Humidity and Traditional Buildings

When I talked about humidity the last time, I realised there was a lot more to say. It's not enough just to understand what humidity is, how temperature affects relative humidity, and how important it is to keep your walls airtight.

Keeping walls airtight is still very important, but we also need to understand how moisture moves through materials, and how important that is if moisture does get into your building materials, which is an undesirable, but unfortunately not unavoidable situation.

In this video I also look at traditional buildings, how they overcome humidity, and how traditional building culture can be influenced by events as well by the local climate and available building materials. 

Jevons Paradox

People say that more is less and less is more, but in economics, often less is less and more is more, particularly with efficiency.


Read more about this here: https://minuszeroeco.blogspot.com/2016/01/lesson-12-part-iii-economics-dark-side.html

Setting standards

This is one of the most boring lessons in the course. Usually I would try to make it intactive by putting students into groups, telling them they are politicians, industry leaders, architects and building physicists tasked with making regulations to ensure low energy buildings are built.

Here is some information on video:

More about the lesson here:

https://minuszeroeco.blogspot.com/2015/12/lesson-8-standards.html

Air and Water: Condensation and Humidity

Whenever I talk about humidity I have a strong sense that I don't really know what I'm talking about. I think this is normal, because humidity is not at all intuitive. I know that my glasses will steam up when I come into a warm room from the cold. But what goes on within walls and buildings is complicated and strange. When predicting which way the moisture will go, I end up just assuming it will go where we don't want it!

In today's video I attempt to explain. In doing so I realised I need to say a lot more about diffusion, and probably do a whole new lesson on summer humidity. I can also talk about traditional approaches to protect buildings against condensation. 

Also I suggested that high humidity could increase the risk of spreading viruses. In fact low humidity can increase the risk of spreading viruses. 

Heating and Cooling

Here's a lesson on heating and cooling. 

More about the lesson here.

And more about air conditioners here.

How to slow Down Heat Part 2: Confounded by Compound Insulation

The sums don't quite add up for the problem we looked at earlier. The two calculations for compound insulation give a slightly different answer. 

You can see the calculations with my terrible handwriting here. Or just go straight to the video below, which is much lighter on maths. 

This is the calculation looking at parts of the wall in parallel first.  

And this is how to calculate looking at the parts of the wall in series first.  

We don't get the same answer. Here's why and what we can do about it.

How to Slow Down Heat

 Now that we know it's impossible to stop heat, let's see if we can slow it down!

More about the lesson here.

How to Stop Heat

 

Watch this video lesson to find out! 

Spoiler alert: it's impossible to stop heat! You can only slow it down. If you want to lose less heat from your house, then the first thing to think about may be the surface area.

Warning: Contains equations.

What is Energy?

 The first lesson. If you want a low energy building, this is the first question you need to ask. 

What is energy? How do you measure it? I thought of a dozen different ways. This shows how confused our language is over the science. 

In politics, language is power, but when it comes to science, power has a different and much more precise meaning. Heat seems like it's hot, but often it's not. In the next video, after explaining that heat and temperature are not the same thing, I described a difference in temperature as a difference in heat. In this video I used the word "precise" when I meant "accurate". I did this while I was talking about the difference between precision and accuracy. Maybe it's not the language that's confused. Maybe it's just me!

Anyway, this has nothing to do with the content of this video. You can read more about the lesson here. 

Please watch the video, and subscribe to the channel. 

Low Energy Building: Thursday 10:40 from 26th September

I never seem to be ready for my classes in the second semester. The Japanese academic year begins in April. The students break for summer at the beginning of August and come back for more at the end of September. In theory I have a holiday of almost two months, but in practice there is plenty to do, from grading and syllabus design to library maintenance and academic publishing. So in theory I would be focused on research and lesson preparation and be completely ready for my lessons when they come around. But in practice the lack of clear and immediate deadlines means I am free to venture down elaborate rabbit holes of negligible relevance. For example, last year I spent a week investigating ornithopters. If you're not sure what an ornithopter is, you should google it. Or perhaps not. 

