A house into a home and a home into a house

It's amazing how quickly our old home has turned back into a house.

There is still some tidying and cleaning to do there, and when we go back it seems strange to think that we actually lived there a few short weeks ago. 

 

The moment we moved the stuff out of there, it lost that essence of home, and our new house seems to have very quickly become our home.

I wonder exactly what it is. Perhaps the fridge. Like the nourishing mother of the modern family. Perhaps the TV, like a father who speaks and everyone shuts up to listen. 

Or is the essence of home there in the details? That jar of pens, most of which don't work. A pair of pajamas with a button missing. An odd sock hanging up, waiting to find its partner. A chip in the woodwork, or a stain in a carpet.

Too bloody hot

December and January could be the hottest months in the house. At least, somewhat counterintuitively, they are the months with the highest solar gain. It's not that the sun is hotter in December and January. In fact, the sun is more or less the same temperature all the time, and cares little whether it is winter or summer in the northern hemisphere on Earth, but of course there is a difference in how much of that heat reaches the surface of our planet.

In terms of the radiation from the sun, there is more in the summer than in the winter. There are two reasons for this. First, the days are longer, so there are more hours of sunlight. More hours of sunlight mean more heat. Second, the angle of the sun is higher. This has two benefits. First, more sunlight is going to hit a given area of the earth. If the sun is directly above, a square metre of sunlight is going to hit a square metre of the earth. If the sun is 60 degrees below vertical, 30 degrees above the horizon, a square metre of sunlight will be elongated over two square metres of the earth so the incident radiation is halved. Also, the higher the sun is, the less atmosphere it has to get through, so the rays are stronger when they reach the ground.

The point with a house is that the windows are on the walls, so we aren't really interested in how much sunlight reaches a square metre of the ground. We want to know how much reaches a square metre of window. And this, almost by some divine intervention, means that in the winter, when we may expect it to be coldest outside, we get the most heat coming in through the windows. And when it gets warmer in the summer, less heat comes in. If we are careful with balconies and eaves, then we can try to keep this radiation to a minimum. Reflection is another thing that may lead one to believe that God invented windows, or at least that God was a double glazing salesman. The smaller the angle between solar rays and glass, the more is reflected and the less heat comes in. This means that more of the low winter sun will get through, and more of the high summer sun will be reflected.

So this is why it got up to 28 degrees centigrade in the living room at lunch time on 12th January, even though it was only one degree above freezing outside. The bottom line on this graph of temperatures over the first few weeks of our residence shows outside temperature (green - averaging more than one degree below zero). The highest temperature is inside temperature south (red at the top), and inside temperature upstairs north is pinkish below that, but dancing to the same tune. The others are slab temperatures. The big leap in inside ambient temperature was when we closed the windows and switched on the ventilation system on 23rd December, but you can see the jump in the temperature at the middle of the floor (light blue) as the underfloor heating started working on 26th December three days later. The effect at the bottom of the foundation slab (middle - dark blue) is slower, with about a three-day delay. At the North West corner of the foundation, the temperature change is much slower.   

Obviously it would be churlish to complain about the house being too hot, when all around are pouring gallons of oil into theirs and still freezing, and of course there are a few things that we can do before resorting to opening windows and letting the heat out. According to the thermometer in the upstairs north room, it is significantly cooler there, so if we open the inside windows from the atrium into the bedroom, the heat should go in there. Also we can open the door into the genkan and washitsu, which are to the north and significantly cooler. 

Part of the reason the north side is cooler is that the slab is much cooler there. This is by design. Kind of. The underfloor heating passes from the boiler to the south side of the floor, then to the north side of the floor, then back to the boiler, so the south side is being heated more effectively. Eventually the slab will probably have a constant temperature, but it actually seems like a good idea to have some temperature difference in the house. It would be nice to be able to control it a bit better, and I'm sure there is something we could do with the ventilation system. At the moment we are using a fan to blow air from the cooler northern parts of the house. 

But, going back to emissivity, I can't help feeling that it may have been a good idea to have had a higher emissivity for the floor and the walls so that they would have been absorbing more heat. What I guess is happening is that the radiation is just bouncing around the floor and the walls and getting the air really hot. The white terrace outside is probably helping by reflecting more sun into the house.

We're going to get some blinds soon anyway. I'd really like Venetian blinds with white on one side and black on the other, but I'm not sure if they are available or aesthetically pleasing. 

The Crookes radiometer shows the difference between black and white, invented by the eponymous Victorian chemist, William Crookes, who was pleased with himself for being able to make vacuum tubes. It was supposed to work as a kind of light mill, the white sides of each panel reflecting the sunlight, the black sides not reflecting anything, and spinning accordingly. When it started spinning, it went the wrong way; the black panels going away from the sunlight. The simple explanation is that the black sides get hotter than the white sides, and heat up the air molecules next to them, because actually the vacuum was far from perfect, which push the wheel around. A more detailed and accurate definition can be found 

here on wikipedia, unless the US government has shut it down. The difference the vacuum makes is to greatly reduce the resistance, so the effect of the heat becomes more significant. 

