Chubu denryoku and the case against solar

Jonathon sent a copy of this poster, showing Chubu Denryoku are actively publicising against solar power.

Point 3 says that the area of solar panels needed to supply Matsumoto city with all its electricity would be 100 times the area of Matsumoto castle, or 80% the area of lake Suwa. The implication is that this is a huge area. Of course, compared to the total area of Matsumoto city, or even the total area of rooves in Matsumoto, it's not that huge an area. Many of these roofs have tiles on, and after the 5.4 magnitude earthquake the other day, a lot of these were shaken out of place and many rooves now have scaffolding around them and blue sheets on top. How long before the cost of solar panels will be in the same ballpark as roof tiles? 

Point 4 is talking about cost. It claims 1 kW of solar panel costs 1.1 million yen, corresponding to 100 yen per kilowatt hour of production. What is telling is that the prices are stickers, in other words they have changed since the poster was produced, and will continue changing. I paid around half that for each of my kilo watts of panel, so their numbers are out of date. To apply for city and government grants, the cost per kilowatt hour must be under 700 thousand yen, and once the grant is taken into account, the cost to consumer is less, although I'll give them the benefit of the doubt and ignore grants as they don't change the cost--just who pays for it.

Even so, as you can see in the graph on the right, the cost per kWh is still going to be high compared to hydro electric (13 yen/kW), thermal (10 yen/kW) or nuclear (9 yen/kW). As the solar installation cost is out by a factor of two, I'm not sure how much to trust the other figures. The real cost of nuclear is endlesslesly debatable, as we continue to grapple with the events at Fukushima in March 2011. For example, how do you measure the cost of people around the world thinking that the whole of Japan is a disaster zone?

Anyway, rather than being 10 times more expensive, solar is certainly less than five times more expensive.

The point is more about power democracy though. As a house builder, I can, and indeed have, just invested in solar panels that will sit on my house for the rest of my life, requiring minimal attention, pay for themselves within ten years. I'm not going to buy a nuclear power station. Although it may rain a few metres on my land, there isn't enough to generate hydroelectric power, and I'm not going to buy a gas fired power station either. 

Costs will continue to come down, efficiency will also go up, and as well as adding stickers to this poster, Chubu Denryoku is going to to have to change the pictures too. 

Wake up. The sun is shining!

Don't be LED astray... search, and you will find the light!

For the past couple of years I've been searching for decent lights to put in the house. I don't have particularly difficult requirements: energy efficiency, low cost and aesthetic pleasance.

LEDs seem to best meet these requirements, but one obvious problem is the timing. Just in the two years of planning, LEDs have gone from monochromes that the Chinese were adding to disposable toys onto the shelves of shops to replace incandescent bulbs and into traffic lights and a whole range of applications. Certainly they have been in camping shops for a while. This is an area where people have always paid a premium for light weight and a long lifetime. LEDs remain far from standard in domestic electrical installation, but I'm sure this will change in the next five years.

Since their invention in 1962, efficiency and light output of LEDs has been increasing exponentially, roughly following Moore's law, which predicts a doubling every 36 months, which has been renamed Haitz's law for the LED. The costs of materials are probably already below those for incandescents or fluorescents, and it's only a matter of time before the other costs of the industrial infrastructure are accommodated, and prices can come down. As of summer 2011, I'm still set to pay an early adopter tax.

Would you like a wiring plan, or a plate of spaghetti?

Just picking up on a detail. Maybe being unnecessarily picky.

I'd planned the telephone to be plugged in upstairs near the north west corner of the house. There is a telegraph pole on the north side of our land, about four metres from the north west corner of the house. They have things called wireless phones, so there is no need to have telephone wires running around the house any more. The internet connection will also come in on the telephone wire, but I have a wireless port, so once it's in the house, the computers can go anywhere.

For any older readers, I should probably clarify that "wireless" refers to internet technology that does not need to be connected by physical wire, and is not a posh word for a radio.

So, it seemed like a no-brainer to bring a wire from the telegraph pole to the north west corner, then bring it into the house with a metre or so of cable, so that the phone and internet gubbins can be connected.

When I saw the plans, which only came after the electricians started working and under duress, I spotted a telephone wire meandering around the house. The wire comes into the house at the north east corner, then goes out again on the east wall, puncturing the walls and vapour barrier twice. Then meanders all the way across the house to the west wall, where we want it.

The reason for the second puncture is that the phone line needs to go through a protection box, in case there is lightning or something. Rather than being up on the wall next to where the telephone line comes in, this protection box is right next to the electricity metres, so it will be easy to fix it if anything goes wrong, "thinking ahead". Clearly a ladder would be out of the question, presumably since the hypothetical workman in this hypothetical situation may be scared of heights.