By early September when the hottest of the summer heat has passed, I'm ready to start teaching again. By the end of September, when the bell rings for the first class of the second semester I am in a state of panic. The only redeeming factor is that I am more prepared than many of the students!

My low energy building class is in the second semester, which makes it a victim to my lack of self-discipline and focus. The course is more-or-less set, the lesson plans made and the powerpoint presentations ready to press play. Good teaching requires effort from the teacher, since students will copy what they see others do rather than listen to what they say. This applies not just to students, but all primates. If the teacher is lazily regurgitating old knowledge then the students will do the same. If the teacher is looking for new information, questioning existing opinions and searching for new ways to engage with people and with knowledge, then the students will do the same. At least that's the hope. 

The stated goal of the class is the same: teach students how physics applies to buildings. The hidden goal is the same: indoctrinate students into Passivhaus.

The story needs to start with energy. First we'll talk about what it is, then how it moves, and then how it moves through complex wall structures. Then we can talk about windows and how heat can be lost and gained through them. Windows 2.0 will cover the complexities of multi-pane windows.

At some point we need to talk about air and water, since humidity control is critical for human comfort and building health. We also need to talk about human comfort in general and look at what buildings are supposed to do. I'm not sure of the best order to tackle these two topics. Humidity is part of the answer to the question of comfort, and talking about humidity first will make it easier to understand. Anyway, these two lessons are mostly independent from the five pure and applied thermodynamics lessons above and could interleaf between them, providing a bit of an air gap to make the lessons on windows less of a pain. 

Cooling is another topic to cover, once the basics of thermodynamics and humidity have been established.

Power generation is another important topic, that can also be introduced at any time. Since power conservation is a higher priority, it's probably best not to introduce this too early and make it seem too important. It may also be a good idea to have a second lesson with details of solar generation requirements, constraints and optimisation.

Once all of this has been covered, we can look at building standards in Japan and around the world. 

That will take us up to fifteen lessons, with an introductory lesson, and one lesson for presentations and another briefing the students on how to give a presentation.

It would also be possible to have a whole lesson on Passivhaus, another on heating, another on thermography, and one on retrofitting. There are perhaps another dozen topics that could be addressed. For the past few years I've wanted to give a practical demonstration of how a heat pump works, using the students as molecules in a Carnot cycle bound by desks in the classroom.

Throughout the course I hope to teach problem-solving strategies, and give them some practical applications of mathematics. Hopefully the numbers will mean something by the end of term. Critical thinking is a skill I think they need.

It would be nice to cover some philosophy of architecture. In many countries architecture courses are twice the length of regular degrees since students must cover both technical and aesthetic fields, making the discipline both an art and a science. Even then, some buildings seem to have been thrown up with no respect for science while others are constructed with no sense of beauty. In Japan architects can be qualified after two years in college, and I can't help feeling that some buildings have been put up neither in the interest of science not art, but just to keep the construction industry going!

Changing groups

Time to shuffle the students a bit.

The lesson on windows went well, and I think the estimation of the room's window U value was not too overwhelming for the students. This was partly because I had structured the problem solving a bit more. Scaffolding is also very helpful in the construction of knowledge. Also I had them change groups at the beginning and tried to get mixed skill sets together.

I had put them into groups in week four and it's a good idea to change after two or three weeks have passed. The dynamics of groups have been characterised by the stages of Forming, Storming and Norming. After norming we hope for performing, but instead it can get boring! Changing groups every week is a bit too disruptive, but leaving the same groups for too long risks unfairness for people who have ended up in a dysfunctional group as well as a missed opportunity for having the students meet more people and make more friends.

The first time I put them into groups, I began by asking everyone these questions:

• What is your major?
• Are you good at maths?
• Are you good at English?
• Are you good at drawing?
• What is your favourite subject?

