Friday, 22 December 2017

Passive House in Canada

While Passive House remains a mystery to most, and a misnomer to many in the building trade, here is some news of steps in Canada. And why wouldn't you?

Tree hugger reports here on a Canadian charity building social housing to Passive House standard.

CBC News​ reports here ​h​ow Canadians are constructing North America's biggest green buildings​.​ And perhaps the greenest big buildings too.

​And here's an article from High Performance Building Supply about why smart cities need passive house buildings, which is not really about Canada​, but they do mention a project in Toronto.

Monday, 18 December 2017

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, 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.

Monday, 11 December 2017

Lesson 10: Take 3: Standards

It's a challenge making building standards interesting. The topic seems as dry as a highly insulated house in the middle of winter with heat recovery ventilation and no humidification. As I started brushing the cobwebs off last year's presentation, my first thought was that I should teach this lesson later, and tackle the altogether more exciting topic of energy generation first. I stopped myself, thinking that I was just trying to put it off, and I've just noticed now that I'd moved it two weeks later last year. A lesson on comfort had been added to the original plan, and Windows 2.0 came after the lesson on standards the first time.

This lesson should really work as a revision of what I've been telling them about low energy building, since standards ideally reflect the essence of low energy building, and promote improvement.

I followed the plan at the beginning, giving them several reasons for low energy building. An obvious reason is to reduce environmental impact, although unfortunately this is a relatively low priority for a lot of people. Money is often a higher priority, and the fact that low energy buildings are cheaper to run, long term, is perhaps a more powerful incentive. Even then, a lot of people are concerned with the immediate costs, and less worried about possible future savings. Grants or tax breaks are another reason people may build low energy, but the most powerful reason is probably where there are laws that oblige people to build low energy.

Then I tried to introduce the idea of standards, with a few examples and their logos, including the JIS (Japan Industrial Standards) logo, which they all knew, and the logos for European Standards, British Standards, and Forestry Stewardship Council (FSC), which they did not.

In order to breathe some air into the topic, I put them into groups and had them imagine they were government committees who had to come up with their own standards to ensure low energy buildings.

First they had to brainstorm for things they could look at. I had to steer them away from things like giving grants, which is a good idea but not actually a standard.

Their ideas mentioned insulation materials, windows, form factor and solar power.

After some brainstorming, I got each group to choose two or three ideas, and come up with some details of what exactly they would stipulate.

They came up with a few concrete suggestions, such as using wood rather than aluminium for window frames, and a minimum percentage of glazing to frame. Other ideas were a bit vaguer, like making the air gap thicker, and having "really thick" walls. There were very few actual numbers, and nobody mentioned U-values, which makes me think I haven't talked about that enough times.​ Also nobody mentioned ventilation.​ One group came up with the two ideas of adding solar panels, and adding a battery to store the power. These are both interesting ideas but have absolutely nothing to do with what we've been talking about for the previous nine weeks. That did make me think I should have done the lesson on generation first.

The lack of detail also made me wonder whether I should have given them that task later in the lesson, after I had given some examples of actual building standards. As often happens in teaching, there is a difficult balance to reach between giving students information and getting them to come up with their own ideas. Perhaps I should start off by introducing some of the early low-energy building standards and then get them to think about what is missing, how they could be improved, and what they would do now.

This may have been a good lesson to produce a multi-dimensional gap fill, or jigsaw activity for. There is a smartphone app called Quizlet Live that lets you add several questions and their answers, which are then scrambled for students to match. The teacher gives students an access code, then the app puts students into groups of three or four, so they have to go and find their partners. Then each student gets around four answers on their screen, and the questions come up in turn. The student with the correct answer must select that, then they will all get the next question. If someone gives the wrong answer, it goes back to the beginning again, shuffling the answers. This may not make the content any less dry, but it could socialise its delivery.

​ ​

Thursday, 30 November 2017

Building Jokes

There was a tweet a while a ago from Nick Grant @ecominimalnick with a picture of a structural engineering joke.

I didn't get it at first, but the joke is that the round black things with the bolts in are supposed to be stopping the walls from bulging, by bolting them onto the floor. Clearly the floor is not in the middle of the windows. This may be a deliberate joke, but I don't think the other pictures are.

A couple of my students did start laughing when I showed them this picture, which Sam sent me. I'd been talking about the relative merits of glass, air and aluminium in window construction, and they found this very funny, although I doubt the joke is deliberate.

I asked them to calculate how much glass and how much frame there was. They all guessed around 70% glass and 30% frame, but actually it's closer to 55% frame and 45% glass.

It's even funnier when you notice the unmelted snow, and see where the sun is coming from and realise this is a North-facing window. So not only is the aluminium going to reduce the performance of the glass, it's not going to get much sunlight coming in. It's possible there is some fantastic view that these windows look at, but even then, most of the view will be obscured by frame.

Of course traditional houses in the UK aren't much better.

I also showed them the windows below from a brand new concert hall in a nearby city. Due to my photographic inability, it's a bit difficult to work out what's going on, but basically the external surface area has been needlessly increased by around 20%, and it's aluminium too.

This time the joke is on the city tax payers, who will be getting the heating bill.

Friday, 17 November 2017

How to build a house Part 4. Paying for the bloody thing

Financing is the main thing stopping many people from building their dream homes. Still others are forced into building a house because they have access to finance​, and that may turn into a nightmare.​

Unless you are one of the lucky few with enough cash to pay for a house up front, you probably need to get a mortgage. Banks can decide who to lend, or not to lend to, but as with many things, the biggest factor is whether you want to borrow money or not. As Henry Ford said, "whether you think you can, or think you can't—you're usually right."