And the reason why the telephone line can't come in at the north west corner and must instead go in at the north east is that it won't look very good. In view of the ten-metre high telegraph pole next to the house, with scores of wires coming out of it, I don't think anyone will even notice the wire going to the house, except perhaps in the architect's photos. Maybe I should offer to teach him how to use Photoshop so he can edit it out

At the meeting with the electrician a couple of days ago I said that it was OK and left it to their plans, but since then it's been really bugging me, and I'm strongly minded to put my foot down and insist that they put it all back to the North West corner, "thinking ahead".

-=+=-=+=-=+=-

This may be a good opportunity to tell Anthony's joke about a conversation between a Japanese, English and Irish  IT expert.

First, the Englishman is talking about an archaelogical dig in Britain that revealed copper having been used thousands of years ago. "And that goes to show", he boasts, "that the prehistoric British were using LAN networks."

"That's nothing," says the Japanese guy. "We had an archaelogical dig in Japan too. And you know what they found?"

The other two shake their heads.

"Silicon," the Japanese guy replies. "And that goes to show that prehistoric Japanese people had optic fibre networks.

"That's nothing," says the Irishman. "We had a dig too, and you know what they found?"

The Englishman and the Japanese shake their heads.

"They found absolutely nothing," says the Irishman with a proud smile. "And that goes to show that the prehistoric Irish had wireless internet."

Publicity - Probably not for publication

A couple of banners have appeared on the North and East of the house, visible from the the road.

Before	After

It may be a coincidence, but the day before this, during a meeting, the architect casually announced that the insulation contractor was going to be showing some people around the site next Wednesday.

The boss of the builder didn't take too kindly to this, saying that he should have contacted me first, with it being my house. I suggested they should have contacted him first as it was his building site.

Heirarchical politics within building projects

We had a meeting with the architect and the site foreman yesterday. The boss of the builders turned up too.  It felt a bit like he was our dad, come to check we were all playing nicely together. A couple of things have brought this to a head, but from my perspective it comes down to the heirarchy of the project management. 

In Japanese, the word "sensei" is applied to architects. This loosely translates to "teacher", but is also applied to doctors, lawyers and politicians. It encompasses some of the confucian notions of seniority and respect. As far as the architect is concerned, and I think this is architects in general and nothing personal about our architect, he's at the top of the tripod. In one direction below him is the client. The client is important as he is funding the architect's creation of an artwork. In another direction is the builder, and in the other are the subcontractors. Architects bring work to builders, so there is a sense in which the builders are working for the architects, and some respect and gratitude are due. The contractors have to work with the architect's plans, and part of the architect's job is apparently to check that the building is built to his plans. (I'm afraid architects are usually "he"s.)

Behind their backs I've heard carpenters call artchitects egakiya (picture drawers) and complain that it's easy to put things in place on a bit of paper, but not always possible in the real world.

In terms of relationships, the one between the architect and client is likely to be short-lived. Very few people will build a second house, and if they do they are likely to use a different architect. Clients may recommend an architect to their friends. 

The relationship between the architect and builder is much more important as the architect needs the builder to turn his drawings into buildings, and the builder needs the architect to bring in business. The architect may meet the same contractors on various different projects, and those relationships are long-term too. Obviously the relationship between the builder and contractors is important, so the three legs of the tripod are not all independent, but, as far as the architect is concerned, the relationship between client and builder should be kept to a minimum, ideally just the handing over of as much money as possible, and there should be no relationship between client and contractors.

The architect is reluctant for the client to talk to the builder because it makes the flow of ideas and the making of decisions much more complicated. Also, architects are human and do not know everything, and conversations between client and builder may reveal some weaknesses. 

So the way it's supposed to work is that the architect talks to the client and decides what kind of building he can get away with. He then takes these plans to the builder. The builder gets all the contractors together and builds the building. The architect checks this when necessary, or when he's not too busy on the next job--after all architects usually need to be starting working on their next project by the time the building starts on the last one. Then the keys are handed over to the client, who lives there happily every after.  

It's difficult to say, but I'm sure a massive percentage of clients are not really happy with the houses that are built for them, but with people in Japan being such stalwarts, and gaman being much more of a national institution than a stiff upper lip ever was in England, they usually don't say anything, and probably often enough don't even realise that their ideas and their ultimate welfare has been largely ignored in the process. 

