Eco con

During the explanation session, I asked the plumber about changing the temperature of the boiler, which he said was impossible. In fact, checking the manual and playing with the controls, I found that it was possible. There are three settings for boiler temperature: high, medium and low. Also, there are three settings for the amount of hot water in the boiler: a full tank (460 litres), 100 l or 50 l. 

The plumber didn't actually fit the boiler, so I don't completely blame him (although he shouldn't be telling people things are impossible when he just doesn't know how to do it), but the people who did fit the boiler also put in the underfloor heating, which they switched on to pump hot water through
the whole time, and did not set the boiler to the maximum temperature, so it was both using expensive day time electricity, and running out on us when it came to bath time. So they didn't know how it worked either!

I suspect there are many people, like my parents-in-law for example, who are producing way more hot water than they need and have not been told how to set their boilers properly. The Passive House lady considers this to be a serious national problem, causing massive excess energy use, and a lot of disgruntled customers.

The idea behind the Eco Cute is basically to use cheap night time electricity, from 24-hour nuclear and gas-fired power stations, and not really anything to do with ecology or saving people money. 

People with large households certainly get a good deal with their Eco Cutes, providing they don't run out of hot water. Meanwhile a lot of elderly couples, victimised by silver-tongued salesmen, find that their heating bills go up, on top of the investment of their savings into this new wonder, or worse still having been encouraged to take out a loan to pay for it. Over-dimensioned tanks with insufficient insulation incorrect settings.

The situation in Hokkaido is apparently that so many people are using Eco cutes that there is now a shortage of night time electricity.

Not sure if it's Eco, or cute, but it can certainly do wonders with hot water

The fancy display panel on the wall next to the kitchen allows us to set the tap temperature anywhere between 35 and 60 degrees, and the clever control system will mix the water from the boiler, at a much higher temperature, with cold water to get us what we want.

The bath can be set to fill automatically to a range of heights and temperatures although only up to 48 degrees. So we can't use the bath for making soup.

The system is very intelligent. We tried to fill up the bath with the plug out the other day and very quickly the eco cute realised our mistake and switched off the water.

In our old house about once or twice every week we would either leave the water running so that it was spilling over the top, overheat the bath so that we needed to throw hot water away before we got in, or both.

Little bars on the display panel show us how much hot water is available from the tank. One bar for 50 litres at 50 degrees. 2 bars for 100 l, 3 bars for 150 l, 4 bars for 200 l and 5 bars for 300 l or more. With a 460 l tank, with water over 60 degrees, there will be a full five bars with just half the heat capacity of the tank. I'm having trouble finding in the manual exact temperatures for the high, medium and low temperatures the boiler can be set at, but in the spec at the end, it gives a range of 65 to 90 degrees.

As well as the bars, the display panel will show how much hot water there is, measured in number of baths and minutes of shower. I think it measures a bath as around 30 minutes of shower. At full tank, I've seen it gives one bath and 95 minutes shower, so it doesn't count in multiple baths. That wouldn't make sense in a communal bathing culture, as you can only have one bath.

There's a display panel in the bathroom, but this just shows how many minutes of shower are left. I suppose if you're in the bath, you won't be interested in how many baths there are, as you already have one, and if you're having a shower, you won't want to have a bath. I keep meaning to compare the number of minutes shower on the bathroom panel with the number of baths and minuts shower on the panel down stairs to get a more precise relationship between baths and minutes shower, but haven't managed yet. Anyway it wouldn't be that precise because the number of minutes shower is only to nearest five.

Everything works really well, but it's very difficult to find exact data, for example how hot is the water in the tank? How much is there? How much hot water did we use each day? 

The machine knows a lot of this, and when the temperature is set to "medium", it is looking at how much water we've been using, and heating the water appropriately. Maybe it's just me, but I'd like to know that information too!

Getting into hot water

The heating system was fixed a couple of weeks after we moved in, and we have a panel on the wall under the stairs to adjust it. For all that we're trying to build a house that doesn't need a heating system in a country where houses traditionally don't have them, we seem to have done just that.

I think this is the first house in Japan I've lived in that has plumbed hot water and it's certainly the first house with any kind of central heating system. It's very European in the sense that it effectively has a boiler with a supply of hot water for washing and also for heating. For a day or two our boiler was running out of hot water, but this was because the heat was all being sent under through the pipes under the floor.

