An extra 2,000 yen

Talking electricity again: this time the bill we have to pay. After the delight of earning ten thousand yen more than expected in July-August, it was a surprise to see the amount we pay go up by a couple of thousand yen in August-September.

There is only one wire going in and out of our house, and two meters outside measuring what goes in and what goes out, so if we use electricity during the day time while the panels are generating, we will use our own power and sell less. 

The electricity bill gives a breakdown by time, and we usually buy the most electricity at night time, about 50% more than we buy in "at home time"  which is in the morning, 7am to 9am, each evening, 5pm to 11pm, and all day Saturday and Sunday 7am to 11pm. We buy very little during the day as we are usually generating far more than we need. Night time is 11pm to 7am, which is 8 hours per day everyday. Considering weekends, at-home time averages a little over 10 hours per day, and day time a little under six. Although we use much more electricity at night, we pay much less for it, and at-home time is the most significant part of the bill we pay.

From the solar panel monitor we can also see how much we consume and how much we generate. At the moment this has to be copied manually, and detailed information is lost after a month, but I hope one day to be able to download the data onto a computer. That's another story.

So why did we use so much more? I don't think we did a lot of cooking or washing, which are two of the main power users. We'd need to charge a few hundred phones to make that difference, and leave the TV on all the time. If we had been using a lot more hot water, the night time usage would have gone up but not the at-home usage, as the boiler heats water at night time. 

Another thing that appears from the bill is that this was a 33 day period, containing two weekends, so there were several more hours of at-home time than usual. Perhaps this is part of the answer. Also, while it was a couple of thousand yen higher than the August bill, that was almost a thousand yen cheaper than the bills for the past three months,

I wondered whether it was the extra load on the ventilation system because we hadn't changed the filters. A closer look at the numbers shows that the main difference was in the at-home time, where we were using around 140 watts more than the last few months. In fact at night time we were using less, if anything, so it doesn't look like a constant electricity user. The ventilation system is on all the time, so we would expect to see both night time and at-home time consumption increase. Day time consumption, as far as the electricity bill is concerned, would be lost in the fluctuations of generation. 

The only thing I can think of that we had changed was switching off the monitor from the solar panels. Before, it had been set to switch on whenever we were generating, and part of the display was encouraging us to save more electricity, or praising us if we were meeting a target. I've switched it back on again, and perhaps that will encourage us to use less electricity.

This echoes something David MacKay said in his fantastic book of energy exposition and explanation,   Without Hot Air, available in full online: "Since I started paying attention to my meter readings, my total electricity consumption has halved" (p. 156)

I had only switched off the monitor to save electricity!

Passive House Days

Here is the press release from Passive House International about an event our house is involved with.

Residents and users of sustainable buildings open their doors

The Passive House Days, 9-11 November 2012

Darmstadt, October 2012 – Affordable, comfortable, environmentally friendly  - Passive House embodies the best in sustainable building. The Passive House Days, taking place internationally from 9-11 November, provides the perfect opportunity for anyone wishing to see this first-hand. For this event, hundreds will open exemplary buildings constructed to this intelligent building standard to the general public. Those with experience in such buildings can pass their expertise on to interested visitors taking advantage of the event to actually experience Passive House first-hand.

Whether residential, office building, kindergarten or swimming pool, there are very few restrictions as to the type of building and building use possible with the Passive House Standard. During the second weekend in November, buildings of almost all types will be open for viewing. With more than 40000 Passive House units in existence globally, Passive House has come a long way since the completion of the prototype more than 20 years ago. This successful concept is becoming increasingly popular.

"Excellent indoor air quality, consistently pleasant temperatures and affordable energy costs guaranteed over the long term: these are the advantages to be gained by building owners and investors," explains Dr. Wolfgang Feist, Director of the Passive House Institute and co-initiator of the Passive House Days.

Besides being cost-effective, this building standard also minimises impact on the environment. On account of the excellent level of insulation and a ventilation system with heat recovery, Passive House buildings can do without conventional heating and cooling systems. The potential savings in energy costs, in contrast with buildings requiring active conditioning, are often greater than 90 percent. "With Passive House, it is possible to manage real estate in a sustainable way and thus contribute significantly to the energy revolution, even today", states Feist.

The Passive House Days, supported by the EU Comission's Intelligent Energy Programme through the PassREg project (www.passreg.eu), are an initiative of the International Passive House Association (iPHA) and its worldwide affiliates.

Information about Passive Houses in specific regions open for viewing from 9-11 November 2012 can be found online at www.passivehouse-international.org. Should you have any questions, the International Passive House Association will be pleased to provide further assistance.

Contact:

Sarah Mekjian | Angela Werdenich

Rheinstraße 44/46

64283 Darmstadt

Germany

+49 (0) 6151 826 99 55

+49 (0) 6151 826 99 54

info@passivehouse-international.org

www.passivehouse-international.org

Endangered Buffalos - Only you can save them!