We have presented challenges to this status quo in a couple of ways. For example, I want as much involvement in the building as possible, and not just in deciding what colour the walls are, but deciding where the wires and hot water pipes are going to go, deciding on the construction of walls, placement of insulation and puncturing of the thermal envelope to get wires in and out. 

We've been meeting the architect on a fairly regular basis for almost two years now, in a long and painful process of getting our ideas from vague notions, theories and preferences into concrete, through the filters of his extensive knowledge of building and his sense of style, and within the constraints of physics and economics, and all of our tenuous understandings of those. 

Before the concrete was laid, we started to have weekly meetings with the builder and the architect. These seemed to go well for a few weeks, but at some point petered out. We went back to the situation of meeting the architect, and the architect meeting the builder. This came to my attention acutely on Friday when we had had a meeting with the architect in the morning to discuss the lights in the house, and in the afternoon, when I went for my daily visit to the building site, I saw him talking to the foreman about installing the shutters, and saw the electrician putting in the wiring, based on a wiring plan that I had not even seen.

Flickering lights? Damn those dumb dimmers!

Mark from Yamagata writes:

Dear Sir
After reading the latest doses of your blog, I have a question for you. We have LED down lights in a number of rooms, and at a certain brightness they flicker, usually only intermittently. We have been told this is an irresolvable issue, a clash of LED vs dimming technology Comments?

LEDs are diodes. Diodes are semiconductors and this means that sometimes they conduct and sometimes they don't. A regular diode will conduct if you send electricity one way, but not if you send it the other. As their full name "light emitting diodes" suggest, LEDs emit light if you send current through them one way. I heard a company in Korea is developing diodes that will light up whichever way you send current through, which is a good idea in the world of AC power supply.

Anyway, there's a threshhold, usually 2 or 3 volts, at which they'll turn on. Since they are diodes and conventionally it only matters whether they pass electricity or not, on or off has traditionally been sufficient for conventional LED uses on displays. LEDs will produce more light with more current, but only above a voltage threshhold, and if there is too much current, the diode will start melting.

Dimmers traditionally work as variably resistors, so the more you turn them, the lower the resistance gets, and the less voltage there is across the dimmer and the more voltage there is going through the light. Conventional Edison-style incandescent lights also work like resistors, so the current is proportional to the voltage (as I'm sure you can remember from Ohm's law) and the amount of heat and light increase accordingly. This kind of old fashioned dimmer may work with light emitting diodes. Alternatively, it might work really badly as the LED will not turn on until the voltage is high enough, and may not dim the light; just turn it on or off.

The problem with resistors is that the current going through them is turning into heat all the time. More recent dimmers work by rapidly switching the electricity on and off. You can see more here on how stuff works dot com. The AC comes in as a sine wave, and each time the sine wave crosses the zero volt line, then switch a little later. If you're only dimming the lights a little, they will switch on very quickly. If you're dimming a lot, they will switch on just before the voltage goes to zero again. This kind of dimmer should work well with an LED as it will switch it on for a shorter or longer part of the cycle.

LEDs use direct current (DC), not alternating current (AC) so within an LED "light bulb" there may a row of LEDs adding up to 100V, and a ring of diodes known as a wheatstone bridge which sends the input AC voltage in the right direction so that one output is always positive and the other is always negative. Or they may have a step down transformer inside them. AC-DC power adaptors usually work by switching the AC to a much higher frequency, then converting it to DC. They may just be switching the voltage off when it's at the top of the sine wave, and far higher than is needed.

The flickering problem with the LEDs may be caused by a number of things. It could be that at a certain level, the voltage is close to the threshold for the LEDs to come on, so they are switching on some cycles and not switching on other cycles. Anything switching on and off 50 or 100 times a second is going to appear to be on all the time. Depending whether it's a US-based system or a UK based system, TVs change their pictures 25 or 30 times a second without appearing to flicker, but if you get down to about ten times a second, it's going to be obviously flickering. Apparently, this is known as the flicker fusion threshold.

By the way, the difference between the 25 frames per second in the US and 30 frames per second in the UK depends, in turn, on whether the voltage is at 50 Hz or 60 Hz. The eastern half of Japan is 50 Hz while the western half is 60 Hz, apparently because in each half generators were introduced from the US and Europe respectively. This means that Japanese electrical appliance are generally made to work at either frequency, which has probably been an advantage in their international marketing. However, I digress.