Black bodies and getting my head around emissivity

There's something about emmissivity that doesn't seem to have made sense, and probably should have done much sooner.

My attention to thermodynamics regarding the house has mostly been concentrating on conduction. Of the three ways heat gets around, this is probably the most significant. Obviously convection is important, but I think if you're dealing with a wall with inside on one side and outside on the other, and you treat the air as being at a constant temperature, then you won't be far wrong. What is actually happening, if the wall is hotter than the air next to it is that it is heating up that air, then that air is moving away and is replaced by a new bit of air which needs heating up again.

The resulting heat flow is more or less the same. 

Probably.

Anyway, I haven't really been thinking about radiation. I can remember a physics teacher telling us that radiators don't really radiate, they transfer heat by convection. And that seems to have stuck in my mind. I have, of course, been thinking about solar radiation, as that is how the sun gets its energy to us. We worry about nuclear power and radiation in the hands of humans, but in the case of the sun, it's an important part of life. If you want to see how much radiation nuclear power produces, you just have to look at the sun, as that is basically a big nuclear power station. In fact it's probably not a good idea to look at the sun as it will make you go blind. 

So the solar heat coming into the house is coming in by radiation. The windows are low-e, which everyone who knows about windows will tell you is important, so that you keep the heat in the house. The "e" is for emissivity, and it doesn't really fit into my idea of common sense. As far as I can tell, "low e" just means that it reflects heat. 

Emissivity, on the other hand, is a measure of how much a body radiates. It is a number between 0 and 1, or zero and a hundred percent. For a black body, which I'll get to in a moment, the amount of radiation is proportional to the fourth power of the absolute temperature. This corresponds to emissivity of 100%. You can read more about that here, if you're really interested.

The black body is a theoretical object that will absorb all the radiation that falls on it. What confused me for a while is what exactly this has to do with windows reflecting heat. It seems that three things are going on when radiation hits glass. First, some of the radiation is reflected by the glass, second some it it goes through the glass, and third, the rest of it is absorbed by the glass and warms it up. These seem to be independent ideas. Obviously all the parts are going to add up to 100% otherwise we'd be breaking the law of the conservation of energy, but what does radiation have to do with absorption?

I've given in to what seems a much simpler reality. It just comes down to one number - the emissivity. Bodies are like mirrors. If they absorb a lot of heat, they can also radiate a lot of heat. If they reflect heat well, they radiate heat badly. 

Polished metals have very low emissivity, which is why the lunar module was wrapped in tin foil. Not necessarily what you'd want around your house as it would conduct the heat away, but in space there is no atmosphere, so conduction is not an issue, and heat is lost, or gained if you're in the sun, through radiation. Radiation and emissivity are issues in buildings on earth, as we shall see in the next post. 

Ten good things about the new house

To make sure I'm not just finding fault with everything, so that I don't sound like a miserable git, and so that I don't turn into a miserable git, here are some things that are really good about the new house. In no particular order, and all little details, but life is made up of little details. Usually little details interspersed with boring bits. The details can be a bit tedious at times too, but here you go!

1. The kitchen counter is at the right height.

2. I don't have to stoop to get through each doorway either. This will be good for my back, once it recovers from moving all the boxes.

3. No parts of the house get scarily cold and become no-go areas in the winter.

4. The handle of the kettle doesn't get hot. We have an IH heater, so the heat is going straight into the water inside the kettle, rather than warming up the sides of it and the handle on the top. We used to need a towel to pick up the kettle in the last house because it got so hot. Now it doesn't get hot at all. IH must be a lot more efficient. It also seems a lot cleaner as the flames and fumes from the gas are not carrying particles of grease around the kitchen.

5. I can park the car in front of the house.  I just changed to snow tires and don't have to wheel them all the way from the car park to store them in the garden.

6. I don't have to worry about coming home to a cold house. It will never get cold, even without the heating on. And even if the heating is on, I can leave it on, and not worry about the house burning down too.

7. I don't have to wear socks inside.

8. I can see outside from in the house. It's nice being able to see snow on top of the mountains, or watch it fall. Also this means I can stay inside all day without getting cabin fever.

9. I don't have to walk through the kitchen after having a bath. The bathroom in the old house was the other side of the kitchen.

10. I can get to the post box without having to cross any roads. From the last house, we had to wait at the really long traffic lights to get across the busy main road, or walk across the river to the one near the new house, or go much further to get to the local post office. Not that I have to post letters very often, but I did say that it was in the details.

