Random Things I Have Learned from My Web Development Project

It’s nearly done (previous episode here).

I have copied all the content from my personal websites, painstakingly disentangling snippets of different ‘posts’ that were physically contained in the same ‘web page’, re-assigning existing images to them, adding tags, consolidating information that was stored in different places. Raking the Virtual Zen Garden – again.

New website: A 'post.'

Draft of the layout, showing a ‘post’. Left and right pane vanish in responsive fashion if the screen gets too small.

… Nothing you have not seen in more elaborate fashion elsewhere. For me the pleasure is in creating the whole thing bottom up not using existing frameworks, content management systems or templates – requiring an FTP client and a text editor only.

I spent a lot of time on designing my redirect strategy. For historical reasons, all my sites use the same virtual web server. Different sites have been separated just by different virtual directories. So in order to display the e-stangl.at content as one stand-alone website, a viewer accessing e-stangl.at is redirected to e-stangl.at/e/. This means that entering [personal.at]/[business] would result in showing the business content at the personal URL. In order to prevent this, the main page generation script used checks for the virtual directory and redirects ‘bottom-up’ to [business.at]/[business].

In the future, I am going to use a new hostname for my website. In addition, I want to have the option to migrate only some applications while keeping the others tied to the old ASP scripts temporarily. This means more redirect logic, especially as I want to test all the redirects. I have a non-public test site on the same server, but I have never tested redirects as it means creating loads of test host names; but due to the complexity of redirects to come I added names like wwwdummy for every domain, redirecting to my new main test host name, in the same way as the www URLs would redirect to my new public host name.

And lest we forget I am obsessed with keeping old URLs working. I don’t like it if websites are migrated to a new content management system, changing all the URLs. As I mentioned before, I already use ASP.NET Routing for having nice URLs with the new site: A request for /en/2014/10/29/some-post-title does not access a physical folder but the ‘flat-file database engine’ I wrote from scratch will search for the proper content text file based on a SQL string handed to it, retrieve attributes from both file name and file content, and display HTML content and attributes like title and thumbnail image properly.

New website: Flat-file database.

Flat-file database: Two folders, ‘pages’ and ‘posts’. Post file names include creation date, short relative URL and category. Using the ascx extension (actually for .NET ‘user controls’) as the web server will not return these files directly but respond with 404. No need to tweak permissions.

The top menu, the tag cloud, the yearly/monthly/daily archives, the list of posts on the Home page, XML RSS Feed and XML sitemap  are also created by querying these sets of files.

New web site: File / database entry

File representing a post: Upper half – meta tags and attributes, lower half – after attribute ‘content’: Actual content in plain HTML.

Now I want to redirect from the old .asp files (to be deleted from the server at some point in the future) to these nice URLs. My preferred solution for this class of redirects is using a rewrite map hard-coded in the web server’s config file. From my spreadsheet documentation of the 1:n relation of old ASP pages to new ‘posts’ I have automatically created the XML tags to be inserted in the ‘rewrite map’.

Now the boring part is over and I scared everybody off (But just in case you can find more technical information on the last update on the English version of the old new website, e.g. here) …

… I come up with my grand insights, click-bait X-Things-You-Need-To-Know-About-Seomthing-You-Should-Not-Do-and-Could-Not-Care-Less-Style:

It is sometimes painful to read really old content, like articles, manifestos and speeches from the last century. Yet I don’t hide or change anything.

After all, this is perhaps the point of such a website. I did not go online for the interaction (of social networks, clicks, likes, comments). Putting your thoughts out there, on the internet that does never forget, is like publishing a book you cannot un-publish. It is about holding yourself accountable and aiming at self-consistency.

I am not a visual person. If I would have been more courageous I’d use plain Courier New without formatting and images. Just for the fun of it, I tested adding dedicated images to each post and creating thumbnails from them – and I admit it adds to the content. Disturbing, that is!

I truly love software development. After a day of ‘professional’ software development (simulations re physics and engineering) I am still happy to plunge into this personal web development project. I realized programming is one of the few occupations that was part of any job I ever had. Years ago, soul-searching and preparing for the next career change, I rather figured the main common feature was teaching and know-how transfer – workshops and acedemic lectures etc. But I am relieved I gave that up; perhaps I just tried to live up to the expected ideal of the techie who will finally turn to a more managerial or at least ‘social’ role.

You can always find perfect rationales for irrational projects: Our web server had been hacked last year (ASP pages with spammy links put into some folders) and from backlinks in the network of spammy links I conclude that classical ASP pages had been targeted. My web server was then hosted on Windows 2003, as this time still fully supported. I made use of Parent Paths (../ relative URLs) which might have eased the hack. Now I am migrating to ASP.NET with the goal to turn off Classical ASP completely, and I already got rid of the Parent Paths requirement by editing the existing pages.

This website and my obsession with keeping the old stuff intact reflects my appreciation of The ExistingBeing Creative With What You Have. Re-using my old images and articles feels like re-using our cellar as a water tank. Both of which are passions I might not share with too many people.

My websites had been an experiment in compartmentalizing my thinking and writing – ‘Personal’, ‘Science’, ‘Weird’, at the very beginning the latter two were authored pseudonymously – briefly. My wordpress.com blog has been one quick shot at Grand Unified Theory of my Blogging, and I could not prevent my personal websites to become more an more intertwined, too, in the past years. So finally both do reflect my reluctance of separating my personal and professional self.