Hot water running out is something that anyone who has lived in a boiler culture will be aware of. My wife has never forgotten getting in trouble for using all the hot water when we were staying in a bed and breakfast before my brother's wedding. 

The concept of hot water running out is perhaps alien to Japan. Japanese has a separate word for hot water "o-yu" rather than "mizu", which it is tempting to argue is due to the abundant natural availability of hot water in the country. In many places it simply flows out of the ground. Hot spas spring up in the middle of cities, and clusters of hotels burst out around them in the countryside, in the mountains or by the sea.

Although this is the first house I've lived in with plumbed hot water, every house I've lived in has had running hot water, and copious amounts of hot water available in the bath. The first house I lived in had no running water in the bathroom, but you could fill the bath with water, and then heat and reaheat that. You could heat the bath a little, then you'd get some hot water at the top which you could scoop out for a shower. When she was a kid, my wife used to have to build a wood fire under the bath at her house. So there was a very visible body of water there. 

All the kitchens where I've lived have had a gas geyser that will produce hot water into the sink on demand. Instant hot water that only runs out if the gas is not connected, or if the battery goes in the geyser and the sparks stop working. 

Meanwhile, at around the same time my wife was loading wood to fire her bath a quarter of a century ago in the mid 1980s, I remember on my first stay in Tokyo seeing somebody going to a pay phone and dialling in some numbers without saying anything. He was setting his bath to come on so that it would be ready when he got home. His bath was electronically controlled to supply and heat the water, and the controller was connected to his answer phone, which could take remote instructions.

A tank in the house

Although we put ours inside, we're surrounded by houses with external boilers. As well as conducting heat to the outdoors, they sometimes have long pipes, probably not lagged, taking a while to deliver hot water, and wasting a lot of heat getting the hot water where it needs to go. 

Likely as not, though, they'll be in the traditional position for the bath water heater, right outside the bathroom, which will have a washing machine right next to it so the main water pipes. Unless some wiseguy architect has told them they can put it anywhere they like because the hot water pipes only cost 150 yen per metre. They don't realise that's also what they'll cost in wasted hot water each month.

External boilers are the norm for most of Honshu, the main island, but from the North East and certainly in the northern island, Hokkaido, putting boilers inside is common practice as well as common sense. It should be both in Nagano, which is a particularly cold area of central Japan, a good five degrees colder than the big cities of Tokyo or Nagoya. It seems people here would sooner have a tank in their house than put a boiler inside. 

Electric pipe heaters are also a normal fixture here, winding around outside water pipes, and switching on when the temperature approaches freezing, which can by as many as half the nights in a year up here. More running costs. More electrical devices. More profit for the electrical companies.

One of my concerns, having the boiler inside, is to keep the tank temperature as low as possible in the summer, when our hot water needs will be much less, and the heat leaking from the boiler is going to be making the house hotter.

0.28 = 0.54, 0.26 = 0.38... Confused!

After another two-month wait, I got the results of the airtightness tests in a letter. I sent the insulation people a reminder by email on Friday and the letter came on Monday, with an apology that they had already sent the information to the architect and assumed he had sent it on to me.

The results, from a Passive House perspective, look very good. The standard we were aiming for was air leaking at a rate of 0.6 times the total volume of the house per hour, with a pressure difference of 50 Pascalls between inside and outside. The lower the figure, the less air is leaking and the better the airtightness.
The result back in August was 0.54. Unfortunately we didn't realise at the time that the result was this good. The result in December, after filling the hole under the front door, adding caulking around the windows and getting the big window to shut, was 0.38. This is 35% better. In the Passive House software, this reduces the performance of the house from 13.5 to 12.6 kWh/m2a (kWh of heating energy per square meter of floor space per year). That's a 7% saving on the house's heating requirement. Obviously airtightness affects thermal losses as leaking air will carry heat in or out of the house.
The Japanese measurement of airtightness, C, the number of square centimetres of gaps per square metre, was 0.28 in August, and 0.26 in December. An improvement of only 6%. Clearly the two figures don't have a linear relationship. We were apparently aiming for a C value of 0.2, although 0.3 seems to have been a closer target.