Japanese airtightness measurements suck

Apparently in Germany, when they do an airtightness test on a house, they test both over pressure and under pressure. In other words, they shut all the windows and doors, and put a blower on one of them to blow air into the building until the pressure gets to be higher than outside, then they measure how quickly the air starts leaking back in again. Next they blow air out so the pressure is lower inside, then they measure how quickly the air starts leaking in again. They take the average of the two values to get the airtightness of the house, which is measured, at least for Passive House certification, in the number of times the air will change per hour. The passive house standard is 0.6.
In Japan, they usually only have the equipment to do the under pressure measurement, which apparently is usually a little better. So, in a sense, Japanese airtightness measurements suck.
They did another airtightness test in December, which I'm still waiting for the results for. I should have done this months ago, but I've just now started looking carefully at the results from August. The experts said that we needed a C value of 0.2, but we only got 0.3 which was not good enough. They said that this was a reverse calculation, making it sound really difficult.
Never trust experts, especially if they make things sound really difficult and complicated. If they do that, it's a sign that they don't know what they're talking about. If they do know what they're talking about it, they should be able to explain it and make it simple.
Anyway, as a result of this 0.3 that should have been 0.2, we became very sceptical of the Compriband's effectiveness, and added caulking around each window to improve airtightness. We had previously planned to add a layer of insulation around the inside of the window frame, on the few centimetres of wall perpendicular to the window. This insulation would have reduced the thermal bridge effect of the window from something like 0.04 W/mK to 0.03 W/mK. This doesn't look like a lot, but when you think of all the windows in the house, and measure around each frame, there are something like 80 metres, and there are 70,000 degree hours temperature difference over the part of the year that needs heating, so it amounts to about 50 kWh per year.
Anyway, it was basically presented to me as a choice between putting caulking around the window frames, to improve the airtightness, which wasn't good enough, or carrying on with the plan to insulate around the frames and improve the thermal bridges. The caulking was going to work out more expensive than the insulation, but the builders offered to cover the extra cost, so it would make no difference to my pocket.
The decision had to be made quickly as other parts of the wall were about to go up, and the frames would no longer be accessible. I agreed to them adding the caulking, which the airtightness and insulation people went ahead and did.
But, while waiting for the results of the latest airtightness test, I started looking a little more closely at the figures of the last one. I should have done this ages ago, and in fact I've been waiting for an opportunity to talk with them and find out more details of this devilishly difficult conversion between the C value and the number of air changes per hour.
According to the figures the airtightness experts emailed me 4th October, almost two months after the test, the result was 259 cubic metres per hour at 50 Pa pressure difference. The bit of the form where the number of changes per hour should have been was blank, I guessed because they didn't have the figure for the volume of the house. According to the Passive House database, the volume was 500 cubic metres. Obviously this is not the exact volume, but it's close and serves as a design volume. Taking this, and the 259 cubic metres per hour, that looked to me like 0.52 times per hour, which meets the PH standard.
So, I surmised that either 1) my calculations are incorrect and it's much less straightforward than [volume per hour / total volume]; 2) the design volume of the house (500 cubic metres) is a lot more than the actual volume; or 3) the architect or airtightness experts were too lazy or too incompetent to perform a straightforward calculation. My money was on 3.　
I spoke to the architect on the phone, broken into two or three calls as he kept having to find information, or calls back because he had found more information. The figure he had was 0.542 exchanges per hour at 50 Pa. The actual volume of the house is 478.1 cubic metres. I'm beginning to wonder whether the airtightness people sent him a different copy of the results to the one they sent me... Why would they do that?
After first denying that the caulking had anything to do with the insulation and suggesting that the airtightness people had done it as an act of charity, he later came back and conceded that yes, the first airtightness test had met the standards, although they had told us that it had not, and that no there had been no need to add caulking on top of the Compriband, and yes, we could have had the extra insulation around the inside of the window frames and reduced the thermal bridge effects.
Another factor prejudicing them against extra insulation was that in some places the insulation would have stopped the windows from opening. As far as I was concerned though, it was a fairly straightforward choice.
Not sure exactly whether he's going to do anything about it, but he did at least say sorry, and not really related but he would get us a ventilation system with a bypass, and would cover the cost for it.
Maybe a complete coincidence but the airtightness and insulation people did the caulking work, and also did the airtightness tests.
There's something very satisfying about letting people know that they have done you wrong, but perhaps only relative to the much deeper dissatisfaction of feeling that you have been done wrong to.

Let it snow!

I love snow.

In England when it snows everything stops. People miss school and don't go to work. Traffic systems close down and people can't get to the airport to go on their skiing holidays. Sometimes power cables are brought down and the food in people's freezers is spoiled.