Then I asked them to make groups of four, with different majors, different favourite subjects, and new friends. I told them that maths was going to be useful, so if they weren't good at maths they should find someone who is. Also, if possible, I wanted different nationalities and mixed genders. The class is about 85% Japanese and 70% male, so this was not going to happen with every group.

In the first couple of weeks, and in previous years, I had tried to have Japanese-speaking and English-speaking groups, but last year I realised that resulted in me having a false sense of the English level of the room, and some parts completely lost. Spreading out the English speakers means they can work more to mediate between my English explanations and instructions, and the Japanese of the students who often have more interest in, and aptitude for, the topic.

Three weeks later they were still more or less in those groups of four, but a group of women had formed in the back corner of the class, and I'm sure the same couple of architecture students had been sitting next to each other every class. It's not really bad to sit next to the same person every week, but a changing environment is conducive to learning since memories are formed by connections and associations. Also they may meet some new people.

So I asked them, within their groups, to first decide who was best at writing. Next, I asked who was best at English. The writer then had to write down those names. Next I asked who was best at communicating. If it was their best English speaker, they should choose the next best English speaker as their English speaker. Finally I asked who was best at mathematics, and if it was their best communicator or best English speaker, they should choose a different best communicator or English speaker.

Then I shuffled the deck by having each writer stay put, each English speaker move around the class clockwise to the next group, the communicator move two groups clockwise, and the mathematician move one group anti-clockwise. I figured the mathematician would be able to handle the negative number. As usual, I had to do some traffic direction, partly because there was one group in the middle of the class, and it wasn't completely obvious which way was clockwise and which was anti-clockwise.

Now I had a high chance of diverse groups. They had all worked in different groups before and would hopefully bring the best experiences into the new group.

When it came to calculating the U value of the windows, I asked them to pick a leader, a designer, a calculator and a checker.


I reminded them of the problem solving steps:
1. Formulate problem, ideally drawing it!
2. Plan a strategy, making sure they write it down!
3. Find equations
4. Find data, but not until they had done the first three steps
5. Calculate
6. Check
7. Check again

After a while I reminded them about surface resistance, then gave them some equations, thermal conductivities and dimensions.

A little later, as I wandered the class looking at their calculations, I noticed a couple of U values of over thirty for the glazing, which looked way out. I went back to check and noticed I'd given them the wrong value for conductivity of air by a factor of ten. It should be 0.024 W/Km but I'd given them 0.24. A great example of how everyone makes mistakes, and how important checking is. Making mistakes is not a problem in itself—everyone does that!—you have to realise when you have made mistakes, and then fix them.

How to Solve Problems

Teaching is a constant learning process. At least it should be. One problem with being a teacher is that you often get into situations where you think you're right, which can make it difficult for you to change what you're doing. In the classical model of the teacher, you can be expected to be right in your knowledge, otherwise you wouldn't be there. But when it comes to how to share that knowledge, or in what order to present it, there is less clear right and wrong and just a whole range of choices.

I believe in the power of problem solving for teaching. This translates to a belief in the power of learners to solve problems, and for them to learn something in the process. The problem is, not all learners are good at solving problems, and many have been through educational systems where they have not been expected to solve them. At least not the kind of problems that I give them. 

So how do I solve this problem?

Given that I want to teach problem solving skills, I probably just have to be a lot more open and transparent about it. I have been mentioning a few things to the students in passing: like suggesting they draw diagrams to help them work out problems, or advising them to write their calculations out carefully and clearly on lots of paper so it's easy to go back later and see what they did. I need to be much more explicit about the steps of the problem solving process, and give them a bit more practice in each step rather than just throwing a problem at them and hoping they'll work it all out. Too often the problem I've been throwing at them is how to solve problems, which is way too abstract.

