Friday, 16 February 2018

Teaching Low Energy Building: Final Answers

Here are the answers to the final questions of my low energy building class.

1. The top priority for a low energy building is insulation.

Not solar panels, the latest electronic equipment, increasing the number of windows or planting grass on the roof. All my students got the right answer. They were 100% successful. In educational assessment terms, this question was 0% successful in discriminating between students. But I'm not so interested in discrimination. Just happy that all of my students got the main idea of the course, which is that insulation is the top priority in low energy building.

I could probably have put some tougher distractors in there, like mechanical ventilation with heat recovery, air tightness, good form factor or avoiding thermal bridging. Perhaps I should make a more difficult question next year.

2. Half the students got the next question completely right; eleven out of twenty-two taking the test.

This question did a much better job at discriminating!

This was a real-world low-energy building question getting them to choose the amount of insulation needed depending on the windows they were using. It assumed an energy budget for a small house of given surface area and floor area, and a fixed requirement of window area.

The question was made more tricky since they had to choose insulation thicknesses rounded to the nearest five or ten centimetres, as you tend to get in the real world. Also, in the real world, you need to round up rather than round down when you're trying to meet this kind of target. This may have thrown a couple of them.

Even worse is question 4  
As a language teacher, I usually despair at closed question, especially multiple choice questions where language is polarised into one correct answer and three incorrect ones. In the case of insulation, there are genuine discrete choices since the insulation comes in standard sizes. You can't buy 17.4 mm thick sheets, however much the calculations tell you that's what you need, although you could blow-fill a cavity of any thickness you like. The choices I gave in my test—15, 20, 30 or 40 cm of nano-porous super insulation—are almost a factor of ten thicker than the options given for Neomafoam by Asahi Kaisei, so I guess the choice would be something like two sheets, three sheets or four sheets thick.

Also, this was a matching question, with four different U values of window and five suitable insulation thicknesses to choose from. Obviously the eleven people who got the correct answer all gave the same answer, but the other eleven were each wrong in a different way.

One piece of low-hanging fruit was that with single-pane aluminium-framed windows, it was impossible to make walls thick enough to stay within the energy budget, and 19 out of 22 students got this bit.

At a conceptual level, the better the windows, the less insulation is needed in the walls, so the lower the window U values, the thinner the walls can be, and 16 of them got this in their overall answers, although two of them missed the answer for the single pane windows. A couple of them were choosing progressively thinner walls for higher U values, but both of them got the right answer for the single panes.

As for the other six students, it's difficult to be sure what they were thinking. They may have just been looking at the materials and assumed that wooden windows were better than PVC. They may have miscalcalated and not been thinking of the answers with top-down reasoning.

Anyway, I think the correct answers are:

  • Two times thinner (around 40cm) for U 1.7 Double, low e, argon, wood frames;
  • Three times thinner (around 30 cm) for 1.3 Triple, low e argon, PVC frames:
  • Four times thinner (around 20 cm) for U 0.8 Triple, krypton, insulated wood frames;
  • You can't make walls thick enough for the single pane windows (U 6).

3. I told you the coffee maker question before.

A one kW coffee maker in a teachers room, left on for 90 minutes, twice a day, five days a week, with a possible replacement for 10,000 yen with a thermos flask pot. How many weeks till the new pot pays for itself in electricity savings at 25 yen per kWh?

Fifteen of them got the right answer. One gave the precise answer of 26.7 weeks, but I was pleased to see most of them rounding it to the nearest week. Seven people rounded up and seven rounded down. Strictly speaking the ones who rounded down were wrong, both because rounding up is closer, and because you still haven't paid for the new pot yet. One person got half marks for giving 30 weeks. In a way, that's a better answer than the more precise 26.7. 

A couple gave 40 weeks, the shortest answer was 3 weeks, and the longest 250,000 weeks, which will take us to the year 6825. I'm not sure whether people will still be drinking coffee then.