My website is self-indulgent – in content and in meta-content. I realize that the technical features I have added are exactly what I need to browse my own stuff for myself, not necessarily what readers might expect or what is considered standard practice. One example is my preference for a three-pane design, and for that infinite (no dropdown-menu) archive.

New website: Category page.

Nothing slows a website down like social media integration. My text file management is for sure not the epitome of efficient programming, but I was flabbergasted by how fast it was to display nearly 150 posts at once – compared to the endless sending back and forth questionable stuff between social networks, tracking, and ad sites (watch the status bar!).

However, this gives me some ideas about the purpose of this blog versus the purpose of my website. Here, on the WordPress.com blog, I feel more challenged to write self-contained, complete, edited, shareable (?) articles – often based on extensive research and consolidation of our original(*) data (OK, there are exceptions, such as this post), whereas the personal website is more of a container of drafts and personal announcements. This also explains why the technical sections of my personal websites contain rather collections of links than full articles.

(*)Which is why I totally use my subversive sense of humour and turn into a nitpicking furious submitter of copyright complaints if somebody steals my articles published here, on the blog. However, I wonder how I’d react if somebody infringed my rights as the ‘web artist’ featured on subversiv.at.

Since 15 years I spent a lot of time on (re-)organizing and categorizing my content. This blog has also been part of this initiative. That re-organization is what I like websites and blogs for – a place to play with structure and content, and their relationship. Again, doing this in public makes me holding myself accountable

Categories are weird – I believe they can only be done right with hindsight. Now all my websites, blogs, and social media profiles eventually use the same categories which have evolved naturally and are very unlike what I might have planned ‘theoretically’.

Structure should be light-weight. I started my websites with the idea of first and second level ‘menu’s and hardly any emphasis on time stamps. But your own persona and your ideas seem to be moving targets. I started commenting on my old articles, correcting or amending what I said (as I don’t delete, see above). subversiv.at has been my Art-from-the-Scrapyard-Weird-Experiments playground, before and in addition to the Art category here and over there I enjoyed commenting in English on German articles and vice versa. But the Temporal Structure, the Arrow of Time was stronger; so I finally made the structure more blog-like.

Curated lists … were most often just ‘posts’. I started collecting links, like resources for specific topics or my own posts written elsewhere, but after some time I did not considered them so useful any more. Perhaps somebody noticed that I have mothballed and hidden my Reading list and Physics Resources here (the latter moved to my ‘science site’ radices.net – URLs do still work of course). Again: The arrow of time wins!

I loved and I cursed the bilingual nature of all my sites. Cursed, because the old structure made it too obvious when the counter-part in the other language was ‘missing’; so it felt like a translation assignment. However, I don’t like translations. I am actually not even capable to really translate the spirit of my own posts. Sometimes I feel like writing in English, sometimes I feel like writing in German. Some days or weeks or months later I feel like reflecting in the same ideas, using the other language. Now I came up with that loose connection of an English and German article, referencing each other via a meta attribute, which results in an unobtrusive URL pointing to the other version.

Quantitative analysis helps to correct distorted views. I thought I wrote ‘so much’. But the tangle of posts and pages in the old sites obscured that actually the content translates to only 138 posts in German and 78 in English. Actually, I wrote in bursts, typically immediately before and after an important change, and the first main burst 2004/2005 was German-only. I think the numbers would have been higher had I given up on the menu-based approach earlier, and rather written a new, updated ‘post’ instead of adding infinitesimal amendments to the existing pseudo-static pages.

Analysing my own process of analysing puts me into this detached mode of thinking. I have shielded myself from social media timelines in the past weeks and tinkered with articles, content written long before somebody could have ‘shared’ it. I feel that it motivates me again to not care about things like word count (too long), target groups (weird mixture of armchair web psychology and technical content), and shareability.

Cistern-Based Heat Pump – Research Done in 1993

One of the most recent search terms on this blog was: ‘cistern for water source heat pump’. I wanted to double-check and searched for this phrase myself.

This was the first Google Search result:

Cistern-Based Water-Source Heat Pump System Design

… a research paper that had been available for download at the website of Iowa Energy Center at iowaenergycenter.org/wp-content/uploads/2017/02/94S-01_Van-Gaalen-Final-Report.pdf [*].

Cistern-Based Water-Source Heat Pump System Design, 1993


A considerable amount of research has been done regarding ground loop heat pump systems which are underground piping networks that extract heat from or dissipate heat to the ground and are coupled with a ground-source heat pump to greatly increase efficiencies for the heating and cooling cycles of the heat pump. The high costs incurred by home owners for installation of such a system is currently a deterrent to their implementation. This paper explores the feasibility of utilizing a submerged concrete water storage vessel, known as a cistern, as a cost effective alternative for storing and transferring geothermal energy for ground-source heat pump systems.

This work was been done as early as in 1993! The authors did theoretical modelling of the expected heat transfer, built a prototype connected to a home, and monitored performance for some weeks.

[For European readers – you will need this: www.unitconversion.org.]

They built a working prototype which resembles our heat pump system in some aspects – but there is one essential difference: They did not use a solar / air collector as they considered its contribution not essential. Experiments were done in spring, and future performance monitoring for a whole season had been announced in the paper. But the document was called a final report – so I assume the follow-up project had not been started.