Here are some steps:

• Formulate the problem

The first step is to work out exactly what the problem is. Draw a picture. Write down what you know. Draw another picture. Put question marks where you need to find an answer. 

• Find solutions

Now that you know the problem, you can think about solutions. What strategies are available? Are there different ways to solve the problem. Make a list!

• Choose a solution

Which is the best way to solve the problem? What are the steps? 

• Prepare tools

If you are calculating, your main tools are equations. If you are using a computer, the tool is the software. You also needs data. There will be physical properties that need to be looked up from tables, some things may need to be measured. Some will need to be estimated.

• Calculate

Use lots of paper. Avoid any shortcuts that will not be obvious to someone looking at the calculations later. If you miss out steps on paper, there's a higher chance you'll make a mistake.

• Check the calculation

Ideally get someone else to check your calculation. It's often difficult to see your own mistakes.

• Check the answer

Eyeball it. Compare it with your real world experience. So you calculated that this pencil weighs a million tonnes? Maybe you should think again.

• Check the error

Answers in the real world are never perfect. Their accuracy depends on the accuracy of the numbers going in, and the accuracy of any equations you used. Know how wrong you are!

That's eight steps, and no fancy acronym to go with them. I can start building them into my lessons and watch what happens.

It's probably also worth talking about engineering problems and how they are different to the problems that come up in education. They have often been conditioned to find one correct answer, but over in the real world there is usually more than one answer, and more than one way of finding the answer. Good engineering will find the best solution to a problem, given a range of criteria. The most important considerations are often cost, safety and performance, and the best solution may be optimised between them. Cost itself can be in materials, equipment and construction processes. 

Of course one factor in this optimisation is the length of time the engineer spends on the problem itself, since engineers are a scarce resource and their time precious.

So I think I've written enough on this topic for now.

[Image taken from https://schooltutoring.com. not sure where they got it from!]

Low Energy Building First Class Fact Checking

The first lesson has some background on the energy problem. I have the carbon graph, showing the emissions taking off around 1800, driven by a smooth exponential growth in coal production. Actually the coal was not really being produced—that happened back in the carboniferous period 300 million years ago—it was being moved around and then burnt. The graph shows oil starting, then gas a little later, each in its own exponential variant. Meanwhile, the emissions from coal have still been increasing. 

I've been saying "until this year" with a quizzical optimism, and finally it looks like "production" of coal is down, which is a sign that we will eventually burn less of it. 

This graph from BP is still pretty scary.  That gray coal line definitely seems to be getting thicker. Also alarming is the sandy bit at the bottom, which is biomass. Before coal that was the only source of heat, and it was more or less constant until the middle of the twentieth century. Now that is on the rise. I'm not sure how much is in industrial use of biomass, for example replacing coal in thermal power stations, and how much is domestic use from fuel-poor burning what they can find. 

If you look carefully you can see the thin yellow strip of renewables at the top, like a sprinkling of snow on a mountain top. While this has increased from its previous levels of invisible and insignificant, it is still a long way off replacing any of the behemoths beneath it.

It should be noted that while BP's data can probably be trusted, their main business is still in selling fossil fuels, and their business model is still based on selling more. The graph goes up to 2013. 

The next graph is from the International Energy Agency, and gives us hope that 2013 was around the high point of coal, with production in China and the OECD decreasing. It's tempting to see that as a peak, and look forward to a steady then rapid decline in coal extraction.

However, Dick Van Dyke nostalgia has been strong in the US, and production was up last year. So, once again, it's too early to tell.

I guess it depends on who wins between the people selling fossil fuels, and people promoting energy efficiency and renewable energy. 

While checking figures, I also revised the proportion of Japanese energy that is imported from 80% up to 90%. The lower figure was pre-Fukushima, which had got into my slides at the beginning, and I've now corrected several years late. (Japan was 20.2% energy self-sufficient in 2010, and 8.3% self sufficiency in 2016 according to METI.)