Another possible cause of the problem is that there are two systems both chopping away at a sine wave, and there is some interference going on, resulting in a lower frequency flickering. If this is the case, and the LED lights have their own devices for chopping 100V AC into lower voltage DC, it may be that an old style variable resistor dimmer would work better.
I asked Mark for more details and found that the "certain brightness" at which they flicker was usually at about two points on the dimmer scale, say 1/3 and 2/3, but not exactly the same for each light, and the nature of the intermittent flickering was that they flicker for a few seconds, then stop, then flicker for a few seconds again, then stop, and so on.

As a solution I suggested he could just try avoiding the level at which they flicker when he dims them, apologising that this was both obvious and not very helpful as the level at which they flicker is clearly the level he wanted! He went on to say:

We have several types of dimmer down lights. The ones that are flickering have replaceable LED bulbs which are not built into the unit. The second type are unreplaceable (as opposed to irreplaceable--a good English lesson there--and built in. They apparently have 200,000 hours in them which will outlive me (though I think the max is really 40,000). These never flicker. At least not yet.

The life expectancy is usually 40,000 hours, but that's 40 years at 3 hours a day, which I think will probably outlive us anyway! In my opinion, irreplacable lights should be unreplaceable.

The ideal solution for dimming LEDs would seem to be a dimmer power supply that will output the correct voltage and current for a DC LED. This is available, even in Japan, for example here on Rakuten. But in the worst case, there is an LED light bulb screwed into a conventional fitting, connected to a dimmer switch, and the dimmer switch and the electronics inside the bulb are left to fight it out.

LEDs may be an irresolvable clash between electricians and new technology.

You can see more about how diodes work here on how stuff works dot com. The graphs above came from this website.

A future without fire... for Chubu Denryoku?

The local electricity supplier, Chubu Denryoku, sent a note to us about reducing our electricity consumption over the summer. They are especially worried about the period from July to September, and between 1pm and 4pm. Apparently around half of domestic electricity consumption is used on air conditioning. They suggest five things people can do:

1. Set the air conditioner to 28 degrees. People usually set it to 18, which is the lowest setting available.

2. Change the filter once or twice a month. This will make it run more efficiently. I suspect a lot of people never change the filter, instead waiting for the air conditioner to break, then they get a new one.

3. Use bamboo or rush mats on windows to keep the heat of the sun out.

4. Use a fan as well as, or instead of the air conditioner.

5. Don't leave stuff around the external unit of the air conditioner. 

They could also add shutting windows, which makes air conditioners more efficient as they just cool down the room rather then the broader environment.

More important still, they could mention INSULATION... 

While these requests for customers to reduce consumption of their product are admirable, they don't seem very interested in increasing the demand of energy. I went to ask them about connecting the panels on my house, and although they were not obstructive, they were certainly in no hurry to get them connected as soon as possible, for example at the beginning of July before this hot summer with its closed nuclear power stations and record cases of heat stroke, rather than in October after it has finished. I got the impression that they didn't really want to connect the solar panels at all.

On the wall outside their Matsumoto office, they have a hoarding advertising All Denka, or all-electric. At the top it says something about a future life without fire, promoting Eco-cute atmospheric heat pumps for hot water, IH cookers, and electric storage heaters. 

The picture is a mountain hut somewhere up in the mountains above Matsumoto. I struggle to find any connection between this and domestic electricity use. I'm quite sure it's heated with paraffin space heaters, or more likely abandoned in the winter when the roads are closed. In fact it looks like a perfect site for solar power, or wind. 

How about this picture of one of your eleven gas-fired power station? What was the expression... "no smoke without fire"...

I know Chubu Electric has 17 hydroelectric, and there is one nuclear power station that is having a rest at the moment. But according to this document from 2010, the gas-fired have a total rating of 23,900 megawatts, the hydro electric 5,300 MW and the nuclear 3,500 MW. They have a "new energy" 新エネルギー powerplant at Omaezaki, which produces 6 MW. That's 

Gas: 73%

Hydro electric: 17%

Nuclear: 11%

"new energy": 0.02%

I'm trying to work out exactly what the Omaezaki "new energy" plant is. Usually Google takes me to the Hamaoka nuclear power plant, which is, perhaps by some bizarre coincidence, in Omaezaki. The "new energy" hall is part of the visitors' centre at Hamaoka. There seems to be a 2.2 MW wind farm, turbines standing proud along the windswept beach. Perhaps used more as a kind of garnish next to Hamaoka, in much the same way that someone on a diet orders a salad and a diet coke, to go with the steak and chips. 

But it's easy to criticise. Putting into perspective this 6 MWatt "New Energy" plant, relating to 0.02% of their total capacity, my solar roof will have 9.12 KWatts, roughly 650 times smaller. This is the biggest rooftop array that the panel fitters had ever made. Most are around 4 or 5, less than one thousandth of the "New Energy" plant, which in turn is less than one five thousandth of Chubu electric's total capacity. 