Here in Japan people are used to snow. Matsumoto is not in Snow Country, but is surrounded by it. The snowiest city in the world is apparently Aomori, where it comes in from the sea like waves over the winter. In Hokkaido they have a different front door upstairs, and neighbourhood battles go on as people clear snow into each other's parking spaces as soon as they vacate them.

Clearing snow here, for the most part seems to me a waste of time, although everyone gets very busy doing it. Sooner or later it's going to melt, so why bother? While it's snowing, you can walk on it or drive in it as everyone changes into snow tires from some time in early November when the first hint of white hits the highest mountain peaks. I don't really like driving in snow, so I don't unless I really have to. Like if I'm going skiing. Usually I don't really have to drive. I cycle to work, but can walk or get a bus if necessary.

As a house owner, my view of snow should have changed a little from this childish enthusiasm, but it hasn't yet. My house is effectively at the end of a cul-de-sac, so I don't have any responsibility to clear the thoroughfare in front of it. The biggest worry is the roof and the balcony on the south. Snow is rather heavy. It may be much lighter than water, but you don't get fifty centimetres of water building up all across the top of a house. Actually we don't get snow building up over our roof either, so far. It slides off the southern solar roof well. Some of it does hit the balcony on the way down making a ridge there that seems to sit happily, although most of if falls straight onto the terrace below. Probably a good idea to clear that off in the interest of balcony longevity, but it is not doing too much harm, and we wouldn't need to worry if it snowed while we were out of the country. 

Snow is more likely to stay on the north roof as it's shallower, and part of it is in the shade. Snow goes through a melting freezing cycle, and bits of ice come crashing down to where we keep the bicycles. 

Obviously snow impedes the performance of the solar panels. When the roof panels are covered, not much sunlight gets through, although of course the radiation that does get through heats the panels, melts the snow on top of it, and helps the snow slide off. Also, when it's actually snowing, few rays get through the clouds and snow. Even so, it was producing something while it was snowing. Admittedly only a hundred watts or so--in the battery charger ball park--and half the 200 watts that the house seems to consume even when everything is switched off. Over a day when it snowed pretty much all the time, we still made 2.3 kWh, which is about 10% of what we used. 

I was hoping we'd hit 1000 kWh within the first month of living in the house, but it's snowing again today, so it's looking unlikely.

Alps talking back

As well as the ideas in the planned talk on Boxing Day, there were several digressions and questions. Beyond my rambling notes, it seems a very good idea to address what actually happened, and especially the feedback from the audience, who I hope will have been changed in some little way by the effort that went into the house, and into my talk about it. 

At some point I told them the joke about the luckiest man in the world and the unluckiest man in the world. First, one man says, "I'm the luckiest man in the world: I've got an English house, an American salary, a Chinese cook and a Japanese wife." Next, the other guy says: "I'm the unluckiest man in the world: I've got a Japanese house, a Chinese salary, an English cook, and an American wife."

I'm not at all sure whether English houses are the best in the world, although there's no smoke without fire. Increasingly, of course, there are no fires without smokeless fuel, and a lot of fireplaces that used to sit at the heart of the English house have been boarded up and electrified, or turned to gas, as in the Dursley's house in Privet Drive. The English house was constructed around the burning of fossil fuels, and as such is part of an old paradigm. There is something very solid and reassuring about an English house though, which you don't get with a typical Japanese house. 

However, trying to get back to the talk, a lot of Japanese people seem to think that Japanese houses are the best in the world. The billions of yen put into advertising in the building trade is obviously paying off!

One member of the audience asked me about the cost of imported windows, which I replied was a lot more than domestic windows, if you just look at the initial price. If you consider the cost of all the heat that is going to leak out them over their lifetime, compared to the net inflow of heat from high performance windows, then the imported windows probably end up a lot cheaper.

The question that got me most, that I have heard several times before and has always got me, and probably always will, was "but Japan has four seasons". This seems to have been implanted deep into the Japanese psyche, so that the first reaction is not one of rationality, science or even morality, but whether it is foreign or not. 

I tried to explain that while Japan does have high humidity in summer and low humidity in winter, humidity itself always stays between 0% and 100%. When it tries to go over 100% it's called rain. And while there may be a lot of rain in Japan, Tokyo having twice the precipitation of London, the rain is still made up of molecules of di-hydrogen oxide, which obey the same laws of physics whatever language is being spoken around them, or whatever flag is being waved above them, as atoms have no nationality. And while the temperature may change a lot between summer and winter, and even between night and day, in the grand scheme of things these temperatures are not wildly different, compared for example to those a space craft may experience, or even those in Antarctica. 

Billy Connolly once said there's no such thing as bad weather--just the wrong clothes. With apologies to Billy, I think that there is no such thing as a tough climate--just the wrong buildings.