Saturday, 10 February 2018

Feedback on low energy building course

There is a well established process for running projects, and many other human endeavors, with acronyms like PDCA, standing for plan, do, check and act. Or adjust. Or again. Whatever the last A stands for, equally well established is the habit of forgetting that last bit. People love the planning, they enjoying the doing, they reluctantly dabble with checking, and have lost interest when it comes to strategic changes. The next time around, they will do things the same way, perhaps with a little less emphasis on the bits they don't like doing. But those little tweaks and readjustments are often the difference between long-term success and short-term failure. 

So this is me checking and adjusting my syllabus for the low energy building course, and I'm actually trying to use the student feedback in the same way feedback is used in control engineering rather than the frantic rush to turn down the volume you get in amateur sound engineering.

Feedback came from two directions: one in the form of paper questionnaires handed down from the university and handed out in class. For the most part students just pencil in the lozenges somewhere between strongly agree and strongly disagree, but I encourage them to fill in the spaces for written comments. In one class I told them they should write something about the paper questionnaires being a waste of time, and the university should administer them online. Four of the students did write something like that, and while I was pleased, it shows that students in the classroom will just write what the teacher tells them to, which is just one of the reasons paper questionnaires should not be completed in class. 

That was a different class though. In the low energy building class, their comments mostly just
reported that they had learnt about low energy building. Important knowledge about low energy building. Knowledge about the importance of low energy building. A couple just said they learnt about buildings, which is perhaps an even better response. One person said it was important to think about economic issues as well. Another valued the fact that the lesson was in English. Most of these comments (70%) were in Japanese, the same language as the university questionnaire, but nobody commented here that I should speak more Japanese, or that the class should not be in English. 

The other formal avenue for feedback was in the final questions, where I asked them these two questions:

  • What was missing from the course? What other topics should have been covered, or what topics should have been covered in more depth?
  • How can the course be improved? How can I make it better for next year? 
I know the pedantic grammarian will find four questions there, but I rephrased each question to make it clear what I wanted to know, and also because the length of answer is often proportional to the length of the question since the human tendency for mimicry is much stronger than the tendency for following instructions. Almost all of the students (90%) answered these English language questions in English.

Six of them mentioned language in their suggestions for improvements. Three suggested I should speak more Japanese, one saying an all-English class was a bit difficult. One suggested adding definitions in Japanese on the slides. Two wanted the students to speak more English, one of them suggesting students should only speak English in class, the other saying her English had become more fluent and that I should continue to English. 

Conclusion on language: Using theories to determine thermal comfort in buildings, it seems the language temperature of the room is OK, judging by the relatively small number of people who are too hot or too cold. Adding definitions in Japanese to the slides is a great idea that I need to do more.

I was worried that I'm doing too many calculations, but it looks more like the opposite. Seven people mentioned calculations, mostly wanting more time to do calculations, or wanting me to spend more time on them. They mentioned U-values, windows, compound insulation and calculating whole-house U-values.

In terms of course content, four wanted more case studies, one asking about low energy buildings in Matsumoto, and two wanting more information about low energy buildings in other countries or about international differences.

Three wanted to know more about insulation materials.

Two mentioned cooling, which I know is an important topic that I should have covered. I just realised that lesson 5 started off as a lesson on cooling, but now seems to focus mostly on comfort. I think the windows from the previous lesson may have spilled into it. Also I had prepared a full lesson on cooling, which I then did not teach.

Two wanted to know about the latest technology, one asking about the latest building techniques, the other giving the example of dye sensitized solar cells.

Other content suggestions were for Passivhaus in more depth, hydroelectricity, window frames, and large scale energy savings, for example at the city scale.

​Other comments were ​more about the delivery and presentation of the class.

Four people gave positive comments on the course​:​ that it was great, perfect, nice, or had a good balance.