A lot of their capacity is to meet peak demand. The gas and nuclear power stations are either on or off, so they need some way of storing extra energy when it is not being used, and supply it when it is needed, and hydro electric works well at this. 

They are also working on the hundred-year-old system of massive power production and long distance power transmission. This goes back to the  war of the currents between Edison and Telsa in the 1880s. Ultimately won by Telsa and Westinghouse. 

Other people in Japan are talking about smart grids, where electricity is generated on a smaller scale, and used or stored in a more dynamic way to reduce consumption.  If Chubu Electric doesn't start thinking about this, it's likely to see people switching off from the grid in a few years when solar panels have halved in price again, and batteries have become cheaper and more efficient. 

Compriband - Magical tape

For a house to have good thermal performance, you need insulation and airtightness. A company called Wuerth provides a magical component called Compriband, which we are using to seal our windows.

Regular Japanese window frames are the antithesis of this as the aluminium is a great conductor. Also, sliding windows, while great at saving space, defy airtightness. This is just looking at the window moving within the window frame; there must also be no gap between the frame and the house, and whatever is filling that gap should insulate.

The problem is what to do with this gap between the window frame and the house, and German manufacturers Weurth have come up with a tape called Compriband, which can be fitted around the window before it is installed, and it then expands after installation to fill the gap with foam and provide an airtight membrane on the inside.

The tape is passed around the whole window frame. It should be cut diagonally at the join, to ensure the seal. Also, at each corner, there needs to be some extra length.

Getting into the corners

One piece of advice the manager of Pazen gave to me was to look into the corners. When the Compriband tape is applied, each corner needs a little extra length, so that the tape can expand to fill the corner, and the insulation is complete and the airtightness maintained. The picture above is what the corners should look like, with the Compriband filling the gap. In one case, it looks like no extra length was given at the corner.

In another case, although it looks like extra length was given, there is some daylight visible at the corner, so the Compriband has not filled its gap.

You can follow Wuerth Japan's blog here
And see a range of their products from their Japanese website here.

Windows going in

They were starting to load the windows from their storage half an hour away in Hotaka at 8:30 and supposed to arrive at the site around 10. Kentaro from Wuerth turned up around 10:30 to show them how to use the compriband.

I heard the crane go past my house at 8.30. Presumably they can only hire cranes for whole days. Crane drivers must be used to sitting in the cabs for hours waiting for something to happen. Perhaps a career worth considering, although it may be a bit late for me to switch.

The windows started arriving after 11:30, which did not surprise me. Kentaro had another appointment later, so could only comfortably stay till 12:00. In the end he stayed a bit longer and showed them how to install the compriband around one of the smaller windows. He reassured me later that he made his next appointment on time. It's a shame that most of the time he was here was spent waiting and listening to my rants on energy efficiency and its enemies in the Japanse building industry, rather than watching and advising on the application of his product.

As of the morning, nobody seemed to know how the large fixed upstairs windows were going to be installed. The fixed windows are triply tricky because they are going upstairs, they are heavy because the glass cannot be removed from them, and they cannot be fixed to the pillars in the same way as the other windows, from inside the frame.  The moving windows can be taken out of the frames and screws put through the frame into the pillars on each side. Small strips of wood and a crowbar are used to adjust the windows when they are installed, and a spirit level to check they are horizontal and vertical. This makes a big difference to windows that swing open, and in the case of the concertina door, another adjustment is needed for each wing of the window. Yesterday I spoke over the telephone to  the manager of Pazen, the German manufacturers. He plans to be in Japan in September and offered to make final adjustments then.  

In the case of the fixed windows, obviously the glass cannot be opened and removed, so the frames must be fixed from the outside. As this is impossible, or at least very difficult with the wall construction and 120 mm thick pillars, they are using metal strips, which they first screwed onto the window, then after putting the window into the building, screwed onto the pillars. 

Just as I could have predicted that the windows would have arrived an hour and a half late, I should also have been able to predict that they would try to get these difficult windows in as quickly as they could, while the crane was still there, with decisions made on the site, and an attitude of "it'll be right". Although I shouldn't have been surprised, I was shocked to see that the three south-facing upstairs windows had all been installed when I got back from teaching my afternoon lessons a couple of hours later.