Re-use existing infrastructure: Thousands of cisterns in the midwestern sector of the United States were built about 100 years ago. They were abandoned when home owners got access to running water. It seems that most of these vessels are still in good shape if filled with water all the time. Untapped potential!
We have re-purposed our useless root cellar, and we work with clients who want to re-use cesspits or cisterns. Here is an American home owner’s photo story on her slightly creepy cistern, and from this article I learned those cisterns are often located under the porch – exactly the idea we have come up with when thinking about heat sources.

Kenworthy Hall Kitchen and Cistern

Cistern in Alabama (Wikimedia).

DIY approach: Adams et al. provide a detailed information on prices and services required and they suggest that home owners could install it themselves. Re-purposing an existing vessel is more economic than building any of the standard heat sources – slinky-type ground source collectors, boreholes, or ground-water wells. This is still true today.
The authors said they had already several requests from local home owners who were interested in installing a pilot system.

Historic American Buildings Survey Lester Jones, Photographer February 28, 1940 CISTERN DETAIL AT REAR OF HOUSE - Lemee House, 310 Jefferson Street, Natchitoches, Natchitoches HABS LA,35-NATCH,6-4

Cistern in Louisiana (Wikimedia).

The pilot home’s floor space was about 60 m2 (640 ft2). The research paper includes a detailed home energy audit, similar to the one home owners need to provide when building or selling a house today in Austria. The design heating load – calculated from the building’s heat losses and the difference between the standard room temperature and the minimum ambient temperature – was about 7,6 kW (25.900 Btu/hour).
Since the test site was at 43° latitude, so 5° south to my home village, I suppose the climate is not extremely different or perhaps milder. Here the minimum daily ambient temperatures are about -13°C. In the past 20 years we have encountered this temperature on a single day; so this is a worst case estimate and the typical heating load in winter is much lower. Heating loads are used for comparing building standards, and the heating load is quite high given the small area. A modern insulated building with a 8 kW heating load would be 3 or 4 times larger. Those 8 kW accidentally match our theoretical load (for about 185m2 floor space) – so the size of the heat source should be comparable.

Photocopy of photograph (from Iowa State University Library, Special Collections) Photographer unknown ca. 1911-1926 SOUTH FRONT AND WEST SIDE - Iowa State University, Farm House HABS IOWA,85-AMES,2-5

I wondered how historical buildings in Iowa look like. This farm house is today situated on the campus of Iowa State University (Wikimedia).

The available cistern had a volume of 4200 gallons / 16m3 – this is about the right size for a house with 8 kW of heat losses. The authors state that the pilot building could be heated for 21 days, based on an heat extraction power of 9.000 Btu/hour. This is based on a heating power of a ton (3,5 kW) which is less then half of the design load. I think this is the heat load obtained from their experiment – venting the house to ambient temperature in early April.

The latent heat of water is 92,7 kWh/m3 so about 1.400 kWh can be gained in total. At an worst case load of 7,6 kW and a heat pump’s coefficient of performance  of 4, those 1400 kWh would be depleted after 246 hours, that is about 10 days. This is still not a bad value, and you would rather use some emergency heating system (electrical or stove) than building a bigger tank.

Heat pump and heat distribution: The heating system used in this project was a water-air heat pump; the paper contains calculation of the detailed design of the ductwork. The source side of the system is similar to any other water-source heat pump. This seems to be the successor product family.
Heat is transferred by a solution 20% polypropylene glycol in water, providing frost resistance for temperatures greater than -20 F (-11°C). The target side is an air ventilation system – rather uncommon in Austria as here we use mainly floor heating loops.

It was planned to use the ice or cold water created in winter for cooling in summer. This is the same idea we use – it is an added value you get for free as long as you don’t cool the floor below the dew point.

Adams et al.’s heat exchanger used in the cistern was made from copper. They calculated heat transfer for copper pipes versus PE plastic pipes (p.91/92 of the PDF) – and the length of copper pipes would be about 1/3 to 1/4 of plastic pipes. We have picked plastic pipes as they allow for rather easy and flexible installation – and perhaps for future 3D printing of the design :-)

Water to Air Heat Pump

Water to Air Heat Pump – bigger than water-to-water heat pumps.

Theoretical modelling of heat transfer and size of the heat source: Adams et al. have made an estimate of the heat flow from ground to their cistern. Their goal was to evaluate if an underground vessel would be sufficient as a single heat source. They also wondered if the surface area of the cistern could be compared with the surface area of typical vertical heat exchanger ground loops.

They calculated the steady-state heat flow between a cylinder and the surrounding ground, taking into account the heat conductance of the materials and a assuming a constant temperature difference of 15 F (8°C). Their calculated flow is of the same order of magnitude as the heat extracted from the source in their experiments (done in April). As the authors said, this is a very rough first estimate, and calculations are tedious and involve large uncertainties.

We did a numerical simulation of the dynamic change of the temperature distribution in ground, based on weather data gathered at least every hour. Calculating the dynamic heat flow from the temperature gradient at the interface between tank and ground results in a lower heat transfer – in agreement with our own experiments that now cover two full seasons. Thus ground should not be over-estimated – the power ‘released’ by ground on average is about half of the ballpark numbers used for geothermal ground loops.

Unterirdische Zisterne

The pilot system described in the paper uses a cylindrical cistern – perhaps similar to modern ones, such as this (Wikimedia).