I've heard foreign residents in Japan say that banks won't lend to them if they don't have permanent residency and permanent employment somewhere. That's certainly true if they think it's true, and don't go and ask any banks.

If you want to get a loan, then get it while you are employed. The bank will be happier to lend if you have a steady income, that has been paid into your bank for several years. Before I got a loan I was worried that I would be stuck to my job forever. I was also somewhat scared of monthly repayments until I'm into my seventies. As it happens, after getting the loan I felt much less chained to my current job, and I hardly think about the monthly repayments. ​They're just like rent, which I had got used to paying. ​

Money used to be bits of metal, then it became bits of paper and later bits of plastic. Now it's just bits on a computer somewhere. It's not a particularly scarce resource, but that may be easy for me to say with an overly privileged background and a life of undeserved comfort​!​


But​ whether you're paying in cash or from a hard-fought loan, the question remains: how much is the bloody thing going to cost?

It's like when you go to a restaurant and look at the prices on the menu. Except there are another few noughts on the cost of everything.

Glass of wine 300 yen. Light fittings: 300,000 yen.

Salad 500 yen. Bathroom: 500,000 yen.

Paint. You want paint?

This should not be surprising when you consider how big a house is.

The glass in our windows could have made a thousand drinking glasses, and the tiles on our floor could make a thousand ​plates. I don't want to think about how many chopsticks the wood could be split into.

It's important to understand the difference between price and cost​, which are not the same. Basically price is what you pay to get something, and cost is what the person who gives it to you had to pay. Businesses stay in business because of the difference between price and cost, and often the relationship is arbitrary. The price depends on how much ​the customer ​is able to pay, and how much other people are charging, not on how much it will cost the​ supplier to produce. The costs can't stay above the prices for long, unless that is funding another revenue stream​, as when Gillette sold shaving handles below cost, or even gave them away because they could make money out of the razor blades.

​House builders are in almost exactly the opposite situation. Once you buy a house from them, you will never buy anything from them again. In fact there is a chance that you will demand some extra work from them to fix the inevitable problems that houses come with. This means they need to ​make all their money up front.

There is a large margin on houses in Japan, ​and​ they will basically charge you as much as they can get away with. If you start asking questions, they can easily justify any price they want by producing pages of lists of items with prices to the yen. Most of these item prices will also have large margins either because they have hiked them, because they are list prices and the actual amount they pay suppliers is much less, or because they are over estimating numbers or lengths or weights.

You could pay anything between 10 and 50 million for a house. Paying more will not necessarily increase the resale value of the house. ​In Japan, the value is basically in the land. In most places land is​ a good investment​ because they don't make it any more so its ​value increases over time​. There are some fluctuations, so timing can make a difference, and the exact location could be vulnerable.

Building a house may not be a good investment in financial terms. But in terms of security it gives you a more solid foundation in the community, and also​ more​ psychological​ stability​, so is worth it if you plan to stay in Japan. Find somewhere you want to live!

​Building a cheap house may end up costing a lot more long term in heating and maintenance.​ These costs are usually not taken into consideration when you're building, but the heating bills are also coming out of your bank each month, just like the loan repayments. The difference is that one day the loan repayments will stop, but you're still going to have to pay for heating and cooling. Even when they do tell you how much the energy bills will be, actual heating and cooling costs are typically twice the estimates and simulations.

​Building a Passive House, or at least using Passive House software during the building process, will give a much more reliably estimate, and will allow you to make realistic comparisons between the cost of heating and the initial costs. ​

Friday, 10 November 2017

How to build a house part 5: What exactly do you need to know about heat

Some people spend six years studying for architecture degrees, and it can take a lifetime to build the perfect house. In fact it's now 90 years after Gaudi was knocked over by a tram, and his is still not finished. Admittedly that wasn't your everyday family house, but I digress.

So, you'd like to build a house in the next year, and you're also going to be busy at work, and spending time looking after your family. What do you really need to know?

If you're trying to build a low energy house, two important areas of knowledge are thermodynamics
and economics. Structural knowledge is essential, but if you are working with professional builders in Japan, they should have all the structural knowledge necessary to keep your building standing, probably even through the strongest earthquake ever.

As well as knowledge of what to do, you need to know how to do it, and procedural knowledge is also important. So you need to know how the design process works, but I'll get to that later. First, here are five things you should know about thermodynamics. In most places in the world, the biggest energy use of buildings is heating and cooling.

1. Heat will leave the building by the easiest route in the winter. And it will get in by the easiest route in summer. Heat is a lazy opportunist. This means that you should be worrying about the parts of your walls, ceilings and floors with the least insulation rather than being impressed by the parts with the most insulation. Be aware of the performance of doors and windows, and anything in your thermal envelope that is poorly insulated. There may be conflicts between the structural desires of the builder and the thermodynamic needs, but it is possible to make buildings that are structural sound and thermally right.

2. There is less heat loss as walls get thicker and areas get larger, and more heat loss as temperature
differences increase. So thicker is better for your walls and roof, and smaller is better for the surface area of your house. When you are designing the house, you can't do anything about the temperature. It will get hot and cold outside, and the people inside will want the temperature to be within their comfort zone. If the building does not deliver that comfort zone, the people in the building will use electricity or other fuel to change the temperature.

3. Heat loss depends on the insulation performance of the material in your wall, roof, floors and foundation. Very broadly, metals are the worst insulators, or the best conductors, followed by earthy things, including stone, concrete and glass. Next come plastics, which we can start to call insulators, then fibres, which include wood. Foams are generally better insulators than fibres. In both cases their
performance comes from the excellent insulation credentials of air, but foams also stop the air from moving, and in some cases can use different gases to air. Other gases are better insulators than air.