Taps

The first time one of the kids went to wash his hands, it sounded like he was using a shower. It's not really the kid's fault for turning it on full volume, but why does full volume have to be like a shower? It's only a sink for washing hands and faces and cleaning teeth, I thought.

However, closer inspection reveals that you can pull the head of the tap out and wash your hair with it. So in fact it is a shower. Even so, it's not a shower most of the time.

When taps used to be wheels that would turn to open, it was more obvious how much flow you were going to get. If you wanted a lot, you had to turn the tap a few times.

Once they started with these new-fangled lever-taps, the electronic generation just thinks of them as switches. On or off. Either nothing or full force, unless you want to be really careful.

So I realised that what they should do is make taps more like bicycle brakes. The more you want the water to come on, the harder you have to twist. At the moment it's the opposite. You have to twist hard to get any water at all, and then there's very little difference in the twisting strength you have to apply between the thinnest trickle and a full torrent. I don't mean you should have to twist really hard to get full volume; just harder than you have to twist to get a trickle.

This is what you'd get if it was an iPhone app.

IOU

Went to the bank to sign the contact for the loan to pay for the house the other. As usual, this wasn't just a simple process of signing one piece of paper, but there were over a dozen, including insurance forms and proxies. I wrote my address so many times that I was beginning to go into a calligraphic trance. I stamped my inkan 37 times. And have since had to go back twice to stamp more papers. This included one re-doing where my stamp only left a partial impression, ten stamps where the wrong numbers had been put in and we had to change them, and a couple of wari-in on the fold between two stapled sheets of paper to show that they were part of the same contract.

Part of the complication was that we'd changed from the original plan of getting the loan for the land and the loan for the house from the bank. The loan for the house is now a Flat 35, which is a government-run scheme entailing low, fixed rates for higher spec buldings. The original bank loan was 1.77%, fixed for five years. By UK standards this is already pretty good, but the Flat 35 is 1.31% for the first ten years, then up to 2.01% for the next ten, and 2.31% for the last fifteen.

Insurance - the white man's burden

Apologies to the Goon Show for the title. This was an episode in which Neddie Seagoon was sold the rights to the English channel at a real bargain, with the only catch that he had to insure his new purchase, against fire. You can probably hear it here if you wait long enough: http://goons.fabcat.org/.  Also apologies to anyone who finds the Kipling work offensive. 

I was talking to a teacher in the economics faculty the other day, and he asked how I was going to pay for my house. "I don't know," I replied, "I thought you were the one in the economics faculty." In fact he teaches constitutional law, not economics and most of the time I was trying to convince him that England doesn't have a constitution.

The insurance man came around in the morning. At the moment, he just insures our car, but we're looking at getting some insurance for the house. Fire and earthquake insurance are both available. He confessed that until March he'd been advising people against getting earthquake insurance in  Matsumoto, although has changed since the big one in the North East, and one in Matsumoto in June that was smaller, although with a magnitude of 5.5 was the biggest around here for a long time. 

Insurance seems to me a bit like gambling, only the other way round. There is a chance you could lose, and if you pay a relatively small sum, that chance will go away. If there is a fire, or an earthquake, then we could lose our home, and if we haven't paid off the loan yet, we would still owe money on it. If there is an earthquake big enough to seriously damage the house, then unless it's very localised, it will have damaged schools, businesses and local infrastucture so our house, in the grand scheme of things, is not going to be so significant, but having something afterwards may be a great help. 

Things I may always just look at and bury my head in my hands III. White walls

It seemed like a really good idea, and looked really good for a few minutes before we started moving in. Even then there were probably a few places where the walls were not perfectly white. Someone who helped us move in also brought one of his kids around, so our kids were playing in the garden and rushing into the house. And the hand prints appeared on the wall. Because of the nature of the walls, they are impossible to wash, but this is what it looked like after a layer of paint went over it. It looks a bit better now, but we will always know.

This was pretty much entirely our fault and an embodiment of the Chinese curse: beware of what you wish for, you may just get it. Nobody said, hey wait minute: the walls will get marked and stained, kids will touch them with muddy hands, people will lean on them, kids will drag sharp or dirty objects along them. 

Suddenly those wall paper designs with a strip of a different pattern or design at around waist height make sense. Wood panelling up to waist height seems like a good idea. Even those hues of wall paint close to children's diarrhoea start to give a knowing wink and a nod. 

It would also make sense to have wall paper for the lower part of the wall and paint on the upper part, out of kids hand reach. 

Putting photos or pictures on the walls also makes sense, and we need to do that as quickly as possible. Once something is on the wall, psychologically it ceases to be something to touch.

Watch this space.

What does he know about? A lot of hot air!