Solar collector versus ground energy: Heat transfer from ground is relevant, so one must not insulate the tank. But the main contribution to the net flow to our tank originates from the solar / air collector. The tank is a buffer that bridges periods of time when the average ambient temperature is much below 0°C. Its direct contribution per interface area should not be compared to the heat exchanger loops’ surface area – it is lower than the typical heat transfer rate per area of ground harvested via ground loops (~20W/m2).

The solar collector was also dismissed for economic reasons – the authors of the 1993 papers calculated a payback time of 18 years. I was not able to identify the collector based on the brand name in the paper. The 1990s have been the golden era of DIY flat plate solar collectors in Austria – the time before companies had manufactured off-the-shelf products. In 2012 Austria is worldwide no. 2 terms of installed solar collector area per inhabitants – and is in top 8 even in absolute numbers, see p.12 of this report. I had once figured flat plat collectors are cheaper than evacuated vacuum tube collectors – but the latter are actually more popular in China. This report also shows that unglazed collectors are quite popular in the US. I wonder if Adams et al. had actually evaluated the same type of ribbed pipe collector we have picked because of superior heat transfer properties, and if such collectors had been considered too expensive in the US 20 years ago.

Monitoring and some adventures: The authors used a pragmatic approach I liked a lot: Do some theoretical estimates first to get a feeling for the numbers, and to evaluate the feasibility … then build a prototype and monitor it closely.
They used an Apple 2 computer for data acquisition, not so different from our first Mac SE. In some sense it is a good thing that they overestimated the contribution from ground as they might not have built the system otherwise.

Apple II plus

Apple II plus (Wikimedia)

This is an academic paper but the authors included some ‘tales from the field’, fighting with fluctuating output of sensors and …

To add to our problems, in trying to fix temperature transducers in the tank, we had left the tank open without water too long during a wet spell, and the tank wall broke [#] in due to the pressure difference between the tank and the ground. We tried to patch it the best we could (a novel could be written on this experience), and filled it with water again. However, the tank continued to leak and we had to continue to add water to it to maintain a desired level in the tank.

[#] I was surprised that wall if this cistern was just an inch thick – much thinner than modern rain water cisterns.

They factored in this unplanned addition of water – adding another Basic program (I wax nostalgic about the code listings in the paper!) that evaluates the balance of heat energy.

So in summary: Kudos to those pioneer engineers! If anybody reading this knows anything about follow-up projects done in Iowa in the 1990s, let met know! I haven’t researched the Iowa climate in detail. I cannot rule out that their heat source might have performed better than expected from experiments in middle Europe but I would be surprise if this cistern without a solar collector would have sustained a whole heating season.

I’d finally add our own schematic drawing again for comparison. The pilot system described in the 1993 paper does not user hot water tanks, and heating of hot tap water is not covered.

punktwissen heat pump system, water tank and solar collector as heat source

Our own system, built in 2012. Components also used in the experiment in 1993: Cistern as water tank, water-air-heat pumps, ductwork directly attached to it instead of buffer and hot water tank. More details in this post.


[*] After a migration to a new domain in 2018 the document is not available anymore. I’ve also contacted the owners of the new site iowaeconomicdevelopment.com who have confirmed this.

“Being Creative with What Is Available”

This is a quote from Simon Dale’s website who has built several eco-friendly ‘Hobbit’ houses. It reminded me of the cave house built into lava bubbles by Lanzarote’s most famous artist César Manrique:

Lava bubble room, César Manrique foundation.

This is very a truly 1970s living room – a ‘The Flintstones’ experience on many levels. (Image: mine)

Being creative with what is available has an appeal beyond economical necessities.

As a teenage hobby astronomer I built a mounting for my small telescope from pieces of wood and metal I found at home. It allowed for rotation about two axes. (I don’t have an image which is probably good.)

As a scientist at the university your labor is cheap but professional equipment is much too expensive. So you have to tinker. My experimental apparatus included a toy motor moving an optical lens, and a water-cooled projector’s bulb was the radiative heater mounted inside my vacuum chamber.

We investigated the growth of superconducting thin films deposited from a vapor ‘plume’ caused by shooting very short UV laser pulses onto a ceramic sample. There was no fancy high-speed device: We took photos of that plume using a normal camera and called it Time-Integrated Photography in scholarly lingo. We found some interesting scaling laws though.

PLD Plume

I am too lazy to scan an old photo of our own plasma plumes. But Wikimedia has it all – this looks exactly as ours did! Oh, the paper authored by The Chief Engineer and myself is worthy $40 today. (Image by Wikimedia user: H. Perowne).

Maybe the desire to build something from anything and to use whatever tool is at hand is the true connection between my diverse activities.

Most IT infrastructures are historically grown and you hardly ever find that green field people would like to install their solutions in. If you don’t like bottom-up tinkering it is just a source of endless frustration. Otherwise it is a noble Apollo-13-like challenge.

The same goes for tinkering with an old house. In the moment we are puzzling about an underground tank powered heat pump system for a house that will be built on top of a high-rise bunker.

Bochum - Baarestraße - Bunker 01 ies

A typical German high-rise bunker, in this case somewhat prettified. Normally they are just bleak grey boxes. (by Wikimedia user Frank Vincentz)

This is not uncommon in some German cities  where unused building land is scarce and thus expensive. Here is an example of a musician’s studio built on top of a bunker in Frankfurt:

… a World War II bunker in Frankfurt that had been previously disguised as a house because it was too expensive to demolish. In a crappy part of town, “a no man’s land between heaps of gravel and dumps, piled-up recycling-products and containers that await their shipping”, the architects decided to rise above it all …

I believe in true innovation driven by necessities and constraints (only). Nassim Taleb’s derision of Soviet-Harvard-style planned ‘research’ struck a chord with me. He challenged the alleged causation usually invoked by politicians and people working in taxpayer-funded committees that ‘steer’ and ‘manage’ innovation at three meta-levels above the ground of honest hands-on work: It is plausible that bottom-up tinkerers trigger innovation which in turn allows countries for building prestigious universities and think-tanks; not the other way around.