This table shows the thicknesses of different materials needed to get the same insulation effect as 10 cm (4 inches) of glass wool. Depending on where you are in Japan, you may need the equivalent of 20 or 30 cm of glass wool to make a low-energy building.

Krypton (gas)2 cmthree times better than air
Argon (gas)4 cm
Phenolic foam5 cmtwice as good as glass wool
Air6 cm
Polystyrene, expanded styrofoam8 cm
Glass, wool Insulation10 cmthree times better than wood
Cork, re-granulated11 cm
Hardboard high density38 cm
Wood, oak43 cmthree times better than medium concrete
Polycarbonate48 cm
Concrete, lightweight50 cm
Polyethylene low density, PEL83 cm
Concrete, medium1.4 metresthirty times better than stainless steel
Concrete, dense3.5 metres
Stainless Steel40 metrestwelve times better than aluminium
Brass270 metres
Aluminum500 metresYes, half a kilometre!

4. There are five to ten litres of moisture in the air inside your house, and given any opportunity it will build up and cause condensation, mold or rot. This happens where air is not moving and there is a cold spot or a sharp temperature difference. It will happen where you are not looking, possibly on your favourite coat. This can be stopped with airtight insulation.

5. Reflective coatings are a good idea, since they will reduce the amount of heat radiated in or out of your house. However, most heat is lost through convection or conduction, so the first priority is to add insulation. Things that look shiny may just look shiny.

Bonus: It may be useful to know how a heat pump works. There's a great explanation here using a rubber band refrigerator.


While 500 metres of aluminum has the same insulating performance as 10 cm of fibreglass, metals are not effective as insulators. As the insulation gets thicker, the outside area of the house also gets bigger, so you will more heat, not less heat, as you put on more layers.

Monday, 6 November 2017

Passive House News

​There's another Passive House blog​ here:​

​And news of an affordable Passivhaus ​development in the UK here: ​

And a great story here about Fridtjof Nanse, possible creator of the first Passivehouse, which floated, and went to both the Arctic and Antarctic over a hundred years ago. While the mess on Scott's ship was underneath the ponies they were taking to Antarctica, Amundsen was staying in comfort on the Fram, with high insulation and airtightness. It also had a windmill generating electricity for the lights inside.

Friday, 27 October 2017

How to build a house in Japan part 3.14159265... How much do you need to know?

Disclaimer: you're going to have to wait for the next post if you want some ideas about exactly what you need to know.

If you buy a car, you don't usually start making suggestions about where to put the seats, where the filler for the fuel tank should go, or the timing of the spark plugs. But when you build a house it's possible to make all kinds of request and suggestions. You may also have noticed that almost all cars are built in factories, where standard parts are assembled in quality-assured processes. Although cars were all bespoke in the beginning, to build a car by hand now you would need a lot of expertise, time, money, or perhaps all three.

It's tempting to think that the same economic forces will push all houses to be factory-built, leading to higher quality and lower cost. But that happened to the automobile industry well within a hundred years, while house building is perhaps a hundred times older, and many houses are still built by hand. So some other factors are at play. Of course there are logistical issues with actually building houses in factories: wall and roof structures can be factory-produced and assembled on site, and sometimes are, but it would be very difficult to transport whole buildings over inevitably large distances from these huge factories. Cars, on the other hand, could be literally driven off assembly lines.

Another conclusion is that building a house is much easier than building a car, and it is within the capability of many more people. So one question you may want to ask is: how much do you need to know to build a house yourself? The short answer is that if you can ask that question, you probably know enough, or at least will find out enough in the process, which you should appreciate will take at least a couple of years.

But before you start thinking about doing everything yourself, how much do you need to know before you start commissioning others, and looking at part 4, which is paying for the project.

High-volume, low-cost builders are likely to give fewer options, but as the scale comes down and the price goes up, so do the choices you can make. Building professionals should probably be giving clients simple choices between limited options or within small ranges, with the kind of user friendliness that Steve Jobs brought to Macintosh. But people do have opinions about the way a house should be, and it may not be on the menu. These ideas may be based on things you have in your existing house, things you saw in someone else's house, things you read about somewhere, or something from your fertile imagination. Whatever ideas you have, if you are paying for your own house, it's reasonable to request it to be your ideal house.

But be careful of what you wish for, as you might just get it. Indeed your imagination may be playing around with what some of those things in other people's houses and in magazines actually are or do. And if you have a great idea for your house, but have never seen another house that uses that idea, then it's possible it's not actually a great idea, and there are very good reasons for not doing it. It's also possible that you have just invented something. 

And it's also possible that it is a great idea and has been used in several other houses, but you just haven't seen them. If the architect or builders tell you it's impossible it may just be beyond their experience. I remember in the early stages of our project suggesting to the architect that we could take heat out of the air leaving the house and use that for generating hot water. The architect laughed at me. Later I was talking about the same thing to the passive house lady, and she said, "Oh yeah, that's what they do in Sweden."

So visit as many houses as possible. You can also look at houses in magazines, but beware that they may be idealised houses that are lived in very differently, and any of the features may have lost their sparkle a couple of years, or even a couple of weeks after the paint dried. Or the features may still be there but are invisible under layers of magazines, homework the kids didn't do, bits of clothing that you're not sure who left behind, and jars filled with pens that mostly don't work.

The internet is a great source of information and you may often be in a position where you know more about a topic than the professionals. Materials and techniques around the world are developing all the time, and what your architect learnt at college twenty years ago may have changed, been superseded or debunked. Watch this you tube video for some brilliant tips for doing it yourself. I particularly liked the idea of putting a rubber band over the head of a worn-out screw to get some purchase on it. But also remember that a lot of professional builders now make a living from correcting projects by people who watched one youtube video and thought they knew what to do.