Three people gave somewhat critical comments: I should make my slides better, I should ask what students want to know, and I should introduce an expert on low energy building to the class.
Actually the last one is probably not critical, and I should take it as a positive suggestion, and in fact a really good idea. They may mean that I should be talking about low energy building experts rather than physically introducing one in the classroom. Just because that's how I would have written "you're crap" doesn't mean that is what they meant when they wrote it. While it's great that so many of them are writing in English, there is more chance for ambiguity when they are writing in a foreign language.

(I didn't have this question)
One student suggested that the range of questions in the online tests was different to the content of the class.

One person suggested I should always give measurements for the sizes of windows and rooms. I think this is something I realised half way through the semester, and something that made me think I would get requests for fewer calculations. I tend to give the students real world problems, and hope that they will be able to grasp the problem, identify what information they need to solve the problem, get exact values for the information where they can, and estimate where they don't have exact answers. This is a chain and is only as strong as its weakest link, and most of the students will fall down at some point. What I need to do is to break problems down in a much more systematic way, and give them several chances to practice each step before putting the steps together. I need to carry on giving them guesstimation problems, for example estimating the dimensions of walls or windows, but not at the same time as giving them thermodynamics problems.

Another wanted a list of formulas which we learn in class, which would be a really good idea. I should produce a low energy cheat sheet!

Another suggested that presentations should all be done in one lesson. Interestingly this was from one of the students in the group that went up to speak first, who had specifically said that they wanted to give their presentations in that lesson, a week before all the other presentations.

Finally, there was a comment that I should "distinguish between good and weak students in good balance". I'm not sure what that means. Perhaps that I should be making sure I'm teaching the students at the right level. Perhaps it means they should be working together in groups based on their level.

Now it's back to the drawing board for next year's class! The syllabus needs to be uploaded next week.

Wednesday, 7 February 2018

Teaching Low Energy Building: Final Questions-part one

Each week ​I've been adding questions on the content of each lesson to an online learner management system called Module. Here are the​ first three​ questions for the final lessons. I'll post the answers next week!

1.​ ​What is the top priority for a low-energy building?

Select one:

​2. ​(This question follows the question in the Windows 2.0 quiz)

You want to build a small house with a heating load under 25 kWh/m2a. The house is 35 square metres, so you want to use less than 875 kWh per year. The wall and roof area of the house is 100 square metres. You want 4 square metres of windows. The house is in Matsumoto where the annual heating demand (G) is 80 kKh (kilo kelvin hours).

If you use U 2.3 windows, they will lose 736 kWh per year. So the rest of the house must lose less than 139 kWh (875-736). The U value of the walls must be 0.017. (U = Q / A G.) Using nano-porous super-insulation material (k=0.015 Wm/K), these walls would be around 90 centimetres thick!

If you use the other windows, how many times smaller are the U values for the wall?

In other words, how much thinner can the walls be?
U 1.7 Double, low e, argon, wood frames
U 1.3 Triple, low e argon, PVC frames
U 0.8 Triple, krypton, insulated wood frames
What about the single pane windows (U 6)?
​3. The teachers' room has a coffee maker. Usually five days a week, twice a day, someone makes coffee in the break time, has one cup. Then for 90 minutes the rest of the coffee sits in the pot, with the heater on, until the next lesson has finished.

Friday, 2 February 2018

Future predictions

Here are some predictions based on current trends.

Computer chips will have one transistor per atom in 2025.

Every car will be electric by 2053.

There will be enough solar panels to cover all land on earth by 2056.

Two of these predictions are very likely to be wrong.

The first is based on Moore's law, which predicts that the number of transistors on a given size of chip will double every eighteen months.

The figure for electric cars is based on the recent increase in proportion of EVs, which in most countries is still less than one percent. The proportion may increase exponentially, and will of course stop increasing when it reaches 100%.