The C value seems to be based on on the air leakage at a pressure difference of 9.8 Pascals, and then goes through some exponential arithmetic. In reality, the pressure difference between inside and outside is surely going to be a lot less than 50 Pa, and probably even less than 9.8.

According to the results sheets (graphs for August above and December below, pressure on the y-axis, leakage rate along the x-axis), it looks like the leakage was measured at roughly 10 Pa intervals, from 10 to 50, and a line drawn on double logarithmic graph, deducing some exponential relationship between the pressure difference and rate of leakage. The Japanese and European standards are at different ends of the range of measurements, so neither estimate will be completely accurate.  This way of testing should give a very good estimate for the leakage at 30 Pa difference. 
I'm really interested to know how the C value is calculated, and the rationale for this. And how does the Passive House software calculate the effect from the figure for 50 Pa?

Rogues and charlatans everywhere

I just paid the fees for registering the building in my name. 233 thousand yen. Almost a quarter of a million yen. That's more than a month's salary for a lot of people. 

Fifty thousand of this was tax. Stamps bought to keep the beaurocrats happy. You could argue that that is lot of tax, but to be honest as far as I'm concerned it's all tax. The fact that only 50,000 yen of it is going to real tax actually means that the tax collectors are only getting a quarter of what I'm paying. They are loosing 75% of it. Gross inefficiency.

I suppose I don't really begrudge the authorities duty and bureaucracy but it's a fair whack for an afternoon's work for a couple of lawyers.

Rogues and charlatans everywhere.

When we bought the land, the estate agents were taking a percentage for selling something they didn't even buy. 

The architect charged to draw our ideas and then say they were his. 

All the while the lawyers, accountants and tax collectors hover.

Microeconomics of solar power

As we look at our power consumption and think about ways of shifting it from daytime, when we lose the opportunity to sell our solar power, to night time, when they are trying to give it away, three basic approaches spring to mind: Design, technology and habits.

We also need to think about comparative power consumption. Lighting began as the major user of domestic electricity, and indeed the Japanese word for electricity, denki, is synonymous with the word for light. But today it represents a tiny fraction of our power use. Our electricity display panel shows our consumption down to the nearest 0.1 kW, or 100 watts, and switching lights on or off has never made any difference to this. Leaving every light in the house on would use perhaps 200 Watts, and require a great deal of running around, inside and outside, as several of the lights come on automatically. We seem to be using very roughly 20kWh per day, over four times this hypothetical maximum use. Of course we don't use any of the lights all the time; neither during the day time, when we're out nor when we're asleep.

The sensors on the lights seem like a good idea as they can't be left on. Someone was complaining that they stayed on a long time after being activated, about a minute, and it would be good to be able to regulate this. These lights use about 6 Watts, so if they're on for a minute, that's 0.1 Watt hours, or 0.0001 kWh. Boiling the kettle uses around 2kW, two thousand watts. Leaving the kettle on for an extra second is equivalent to leaving one of the lights on for five minutes. Watching the pot boil, and not  putting too much water in it makes much more sense than worrying about putting lights on. In fact, in terms of energy usage, I'm not sure that the decision to use sensors was sensible. It certainly makes sense in terms of light switches, or their absence, but that is another story.

In rough orders of magnitude, heating appliances use a hundred times more electricity than lighting appliances.

A lot of technology exists that can shift power consumption into the night time. For example our washing machine has a timer so we can set it to finish the cycle by 7am, and use the night-time electricity. The washing machine is using hot water from the boiler, and electric motors use less power than heat, but more than light. The washing machine has a heat pump to help with the drying cycle, which uses more power than the motor, but not as much as a heater. I'll come back to that in a moment.

The dishwasher, on the other hand, has no timer, so it relies on us remembering to set it off after 11 at night, or first thing in the morning when our electricity is cheaper. Also, the dishwasher heats cold water, rather than using hot water from our boiler. We were advised that this was wise, although that was before we realised that the adviser did not know about pipe insulation, and in fact the manual for the dishwasher advises using domestic hot water to save energy.  

The rice cooker has a timer, and we have been routinely washing rice at night and setting it to be ready for breakfast, so we are using electricity at the cheap rates.