The day after we moved in was instruction day. It was also Christmas Eve. From one-thirty a series of plumbers, heating engineers and electricians came to show us how everything worked. The site foreman had scheduled them at thirty-minute intervals, although a lot of things were going on and some of them were waiting among the boxes.

The insulation and airtightness boss came along. I was hoping to hear something about the airtightness tests, and perhaps some apologies for the mistakes they had made, putting the machine the wrong way around, and forgetting to add insulation to the outgoing duct. 

As it was, he took me and the architect to the machine room, and proceeded to open the manual in front of him and try to find how it worked. In spite of his confident words, it has previously struck me that he doesn't know much chemistry, and his physics is a bit shaky. Now it seemed he didn't know how the ventilation system he had supplied worked.

The machine room, directly above the boiler, and housing a couple of power conditioners, is already the hottest room in the house. But it was about to get hotter. It's not a good place to jump up and down as the ceiling is low. The architect, who was sat behind me, patted me on the shoulder to try to prevent an outburst. I got up and told him to give me a shout when he was ready to explain how it worked. I did have a lot of important things to do, and I can read manuals myself.

I went back later and heard the explanation, and saw how to change the air flow. While there are still some volatile building materials, he suggested setting it to 180 cubic metres per hour, but usually, with four of us in the house, 120 cubic metres per hour should be enough. As the flow goes up, you can hear the water starting to gurgle as the air heading out of the house drops in temperature and sheds its humidity, because the capacity of air to hold moisture decreases with temperature.

A few days later, I finally got some time to sit down next to the machine with a manual, and I realised that it has no bypass on it. We had been talking about this for two years, and I had assumed it would be part of the system. I should have paid more attention to the model they installed. This may be bad news come summer.

Just as the heat exchanger works in the winter to maintain the inside temperature while taking fresh air from outside, it will also maintain the summer temperature. Matsumoto has a large difference between day and night temperature, averaging around 10 degrees. Almost every night, the temperature will drop below 25 degrees, but there's a possibility that the temperature inside the house is above 25 degrees. In this case, rather than exchange the heat from the house to warm up the incoming air, we want to expel the warmer air from inside the house, and take in the cooler outside air. 

Stiebel, and no doubt other manufacturers of ventilation systems, have already thought of this, and there is a bypass function, which will stop exchanging heat under those circumstances. Closer inspection reveals that this is not standard, but a slightly different model, with a plus on the end.

Things I may always look at and shake my head II. Wires in the ceiling

I'd been talking about electrics for rather a long time, and had some ideas about keeping things simple, using as few circuits as possible, keeping wires out of the way of ceilings and walls, and generally making the wiring reflect a low energy house with a functionally minimalist aesthetic. I had imagined a single pair of wires venturing from the fusebox, travelling from fitting to fitting and letting off current in parallel.

It was with some shock that I saw the electrician laying miles of wire around the house before I'd even seen the wiring plan, but perhaps not so much surprise as I was getting used to being ignored in the detailed work going into the house. He did manage to keep the lighting circuits down to two, as per my explicit instruction. One of these is for lights with switches, and the other for lights with sensors. The low voltage cable lighting LEDs probably go on another circuit along with the upstairs windows, although I'm not exactly sure.

There are still over twenty different circuits on the breaker board.

The old house had three circuits on the breaker board. One was for the light in the front room. One was for the socket in the middle room, and the other seemed to be for every other circuit in the house. The breaker usually came down and all the lights went out if the tumble drier and oven were used at the same time. One of the circuits has been added to steadily, with branches coming off the branches, and more branches coming off those. The old house used knob and tube wiring in a lot of places, which was apparently commonly used in the US until the 1930s, and evidently in Japan too. Single wires travel around the house, although usually in pairs.

The wires are insulated with several ends of cotton, as was customary before plastic shielding. This kind of wiring can apparently lead to much shorter circuits, so there is less wire needed and less power lost over it, as the supply and return wires can follow different paths. It could also lead to short circuits, if the electrician doesn't know which wire is which, although usually they should be quite safe. 

However I digress from the problem of wiring in our new house, and why the problem is not invisible. The extent to which it can be seen comes down to the ceiling of the living room. I wanted to break this up as much as possible, and instead of having one flat, even ceiling I would have been most happy with the ceiling beams exposed.

I would have really liked simple, explicit wiring, although this would neither have got past the modern aesthetic nor the electician's rule book. In the early stages I had argued for a ceiling indented between the beams above, persuading everyone, I thought, that this would create a sense of greater space without affecting the overall aesthetic, because nobody ever really looks at ceilings. It would have this space breaking effect without anybody being consciously aware of it. A broken ceiling would also make for better acoustics.

But when it came close to the ceilings being put on, I noticed that in the plan it had all gone flat again. This time I didn't have to do any arguing; it was among a spate of aplogies and the machine was in following-instuctions mode.