I had been telling student that Japanese houses use 30% of the country's total energy, while in fact its more accurate to say that buildings in Japan use around 30% of the total energy. 

Whichever way you look at it, the amount of energy imported can be reduced if we get serious about low energy buildings.

I also found some interesting changes in energy use, which I may need to mention some time, although should probably work out more carefully first. 

Between 1973 and 2015, residential energy use in Japan increased by 90%, office energy use increase by 140% and industrial energy reduced by 20%. 

I'm not sure to what extent this is a sign that houses and offices have become much less efficient, while industry has become more efficient, or whether it shows that Japanese industry is producing less, and people are spending more time in offices and more money on energy-consuming appliances in their houses. 

(Dick Van Dyke from trailer screenshot - Mary Poppins Trailer, Public Domain, https://commons.wikimedia.org/w/index.php?curid=34700974)

Low Energy Building Course: Every Tuesday Afternoon—Starts 2nd October

Not only can students at my university take the 15-week Low Energy Building course, it's also open to members of the public!

You can read the syllabus below. And find more information about other courses open to the public here.

See you in room 26 half past two!

(1)授業のねらい	【授業の達成目標】 ・Students will learn how basic science affects buildings ・Students will learn how buildings affect the environment and how culture affects building practices 【授業のねらい】 Buildings use over one third of all energy consumed in Japan, as in many other developed countries. In a world of increasing population and limited fossil fuel reserves, reduction in building energy consumption is important. As well as drastically reducing consumption, low energy buildings can be more comfortable, more healthy and less expensive over their lifetime. This course will introduce students to the principles, the practicalities, and the future of low-energy building. 他の先進国と同様、日本で消費されているエネルギーの3割は、住宅で使われています。人口が増加し、化石燃料が限られてくる世界では、省エネルギー住宅が必要となります。エネルギー消費を減らすことで、居住者に快適で健康的な暮らしをもたらし、建物の耐用年数においても経済的です。本講義では、省エネ住宅の仕組み、その実用性と将来について紹介します。
(2)授業の概要	This course will show how simple scientific principles affect buildings, and how insulation, airtightness and good windows can lead to houses with very low energy consumption. We will see how the use of solar power can make buildings that produce energy. We will look at low-energy buildings around the world, including the German Passivhaus standard. We will also consider the design process, including compromise, optimisation and guesstimates.
(3)授業のキーワード	環境、物理学、建築、省エネ、熱力学、太陽光発電
(4)授業計画	1. What is a low-energy building? 2. What is energy? 3. Insulation and thermal envelopes 4. Compound insulation and thermal bridges 5. Why do we feel hot or cold? 6. Air and water 7. Windows 8. Ventilation 9. Windows 2.0 10. Energy standards and low-energy building around the world 11. To zero energy and beyond: Buildings as solar generators 12. Passivhaus 13. Economics and ecology, embodied carbon and life cycle analysis 14. Presentations 15. Review This plan may change to meet the needs of the class
(5)成績評価の方法	Students must complete weekly online activities in eALPs to pass this course. Students will be expected to participate in class and give presentations. Online quizzes: 80% Online forums:  10% Presentations: 10%
(6)成績評価の基準	The university policy states that students need 60% to pass, 70% for a B, 80% for an A, and 90% for an S.
(7)事前事後学習の内容	Additional information will be made available on eALPS.
(8)履修上の注意	The class will mainly be conducted in English. It will be possible for students to ask questions, complete assignments and give presentations in Japanese. 本講座は主に英語で行いますが、受講生からの質問、課題の提出、発表は日本語でも結構です。

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.

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.