The boiler, AKA Eco Cute, has a heat pump, which uses the power of a compressor to bring heat from the atmosphere. This uses a lot less energy than it would to directly heat the water with a heating element. The ratio of heat out to energy in is known as the COP or coefficient of performance. If the heat pump has a COP of 5, then it will get 5 units of heat energy out for each 1 unit of electrical energy. I need to look into what exactly the COP is, and how it varies with temperature, but if we were to take it as 5, and compare the dishwasher using hot water made in the Eco Cute at night time with hot water made from cold water in the middle of the day, then the former would use five times more electricity at five times the rate, and so would be twenty-five times more expensive.

If the design is right, and we use appropriate technology, we don't need to worry so much about changing our habits.

If we make breakfast before 7am, this will save us money. Easy on a weekday. Can be tough on weekends. Putting the oven and kettle on, and cooking with frying pans uses a few kilowatt hours. In fact before the breaker was boosted from 60 amps to 50 amps, the breaker would trip if the kettle and oven were both on while the eco cute was was still boiling water, and the washing machine or dishwasher were on. So we were using perhaps 5 kW to make breakfast. We weren't using all those kilowatts for an hour, but over a week, that adds up.

Another thing that would make a small difference is an electric thermos flask, with a timer to boil water before 7am, rather than a kettle using live electricity.

I'm sure, in an ideal word, the fridge would do it's cooling when the electricity is cheap and abundant, whereas now it comes on when it feels like a chill. This is more likely to happen in the middle of the day when it's hotter inside rather than the middle of the night. The fridge seems to use a couple of hundred watts for its heat pump.

It would be nice to have a power logger on each appliance so that we can see when it's using electricity. I've started tracking the hourly electrical consumption and production, so we should be able to infer some of the major users.

Apparently Eco Cutes, which have been sold largely to utilise night time electricity, have been so successfully sold in Hokkaido, the northenmost, coldest island of Japan, that night demand is now stretching the generating capacity and they're considering building more power stations.

Solar sell out

We got the first electricity bill, which was for 45,000 yen. When I say bill, actually that's what they are going to pay us. The actual bill--what we have to pay them--came a few days later for 12,000. It should be a bit less than this once we get the heating and hot water sorted out. 

The 45,000 yen is based on 951 kilowatt hours, for each of which they pay us 48 yen. The counter on the display panel went over 1000 kWh on 24th January, so in the first month we generated slightly under a megawatt hour and we sold almost all of this. 

When we buy electricity, there are three different time zones:

Off peak "Night time" is between 11 pm and 7 am at 9.33 yen per kWh. 

"At home time", 7 to 9 am and 4 to 11 pm, is 21.23 yen per kWh.

"Day time", 9 am to 4 pm is 31.43 yen per kWh.

In terms of our electricity production, although there's a fair bit of difference depending on cloud cover and temperature, it follows the geometry of the sun's arc across the heavens, and in the middle of winter comes in from around 7 in the morning till 5 in the evening with most of the generation between 10 am and 2 pm.

There is a single wire coming into the house from the grid with two meters on it. When we're using more power than we're making,  electricity comes into the house, and adds up on the spangly digital meter. When the solar panels are making more power than we're using, electricity goes out of the house and adds up on the clockwork meter. I thought the reason for their meter being different to our meter was some kind of discrimination, or that it would be easier for them to misread and pay us less, but apparently it's because the meter for electricity we buy has to distinguish between electricity at different times, while the electricity we sell is all at the same price, so it just needs to clock up.

Ideally, as far as our domestic finances are concerned, we want to only use electricity during offpeak hours - 11pm to 7 am, when we can buy cheap electricity, and each kWh is costing us around 9 yen. Then, while the panels are generating, we don't want to use any electricity as we would lose 48 yen for each kWh that we don't sell. 

Of course this is not entirely possible, and sometimes we need to use electricity in the middle of the day. We're also talking about a few yen here and there, and it may not make a big difference, although if those yen are adding up every day over the next ten years they will. 

None of this is going to make a big difference to global warming or carbon emissions. Whether we use the electricity at night time or day time is not going to change the total electricity consumption. In fact in view of line losses, it may be better for the environment for us to use all of our own electricity and stop using cheap night-time electricity. 