Stick some foam in, she'll be right! (not)
But beware of the Dunning-Kruger effect. This means that your ability to know how good you are at something depends on how good you are at doing it, because the skills needed to judge an ability are similar to the skills needed to have that ability. This should make you humble about your ability to specify the building you want, choose contractors, or take on a project management role. It may also apply to the architect or builder if you are expecting them to do something new. They may have no relevant experience with insulation, airtightness, installing high performance windows, ventilation systems or any other features essential to low energy buildings.

So when talking to professionals, while they probably know more than you know, remember:

  • they probably know less than they think they know 
  • you probably know more than they think you know
  • you may know less than you think you know

People say that a little knowledge is a dangerous thing, but in fact any amount of knowledge can be dangerous.


1. For most calculations, pi is a bit over three. The precision in the title would give you the length of a piece of string around the equator to within 40 centimetres, if the earth was perfectly round, which it is not, and you knew the diameter to within a few centimetres.

2. How long is a piece of string?

Friday, 20 October 2017

Are renewables helping gas burn, or is gasoline stopping electricity going to cars?

First they ignore you
Then they say you're stupid
Then they say you're wrong
Then they say you have an interesting idea
Then they say they thought so all along

"You have enough electricity to power all the cars in the country if you stop refining gasoline." According to Tesla Motors CEO Elon Musk via green transportation. "You take an average of 5 kilowatt hours to refine one gallon of gasoline, something like the Model S can go 20 miles on 5 kilowatt hours."

We often hear complaints about renewable energy not really being renewable, because it uses some fossil fuels to produce the materials. It's interesting to note that the petrol that goes into cars is actually using electricity.

As usually things are much more complicated than it seems. Advocates of renewable energy see a future with 100% renewable energy. Skeptics see the energy costs of producing renewable infrastructure, and the source of that energy, and claim that the march to renewables will produce more carbon emissions so we are better off burning fossil fuels directly.

Some of the nuclear lobby, meanwhile, attack renewables and claim they are just being used as greenwash for the fossil fuel industry, which wants to be there when the wind stops blowing and the sun stops shining. In fact there are many common interests of the nuclear industry and renewable industry. One is electrification. Also, they can also both benefit from increased capacitance in the system: renewable energy because the production is unreliable and may not meet or match peaks in consumption; nuclear for exactly the opposite reason that production is constant and energy storage will mean demand can be met with less plant.

It's very unlikely that burning fossil fuels will lead to a fossil-fuel free future, unless you are cynically hoping that the only realistic fossil-free future is one where they have all been burnt. As a technological development, electrification makes renewables possible since the energy is easy to convert and transfer over large distances. The internal combustion engine has a much more limited diet.

Low-cost solution to the grid reliability problem with 100% penetration of intermittent wind, water, and solar for all purposes  is a 2015 paper by Mark Z. Jacobson, Mark A. Delucchi, Mary A. Cameron, and Bethany A. Frew from the Department of Civil and Environmental Engineering, Stanford University, and the Institute of Transportation Studies, University of California, Berkeley.

They claim that existing technologies can be used to get the US onto 100% renewable power. The paper has some critics, of course.

This podcast from Science Vs asks whether 100% renewable energy is possible, and features Jacobson and Delucchi as well as some of their critics and more neutral observers. The answer is not exactly yes, and they point out a few areas will be very tricky to get onto renewables, such as iron smelting. But they suggest it's a pretty good direction to think about moving in.

In the conclusion, the podcast suggested people may need to change the way they live, using energy depending on how much is being generated. Use the air conditioning when the sun is shining. Do the washing when the wind is blowing. It's easy to see some logic there. It may be more tricky if people are expected to switch off the heating when there has not been much sunshine, since that's known as winter in several places.

It's interesting to note that at no point did the podcast mention efficiency. Increases in efficiency do not rely on people's behaviour. Also they are cumulative and compounding, so a seven-percent annual improvement in efficiency means half the energy use in ten years. This is certainly a high level of improvement, but the predictions of most of the renewable skeptics assume efficiency improvement of zero. This is also true of fossil fuel advocates and the nuclear industry, whose forecasts are consistently based on increased consumption of energy, and whose forecasts are consistently wrong,. Since they are in the business of selling energy, increased consumptions is in their best interests, and it's not at all surprising that it gets into their forecasts. If I was running a bakery I'd be hoping to increase my sales, and if I was planning for fewer customers in the future, I should probably be taking an early retirement, or at least changing my profession. Even in the paper by Jacobson et al., future energy production is based on the predictions of the IEA, International Energy Agency, who have been predicting the end of solar power growth for fifteen years.

Friday, 13 October 2017

Lesson one take three

The low energy building class is now in its third year, and the make up of the students was much more like one of my regular classes. There were over thirty students, up from seventeen last year and nine the previous year. I think there is only one foreign student this year, where half the class or more has been s is much lower too, with

Around half of the students are architects, again. There are a few from the Faculty of Textile Technology, a biologist, an economist, and others studying education, humanities and American Cinema.

There are also a couple of members of the public taking the class. In the first year I also had two of these students, although they stopped coming after a few weeks. I'm not sure how much this was an indictment of my class or wether they just got too busy in their lives, and could write off the very low fees that the university charges. Anyway, I hope they will stay this year. One of them works for a large supplier of building parts, so I hope to have some time to discuss business with him.

In the first week's online quiz, I asked them what language they wanted to speak, and what language they wanted me to speak. The majority want me to mostly speak in English, and they want to speak some English and some Japanese. Nobody wants to only speak English, and only one person wants me to only speak Japanese. This gives me a mandate to speak some Japanese in class, and also an incentive to add some Japanese to my slides.

The first lesson followed the same plan as before. I gave them a few simple mathematics problems to make sure they will not be too overwhelmed in the rest of the class. They were just designed to check they can manipulate formulae.