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:

Add solar panels

Buy the latest electronic equipment

Increase the number of windows

Plant grass on the roof

Use insulation

​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	Choose...three times thinner (around 30 cm)five times thinner (around 15 cm)two times thinner (around 40 cm)four times thinner (around 20 cm)you can't make walls thick enough
U 1.3 Triple, low e argon, PVC frames	Choose...three times thinner (around 30 cm)five times thinner (around 15 cm)two times thinner (around 40 cm)four times thinner (around 20 cm)you can't make walls thick enough
U 0.8 Triple, krypton, insulated wood frames	Choose...three times thinner (around 30 cm)five times thinner (around 15 cm)two times thinner (around 40 cm)four times thinner (around 20 cm)you can't make walls thick enough
What about the single pane windows (U 6)?	Choose...three times thinner (around 30 cm)five times thinner (around 15 cm)two times thinner (around 40 cm)four times thinner (around 20 cm)you can't make walls thick enough

​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.

The coffee maker uses a 1 kW heating element to keep the coffee warm.
There is a new coffee machine with a thermos flask pot. It does not need a heating element.
It costs 10,000 yen.
Electricity costs 25 yen per kWh.
If we buy the new coffee maker we will pay less money for electricity.

How many weeks will it take to save the money?


Answer:

​

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.

Answer:
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".

Talking about Passive House. Lesson 14

This low energy building course is really just propaganda in disguise. The whole course has been framing the question, and the answer is Passivhaus. I also like to talk about differences in building culture, and mention my own experience trying to build a low energy house in Japan. I can, with honesty and some innocence, present my discovery Passivhaus as an epiphany on my road to building a house.

As usual term starts running out with too many lessons left over. In week 13 of 15 I had to get them into groups for their final presentations, and then give them some guidelines of what to do, and what not to do, when designing and delivering their own presentations. I could spend a whole lesson talking about preparing presentations. In this class I probably should, focusing on presentation construction as a piece of architecture.

They had put their own presentation ideas into a forum on the online part of the course, and then chosen their top three choices in an online quiz, so I had most of the data needed to make the groups, but of course a few students had not actually added their top choices for a presentation topic, a few others missed the lesson, and as usual a small number of the topics were very popular and they did not fit neatly into seven topics that were the first choices of exactly four students. In the end over half the lesson was taken up discussing their presentations, and I could only get through half of my beautifully prepared full lesson, with its narrative from building cultural differences between the isles on the East and the West of the Eurasian continent, to my own journey into house building, and discovery and application of the Passivhaus standard.

Energy balance for a Passivhaus

Descriptions of standards can be dry, and there's a maximum of ten minutes I can talk to any class in English before they lose attention, so tasks are needed. I like setting them problems to solve, and also want them to practice real-world calculations where possible.

First I had them brainstorm heat gains and losses in a house. They got most of these, but needed a bit of a hint to remember ventilation.

The next task was to get from the definition of Passivhaus in English to the numerical heating load. This is a fairly straightforward calculation from the floor area per person, the volume of air needed per person, the maximum temperature air can be heated to before it burns, and the heat capacity of air.

Next, I wanted them to work out what U value they would need for the walls of a Passivhaus in Matsumoto. This involves several steps, and I made the mistake of giving them too many of the steps to work out in one go. I don't think the calculation itself is particularly difficult, but I guess I'll find out because I've set that for their homework!

The first step, to make the calculation easier, is to assume that the heating load is equal to the loss of heat through the walls. Remembering the energy balance of a building, you can get to this by assuming that solar gains through windows roughly equal heat losses through windows and internal heat gains roughly equal heat losses through roof, ground, and ventilation.

The next step is to work out the wall area of the house. I gave them the volume, told them it was two-story, and assumed they'd just be able to work out the wall area from that. Half of them are studying
architecture so I think I can be forgiven for my assumption. It turned out to be wrong though. Perhaps there were too many assumptions for them to make: the height of the walls, the squareness of the building footprint, the use of square root to get from an area to one of it's sides, the number of sides on the square... Perhaps they were worried about other things: did they need to subtract the windows and doors? What shape was the roof going to be? Perhaps they were distracted from this question because they were expecting thermodynamics rather than geometry. Anyway, I think have learnt my lesson, and will chop the problem into bite-size chunks for them next time.

