Awnings and shade

At some point, probably in a couple of weeks, we're going to want some shade over the terrace. Otherwise we may get hot feet. There is 20 cm of concrete under the tiles, which should sink some of the heat, but in direct sunlight, it's going to get hot. The range of options, and corresponding range of costs is quite wide. 

The ideal solution would be a shop-style awning, that can be drawn in or out as we like it. My feeling is that we should put up some semi permanent shade over the terrace at the beginning of the summer, and take it down at the end of summer. My wife prefers something much more variable, which may be a cultural difference. The same thing seems to happen with heat in Japan and the UK. In the latter, houses usually have central heating, so you set the temperature you want, then it is warm enough. Japanese houses typically have fan heaters and air conditioners, so if the temperature is not how you want it, you can press a button.

I'm not sure whether it's enough to have a button like the one next to the traffic lights that you press, and it says "please wait". These are often not connected to the traffic lights, but people feel much better if they have something to press. 

Or there's the joke about the Englishman, Scotsman and Irishman stuck in the desert. I must apologies for the mild racial stereotyping in this joke. If anyone takes offence, they should just remember that the Irishman was from Kerry.  

Anyway, they walk through the heat for a while, and meet a genie, who gives them a wish each. The Englishman asks for gallons of water. The genie grants the wish, the Englishman drinks and is cool and happy. The Scotsman asks for gallons of whisky. The genie grants the wish, the Scotsman drinks and is happy. Then the Irishman asks for a car door. The Englishman, Scotsman and genie look at him, and ask what on earth he wants a car door for. "Well," he replies, "If I get too got, I can wind down the window."

In our situation, of course, when it's really hot outside we will want to shut the windows. We could still do with something outside to stop the heat getting in by radiation through the glass. I think we underestimated the effect of the white-tiled terrace to the south reflecting more heat in through the windows. This probably increased the solar gain in the winter, and of course it will increase the solar gain in the summer unless we shade it.

Trawling the internet, mostly Amazon and Rakuten, the cheapest solution is canvas strips, anchored at the top to the balcony above and at the bottom pegged into the garden. There are some framed awnings for a few thousand yen, but usually only 2 or 3 metres wide and not so sturdy. Our terrace is almost 6 metres wide.

These people, Minowada, make them much wider. This place seems to sell their awnings for 400,000 yen. Tostem also has some, about half the price, but not as wide.

As an option, for another 120,000 yen, they have a wind detector, that will automatically close the awning if the wind gets up. We're not in a particularly typhoon-prone area of Japan, and actually the terrace is probably well sheltered as it's surrounded by houses. Perhaps we can design ourselves not to put the awning out when there's any chance of wind. 

My wife's biggest worry is the heat, and influence from the terrace into the house. According to calculations, the windows will let in some of the heat of the sun when it's low and shining through them in the winter, but much less in the summer when it is higher. This is for about three reasons: one is that as the sun gets higher the angle becomes more acute, and more sunlight is reflected from the window. Another reason is that as the angle gets more acute, there is more glass to go through, so less heat gets through. At the best of times, the south-facing windows will only let in 60% of the sunlight, and that's because they are special high-g glass. Another reason is that in the summer the sun rises north of east, so it won't be shining into the south-facing windows at all in the early morning, and the balcony above the terrace should form a complete block of direct sunlight, at least until the end of August. Some heat may be reflected off the terrace, but it's still going to be the same acute angle. As for heat getting in by conduction, this should be very small, and hardly worth bothering about. The only difficult thing will be to keep windows closed during the daytime, so the heat exchanger will start working to cool down the incoming air, rather than letting in hot air.

At the moment we have a camping flysheet over the terrace, but may go for a slightly more sophisticated set of canvas pieces for this year at least. 

Bypassing the heat

In the past I have been vehemently opposed to bypasses. Now I am delighted to have one in my house. Perhaps this is mellowing with age. More likely it is because the bypasses I hate are strips of concrete laid around towns encouraging more cars and trucks to speed through countryside, while the one in my house fits neatly as a part in the ventilation system.

I had assumed the ventilation system was fitted with the bypass, and shocked when I realised it was not. Six months later, on Friday 15th June, they came to put one in.

The ventilation system, rather crucially, has a heat exchanger. It's not perfect, but it means that if it's freezing outside, and 20 degrees inside, then the heat from the expelled air will be transfered to the incoming air, so rather than an icy draft, the fresh air comes in at around 18 degrees. This is great in the winter. It's also good news on a hot summer's day when it may be 35 outside, in the shade, and 25 inside. In this case the heat will be exchanged the other way, dutifully following the second law of thermodynamics, and fresh air will come in at perhaps 26 degrees.

Either way, the temperature comes into the house at more or less room temperature, keeping that temperature stable.