I also threw in a different kind of question: How many pencils are in this room?

They were working in groups, but not allowed to talk to other groups. Answers ranged from 12 to 60. The middle answer—30—was remarkably close to the actual number—31. This was an opportunity to introduce guesstimation, and emphasise that usually we need to find answers based on limited information.

Friday, 6 October 2017

Graphs of words show Climate Change is still increasing, while Global Warming has stabilised

According to this graph from Google Ngram, Climate change is still increasing. Ngram measures how often words are used in our language by counting occurrences in a huge swath of publications that have been digitised. This is a form of corpus linguistics, a field of study that goes back to Vedic scholars counting the occurrences of different sounds in Sansrkit holy texts. Arabic scholars also studied the Koran, and back in 1230 Hugo de Saint Cher made a concordance of the Bible, noting where and how often each word appeared in the holy book. Computers have made this a lot easier, and Corpus Linguistics has really taken off since the 1960s.
Ngram opens that door to anyone interested in what people have been writing, and we can see here that climate change, global warming and greenhouse effect all steadily increased until the mid 1980s, where they received a bit of boost. Global warming used to be more commonly used than climate change, but slowed and then plateaued in the early 1990s, slighly increasing since. At about the same time use of the phrase "greenhouse effect" peaked.

A climate denier may be tempted to interpret this as the greenhouse effect peaking in 1992 and decreasing since, and evidence that the data for climate change and global warming have been tampered with by NASA.

My interpretation is that discussion of this topic became increasingly important from the 1970s, initially led by discussion of the greenhouse effect. This is the method by which global warming was
happening, and reliable historical temperature data began to become available from this time.

By the end of the 1980s the discussion of how global warming happened was more or less decided, and we didn't need to talk about the greenhouse effect so much. I suspect discussion of "round earth" peaked shortly into the age of discovery when returning ships removed any serious doubt about the shape of the planet.

Global warming and climate change were discussed equally, and largely synonymously until 1992. It's not clear why this happened, but in 2002 a Republican party memo by Frank Lunz recommended that the term "climate change" was used rather than "global warming", which people found frightening. It seems that George W Bush did respond to the calls to "stop global warming" by not using the phrase any more. This is not exactly what people wanted! (See also Guardian, 4th March 2003).

A more detailed linguistic investigation by Dr. Martin Döring of the Institute for Geography at the University of Hamburg into perceptions of regional climate change in North Frisia found: "six prevailing conceptual metaphors: Climate change is an enemy, preventing climate change is fight/war, climate change is punishment for human sins, climate change is overheating/heat, climate change is hot air/hoax and climate change is eco-dictatorship."

Those of us who want to "fight" climate change need to take account of the last idea: climate change as eco-dictatorship. For some people this may be overwhelming, for examples libertarians who make up the right wing of the US Republican Party, for whom denial of climate change is perhaps primarily a rejection of government intervention.

Friday, 29 September 2017

Just how smart are smart homes?

When I first lived in Tokyo in the mid 1980's I remember being out somewhere and a friend got up to use the telephone. It was a payphone since this was before the age of mobiles. He didn't say anything, but punched in some numbers then put the phone down. He told us he'd just started the bath running at home.

If you don't know what a payphone is,
you probably won't know what this is either
This seemed like science fiction to me with my perspective from the primitive plumbing of England. Indeed it was science fiction compared to the Tokyo flat I was staying in where there was no running hot water, and the bath had to be filled with cold water, then heated by circulating water through a gas burner. Once, after a long day, I got into one such bath while the heater was still on. I dozed off in the bath and woke up very hot, and when I moved I got even hotter since I had been cooling the water immediately around me.

Most bath heaters had simple mechanical timers in the switches, so they would not overheat the bath. Even in the 1980s some of them could be programmed to switch on at a certain time, so the tub would be hot when you got home.

We can't call our bath on the phone, or send it text messages, but it can be programmed to come on at a certain time, and it does know how to say "I'm filling up the bath" and will happily tell us "The bath's ready". Unfortunately it doesn't know how to say "Whoops, I ran out of water so your bath is luke warm." And the phrase, "Hey, you forgot to put the plug in, you idiot" is also missing from its vocabulary. In both cases, the light just goes off and it remains silent. It's really not very smart.

So how smart are smart houses? Not very, is the short answer. Will they help us to save energy? Our bath could have saved us a few hundred litres of hot water if it just knew to tell us that it wasn't filling up and we'd left the plug out. So excuse me if I'm skeptical of the age of the smart house and the brighter future offered us by the internet of things.

If you want energy efficiency, then it is dumb things that will deliver: geometry, wall thickness, window quality, airtightness and attention to detail in the construction.

You can get gadgets if you want, and they may make your life better, but if you want to save energy start with the thermal envelope. You can stick as much as you like onto the envelope later. This applies to solar panels too, which are probably a good idea to add to your house, but they will not make your house more energy efficient. Putting insulation under the roof is a much higher priority than putting solar panels on top of it.

But don't just take my word for it. In Bringing users into building energy performance: Learning to live in a smart home, Tom Hargreaves, Charlie Wilson & Richard Hauxwell-Baldwin tell us that smart home devices are "technically and socially disruptive", are limited by the householder who is using them, and have a steep learning curve with few people to help you climb it. They also find "little evidence that smart home technologies will generate substantial energy savings and, indeed, there is a risk that they may generate forms of energy intensification."

Wednesday, 27 September 2017

Low Energy Building Course - Open to the public!

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 find the syllabus here. And more information about other courses here.