Once again I digress from the immediate topic of building houses that leave small footprints and don't cost the earth.

At work I was looking through some electronic archaeology and have been trying to resuscitate some old Buffalo Linkstation external hard drives. When I say "old" I mean more than five years old. There were three altogether, each 500 gigabytes. That was when 500 gigabytes was a lot. They were LAN drives, so could be accessed from any computer connected to the network. This is usually a sure way to let them fill up with crap and corruption.

Anyway, all three of them are broken. They flash seven times for an error message that the disk is knackered. I think that's just the way things are with disk drives. The guarantee is for a year or two, they may work for five, after ten they are rubbish. The moral of the story is probably not to buy storage devices together, otherwise they will probably all fail together. Instead you should get one at a time, over a period of time.

I asked my friend John about these, knowing him to be technologically savvy and also concerned about the fate of the planet and all it's little creations.

This was his reply:


Not sure if those external hard disks can be revived. On the continent I come from, whiteys and buffalo, they just didn't go well together. ;-)

I recommend ... kneel over them, utter the words:

"oh holy beast, you roamed this great LAN, 

you served us, you gave us sustenance, 

and your blood, and 500 gigabytes of storage, 

for the good years and the bad, 

thanks for the memory, 

the bits and bytes now forgotten, 

we see your red lights, 

they blink, faintly;

and to you our fading friends, 

this final data to each of us must come, 

goodbye and an eternal power down. 

amen"

Under Pressure

The door was sticking a little the other day. It felt a bit like it does when the extractor fan is on in the kitchen. Because the house is very airtight, when the extractor fan in the kitchen goes on, it's difficult to open the front door. As is traditional in Japan, the front door opens outwards, so the decreased pressure sucks the door in and makes it feel like the door is locked. If all the windows are closed it's almost impossible to open.

The flow of the extractor fan is several times more than the ventilation system. There was an option to get an extractor fan which also lets air in to replace the air that is being extracted, but we decided against it as it was likely to reduce the airtightness. The doors and windows are all carefully sealed, and the vapour barrier and outside layer of tyvek have been carefully installed to get an airtightness around ten times better than the average house being built in Japan. The extractor fan is not designed to these exacting standards. In fact during the airtightness test the extractor fan was taped over, which apparently is standard practice, but seemed to me more like cheating. Regardless of the test result, throughout the life of the building an extractor that sucked air in as well would have two holes in the wall rather than one, and twice as many gaps. 

Anyway, the extractor fan wasn't on, and it didn't seem quite like a pressure issue, so I thought it was another problem with our front door. We've had problems with the key on our front door, making me wonder whether it is a big crooked door to go with our big crooked window that we all got from what I worry is a big crooked German. Then I remembered the ventilation system. 

I used to clean the filter every month, at the same time as my monthly collection of the temperature data from the thermometers around the house, and my monthly inputting and uploading of power generation and consumption data from the solar panel monitor. Since they put in the new ventilation system with the bypass, I haven't actually cleaned the filter. 

When I went into the machine room, which was up in the thirties due to the power conditioners in there and the boiler below, and the insulation around the room keeping that heat from getting to the rest of the house, I saw "FIL" flashing on the ventilation unit. I had heard stories of people with ventilation systems very happy with them until they open them to clean the filters and are attacked by swarms of insects. No insects swarmed out, but there were plenty in there, mostly dead, and several fat spiders scurrying around. One moth flew out. The vacuum cleaner took care of them all.

The filter for air coming from outside had evidently become rather clogged, leading to less air being pumped into the house than being pumped out of it and, in spite of a few windows being open most of the time, lower pressure inside than outside. This was enough to suck the front door in and make it harder to open. It took a few hours for the pressure to balance, but the front door now opens normally. 

The filter for air coming out of the house, there to protect the other side of the heat exchanger, had grey dust growing from it like small drifts of snow. 

Once a month seems to be the right frequency for cleaning the filter, especially in the summer!

Getting through the paperwork to get rid of a car

Diverging once again from the topic of houses, I got a call from the garage that took away our old car. In order for them to scrap it, they need a document showing that it was my car. Documents in Japan are often very precise. You can't just show a passport or driving license to show who you are. You need to go to the city hall and get a document showing where you live. This is called a juminhyou. 

The important point with the paperwork for scrapping my car was that I needed to show that I lived in the house where the car was registered. Since I moved last year to my new house, I had to a get a juminhyou showing my previous residence, which is normally kept in the city hall's records and can easily and quickly be added to the form. 

At this point I should say how helpful and efficient Matsumoto City Hall have become over the time I've lived here. You used to have to wait for about an hour to see someone, then get looked down the nose at and met with surly grunts, then sent away to be called up again at their whim. Another hour later they would tell you the document was ready, and then you had to pay for it, which was at their convenience and would take another hour. This usually meant taking half a day off work. Heaven forbid you try to go in your lunch hour. 