When the ceiling was done, all the beams were covered with fire-resistant plasterboard to meet the optional fire regulations that will halve our insurance bill and loan repayments. But the loom of wires was nonchalently passing under the beam where the wiring plan, which I hadn't seen, allowed wires to roam wherever they pleased. So there is a difference in height of a couple of centimetres between the hidden beam across the atrium and across the ceiling.

If I look at this it will make me shake my head, but to be honest, nobody really looks at ceilings, and I have hardly noticed it.

Turning up the heat

When we moved in, the underfloor heating wasn't working. If you're going to have no heating, then it's a pretty good house to be in.  The next morning it was -8 outside and 14 at the coldest place inside.

The heating engineers are on a direct contract, so they are not under the skilled and careful control of the builder, which may be why they hadn't got this ready, and it is probably a very busy time for that trade. There seemed to be some problem with the eco cute boiler and a new part needed sending. The architect had brought the heating engineers in a couple of years ago when we were still trying to work out some basic approaches. After this problem, he said he'd get them to throw in the air conditioner for free, telling us that the list price was 300,000 yen on it. For starters we didn't ask for a 300,000 yen air conditioner, and it seems to be massively over spec. It was certainly useful, though, to have the air conditioner to add some heat to the house, but working underfloor heating would have been much better. 

We moved in on 23rd, and the heating engineers came back three days later on Boxing Day to fix it. In the evening I went to play with the controls, which are still dangling from wires sticking out of a hole in the wall under the stairs. We went through lengthy discussions about the system with them last year, before the concrete slab went down and the pipes went into the screed on top of it. The original plan was to put pipes in the bottom layer of the slab too, so that it could be used as a heat store when solar heat was available but we didn't want to use it until later. In the event we just put pipes below the floor. Another item on the "wish I'd" list. 

Basically there is a figure of eight circuit, with the boiler upstairs, the underfloor piping downstairs and a mixing valve in the middle. One pump will circulate the water around the pipes under the floor, and a pump in the boiler will send water through the tank to get heat down to it. The mixing valve will turn the hot water from the boiler to a lower temperature. Each pump has a switch with a timer.   

The system seemed to have been working fine when I got back in the evening on Boxing Day. The floor was a lot warmer, up from 14 degrees in the morning to around 17 degrees. But the hot water tank was empty. In view of the heat capacity of the concrete, a good part of a metre thick and scores of square metres wide, this is not surprising.

Economically, I've been hoping to use cheap night-time electricity for heating the water, at 9 yen per kilowatt hour, and selling as much of the solar-generated stuff in the daytime as possible for 48 yen per kWh. So I set the boiler to start making hot water, and set the timer to start pumping heat around the floor. 

In the morning, the error was back again, and the pump from the boiler wasn't working. I called the heating engineer, who had not been planning to come again until January 13th, and he said they'd get here in the evening. The sun was up and a fair bit of heat gets in during the daytime, and we would certainly survive until then, and were in no danger of freezing to death anyway. 

As it happened the electricians were in that day, and part of their work involved switching the boiler on and off again, which cleared the error. I called the heating engineers, but they were coming anyway, and I did want to talk to them about what was happening. When they came they showed me how to reset the error, by pressing two buttons on the Eco cute control panel at once.

At that point, I hadn't realised there was a timer on the switch for the underfloor pump, which we're going to want to use during the daytime to get some of the heat from the sunny South side to cooler North. It just looked like a normal light switch, but they showed me how you can open it to reveal an LCD and some buttons.

The problem behind the error, it seems, is that the water coming out of the boiler is too hot. There's a thermyster on the pipe, and if it stays above a certain temperature for over 20 minutes, alarm bells start ringing and the boiler switches it off. The problem is a combination of the level of insulation we have making the water coming back from pipes into the boiler too warm, and the slow speed of the pump allowing it to heat up too much. This then gets to the mixing valve, and the hotter it gets the less goes into the floor circuit, because the mixing valve works to a certain temperature, so the slower it gets and the more it will heat up in the boiler upstairs.  

Later they will fix this by moving the thermyster to somewhere less critical. Already we've had to trick the boiler to let us use heat under 60 degrees. In the mean time we have to juggle the timing so that we get heat under the floor but leave enough in the boiler for baths and cleaning.

When we moved in the slab was around 10 degrees, thanks to building work and doors left open over the beginning of winter, rather than keeping doors shut and using the ventilation system, which seemed like a good idea to me.

It was never intended to get that cold. When we pump heat into the floor, a lot of it will be moving down to the bottom of the foundation to heat it up. Once it's up and running, the system should only have to add a little heat when it gets really cold. 
It's like we built a bicycle for climbing mountains and we're using it to start a hike from the beach. We will get there eventually though.