(1)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.
(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.
(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)成績評価の基準Participation: 20%
Online assignments, quizzes, presentations: 80%

Students must complete online activities to pass this course. Students will be expected to participate in class and give presentations.
(6)事前事後学習の内容Additional information will be made available online.
(7)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.

Friday, 22 September 2017

Top Ten Top Tens

I've already posted my own top ten tips for building a passivhouse and posted about Alessandro
Merigo's but I've now added eight more to give you a top ten of top tens. Please note that most of these will just appear on one internet page, and none of these are click-bait with a button for the next page hidden between several traps.

1. Here are my ten tips for building a house.

2. Alesandro Merigo's ideas are here:

3. Dieter Ram has ten principles for good design, which apply when designing anything.

4. has an engineering perspective, which is close to my own ideas in
Ten Amazing Tips for Building Energy Efficient Homes.​

5. Think architect has Design-based ideas for building affordably.

6. have the top 10 most helpful tips for building a house.​

7. NZI Architects expose 10 myths about architects.

8. has ten mistakes to avoid when building a new home, although I'm not sure about their advice to have as many windows as possible, and to think about skylights. I'm beginning to wonder whether I should have stuck at seven.

9. has Ten green home building ideas, although they don't talk about the importance of insulation. Green may be more of a colour than a practical strategy to save the planet.​

10. And just in case​ you now need them​, here are ten tips on anger management from Mayo Clinic.

Friday, 15 September 2017

Too Much Humidity

When we built the house I refused to add an air conditioner for two reasons. First because I didn't think we needed to spend money on cooling when the house was not going to be so hot, and secondly because I'm from Yorkshire where we don't use air conditioners. Actually that's probably just one reason.

It may be global warming, acceptance of reality or weakness to luxury, but I think we need take active measures to remain comfortable in the peak summer heat. I need to take a closer look at passive house and high-temperature high-humidity in a different post.

The temperature is not a huge problem. It rarely goes over 28 degrees, and when it's 35 degrees outside, 28 degrees is a relatively pleasant temperature. The problem is when it is humid, and when it gets over 70% humidity it starts to feel really hot.

A de-humidfier would make the house more comfortable without making it cooler. In terms of thermal efficiency, de-humidification is a good idea since heat gain depends on temperature difference, so taking moisture out of the air makes it feel cooler without encouraging more heat to come in. On the other hand, making the house cooler means a bigger temperature difference, and more heat leaking in from outside.

Actually, we do have an air conditioner in one room, and that air conditioner does have a dehumidifier. But the de-humidify function just seems to work by cooling the air, and that room was not designed for the air to circulate through the rest of the house, so it just gets very cold in there when the dehumidifier is on.

Most dehumidifiers work by running air over a cooling element so that humidity condenses out of it. They differ depending on what happens to the heat that was taken away to cool the air. Either the heat can be put back into the air, or it can be taken out of the building. Our air conditioner does the latter, sending out cold, dry air. If you have a dehumidifer for a basement that gets damp in the winter, you want the former.

So do we want a dehumidifer that transfers the heat out of the house, or one that keeps it inside?

Should we try to dehumidify the air as it comes in through the ventilation system or should we get a standalone dehumdifier?

Would it just be cheaper and easier to get an air conditioner that can de-humidify?

Even if it was more expensive, would we be better off getting an air conditioner that can also cool and heat and do other fancy stuff? Maybe we could even get one that humidifies as well, since we need more moisture in the air in the winter.

Can I fit another air conditioner unit to the compressor that spends over 360 days of the year idle on my roof?

Or will it be cheaper to get another air conditioner with its own compressor?

How much moisture are we talking about?

The last question is easy.

If it's hot and humid outside, the ventilation system is going to be adding saturated air to the house. If it's 28 degrees, 60% humidity inside, with the ventilation system working at 150 cubic metres per hour, that is going to add 1.6 litres per hour. This is how much the dehumidifier needs to remove at peak load.

A closer look at some actual data for temperature and humidity here in July and August shows that the outside air was never actually hot and humid enough to come in saturated. But with a more comfortable 50% humidity at 28 degrees, the peak dehumidification load is 24 litres per day.

One very simple solution would be to switch off the ventilation system, or at least turn down the flow. This is a short term measure, because we do need fresh air in the house, but at night time and in the morning we open the windows and get plenty of fresh air in anyway. In fact the main demand for ventilation is to remove the moisture that we produce when we breath, wash and cook. If there are just a couple of people and a cat in the house, then we should be OK for a few hours. Turning down the ventilation would also be a good solution on cold winter nights when there is a risk of freezing in the drain from the ventilator.


​Assume on a hot day ​the air coming in is humid and hotter than the inside air, so humidity will rise to saturation as it passes through the heat exchanger in the ventilation. (Actually this is a pessimistic assumption.)
28 degree air at 100% humidity holds 27 grammes water per cubic metre.
Assume 60% humidity inside. That means an extra 11 g/m3.​
Air flow of 150 cubic metres per hour.
That's 1.6 kg of water per hour to get rid of.

Humans breathing out humid air:
In one hour we breathe in about 450 litres of air.
Assuming exhaled air is 100% humid at 36 degrees C; inhaled air is 60% at 28 degrees C.
1 cubic metre of exhaled air holds 42g of water vapour.
1 cubic metre of inhaled air holds 16g of water vapour.
We each contribute about 12 grammes of water per hour. Is that all?

Friday, 8 September 2017

What is Passive House? Probably not what you think

Here's my short answer:

Passive House is an excel spreadsheet.

There are loads of other definitions and mis-definitions out there. The term is frequently used loosely for any superinsulated building, and often mistakenly for passive solar buildings.

Passive House is not a way of using natural energy. It's true that Passive Houses will take natural energy into consideration, for example considering heat from the sun, but just pointing big windows south will not make a Passive House.