The figure for solar panels is based on a compound annual growth rate of 30%, which has been been happening for the past twenty years. I'm assuming that power output per area of solar panel will stay the same, which it probably won't. New panels will steadily produce more electricity for the same area, but the increase will not be large, let alone exponential.

Of these predictions, I think Moore's law is the most likely to come true. This law has held true for fifty years. I don't think atoms will necessarily stop it, since quantum computing is now a thing.

Moore's law has been enabled by the success of electronics leading to a steadily increasing budget for development of ever smaller chips. Developments have tended to compliment each other, rather than replace them. The budget is not increasing at a Moorean rate though.

These exponential growth rates are usually unsustainable since at some point they are limited by physical constraints of the real world. If things are getting smaller, of course, there is no limit. Right now there is a limit to our understanding of the very small, but if science shows us one thing it is that when we ask questions, sooner or later we find answers. The harder we look for the answers, the quicker we find them.

More interesting is Wirth's law, which states that "Software is getting slower more rapidly than hardware is getting faster." So all these improvements in the computer power are eaten up by extra complications and functionality that we don't necessarily need. I noticed this around 1992, and decided to stop spending so much time programming computers. I now wish I'd written a paper on it, like Dr. Wirth.

I'm pretty sure solar panel production will peak before we cover the whole planet, although I will not be surprised to see nature reserves clear cut for solar farms, massive floating arrays, or increased solar installation in space. They may even start making the panels up there. The economic effects of increased solar power will likely be that some electricity is effectively free, which will drive down the price of electricity, and reduce the value of the panels, making their manufacture less worthwhile. So I don't think this prediction will come true. I'm hoping to still be alive, and will be able to find out.

There will very likely be a point in the future when the only people not driving electric vehicles are stupid and rich, and I think this point will come sooner rather than later. By the time our computers are firing on subatomic logic, the majority of people will be buying new electric cars. I'm sure this will sound as ridiculous as someone predicting the wide use of steam trains in 1818, or motor cars in 1918. Also, we must not underestimate the size of the stupid and rich demographic, and its disproportionate political power. There will always be a bit of liquid fuel sloshing around, and we are unlikely to ever have 100% electric vehicles, but I think we'll be close to that long before 2053.

Here's an article from the Guardian about accelerating car sales. Here's another claiming that the electric vehicle revolution in Australia is stuck in first gear. The press is never shy to use motor-industry metaphors, but they don't realise EVs only need one gear. Also they may never have experienced the excellent acceleration of electric vehicles.

Friday, 26 January 2018

Great Student Presentations

Another year and another brace of student presentations. This time, perhaps with the higher number of architecture students, there are more practical topics.

1. Energy independent buildings

One brave group out of seven decided to give their presentation in the penultimate week, and they set the bar high. One of them even gave the presentation in English, which I had suggested, but not mandated.

This began with a look at carbon emissions, and went on to talk about cogeneration, which is big in Northern Europe, but not common in Japan. The idea with cogeneration is basically to generate electricity on a small scale, and use the heat for domestic hot water and heating. They talked about a gas-operated system on the market, which seemed quite expensive as a capital cost, and also would be buying in gas and therefore no chance of being zero carbon. Of course the reality right now is that nothing is zero carbon but cogeneration has obvious energy savings.

2. Biomemetics is a really interesting topic, and the second group also did a great job.

They started by asking if we knew who had invented velcro, which we did not. The answer is at the bottom of thiw page. This is a great example of human ingenuity mimicking nature, as the inventor decided to copy some burdock seeds that had stuck to his coat and dog.

Bullet train design from the kingfisher
Another example was a bath that imitated cuckoo spit, otherwise known as the foamy spawn of the frog hopper or spittle bug. The foam radically reduces the amount of water required for a bath, and keeps it hot better!

Finally they talked about termite nests, which have elaborate vertical air circulation channels that change direction of flow between night and day, keeping the building cool or warm. They are also porous to allow carbon dioxide out. This natural design was imitated by the Eastgate Centre in Harare, Zimbabwe, which was designed to cool by entirely natural means.