The only way this penny pinching is likely to help in the grand scheme of things is by increasing awareness of our power consumption. 

You can see Yatsugatake from the window

I hadn't realised this until one winters morning with a clear sky. This is exciting because Yatsugatake used to be the tallest mountain in Japan.

The story goes that Asama-sama and Gongen-sama were having an argument about which mountain was taller, Mount Fuji or Yatsugatake. Everybody knew that they were both really tall. Asama sama thought it was Yatsugatake, but Gongen sama thought it was Fuji. Gongen sama also thought that Fuji was much more beautiful.

To find out, they put a channel from the top of Yatsugatake to the top of Fuji, then put some water into it to see which way it flowed. Whichever mountain it flowed towards was surely the smaller one, and they'd be able to find out which was bigger. When they put the water in, it flowed towards Fuji, showing that Yatsugatake was taller.

This greatly upset Gongen sama. After all Fuji was so much more beautiful than Yatsugatake. So Gongen sama, in anger, caused Yatsugatake to break up into several pieces, and it wasn't taller any more. Yatsugatake's sister, Mount Tateshina, wept at his broken figure and her tears created Lake Suwa.

(Note, much of this was made up, or half-remembered, but there is definitely some kind of myth out there upon which it is based. It may have been Konohana sakuya hime...)

It's a nice story, overlooking a couple of issues with it. First of all, the logistics of building such a long channel would be significant. Not only would it curve significantly under it's own weight, but the curvature of the earth would mean that it was not straight.

Second, and more significantly, the name "Yatsugatake" means eight peaks, so called because of the rugged structure of the mountain after it was broken into pieces. So it wouldn't have had eight peaks in this story, and wouldn't have been called Yatsugatake.

Anyway, mythology aside, the story is plausible from a seismic perspective. There was very likely a volcanic eruption at Yatsugatake causing the massive mountain, which is much older than Fuji, to become smaller.

Talking rubbish

We moved over a month ago and there is still some rubbish to clear up in the old house. We've been trying to get back there in between working, sorting out our new home and looking after the kids, and it's mostly cleared up, but there is still work to do. I switched off the electricity at the breaker, so the water pipe heaters have been off, and the pipes are now frozen. It's been below freezing for most of the last fortnight, and was minus 2.4 at the height of the midday sun today.

We moved what we immediately needed as soon as we could. In fact we moved most of our stuff on the first day. Some things that we're going to need later, we moved later. Then, out of what remains, we've been taking the things that we want and throwing away what we don't want. There still seems to be stuff left in the gap between. Then there are things we don't really want, or need, but feel that somebody, somewhere must want or need them so we shouldn't throw them away.

For example, the things that people gave us when we had a baby, that they had used when they had had a baby. Should we throw them away or give them to someone else who has just had a baby? But actually, a lot of these thing we never really used when we had a baby. Maybe the people who gave them to us didn't use them either. These things just get bought by one pair of gullible parents and passed on from couple to couple without ever being used. This must be a lucrative business.

Anyway, the remains of our residence are becoming increasingly large and undiscernible. Even if we decide to throw something away, Matsumoto's rigourous rubbish regime takes some navigating, and you can't just leave any old crap in a wheelie bin out the back whenever you like, but that is a topic for another day.

Tripped the lights - fantastic!

The breaker had gone a couple of times already, in hurry-up-and-make-breakfast mode. The total electricity is limited to 60 amps on the breaker board. The IH will use two or three kW to boil the kettle at full power, the boiler uses about two-and-half and is sometimes still going until 7 am when the cheap rates finish, and the oven uses a couple of kW, so that's well over 60 amps.

We were a bit surprised when the lights went off at about 10:30 on Saturday 14th January, when we weren't really using any power. In fact the lights didn't go off because none of them were on, and I'm not sure exactly how we found they had gone off. We had guests around, so perhaps we were trying to put the kettle on.

I'd noticed the panels were producing 8kW a little earlier, which was the most I had ever seen. The highest before that had been 7.3. I put the breaker back on again, and a few minutes later it went off again. Since then it has been fine, and the only reason I could think of was the panels producing too much power. I contacted the electrician and he said the same thing.