When I first saw these metal strips sticking out beside the windows, they started ringing alarm bells as thermal bridges. Especially these ones, on the opening window upstairs on the South East. Obviously the assembled window is heavy, and they wanted to get it in when the crane was there, but each glazed wing could be removed, and the three parts could be lifted and put into place. In this case the metal strips are unnecessary. I spoke to the window importer who did not seem terribly interested in thermal bridges. I also contacted someone at Passive House Institue in Germany who seemed much more interested, although has not got back to me yet. I've since calculated them at 0.0009 W/K per strip. 

The manager of Pazen in Germany was also interested but seemed confident the thermal bridge effects were negligible. He was more concerned that the window in this picture was moving, and so did not need to be fixed with steel strips. He had sent the right number of steel strips for the two fixed windows, so he was worried that we hadn't used enough on the big heavy fixed windows to keep them in the house.

In the case of the large window in the middle, the metal strips have been screwed onto the frame after the compriband was added. This means that the compriband has not been able to expand to fill the gap between frame and wall, doing its job of insulator and airtightener. You can see a bit of daylight. If we can see daylight, the air will be able to see daylight too, and the airtightness will drop. I need to find out what they are going to do about this. The carpenter and site foreman seem to think the job is done. The architect thinks that they have been temporarily put into place and will all be reinstalled. The insulation and airtighntess contractors are on site at the moment, and I think airtightness issues are in their ballpark. Perhaps they will be going around with a needle later checking the corners.

The smaller window to the west (on the right looking out of the house) seems to be fitted correctly, at least if we can really ignore the steel strip thermal bridge effect, and if two strips on each side is going to hold it in place.

So that's one out of three. 

The house feels really good with windows, and it may make it a bit cooler over the summer, but with the vapour barrier almost completed, they will have to keep the windows open to avoid suffocation.

The Levi Strauss effect

One way of explaining the thermal bridge effect is retelling a story from the history of fashion. This story comes many years after Levi Strauss started using a fabric of Nimes (in France) for trousers in the style of Genoa. To increase the strength of these denim jeans, he put copper rivets in strategic places. In the early garments, one of these rivets came where four bits of cloth meet at the crotch. At least until one day in 1933 when Levi Strauss president, Walter Haas Sr. was out camping, wearing a pair of 501s, and he sat down by a campfire. He hadn't looked very carefully, and on the seat was an iron that had just been in the fire. 

I'm sure you can imagine the effect of the hot iron on the rivet, the speed of the heat transfer, and the part of Mr Haas's body to which said heat was transferred. Needless to say, the crotch rivet was removed from the design.

This is a good example of a conflict between structural considerations and thermal considerations. In fact, the truth is a little less colourful, and although Levi Strauss used this story in an advertising campaign, the main reason for removing the crotch rivet was rationing of copper during the second world war, and economics played its hand. 

Turning the heat up in the kitchen

I suppose when most people hear about house building, they think about what colour the walls are going to be, and what's going in the kitchen, so I'm pleased to say this post has nothing to do with thermodynamics, lumps of wood or bits of wire. 

We're getting a Toshiba IH cooking top. They seem to have the best design, at least among Japanese models. A lot of cookers seem to have been made by somebody who has never had to clean one. Actually, that's true not just of cookers, but of many appliances here, and even of houses. It may be a sweeping generalisation, and a little sexist, but most architects are men, and most of them don't do any washing up, cleaning or cooking.

A lot of the cookers have edges designed to attract grime, but the Toshiba has a flush top with bevelled edges. A lot of them have a control panel that swings out with lots of buttons and switches on it. When we looked at an earlier model, the Toshiba just had a touch screen as part of the glass top. Unfortunately it looks like the newer model has imitated its rivals with the control panel that swings out. Increasing the number of moving parts doesn't fall into my definition of progress.

Actually AEG and Electrolux had the best design, as the Toshiba has an air vent coming out of the top at the back. Most of the Japanese IH tops have two airvents coming out of the back. One is for the grill, a standard part of a Japanese cooker, while the other is for excess heat coming off the IH parts. The Toshiba just has one for the grill. It seems like a grill is an indispensable part of the kitchen, and it's difficult to find cooking tops which don't have one, but they do seem to take a lot of cleaning. I keep thinking the old-style English gas cooker design, with the grill at the top would suit a Japanese kitchen with limited space. The grill would then be just under the extractor hood, and the heat in the summer, and the fragrance from grilled fish and smoke from burnt toast would go outside much quicker. The extractor hood may need a lot more cleaning though.