In the summer, all the things that help keep the house warmer in the winter, like solar radiation, heat from appliances and boilers, and even human bodies giving off 100 watts each, are now risking overheating the house.

On summer evenings, it tends to cool off and the trick of the bypass is, rather than exchanging heat, it directly expells the warm air from the house and draws in cool air from outside. I looked over record temperatures fo r Matsumoto and among the figures was the number of nettai-ya or "tropical nights", where the temperature stays above 25 degrees. The record was  two nights in a year, back in 1983. Past performace is no guarantee of future climate, but pretty much every night throughout the summer is going to drop to, or below, comfortable room temperature, and if we can keep the sun out during the day, the house is not going to get too hot. As long as the laws of physics hold up, that is.

The only question is, what exactly do the two temperatures in the settings mean? One is the "inside temperature", with a default setting of 22 degrees. The other is "outside temperature", with a default setting of 10 degrees. The people who came to fit the system had absolutely no idea.

It seems their boss was against this kind of bypass. I'm not sure why but one reason I heard was a fear that the pipes in the heat exchanger would start to get moldy from condensation if they didn't have air flowing through them. As the bypass is not going to be working the whole time, this seems like an unwarranted worry.

It would be nice to be sure but I guess that if the inside temperature is above the higher temperature, then the bypass will switch on when the temperature outside is below that. But if the outside temperature gets below the lower temperature, then it will stop bypassing and go back to heat exchanging. It seems like we're getting cool air coming in at night, and at the end of the month there may be some actual results to show. 

A watt metre

How much is that fridge costing? Apparently as fridges get older they become much less efficient. In a more rational world, we might have MOT-type tests to check whether the fridge is still environment-worthy, and fridge maintenance teams to fix it if not. Perhaps they would come and top up the refrigerant or change the seal around the door. 

At the moment if we want to do something about it, the only choice we have is to get a new one, and when we do, this is up to chance, how long we've had it and what's growing inside or whether it matches the wallpaper.   

And maybe the argument that new fridges are much more efficient than old ones is just propganda from the manufacturers to get us to buy more fridges, and in fact the energy and resources used to make a new one are equivalent to several decades of running costs keeping the old one off a scrap heap.

Anyway, here's something that should be cheaply and widely available. A watt metre that you can plug any appliance into, that will keep track of how much electricity it is using. 

http://store.shopping.yahoo.co.jp/dejima/44135.html 

At 3,150 yen, I'm not sure how long it would take to pay for itself though.

Ten tips if you are building a house

1. Don't do it. Do you really need to make one? There are loads of houses out there. Just find one. There are lots of people already making houses. Do you really have to add to all of this?

2. OK, so you've ignored the first tip. Next then, don't trust anyone who knows everything. If they don't tell you about mistakes they have made and things they have done wrong, then either they have done very little, they are lying, or they are deluded. 

In fact, don't trust anyone at all. There are almost limitless options and permutations in building, and everyone has preferences and prejudices. If they like some material or technique, it may be because their favourite architect used it, or because they have a friend who is good at it and buys them a drink every time they send business their way. If they don't like it, it may be because of a single bad experience, or because they saw it once on a building and it didn't match the colour of their socks.

So if they are recommending you do something, or worse and more common, assuming you are going to do it, ask why, find out the options, get a second opinion. 

In considering advice, you should be particularly wary of anything coming from a blog by someone who has just built their first house.

3. Evidently you've ignored the first couple of pieces of advice, so it seems hardly worth continuing, but I will.

Dedicate a couple of years of your life with this project as your main concern. The way life works out, there's a good chance that building a house will coincide with having small children, and working very hard at your career, both of which may seem, and in fact are, more important.

4. Work out who is in charge. It probably should be you, but if it's not, everyone should know who it is, and you need to make sure you have a good relationship with them. It may not be apparent who is in charge, the architect may try very hard to keep himself as your sole contact and prevent you from talking to anyone else. He may then leave everything up to the site foreman.

It probably isn't you, so if you want to be in charge you may have a battle on your hands unless you are really going to build the house yourself. This seems like it will take much longer than relying on professionals, but if you are going to try to get what you want then it might not take any longer, and would probably cost less, as long as you don't make any disastrous mistakes.

5. Assume that everyone thinks you are a complete idiot who knows nothing about anything, especially house building. For the most part, they are probably right. The building trade, like many other trades, works on the principle: a fool and his money are easily separated.

People will only be interested in what you think or what you want at the beginning. Very soon they will just ignore you and work on what they think you want, or they may not even think that what you think you want is what you really want and they will ignore that too. Once they start working and after they have finished working, they will have less and less interest.

6. Don't let them rush you. Take your time. Spend another few days making that decision. It's like shoes: if they don't feel comfortable when you try them on in the shop, then don't buy them. They won't ever feel comfortable on your feet outside, you won't grow into them, and they won't be just right when you've worn them in.