A couple of days later the solar suppliers came to explain how everything worked as they'd missed explanation day on Christmas eve. Actually it made a lot more sense to come after we'd been producing electricity for a month and had some actual data to look at on the display. A younger guy with a loud suit from the manufacturers, and the older man in company uniform from the installation company. They were impressed by how much we were producing and explained a bit more about the system. The power conditioners are rated at 4 kW each, and will limit their output if they are overheating or if too much power is coming from the panels to them. As the panels are rated at around 9.3 kW, when the conditions are good they will produce more than the power conditioners can take.

The display panel keeps track of how many minutes the power conditioners have been limiting output each day, and on some days it has been over 20 minutes, which they have never seen on a system at this time of year.

The electrician, in an email, said it should be be OK if we changed the breaker from a 60 amp to a 50 amp. This rather confused me, as 50 amps seems to be less than 60 amps. He explained that the 60 amp one is a special Chubu electric limiter for a total of 60 amps on either channel whereas the 50 amp is for 50 amps on both channels. The electricity seems to come in on two wires, 200 volts between them and each 100 volts from ground. Most electrical appliances inside the house use one side of this and ground to get 100 volts. I had thought it would be three phase but evidently not.

The solar power is going out at 200 volts, so even if it is at 8 kW, that's only going to be 40 amps (P = V I). However, the 60 amp fuse breaker adds up the current on each wire, and will look at that as 80 amps. If we change to a non-Chubu breaker, it will just work on the current, and 50 amps will be plenty.

What still confused me is why it had been fine before and since, and only tripped on that one morning. Why was 7.3 kW OK, but not 8kW? It seems that there is some variety in the actual current that the breaker will let through, and it looks like our 60 amp breaker will let through up to something like 75 amps. I asked if we could get an even weaker 60 amp breaker. The electrician laughed at my joke.

In terms of solar production, that day was a difficult case as it was partly cloudy. Otherwise it has either been sunny for the whole day, or cloudy for the whole day. On this day it had been a cold night, then a cloudy morning, so the panels and power conditioners must all have been cool and highly efficient. Then, suddenly, bright sunlight came out from the high sun, almost in the south. Maximum power attack.

This happened in the middle of January, but as the sun gets higher and more of its rays get onto the panels, there's going to be a significant amount of potential power lost because of the limit of the power conditioner. I'm not sure what can be done about this, but I wonder about a battery between the panels and power conditioner, and perhaps rewiring the panels into eights rather than sixes so they put out a higher voltage. The power conditioner will start producing AC as soon as the voltage gets over a threshold. The battery will charge when the panels are producing more voltage than it has, and discharge when the panels are producing less. As it discharges, its voltage will go down and the system should make the output more even, especially on those tricky days that are partly cloudy.

Obviously this is all just theoretical, and I wouldn't dream of actually adding a battery to my system as it would contravene the contract with the electrical company.

Things IV. Power sockets at the top of the stairs.

Doesn't this look a really silly place for a power socket?

Especially when there's lots of space on the other side.

It's an invitation to make a trip wire. Shouldn't this be illegal? Like having a door opening onto a staircase, it is inviting danger. There's another one further down the steps too. What was he thinking? Fair enough having as many sockets as you can, but do you need them where there is a chance of sending somebody tumbling down the stairs and being electrocuted? It was on the drawings and I should have picked it up.

I think the reason it is there is because he wanted to put a power socket with a built in nightlight there. Something that would automatically come on when it got dark so that you can see where the steps are. A very clever invention, apart from the rather obvious fact that you don't necessarily want a socket where you want a light. I suppose they are a good way of making sure that you're using electricity all the time, even if it is just a watt or two. I can just imagine how it was invented by some old fart who had inherited a big electrical company from his dad, and came up with the brain wave when he got home drunk one evening. The next morning, when he told everyone else about his wonderful idea, they all went "yes boss, that's a wonderful idea," massaging his ego and nursing their hangovers.

Also, in the case of our house, it's even more ridiculous as there is a sensor light in the ceiling above the stairs so the lights come on automatically when you walk near them. I told him I didn't want his stupid nightlight power sockets, but he left the sockets in exactly the same place.

Another fossil of a silly decision, carelessly missed in my checking of details, exposed in the house for all to see but few to notice.