eigentlich möchte ich gar nicht erst anfangen, zu erklären, warum. Eigentlich möchte ich einfach voraussetzen, dass wir alle der Meinung sind, dass wir unseren Fußabdruck so klein halten sollten, wie möglich.

Re-claiming my content

Yesterday I was stuck in a commute situation, so I had a rare moment of boredom and reflection and decided to google jekyll microblogging to find out how easy it would be to make my blog fit smaller content chunks. I felt like gathering what I’m emitting on my home turf, at, which is a Jekyll site served by Github Pages. What I found was a great post by Fiona Voss that shows a way to re-claim my content by using my own blog as the center of my conversation in other channels.

Visualizing the Tour de France General Classification Build-Up

The 104th edition of the Tour de France is in full swing. Time to have a look at how the General Classification developed so far. Wait, what? General Who? Tour de WTF? OK, sorry. If you have no interest in the sport of riding bicycles and never heard of the most popular bike race in the world, maybe start with a Wikipedia article. To the rest who knows at least that there is such a thing as the Tour de France, let’s revisit how that race works.

Idea: DIY Sourdough Incubator

The idea of breaking bad baking bread, really good bread, is super-fascinating to me. I got recently amazed by this guy named Lutz Geißler, who seems to be on a mission and already published nearly 800 bread recipes in his blog called Plötzblog. I found him via an episode of the radio show Alles in Butter on local radio WDR5. If you want to find out more about him, bread and his driving forces, check out this lengthy and fascinating talk with him and Tim Pritlove (all in German).

Idea: DIY Sourdough Incubator

December 13, 2016

The idea of breaking bad baking bread, really good bread, is super-fascinating to me. I got recently amazed by this guy named Lutz Geißler, who seems to be on a mission and already published nearly 800 bread recipes in his blog called Plötzblog. I found him via an episode of the radio show Alles in Butter on local radio WDR5. If you want to find out more about him, bread and his driving forces, check out this lengthy and fascinating talk with him and Tim Pritlove (all in German).

The Goal

Inspired to try and bake my own bread, I started setting up a “Sauerteig”, as we call in in German. Because that’s the real thing.

A sourdough is basically a culture of natural yeast fungi and lactic acid bacteria, nurtured by flour and water. I doesn’t require much: the right type of flour (I took rye whole grain), warm water, and a warm place to rest. Then some time, like four to five days. How hard can it be?

The hardest part seems to be the warm place. We have it rather warm in our living room/kitchen, but it’s far below the recommended 30°C (86°F). And our oven has 50°C as a minimal temperature.

I tried creating a sourdough at room temperature, however the result after four days doesn’t convince me. I see some bubbles and I smell some gas, but I don’t see any volume increase or surface elevation. I saw a lot more activity in the dough when I had it in the still warm oven for a couple of hours. But that is hard to maintain for a longer time.

The Solution

So how about an automatic incubator that maintains the right temperature for the sourdough to grow its cultures?

Prior Art

Of course, this has to exist. After a few minutes of research (a.k.a. googling), the terms proof box, proofing box or rising box come up. Wikipedia has an article about the concept and there is a quite informative article on

This brings up issues I haven’t thought of so far. First and foremost: keeping the humidity level, as the dough would otherwise likely dry out on the surface. Second: different temperatures might yield different qualities (as in tastes). Something to keep in mind.

What about DIY solutions?

A simple setup to be found in many places (ex. 1, ex. 2) is this: Take a box, put a light bulb and a thermostat inside, and make the thermostat control the light bulb. Put your bowl of dough and a bowl of water inside.

While this might work well, for me this appears a bit too simple and too “analog” to be fun. And I’m not too thrilled about the 220V (or 110V) circuit in a case together with a water bowl.

The Electric Gardener’s approach is more what I’m after. The solution looks interesting, but there are two things I don’t like so much when looking at it:

It makes use of a 220V lamp to heat the dough (see above). I assume that this generates a much higher temperature on the dough surface than actually required.

Then there is this fan. I have a feeling that there shouldn’t be too much air flow around the dough. At least the instructions I have read recommend covering the dough lightly with some cloth, probably to protect from air flow. I am also worried that too much air exchange would increase the problem of keeping the dough moist.


On a blank sheet of paper, here are my wishes (I don’t dare to call them requirements, as I’m more thinking of it as a moving target):

  • The temperature should be adjustable, to experiment with different settings.
  • Humidity should be measured at least, maybe actively controlled.
  • The dough container should ideally heat up the dough from the bottom and/or from the sides, to heat the greatest possible surface.
  • The heat source should be regulated so that no extra cooling would be required.
  • Only low voltages (say up to 12V) and currents should be required for safety reasons.
  • I want the option to log some data, like temperature, humidity and maybe more. What if we could tell, based on the data, when the dough is ready? Maybe some gas concentration, the conductivity of the dough or something like that will work as a marker? Maybe we can even measure the volume of the dough to tell when it has risen? That’s where the fun starts.

Let’s think

First thoughts:

  • Robust metal container (thinking lathe or mill) with direct heating, plus a temperature sensor in the container wall. Maybe use Peltier element for heating. No idea how I would manufacture this though. Also no idea what metals would be fine for direct contact with dough. And how strong the Peltier element and the current would have to be. Possibly there are ways to calculate that.
  • A terrarium heat mat could work, with a metal or ceramic bowl placed on top. They come in various sizes, with the smallest consuming about 8 Watt and measuring 16 by 23 cm. And they have some protection against humidity.
  • Moisture could be provided via a heated water container next to the dough container, with a common enclosure. The warmer the water, the more water should evaporate. So to maintain a humidity level, the temperature of the water would have to be maintained, independent from the dough. An alert when moisture gets too low would be nice (probably indicating the water bowl is empty).
  • Logging data is the easiest part. A Wemos D1mini (that’s an ESP8266 board I happen to have a spare of) with a few sensors attached will push data to a service like Blynk or something I would run myself.

The Solution

If you want to join the brainstorming, be my guest! If I really come up with something, which depends on time, priorities, and feasibility, I’ll definitely write a follow up.

Update 2016-12-15

I ordered a very small (14 x 15 cm) heat mat which is sold as terrarium equipment. No idea whether it is really useful for that! However I placed a plastic bowl with roughly 280 gram of sourdough on it. With its ~5 Watts (confirmed with a power meter), the mat rose the dough temperature from roughly 25°C to 32°C within a few hours. Bottom line: that seems to be a suitable source of warmth.