There are two main reasons they will want you to make a decision quickly. First, they want to get your project out of the way, and start working on the next one. Second, they have told one of their friends in the building trade that they are going to be contracting some work at a particular time. Third, they have to go to a dentists appointment. 

But don't let them relax and take their time. Remember, they are working for you.

7. Make the decision and move on. Although this advice opposes the last piece, sometimes you just have put the decision behind you and start treating it as an unchangable fact that you will have to live and which there is no point in agonising over any more.

8. Don't worry about changing your mind. Again, this is the opposite of the last piece of advice.

You will probably be living in the house and possibly paying back the loan for the rest of your life, and it should be just what you want. 

9. Beware of asking for what you want--you may just get it. The ideal home, what you want, what you ask for and what you get are four different things.

A large part of an architect's job is, or at least should be, persuading you that what you are getting is exactly what you wanted.

10. When it's all finished, if you get more than about half of what you wanted, you've done really well.

11. It is likely it will take longer than you originally thought, or were told.

12. Also, they may try to charge you more than the price you thought you had agreed on. In the feedback questionnaire from the builder, one of the questions asked us whether the extra costs had been explained adequately. I have a problem with a question about extra costs being included on a pre-printed form and so obviously a part of standard practice. It's like being charged for how much salt you used when you're paying for your meal at a restaurant.

Not my fault

I wrote to the solar panellists about the excessive limitation of our electricity and got back a letter basically blaming the electricity company. They said that the situation in the local grid can effect the electricity going out of the house. 

The way the wiring is set up, the electricity is going in or out of one line, and will only flow from a higher voltage to a lower voltage, if my understanding of electricity is correct. I may be confusing it with heat only being able to flow from a hotter body to a colder body, but I think the principle is the same even if the physics is different.  Thermal conduction and electrical conduction share some features and characteristics, but the so does bus conduction. Different things are happening at the micro, or nano level.

So it's possible that the voltage on the lines in the neighbourhood is higher than the voltage that we are trying to produce. Although mains electricity is rated at 100 Volts, it's actually 101 V plus or minus 6, so somewhere between 95 and 107 V.  The power conditioners are set to not exceed 107 V. The power conditioners should be set to produce electricity at as high a voltage as possible, and if not over 107 V, then not much under. If they were producing at 105 V, and the grid voltage was 106 or 107 V, then I think no voltage would be flowing out. 

They suggested that something like this is happening, and that I should contact the local electricity company asking them to investigate the local voltage, to find out if there are any unusual conditions.

I wrote back to them saying that I was reluctant to write to the local electricity company without further information. I explained my understanding of electricity that if the voltage of the local grid is higher than the voltage coming out of the house, then no current will flow and we'll supply zero power.  I have never seen this situation, although frequently seen it producing 5 or 6 kW, and the display indicating that the power conditioners are limiting the voltage. 

They also said that the power we are not sending only amounted to 1000 yen or so in March and in April, and whatever we do, we are unlikely to get the time it is limiting power down to zero.

I still feel to have been a little misled when they told me that two 4kW power conditioners would be fine for our 9.12 kW solar array. This was perhaps my fault for assuming that 4 kW was a rough rating, in the same way that 100 volts could be anywhere between 95 and 107 or our 9.12 kW array is actually 9.34 kW when you add up all the measured ratings of each panel. 

More than just a pretty name

Having established that the Eco Cute is not particularly cute, and is only 'eco' if you're talking about economics, and macro-economics rather than anything on the micro level of the household or consumer, we have to admit that it is an intelligent device.

I somewhat maligned the eco cute in how much electricity it was using while we were away. Here's a graph of the daily usage. You can see that it's using more for the first week (average 6.6 kWh/day), then very little for several of the remaining days (average 3.9 kWh/day). The least the house used in a day was 2.1 kWh, ie running at a little under 100 watts. Looking at the hourly usage for that day, there was a flat graph whereas there are usually some bumps in the nighttime up to a few kWhours each hour while the Eco Cute is doing its thing. Taking this 2.1 kWh/day as the house base usage, for the first week the Eco Cute was using 4.5 kWh per day, then for the rest of the time 1.8 kWh per day. At 9 yen per kilowatt hour, this is hardly going to break the bank!
From the perspective of heat, this heat is going to be leaking into the house, so it gives us an idea of the extra heating bonus in the winter, and also the extra over-heating burden in the summer.
As far as working out what goes on inside the Eco Cute's brain, it appears that it calculates how much hot water is needed based on the usage over the past week, so for the first few days while we were away, it was labouring under the misconception that we were about to run baths of water. Doing this led to a tank full of hot water, leaking 4 and a half kWh of heat into the house each day. After a week, it realised that we weren't using any water, so it started producing more modest amounts, or in fact none for a couple of days.