3. The next group talked about Energy Standards in Five Different Countries.

These were the US, the UK, Germany, Korea and Japan. The introduction explained what was specified in the building standards, and went on to show how relatively lax Japan's standards were and what a low proportion of PVC windows Japan had, but also showed that Japan has
the lowest energy consumption per household.

A comparison was made between Japanese buildings and South Korean buildings, where respectively rooms are individually or collectively designed. It was argued that Japanese design allows rooms to be heated individually while Korean design, and that of Europe and the US, typically requires that the whole building is heated.

To be honest, I was not completely convinced by this, and look at it rather as holistic design allowing whole buildings to be heated, while the Japanese vernacular discourages it.

They concluded that there were many different approaches to low energy standards, that the Europeans are working hardest to lower environmental impact, and that Japan is behind other countries, but that there are plans for Japan to have low energy standards by 2020.

A questioner asked why Japan—ostensibly a developed country—has such weak building energy standards. A couple of answers were given, one by one a presenter, and one by the questioner, which was supported by another of the presenters. A discussion of this needs a whole other blog post, and in fact I've already written one here!

4. The Latest Low Energy Buildings was the topic of the next group.

The first speaker talked about the Cardboard Cathedral in New Zealand, built after the 2011 Christchurch earthquakes. Another was built in eight months in Kobe Japan, intended to last two or three years, but still in use ten years later. A good example of low embodied energy.

The second speaker talked about Ichijo Komuten's i-series of low-energy buildings, which are the closest thing to Passivhaus at scale in Japan.

The third speaker talked about ZEB—Net Zero Energy Buildings—giving an example of a building using a combination of solar power and biomass to meet all its energy needs.

The fourth speaker talked about the Zollverein School of Management and Design in Essen, Germany which the presenter rather suspiciously described as choosing geothermal energy rather than insulation. It got away with a thin concrete shell with naturally occurring hot water
piped through.

I couldn't help feeling that maybe the pipework and certainly it's maintenance would be more expensive than insulation.

Also I notice that they are only talking about Japanese buildings, and buildings by Japanese architects, which is a curious position in light of the last group's findings on Japan's low-energy building credentials.

5. The next topic was Hydroelectricity, which is probably the cheapest and least fossil-energy demanding source of electrical power.

They discussed pros and cons, different systems of generation and then some interesting ideas on microgeneration from domestic water, one taking energy out of the incoming pressurised water main, the other out of water coming out of taps. I didn't want to ask them about any conflict with the need to save water in the house, and whether the mere hundreds of milli-watts they could get from the taps was worth it, but the idea of looking for energy sources is a good one.
Habitat 67—because modern architecture means ignoring physics

6. Famous Buildings was the topic of the next group.

The Farnsworth House in one of the four seasons it is not fit for
I worried this would just be a slide show of beautiful buildings, and have nothing to do with the subject of the course, but this group set their parameters well. They were looking at a few famous buildings from the perspective of form factor, thermal bridges, materials and windows, pointing out both good and bad points. Though mostly bad!

Their buildings were by Hundertwasser in Vienna, Habitat 67 in Montreal, Canada, the Farnsworth House in Illinois, USA, and the Gassho-zukuri houses of Shirokawa village in Gifu, Japan.

They did a nice assassination of the form factor of Abita 67, and showed how Farnsworth's concrete sandwich with glass is more of a sacrificial altar to comfort and energy use than a useful contribution to architecture.

7. The final presentation talked about the Merits and Demerits of Low Energy Buildings.
They did as good a job of concluding the course as I could. The demerits included the extra costs and the lack of skilled designers and builders, and the presenter hoped that everyone in the class would be working to change this.

Velcro was invented by Swiss electrical engineer George de Mestral in 1948. For any etymologists out there, the word is a portmanteau of "velvet" and "crochet".