Colder than air - beating the second law of thermodynamics

The temperature of the roof seems to go lower than air temperature at night. I noticed this before with a simulation from OM Solar on the temperature of their roof. OM Solar runs on the principal of heating air under the roof, which it uses for space heating in the winter or  heating water, via a heat exchanger in the summer.

It starts to get cold at this time of year, and if you go out on a clear night, it really feels like the heat is being sucked from your face by the starry sky. This is because the heat IS being sucked from your face by the starry sky. Heat transfer by conduction depends on the temperature of the air, and convection keeps making sure that as soon as the air next to your face wams up, it  moves away and will be replaced by some cold air. Wearing a fur lined hood reduces the air flow around your face. Something more is happening on a clear night. Beyond the clouds, that are not there, it's very very cold, around fifty five degrees below freezing.  

But in fact the heat is not really being sucked from you at all. Your body is constantly radiating heat, depending on its absolute temperature and regardless of whether you stand in front of a starry cold night or a burning open fire. Usually, something is radiating the heat back again though. If you're inside, the walls and ceilings. If they're low e, the windows are going to be reflecting your heat back to you, because low emissivity means high reflectivity. If you're outside, the clouds are radiating heat back. Even though they are a long way away, below freezing and have a high emissivity, they're still radiating a lot more heat than the vacuum of space beyond. If it snows, the snow is radiating much more heat than any clouds. It may be below freezing, but that's still a few hundred degrees above absolute zero, where nothing is going on at all. That's why it feels warmer when it snows.

http://www.webcitation.org/6300EDKJi

Baby sitting

The architect asked whether it would be OK to show some people around the house before we move in. I said it was OK, but I told him I wanted to be there, and that I was free on Wednesday morning. He came back later to say that he'd told them to come between 10 and 2pm. Fourteen o'clock is not usually considered morning in my book, but perhaps time is different for architects. It would at last explain why a house that he said would be ready October 2010 is having people running around like blue arsed flies to be ready by December 2011. 

The Wednesday in question was the day before they handed the keys over and two days before we moved in. You would think that he may be sensitive to all the people working on the house and not turn the place into a lounge for his ego for four hours in the middle of the day. 

My worry was that he would be going around the house showing off all the things that he had decided to do, taking credit for things he had variously disagreed with, ridiculed, failed to work out or required somebody else's expertise to make.

He was talking to someone about the windows at the top of the house, on the little bit of North wall that makes up the difference in angle and size between the North and South roof. He was explaining that wind blows mostly from the North, even in the summer, so those windows will bring a lot of air through the house, and that's why he decided to put them there. 

Wait a minute, I thought. Hadn't his plans put those windows facing South?

A hot slab of concrete

Actually it was a rather cold slab, and what we really want is a warm slab of concrete, not a hot one. Well, perhaps a luke warm slab. In fact what we really want is a room temperature slab. 

To be honest, the temperature of the slab is not a direct concern, but we want the temperature inside to be warm in the winter and cool in the summer. Because the concepts of warm and cool are relative, we may reasonably get away with cool being hotter than warm. 18 degrees may be warm in the winter when it's below freezing outside, and 25 degrees cool in the summer when it's over 35 outside.

So we want the slab to be slightly above room temperature in winter, and slightly below in Summer. If we can keep it somewhere between 20 and 25 degrees for the whole year, we should be comfortable.

The slab itself, with fifteen centimetres of concrete at the bottom, ten at the top and 70 centimetres of aggregate between, is mostly going to work as thermal mass, maintaining such a steady temperature,as I wrote before.

We have a 460 litre tank of hot water, which will be heated by an atmospheric heat pump, using cheap nighttime electricity to elevate the abundant but cool heat in the nighttime air to piping hot water. Actually, it may make more sense for us to modify this to take heat from the hot air under the solar panels in the day time, but that needs to be dealt with in a whole new blog. 

The heat pump, known as an Eco cute, is capable of controlling four heating circuits as well as providing domestic hot water and reheating the bath. But, the heating circuits send water at around 60 degrees, and keep sending it until the temperature sensor reads something like 50 degrees in the return pipes. As a 25 degree slab is going to be sufficiently warm, the heating circuits, as they are, are not much use to us. Instead they pass through a thermostatic mixing valve, which can be set to some temperature between 30 and 60 degrees, that will mix a suitable amount of hot water from the boiler to the water coming back from the slab. I suspect we will usually set this as low as possible, although as soon as we move in, we may want to get the slab up from 10 degrees as quickly as possible. 

They filled the underslab water pipes with antifreeze. It will be a very cold day when anywhere near these pipes gets anywhere near freezing, but I suppose there are advantages with protection from rusting, and there may be an increase in heat capacity. The water may need changing every couple of years, but we will see.