Having finished my PhD I saw a report on TV about a mechanic – a craftsman without a degree who was introduced as an inventor. I forgot what the invention actually was but I do remember his apparatus very much reminded me of the vacuum chamber I had worked with – when doing Time-Integrated Photography. I figured: Wow, he calls ‘tinkering’ what we would have written academic papers about! Fast-forward 20 years, I read conference papers on heat pumps and think: Wow, they call research what we call tinkering!

Exit the scientist and enter my subversive, poetic subconsciousness. They are perhaps not that different.

Isn’t this question – What is research? – remotely related to What is art? Or am I just too fond of satirical submissions to academic journals – both art- and science-related ones? It is maybe not an accident that an artist’s cave house came to my mind.

I have called our solar collector Art from Plastic and Wood tongue-in-cheek, here shown in behind another object awaiting further art-ification:

Organic space probe

An organic space probe, sending signals from a distant, ecologically minded, civilization.

Search Term Poetry and Spam Poetry are just another way of tinkering with something at hand. I was recently baffled by academic articles on so-called Flarf Poetry – so there are at least some experts for whom my so-called art would qualify as such. Don’t worry – I don’t insist of this. But I do wonder if ‘serious’ art is always driven by some sort of necessity, too.

By the way, right when I had the linked post on flarf poetry in the making I was invited to contribute some – to a real serious (?) art project. And so I did – consider this a cliffhanger.

On Learning

Some years ago I was busy with projects that required a lot of travelling but I also needed to stay up-to-date with latest product features and technologies. When a new operating system was released a colleague asked how I could do that – without having time for attending trainings. Without giving that too much thought, and having my personal test lab in mind, I replied:

I think I always try to solve some problem!

tl;dr – you can skip the rest as this has summed it all up.

About one year ago I ‘promised’ to write about education, based on my experiences as a student and as a lecturer or trainer. I haven’t done so far – as I am not sure if my simplistic theory can be generalized.

There are two very different modes of learning that I enjoy and consider effective:

  1. Trying to solve some arbitrary problem that matters to me (or a client) and starting to explore the space of knowledge from that angle.
  2. Indulging in so-called theory seemingly total unrelated to any practical problem to be solved.

My post about the positive effects of reading theoretical physics textbooks in the morning was written in the spirit of mode 2. The same goes for cryptography.

I neither need advanced theoretical physics when doing calculations for heat pump systems, nor do I need the underlying math and computer science when tweaking digital certificates. When I close the theory books, I am in mode 1.

In the last weeks that mode 1 made me follow a rather steep learning curve with respect to database servers and SQL scripts. I am sure I have made any possible stupid mistake when exploring all the options. I successfully killed performance by too much nested sub-queries and it took me some time to recognize that the referral to the row before is not as straight-forward as in a spreadsheet program. One could argue that a class on database programming might have been more effective here, and I cannot prove otherwise. But most important for me was: I finally achieved what I wanted and it was pure joy all the way. I am a happy dilettante perhaps.

I might read a theoretical book on data structures and algorithms someday and let it merge with my DIY tinkering experience in my subconsciousness – as this how I think those two modes work together.

As for class-room learning and training, or generally learning with or from others, I like those ways best that cater to my two modes:

I believe that highly theoretical subjects are suited best for traditional class-room settings. You cannot google the foundations of some discipline as such foundations are not a collection of facts (each of them to be googled) but a network of interweaving concepts – you have to work with some textbook or learn from somebody who lays out that network before you in a way that allows for grasping the structure – the big picture and the details. This type of initial training also prepares you for future theoretical self-study. I still praise lectures in theoretical physics and math I attended 25 years ago to the skies.

And then there is the lecturer speaking to mode 2: The seasoned expert who talks ‘notes from the field’. The most enjoyable lecture in my degree completed last year was a geothermal energy class – given by a university professor who was also the owner of an engineering consultancy doing such projects. He introduced the theory in passing but he talked about the pitfalls that you would not expect from learning about best practices and standards.

I look back on my formal education(s) with delight as most of the lectures, labs, or projects were appealing to either mode 1 or mode 2. In contrast to most colleagues I loved the math-y theory. In projects on the other hand I had ample freedom to play with stuff – devices, software, technology – and to hone practical skills, fortunately without much supervision. In retrospect, the universities’ most important role with respect to the latter was to provide the infrastructure. By infrastructure I mean expensive equipment – such as the pulsed UV lasers I once played with, or contacts to external ‘clients’ that you would not have had a chance to get in touch otherwise. Two years ago I did the simulations part of a students’ group project, which was ‘ordered’ by the operator of a wind farm. I brought the programming skills to the table – as this was not an IT degree program –  but I was able to apply them to a new context and learn about the details of wind power.

In IT security I have always enjoyed the informal exchange of stories from the trenches with other experienced professionals – this includes participation in related forums. Besides it fosters the community spirit, and there is no need to do content-less ‘networking’ of any other sort. I have just a few days of formal education in IT.