I should probably have realised this sooner, and modified the task, but while preparing the lesson I had been more impressed by the result of the calculation: 0.162 W/m2K. This number may not mean a lot to you, but as I scrolled down the slides to the introduction to my own house, I noticed that in fact the U value of my walls is 0.162 W/m2K. Perhaps just a coincidence, but it does show you
the power of rough estimates!

Unfortunately I didn't have time to share this bit of synchronicity with my students as the lesson had somewhat dissolved into scratching heads, spurious scribbling and many over-precise, under-accurate sums. The bell was going to go before I got to the happy ending that is Matsumoto Passive House.

Carbon payback in a month not three days: Check those facts!

It looks like a simple arithmetic mistake has struck again.

In preparation for my lesson, I noticed my slides proudly announcing that five jerry cans of paraffin will put out two hundred times more carbon emissions than ten square metres of glass wool insulation. I had the carbon emissions for paraffin at a quarter of a tonne, which at first seems like a lot, but it's pretty much all carbon, and each one of those atoms is going to bond with a couple of oxygens from the atmosphere as they set of heating up the planet in their cosy little threesomes. You have to remember that fossil fuels are worth more than their weight in carbon dioxide emissions! Adding this to the extra density of the paraffin, a factor of two hundred is reasonable.

To give a little extra support for my students who are good with numbers but less good with foreign languages, I wanted to add a more precise weight of carbon equivalent to the glass wool. I could have just divided the quarter tonnes by two hundred, which would have given me one and a bit, but I wanted to get a more precise figure.

My first port of call for fact checking, as usual, was google. I assumed I could just ask it how much embodied carbon was in glass wool, and it would tell me.

I quickly found this greenspec.co.uk, which doesn't have any actual numbers, but has a few graphs. Very sensibly, it starts with different thicknesses of insulation to reach a respectable wall U value of 0.15 W/m²K, which would be about 23cm for glass wool. Then it has the embodied carbon value for a square metre of wall. If my I've read the graphs right, and my sums are correct, this gives 25 kg of carbon dioxide equivalent for my ten square metres of glass wool. Not two hundred times less than the paraffin, but ten times less.

I started looking for my own workings or references, but didn't find any. Usually I add a reference somewhere nearby, in the last few slides of a presentation or as a footnote of a blog post. At least it's good practice to do that, and I always expect it from my students!

So back to google again for a second opinion. I found a carbon footprint of 1.35 kgCO₂/kg for glasswool in table 4.3 on page 118 of Sustainable Construction Processes: A Resource Text, by Steve Goodhew, which is the same as the University of Bath figure I wrote about before. The density is 25 kg/m³ here on engineering toolbox, which gives a slightly higher figure. But if I go with the spec on google shopping of 10kg/m³, I get to about 13 kg of carbon dioxide equivalent for the roll. Twenty times less, not two hundred times less.

There's a factor of ten error somewhere, but since I didn't keep my original workings, I can't see exactly where it is. I've checked a few times, and I'm pretty certain that the roll of glass wool is 10 square metres, and since it's 100 mm thick, it's going to have a volume of one cubic metre. I can well imagine a factor of ten error sneaking in somewhere around there.

Anyway, in terms of the return on carbon investment, instead of a three day carbon emissions payback for switching from paraffin to insulation, it's actually a month. Still seems like a pretty good idea!

This does go to show that it's always a good idea to double check calculations.

When I prepared the lesson two years ago, I was comparing an 11-metre roll of 910-mm wide, 100-mm thick glass wool with five 18-litre cans of paraffin, both of which cost 6000 yen. I'm not sure if it's a trend, or there is some fluctuation, but now the glass wool is a thousand yen cheaper, and the paraffin a thousand yen more expensive.