The other thing is the oven. We had planned to have an oven under the cooker, but it turns out that Toshiba have stopped making them. Because these kinds of ovens use the same vents as the cooking tops, we can't just stick an oven from another maker underneath. Another problem is that sticking an oven from another maker underneath the cooking top would mean that the controls are very low down. So it's going on the other side of the kitchen, next to the window, where the microwave was going to go. It'll be higher up, so the controls will be easy to get to. Ovens these days can work as microwaves too, but we may put a microwave in the pantry so the little one can heat up cups of milk when something is cooking. I'm sure we'd survive with just one cooking machine though.  Apparently people used to just sit around fires burning wood.

What's that sticking out of the envelope?

Just to follow on from the excitement of my last post on thermal bridges, here is a practical application.

A couple of places on the north side present challenges to the insulation performance of the building envelope. The first problem is the external structure of the steps and the roof over the front door. I'd hoped this could be kept as a separate structure to the house, just as the balcony over the southern terrace is, so that it would not affect the building envelope. However, it seemed to be very difficult for the architect to reconcile structural demands. For example, in the case of an earthquake two separate structures would move independently and damage where the roof connects to the wall. Also, with no beams protruding from the main structure, pillars would have had to come out of the foundation right next to the house, which would have been difficult.

Anyway, the result is six beams sticking out through the thermal envelope, some 120 x 180 mm, some 120 x 240. 

Using Therm again, and starting with the pillar in the middle of the wall, we can estimate how much extra heat is being lost by this disturbance in the insulation-wall continuum. I looked at three cases. First, what would happen if the beam just reached the outside wall? Second, how about if it stuck out for 500mm? Next, what if it stuck out for a metre?

There was virtually no difference between the 500mm protrusion and the one-metre protrusion (Ufactor 0.169874 versus 0.169972 W/m²K, around 15% extra heat loss for a unit area) so we probably don't need to worry about what exactly is happening to the beam after the first two or three hundred millimetres. Interestingly, the beam that just stopped at the outside wall did much worse (0.179 W/m²K, around 20% worse). I looked at 200 and 300 mm protrusions, and it looks like the ideal length for a protruding beam is somewhere between these two lengths. When I say the ideal length, obviously it's ideal not to have anything puncturing the thermal envelope.

The moral of this little tale so far, although of no use in our case, is that if you have insulation on the outside of the structure, and if you need to have wood sticking as far as the wall, it's better to have it stick out than flush with the wall, but much better to not have it stick out at all. 

The colours in these pictures show thermal flux, white representing a high heat flow and black representing a low heat flow. So you can see that heat is leaking through the corners where the beam protrudes, but is leaking through the surface where it is flush. Practically, to the extent that we should be worried about this thermal bridge, there is a chance that on a hot and humid day in summer, these corners may have a much lower temperature than the ambient, and attract condensation. This is going to be outside in summer rather than inside in winter, and the outside is designed to stand up to rain. Also, it will be most critical when the temperature has just risen, and in these situations the humidity usually drops.

This kind of thermal bridge is called a punctual thermal bridge, where punctual refers to a puncture in space, rather than it's usual temporal meaning. It may in fact have the opposite meaning to that of "on time"--if you have a puncutal thermal bridge in your structure, it's probably too late!

For punctual thermal bridges, rather than considering heat loss per unit length, in W/mK, we need to consider the heat loss for each beam sticking out, in W/K. There are six of them, so once we have a number, we need to multiply by six.

  

While simple calculations only take into account one-dimensional heat flow (ie what the material is and how thick it is) Therm can simulate two-dimensional heat flows. In fact, and of course, the heat is in a three dimensional world, or in fact a four dimensional world as it's not a steady state, but temperatures are changing all the time. To use the two-dimensional models from Therm to estimate the three-dimensional situation of a beam sticking out of the wall, we can look at two slices of the wall, one vertical, which will include the pillar running up and down the whole wall, and the other horizontal, which will have a few centimetres of pillar in the middle, but the rest of the middle layer will be insulation.

As well as the situation above with a wooden beam sticking out from a perfect wall, as we'd see if we made a horizontal slice through the wall, we should consider this situation, where the middle layer of the wall is wood. For a unit metre of wall, with a metre of beam 240 mm wide sticking out, the U value for a section with the above situation is 0.170 W/m²K, compared with the ideal 0.145 W/m²K. If we look at a 240 mm square section beam, this will represent a difference of 0.006 Watts per Kelvin for the puncture. This amounts to 0.43 KWh lost per year, per beam. If we look at the more severe situation, as if the whole of the the middle layer were wood, the U value (again for 240 mm wide beam sticking one metre out) is 0.215 W/²K; corresponding to a difference of 0.017 W/K, again assuming a square section 240 x 240 mm. The real answer is likely between the two, around 0.011 W/K. Actually, the beams are smaller, so this is a mean estimate. A 120 x 240 mm beam looks closer to 0.006 W/K. There are six of them, so over the year, with 70,000 heating degrees, this comes to a significant 4.8 kWh per annum. We should still be within the passive house limit of 15 kWh/m²a (kilowatt hours per square metre of floor space per year).