Your mileage may vary. I applied my preferences to my teaching, that is: explaining theory in – probably too much – depth and then jumping onto any odd question asked by somebody and trying something out immediately. I was literally oscillating between the flipchart and the computer with my virtual machines – I had been compared to a particle in quantum mechanics whose exact location is unknown because of that. I am hardly able to keep to my own agenda even if I had been given any freedom whatsoever to design a lecture or training and to write every slide from scratch. And I look back in horror on delivering trainings (as an employed consultant) based on standardized slides not to be changed. I think I was not the best teacher for students and clients who expected well organized trainings – but I know that experts enjoyed our jam sessions formerly called workshops.

When I embarked on another degree program myself three years ago, I stopped doing any formal teaching myself – before I had given a lecture on Public Key Infrastructure for some years, in a master’s degree program in IT security. Having completed my degree in renewable energy last year I figured that I was done now with any formal learning. So far, I feel that I don’t miss out on anything, and I stay away from related job offerings – even if ‘prestigious’.

In summary, I believe in a combination of pure, hard theory, not to be watered down, and not necessarily to be made more playful – combined with learning most intuitively and in an unguided fashion from other masters of the field and from your own experiments. This is playful no matter how often you bang your head against the wall when trying to solve a puzzle.

Physics book from 1895

A physics book written in 1895, a farewell present by former colleagues in IT – one the greatest gifts I ever got. My subconsciousness demands this is the best way to illustrate this post. I have written a German post about this book which will most likely never be translated as the essence of this post are quotes showing the peculiar use of the German language which strikes the modern reader quite odd.

Big Data, Big Plastic Worms, and How to Utilize Your Cellar

Our heat pump system will soon commence its third heating season. The amount of measurement data collected so far has exceeded the capabilities of the software I had once developed; so I crafted a new application based on a real database server. Now you know why I was not very active on social media recently.

I have an excuse to talk about our system again: A reader asked for an English version of one of our German articles.

While I was taming Big Data, the Chief Engineer was fighting with plastic worms and snakes:

A dangerous red snake.

The solar/air collector had to be re-built!

In German we say that the shoemaker has the worst shoes – but we did not want our collector to look less cool than the one built with a client recently:

Solar collector on top of garage – as a ‘fence’ or ‘railing’. (More images in this blog post)

After all, our own system is also the live demo we show off to potential clients!

So here is the new version of our own collector:

Unglazed solar/air collector from plastic ribbed tubes, supporting construction from larch wood. Designed and built by the Chief Engineer, physics PhD and carpenter-artist at heart.

One of the guiding principles in designing this system was to use off-the-shelf components only so that it could be built by a DIY enthusiast. Fortunately this type of cheap collector has also superior properties with respect to convective heat transfer.

The heat pump involved is actually the simplest, the ‘most stupid’ device you can buy. We don’t like the trend of equipping any heating system with a so-called energy management system that tries to control nearly any device in the ‘smart home’ – doing all that running on some proprietary black-box software.

We use a freely programmable controller instead – here is a photo from the ‘engine room’:

A controller is needed to control the valves for diverting the flows of brine and heating water, to switch on and off the heat pump and all other supporting pumps, and to log those tons of big data generated by sensors for temperature, flow, and radiation.

A single brine circuit connects the heat pump, the solar/air collector, and the underground water tank. Depending on ambient temperature, water tank temperature and heating demand, the collector may be bypassed.

Here is the latest attempt to draw the hydraulic design in the simplest possible way:

punktwissen heat pump system, water tank and solar collector as heat source

(1) Off-the-shelf heat pump. (2) Energy-efficient brine pump. (3) Underground water tank, can also be used as a cistern. (4) Ribbed pipe unglazed solar collector (5) 3-way valve: Diverting brine to flow through the collector, depending on ambient temperature. (6) Hot water is heated indirectly using a large heat exchanger in the tank. (7) Buffer tank with a heat exchanger for cooling. (8) Heating circuit pump and mixer, for controlling the supply temperature. (9) 3-way valve for switching to cooling mode. (10) 3-way valve for toggling between room heating and hot water heating.

The brine-water heat pump is the same that would be used with ground loops. Every heat pump needs a big reservoir of heat energy, and electrical energy is needed to extract (‘pump’) that heat. Typical heat sources are the ambient air, ground, or ground water.

Different types of heat pumps are used in different countries – I guess for historical reasons and thanks to lobbying of vendors. It seems to me that geothermal heat pumps are more common in Europe while elsewhere air heat pumps are more popular.

With geothermal systems the heat source is a volume of soil – the cylinder surrounding the bore hole or the cuboid confined by the surface above the ground loops:

3-ton Slinky Loop

Slinky collector, ground loops (Wikimedia user Mark Johnson, public domain)

‘Geothermal’ is a misnomer as this is not real geothermal energy from the core of the earth that’s harvested here – it is energy from solar radiation stored within with first 100 m of ground within the warm season. This is true both for ground loops placed in about 1,5 m below the surface, as well as for deep bore holes.

But the principle is the same if you immerse those loops in water – here the volume of a pond is utilized:

Pond Loop Being Sunk

A pond used as a heat sink for a heat pump (Wikimedia user Mark Johnson, public domain).

We had been searching for an option to heat our old house, and that can be built rather easily – that is: without creating a huge pile of soil we had no place for ‘parking’ it while installing ground loops.