A Passive House is not a building without a heating system. Passive houses invariably have heating systems, but the amount of heating needed is very small. In fact the best definition of a Passive House is one where all heating and cooling needs can be met by heating or cooling the air coming in through the ventilation system.

There are many other things that Passive House is not, and in his excellent blog, Elrond Burrell gives a longer list.

My definition may put you off. I think excel spreadsheets put a lot of people off, including many architects. This is one barrier to the standard's popularity. If Passive House was a simple product you could buy to stick on your house, then lots of people would no doubt buy it. If it was a simple step you could add to the design process, designers would probably take it.

Passive house will help you to reduce your energy bill, and probably help reduce your environmental footprint. But if you want to save the planet, you need to do some sums. Laying a bit of turf on top will not make it green.

And now that we are firmly in the computer age, we can get a spreadsheet to do the sums for us. As with all good spreadsheets, you put various bits of information into the Passive House software, and you get out a simple and accurate picture of what is happening. In this case all the information going in relates to the building size, shape, location, materials and systems.

It is not difficult to find most of the information that you need to put in. But you do need to find it. You need to know the dimensions of the walls and the thicknesses and relative proportions of the various materials going into them.  The spreadsheet needs to know the insulation performance of each material, but most of them are already in there. You can also choose the hot water and ventilation systems, and their efficiencies. You need to know the size of the windows, and also their U values, and the psi values for the thermal bridges. The supplier of the windows should be able to supply these, and if not they may not be the right windows for a low-energy house. You need to know which direction each wall is pointing in. You need to know your local climate, or at least choose your location so that it finds your local climate.

The only piece of information you need to get up from your desk to find is the results of an airtightness test. If you're building an airtight house, then you probably should run an airtightness test anyway, and if you're building a house that is not airtight, start thinking about it.

W​hen​ all the information is in there, you know whether you have met the standard or not. More specifically it will tell you how much energy you need for heating over the year, how much total energy you need, and how often the house will go over 25 degrees centigrade. Even if you are not interested in meeting the standard, the software will give you a very accurate estimate of how much energy you are going to need to run your house.

Thursday, 7 September 2017

Electricity demand in southern Europe to soar with air con

After the hurricane in Texas, there has been a lot of news about how the weather will affect energy use. Of course the big story is how energy use is already affecting weather! I'm sure I heard people twenty years ago warning about global warming making storms bigger and more frequent. 

Another angle is news from the Guardian here about the increase in electricity demand in southern Europe for air conditioning due to increased temperatures. The UK will probably also need more cooling, but will need less heating, so in terms of energy may break even. Obviously the increase in temperature depends partly on whether we do anything about carbon emissions, and of course there will be some feedback if Europe does not de-carbonise the electricity supply.

The article does mention increasing insulation as a way to maintain comfortable temperatures, which is good.

The picture accompanying this shows an array of air conditioners from four different manufacturers, all Japanese.

Here is a report on global demand from the Japan Refrigeration and Air Conditioning Industry Association which shows that demand for air conditioners is already increasing around the world. They estimate 2016 global demand to be around 100 million units, growing 2.9% from the previous year.

In terms of market size, China is the biggest with 40% share, followed by Rest of Asia, North America, Japan, Latin American and then Europe with 6 million unit sales. In terms of market growth there is a very different picture, with Europe growing at over 12%, followed closely by Latin America, then Rest of Asia growing at over 8%. The more mature air conditioner markets of North America and Japan show the lowest growth rates of 1.8% and 2.8% respectively.

Since they can work as heaters as well as coolers, and since they run off electricity which is the medium of choice for renewable energy, split-unit heat-pump-based air conditioners may increasingly become the unit of choice for domestic heating and cooling needs. I may even get one myself.

Friday, 1 September 2017

These solar panels... are they going to last?

Ugo Bardi writes about the energy return on photovoltaics. Citing an article from Bhandari et al. that looked at 231 studies on ​how much energy comes out of photovoltaics​, and how much energy went into producing them, he comes up with an average return of 11-12 for southern Europe. ​This sounds worthwhile.

(From Dale and Benson)
​This graph paints a slightly different picture. It plots the number of years it takes for panels to generate the energy it took to make them against the growth rate of solar production. The payback got at least three times better in ten years, and the growth also increased three times. This means that, so far, more energy has gone into making solar panels than has come out of them. Hopefully, the growth will stop at some point, and the line will swing into the green as panel production stops growing while the installed panels keep generating. That depends on economics. 

Older estimates were that panels would still generate 80% rated power after 20 years, but according to Engineering. com, panels produced after 2000 will still be producing over 90%, losing only half a percent per year. So technically the panels will still be generating.

Economics is about resources. Somewhere human time is factored into ​it. We consider this resource very precious. ​I remember large scale road building projects in the UK that would decimate forest, destroy habitat and create pollution ​just to take a couple of minutes off people's car journeys. There is an economic pressure to reduce the amount of human time needed for tasks.

Another view is that human time is infinite, and the natural resources are limited. The classical economic view looks at productivity and considers environment assets to be externalities and essentially deems them infinite.  

​Hopefully growth of solar panels will go down, and they will become net energy contributors, but there is a powerful economic mechanism supporting production. If growth increases and we start throwing away the old panels, then that line may stay permanently in the wrong part of the graph, and photovoltaics will have just helped in our longer mission of depleting the world's resources.

The only redeeming feature is that they work very well in space, so we can take them with us when leave the planet! 

Bhandari, K. P.,  Collier, J. M., Ellingson, R. J. and Apul, D. S. (2015). Energy Payback Time (EPBT) and Energy Return on Energy Invested (EROI) of Solar Photovoltaic Systems: A Systematic Review and Meta-Analysis. Renewable and Sustainable Energy Reviews​,​ 47(July): 133–41. doi:10.1016/j.rser.2015.02.057.