Now they have become much more efficient. Often the person at the counter simply presses a button on their computer, walks a few metres across the room and collects the document from a printer, then hands it over and asks for the fee. It's like being in a shop.

Perhaps this is the benefit of new technology, but I think it's more than that.

They smile. They say thank you. They are helpful. This also adds to the impression of being in a shop, rather than being a pitiful peasant paying homage to the king of the local castle, or presuming to seek audience with him. I think the change came about when the mayor changed from an old-school bureaucrat to a doctor who had spent some time in Chernobyl helping children with thyroid cancer. 

Anyway, going back to the documents for my car, the problem was that the law changed in July so instead of being registered as foreign residents, foreign residents are now registered in the same way as Japanese citizens. Previously we didn't get juminhyou, but some other document, the name of which I could never remember, and now I no longer need to. Generally speaking this is good news as a layer of discrimination between Japanese nationals and foreigners has been removed, and a layer of fog has cleared. 

Unfortunately, I'm now only registered as having lived here since since the new system started in July, and all previous records, including my previous address, have been sent away to the Ministry of Justice in Tokyo. 

So, the very helpful staff at Matsumoto City Hall carefully talked me through the process and the five things I needed to send to the Ministry of Justice: the form I had to fill out, a 300 yen revenue stamp, a juminhyou, a photocopy of some form of ID, and a self addressed envelope. They said it should take two to three weeks, but maybe longer as it's a new system and they probably don't know what to do.

Back at the garage they seemed to be happy with this. I suppose if they'd been in a hurrry they would have contacted me a couple of months ago.

PCMs in the house and in the pocket

So the beauty of phase change materials is that they store heat at constant temperature. One of the challenges in our house, with its passive solar design and extensive south-facing windows, is the daily temperature difference in the winter, when it gets warmer from the sunshine in the day, then when the sun sets cools down from the loss of heat over the massive, thirty-degree temperature difference. Because of the insulation, it doesn't cool down so much, but insulation does not stop heat from moving—it just slows it down.

Building thermal inertia into the house is important—our slab of concrete and stuff under the floor has been doing a great job—but if the thermal mass were in phase change materials, that would be even better. When we were looking at solar thermal collectors, we looked at underground phase-change storage to transfer the heat of summer to warm the winter.

The principle is a bit like the pocket warmers we send the kids to school with in the winter. You put them in a pan of hot water until they melt. They stay molten in your pocket until you need the heat, and when you do, you click the metal strip inside. This causes the liquid to freeze, and in the process release a lot of heat. You can see the liquid freezing in the photos, taken in rapid succession.  Somewhat counterintuitively, they are giving out heat when they are freezing, and taking in heat when they melt. Because of hysteresis, the freezing point is a little bit lower than the melting point. Water will freeze when it is below freezing, and ice will melt when it is above freezing. Some hysteresis is very helpful because we want heat when it gets colder, and we want heat to be taken away when it is hotter.  As long as the liquid is not interrupted, its temperature can cool well below the freezing point, which I guess is a little over 40 degrees C. It's ready to freeze, though, just like the moisture is ready to freeze in the cold winter air. There needs to be a catalyst for the molecules to solidify around, and a clicked metal strip will act as that. Then the molecules will all freeze onto each other, like a rapidly growing crystal. A bit like snow crystals growing from the moisture in the air. As the molecules freeze, they release heat, warming up your pocket. I guess snow is releasing heat too, if the flakes are growing and taking moisture from the air. Perhaps that's why it feels warmer when it snows. I'm not sure whether snow counts as a phase change building material. You'd have to ask an Inuit.  One possibility for using PCMs in the house was inside the hot water tank. Effectively the hot water tank has a load of wax floating around in it. When heat is coming into the tank from the solar panels, the wax gradually melts, absorbing the heat but staying around its melting point. When hot water is drawn out of the tank, the water cools, forcing the wax to freeze and release heat in the process, just like the pocket warmer. The combination of hot water and PCMs floating around in it, is very effective for increasing the thermal mass of water, and avoiding some of the issues of PCMs such as super-heating and hysteresis.  I suggested that we use a hot water tank with PCMs when we were negotiating with the Solar thermal people, but they didn't seem to understand what I was talking about. I may as well have been suggesting that we build the foundation out of blancmange. Perhaps it was my language inability, or it may have been their reluctance to grasp the science. It was probably their stance as experts preventing them from listening to a technical opinion from a potential customer.

Here is a paper on a system in India using cans filled with paraffin, storing and releasing solar heat.

This is one of the tanks that I would have liked to get for our solar thermal system, which works on the same system.  I suggested this to the people who were trying to sell us the solar thermal system, but they didn't seem to understand. 

Another interesting idea with PCMs is this one from China.  Solar vacuum tubes are filled with phase change material. When the sun shines they change phase and charge up. When you run water through them, they draw off the heat and charge down. 

So the pieces are all there. They are just scattered around on the floor rather than coming together into the plans of buildings.