In the region where we live, traditional homes and premises are rather small – the plot layout resembling stripe-like elongated rectangles. Think 5×15 m2 house on 10×60 m2 land.

To the left: The other part of the mansard roof of the L-shaped attic (The rooftop shape is not typical – it was rebuilt from scratch a few years ago). One long side of each building coincides with the plot boundary.

These old houses had been very small farm houses decades ago – we found some remainders of the equipment for processing grapes in the shed. In contrast to other regions, splitting of farm land among heirs had not been forbidden for a long time  – so individual property became smaller and smaller. These pieces of land are called ‘belt fields’ because of their shapes.

Here is a video documentation with English subtitles – about the traditional Pannonian ‘Streckhof’ (‘stretched house’).

Cellars were small as well – only about as 1,75 m high with an area of just a few square meters:

The earth cellar beneath the shed.

This cellar was converted to a water tank:

The water tank, lid open. The black tube is a manifold connected to the heat exchanger tubes.

The cellar has been made water-tight with pond liner. The heat exchanger is immersed in the water – the ‘loops’ have been built from the same type of ribbed plastic pipes as the solar collector in the garden.

The performance of a heat pump is the better the higher the temperature of the heat source is. But even when the water starts to freeze the temperature remains at 0°C degrees and thus the performance of the heat pump is kept at reasonable levels. The energy gain from freezing is high: One cubic meter of water translates to 93 kWh.

From previous discussions on this blog I learned that it might be helpful to add some ‘cultural’ or ‘political’ context:

A heat pump system does of course not make you less dependent on electrical energy – but it makes us here in middle Europe less dependent on Russian gas while providing the same convenience to the user. We have fairly good power infrastructure and upgrades to the (smart) grid are required as we need to integrate decentralized sources renewable energy like solar power and wind power.

Wind Turbines

I can see the blades of those wind turbines from our office (Enercon E-101, 3MW rated power each).

Heat pumps can help to make grid operations easier as they usually heat a hot water buffer tank (or the concrete ‘buffer’ of the house). So utilities may cut off electrical power for some hours at an arbitrary point of time as heat pump systems need to have energy storage for ‘offline times’ built in.

Measurement Data for Our Heat Pump System – Finally Translated Documentation

In an earlier post  I said

Although we have very innovative, and if I may say so, geeky / nerdy customers it is rather unlikely that we will plan heat pump systems in Australia via sending checklists or doing ‘remote support’ in the same way we work in IT projects.

OK – now we really got a question from a non-German speaker in a remote place who tried to make sense of our mostly German documents. Thus finally I really got started and translated the documentation of measurement data and systems parameters for our heat pump system.

That work sucked all the creativity and research capabilities out of me – so In this post I try to mix some of the diagrams presented in that document with replies to some FAQs.

We had a very warm winter and early spring here in Austria – this was the solar collector last month:


Solar Collector in March 2014. Beauty is in the eye of the beholder.

It is also reflected in the long-term measurements of ambient temperatures:

Ambient Temperature 2014-04, measurement data heat pump system LEO_2, punktwissen

Ambient air temperature in Zagersdorf, Eastern Austria. ‘Maximum’, ‘average’, and ‘minimum’ refers to one day, respectively.

Although I find that the collector is quite a cool decoration / replacement for a fence the typical question by visitors is (in addition to the question: Where can we install this so that nobody sees it?)

Can I use flat plate collectors?

Not really if the system should work in a performant way. Actually, those unglazed collectors have been picked deliberately, not because they are cheaper or lighter.

This system should replace any other fossil fuel powered system – we haven’t switched on our gas heater in two years now. Thus it has to harvest energy when it is really cold. Flat solar plate collectors are optimized for harvesting energy from solar radiation in summer; they are designed for minimum losses via convection of air.

Unglazed collectors are typically used for heating swimming pools as you can live with rather high convective losses here. But the highly efficient convective heat transfer is to our advantage in winter – then you gain energy even in the night if the temperature of the air is just a few degrees above the temperature of the brine flowing through the collector.

In summer you have more energy than you need anyway, so we don’t care about ‘convective losses’. Rather on the contrary: we are happy that we dont’ have to worry about high temperature making the brine decompose.

In addition the system is used for passive cooling in summer – that is, the temperature of the water tank (the ‘heat source’, then ‘cold source’) must not exceed a reasonable temperate which is well below the room temperature. This is also in line with the fact that there is a maximum heat source temperature the heat pump can deal with, specified by the manufacturer (about 20°C).

Energy Harvested by the Collector 2014-04, measurement data heat pump system LEO_2, punktwissen

Energy harvested by the collector. The total heating demand of the building is about 18.000 kWh per year, incl. hot water. Nearly all the energy needed is delivered to the water tank via the collector (and a minor part directly from ground). Collector power becomes negative if the system operates in cooling mode.

Can you explain BRIEFLY how the system works?

It is all about using a large tank of water as energy storage: The heat pump extracts heat and cools the water, then freezes it. Either the collector transfers heat to the tank in winter, or the floor heating system delivers heat to it in summer when the heater is actually a cooler.

Energy Stored in the Water Tank 2014-04, measurement data heat pump system LEO_2, punktwissen

Energy stored in the Water Tank. The 25m3 water tank corresponds to 430 kWh sensible heat – extracted when cooling water – and 2.300 kWh latent heat – extracted when freezing.