Friday, 25 August 2017

How to build a house in Japan Part two: Two-by or zairai?

One choice that you probably won't be given by any architect or builder in Japan is whether to build in zairai koho or two-by-four. If you're building a wooden house it's a choice that is made early in the project.

Zairai koho is the traditional wooden building technique in Japan. It consists of a framework of pillars and beams,​ fit together with joints carefully designed to avoid excess stresses, and​ originally held together without any nails or screws, hence the nickname nail-less construction. The standard section size of the pillars is 120 by 120 millimetres, and the beams are multiples of this.

Two-by-four refers to a building technique using beams of two-by-four inches. Rigid panels such as plywood or OSB are added so the structural strength is based on the walls, where zairai traditionally relies on the pillars and beams for the structure. Just to add a little confusion, 2 x 4 beams measure half an inch less by the time they've been cut and dried, measuring 38 x 89 mm rather than around 50 x 100 mm that you might expect.

The two-by-four construction technique developed from balloon framing in the 1830s in the US. It allowed standard sizes of timber to be put together with mass-produced nails by relatively unskilled wood workers.

Compared to zairai, two-by-four constructions is probably cheaper, stronger, easier to build, and easier to insulate. Since the beams are rectangular rather square in ​section, the building more efficiently derives structural strength from the wood. Insulation can be added between pillars and studs, and the wood make​s​ up a smaller proportion of wall, so the insulation performance will be better than a building with square pillars. If the same technique uses 2 by 6, 2 by 8, 2 by 10 or​ even​ 2 by 12 beams, a suitable thickness of insulation can​ easily​ be added between the beams.

It's difficult to find tangible advantages to zairai construction, but I will try.

Zairai construction is traditional.

That ​is probably enough to illicit approving nods from fans of tradition, and disparaging scowls from anyone who has been paying attention since the Age of Reason.

Zairai construction is based around standard sizes and scales that suit the human body. Measurements are in the traditional units of shaku and sun. One shaku is within a hair of an imperial foot, and was standardised in 1891 to 10/33 of a metre. Traditional Japanese units are decimal, so a sun is one tenth of a shaku. Traditional zairai beams are 6 shaku, or 180 cm, from the floor. That's around my height, and​ after a few years living ​in a traditional Japanese house I was beginning to develop calluses on my forehead and a stoop in my back. The average height in Japan increased 8 cm in the second half of the twentieth century, so I suspect for most of the history of Japanese architecture, the lintels were at an appropriate height. ​In modern houses they are higher. Of course there is nothing to stop you from using human-scaled dimensions in a two-by-four construction. Also, you may have noticed that the shaku is remarkably close to the imperial foot, and the standard lengths of two-by-four (inch) beams are all in feet.

Zairai construction is based on a woodworking tradition at least a thousand years old, which can be seen in the oldest and the largest wooden structures in the world. By building a house in zairai you are helping to keep this tradition alive. But what exactly is being preserved? Why do home builders have to pay more to preserve it? They still make temples and shrines, so couldn't the fantastically wealthy priests preserve their tradition?

The joints of zairai are all supposed to fit together without any nails, except now they do use nails.
bolts​ or other connectors for the joints. And since the traditional pillar-and-beam structures do not meet modern earthquake regulations, to get planning approval for zairai buildings, you need to add structural walls, just like they do in two-by-four construction.

The square beams were traditionally prepared locally from​ round​ trees. Now timber is usually cut in saw mills, often using state-of-the art CNC machinery.

​So is your modern zairai building just a two-by-four construction with more wood in it, and more complicated joints?

I guess you could see an advantage in it being more difficult to build, since that means you have more highly-skilled carpenters. You have to squint a bit to see this, since you are also making the job more difficult, but there are some places where more highly skilled wood workers will make a tangible difference to your house.


Our house uses zairai koho, and it is on the list of things I would probably have done differently. Luckily ​that​'s a short list! The point when I realised that there had been a different option to this vast array of square-section wooden pillars was at the stage in the process where it was not possible to change the building technique.

You're always at some ​stage in a process.

There had earlier seemed to be a great rush to get the structure all sorted out, coinciding with a busy time in my day job. I was a bit disappointed as I was quite interested in structures, and would have liked to have had some input into it. It seemed like a lower priority than the insulation work and the systems we were considering, so that was a battle I chose not to fight. Qualified architects in Japan, or anywhere else, can be trusted to make structures that will not fall down.

After this urgent decision had been made​ to finalise the structure​, there seemed to be a couple of months when absolutely nothing happened. Ben talks about a similar artificial deadline in his retire Japan Blog and I think this is a common technique in the building trade.

When we were looking at ways to fit at least 250 mm of insulation into walls with 120 mm pillars, I had an idea of using two-by-tens as studs between the ​load-bearing ​pillars, which would have allowed one insulation layer rather than the three we have ended up with. This seemed like a bad idea as it was mixing two different techniques, and would leave a few awkward sized gaps. So I wondered about getting rid of the square pillars ​altogether ​and just using two by tens throughout.

As you will remember from lesson 4, the calculation of the thermal performance depends on how much wood there is in the insulation layer. This information needs to be added into the Passive House software, and I was checking the figure of 18.1% that we had. A more conservative estimation put it more like 25%, so a whole quarter of the wall was made up of wood, much of it by square pillars. This could have been halved by switching to rectangular sections. That would also have meant less wood​ to pay ​for​.

I suggested this to the architect who said it would take a month or two to change the structure, and he'd need to get someone else to calculate the stresses.

So we have a house beautifully built in wood, but ​we can't see any of it it, since it had to be covered to meet fire regulations.