It would have been better to work harder to keep this structure outside the envelope, although this may have had structural problems, stuck further out of the house and been more expensive. It could have been a lot worse. Wood is a relatively bad conductor (under 0.2 W/mK). Had it been concrete (around 1 W/mK) or steel (around 40 W/mK) it would have been much worse.

More info, and coincidentally the same example as in my last post here on wikipedia and more here here from the Passive House institute who have pioneered work on thermal bridges.

Sparks start to fly

The electrician turned up at the building site on Friday. I asked about getting the solar panels connected to the power conditioners so that it would be possible to use the free electricity I've paid a lot to get, rather than the builders having to pay for electricity brought to the site. He proceeded to give reasons why this was not a good idea, which mostly annoyed rather than illuminated. I'm already more or less resigned to the fact that the panels will be sat on the roof soaking up a whole summer's sun from the beginning of June, and I won't be able to sell any to the electricity company until I move in and start a contract with them in October.

Actually, first I asked what would happen in the event of a power cut, and he said that, in the case of an earthquake or disaster, a signal would be sent from the electricity company to switch off the power conditioners. This was also a bit of shock (though fortunately not an electric shock) but seems sensible as there may be a loose wire somewhere after an earthquake and it's best to shut off the power. A plug is available on each power conditioner for emergency use.  

Anyway, the first reason he gave for not connecting the panels was that it would be dangerous. Apparently there's a lot of electricity in those wires, and it would be dangerous to connect them. Somebody might die. The panels are there soaking up sunlight now, sending frustrated electrons and holes in opposite directions, but destined never to meet on the other side of a circuit. So, I asked, if the wires are going to be connected to a power conditioner, then what's the difference? 

But somebody might cut the wires. 

Well, surely there's a lot of electricity in the wires now anyway, and somebody might cut the wires now? 

Next, he seemed to think there wouldn't be enough electricity. It's rated at over 9 kilowatts. If it's running at half power, that's still over 4 kilowatts. At 100 volts, that's 40 amps. I know they're running a workshop, but that seems like quite a lot of electricity. As long as there's more coming into the power conditioner than going out, it shouldn't cause a problem. Well, electricians like to work at night time. 

Couldn't they bring a torch?

This makes me wonder how much the idea of a low-energy house has got through to the people making it. 

By the way, he told me, it didn't make any difference to the electricity bill how much they used. There was a standard rate, paid regardless of how much power was used.

But, actually, really, the main reason for not connecting the power conditioners was that they didn't want to start using the them as they will start wearing out. They want to hand everything over in pristine order. Also, they didn't want the power conditioner to get damaged. If they put it in place, there's a chance that it'll be damaged by the workmen. 

In and among, they were talking about new government plans for houseowners with solar panels to be able to sell all the electricity they produce, at the premium rate, and buy all the electricity they use at lower rates. One argument they had against this was that it would not encourage people to save electricity. The current system means that you're much better off selling your electricity than using it, so people will generally try to switch things off, especially during the day when electricity demand is higher. 

I may be over sensitive or paranoid, but I can't help feeling from their general tone that they think all this energy saving and solar power is complete nonsense, and they may of course be right, but more about that another day. 

I was looking, later, at the 230 watt incandescent bulb that the carpenter has brought to illuminate the workspace. Just wondering what that was doing in a house that's trying to reduce carbon emissions. This one bulb will probably use more electricity than all the lights in the completed house. It would be a great heater on cold winter nights. I'm sure the carpenter has heard of low energy lighting, but it comes down to economics. This kind of bulb is cheaper to buy, and he doesn't have to pay for the electricity. The builders pay for the electricity and the carpenter is just their subcontractor. In fact not even the builders really pay for the electricity, because there's a flat rate regardless of how much is used. 

Energy efficiency is not just a question of technology. Energy efficient technology must be used. In fact, that may not lead to energy efficiency; the important thing is that energy-inefficient technology is not used. Even energy efficient technology should be used as little as possible. These are not questions of technology but of design, economics and politics. The technology is actually not so difficult! Anyway, it may be a little optimistic to think that energy efficiency is going to reduce energy consumption.