Anything else is the details of hydraulics and control – this is a screenshot of the online monitoring system (a different way to present the hydraulic design shown in the earlier post)

Online Diagram, Hydraulic-Setup. Heat pump system punktwissen.

Online monitoring diagram – sketch of the heat pump system showing measurement data. The water tank and the solar collector are the combined heat source of the heat pump. The heat pump works either in ‘space heating mode’ or ‘hot water heating mode’ and diverts the heating water to either circuit. Buffer storages are important for efficient control as the heat pump always operates at its maximum power.

Regarding the hydraulic design a question that comes up very often is about hot water heating:

You heat hot water indirectly by using a tank at 50°C? I don’t believe you that this is sufficient.

Believe me, it is. My very own very long and very hot showering – elementary showering as I call it – is a worst case test. The heat exchanger in this hygienic storage tank has an effective area of nearly 6m2 – that’s rather large, and this is crucial for a heat-pump-powered system.

The operating temperature of the heat pump should be kept as low as possible in order to obtain high coefficients of performance. Thus the temperature difference between tap water and heating water is rather low, and in order to compensate for that and still get reasonable heating powers the area of the heat exchanger should be big. The effective heating power of this heat exchanger is 12kW.

What’s the performance?

We proudly present:

 Monthly Performance Data 2014-04, measurement data heat pump system LEO_2, punktwissen

Heating Energy: Space heating and hot water. Total Electrical Energy: Heat pump, brine pump, heating circuit pump. Monthly Coefficient of Performance: Ratio of heating energy and electrical energy. The dotted line indicates the performance factor for the whole period covered in the diagram.


Solar Collector in April 2014






Controlling the Four Elements. Or: Why Heat Pumps Are Cool.

Despite my attempts to post mainly geeky and weird stuff peppered with (very often not down-to-earth) physics, I got involved in some serious discussions on renewable energy, sustainability, heat pumps, and the pleasures of Building Your Own Stuff. So I will describe what I am actually working on / playing with when I am not blogging, liking, sharing or tweeting.

Elkement is an amalgam of my first name, Elke, and one of my nicknames, The Subversive Element. I have a penchant for the words elementary and elemental, any puns comprising those, and I like geek gadgets exhibiting the periodic system of elements. It is straight-forward that I have to work on a heating system that utilizes The Four Elements: Earth, Wind, Air and Fire.

As usual, I first considered this an incredibly creative way to describe a heating system – until I discovered that zillions of companies in the HVAC business use the same analogy. Besides I like the philosophical, if not new age-y, connotation contrasting with down-to-earth engineering.

I (we) work on optimizing a heat pump system that uses these said elements, which actually is: An unconventional source of heat that makes the system different from geothermal, ground water or air source heat pumps.

This is a simplified schema. Please bear with me!

The Four Elements are indicated: A rather large (about 20 m3) tank filled with Water is heated using an unglazed solar collector.

This collector allows for harvesting energy from solar radiation (Fire), but – above all – from ambient Air via convection.

The tank is located below ground (Earth). Actually, in the prototype system the ‘tank’ is a former small cellar that once had been used to store potatoes and wine (This is common in the region where I live). The cellar had been lined with plastic sheets which makes it a pretty cheap tank. There is an average net flow of energy from the ground to the tank – it would be detrimental to insulate the bottom and the side walls of the tank.

Heat pump system utilizing a water (ice) tank as heat source (Copyright: http://punktwissen.at)

Heat pump system utilizing a water tank as heat source. Energy is harvested from ambient air, solar radiation, heat transfer from the ground, and from freezing water (Copyright: punktwissen.at).

The water tank constitutes the heat source: Instead of burying pipes in the garden (ground source loops), the heat exchanger pipes are immersed in the tank.

It is a single (simple) closed cycle:

Heat pump –> solar collector –> tank –> heat pump

The combination of the tank and the collector is the actual heat source of the heat pump.

Depending on the temperature difference between ambient air and the tank and on the heating demand of the building the controller decides whether the collector is used or circumvented and whether the heat pump is turned on.

The heat pump heats two different hot water tanks – one is for heating the tap water, the other one is for transferring heat to the room heating loops. A heat pump cannot be “dimmed” continuously to different output powers: It delivers heat at full power or it is off. Thus you need an intermediate storage that allows for gradual heat transfer to the heating loops.

There is an important 5th element (You have expected me to add a link like that, didn’t you?): Ice.

During the heating season about 75% of the heating energy is harvested from air and fire channeled through the solar collector, freezing of the water in the tank and heat transfer from the ground yields the remaining 25%.

But heat pumps are cool, and this setup allows for a simple way of passive (“free”) cooling: In summer the room heater becomes a cooler: The ‘Hot Water Tank for Room Heating’ becomes the heat exchanger that transfers heat from the room heating loops to the underground tank. The heat pump can still heat the tap water in parallel – actually this is beneficial for cooling!

The overall goals for this design have been:

  • Using a heat pump with a high seasonal performance factor, but avoiding the drilling of deep bore holes or having to turn the whole area of your garden into a huge pile of soil temporarily.
  • Using rather simple, state-of-the-art components that could be purchased by home owners in online shops and that would allow skilled Do-It-Yourself enthusiasts to built the system themselves.
  • Allowing for cooling without adding complicated components or needing air-condition (to American readers: AC in homes in uncommon in Europe).


Further reading: This was the pre-quel of the story (“How I started loving heat pumps more than IT.”)
Our German blog has more detailed technical information – I am not sure of we will ever provide the same level of details in English.