In praise of shadows... at least if they surround light

Actually, rather than being part of some consumerist conspiracy, the dearth of LED fittings for is probably much less sinister and just a lack of a market among house builders for new lighting. The electrics seem to be the last thing that is thought about in the building process. By this time the consultation process between architect and client has probably dried up and a sketch is handed to an electrician to put fittings in the ceiling in the middle of each room so everywhere is bathed in uniform light. Eat your heart out Jun'ichiro Tanizaki 

I've been reading a translation of his essay, "In Praise of Shadows" (1933) which apparently is required reading for any student of architecture in Japan, although Tanizaki is no architect. Of course architecture contains a great deal more philosophy than anything else, and you don't need to be an architect to know how buildings and spaces work. In Praise of Shadows is a good critique of modernisation and the westernisation of Japan. Tanizaki, who was born in 1886, just after the Meiji Restoration, laments the introduction of electric light into restaurants. He goes off on a crusade to find a deeper appreciation of subtlety and cloudiness in orientals from the colour of their skin to the materials used in their soup bowls and on their sliding doors. 

He wrote that "Japan wastes more electric light than any western country except America." This was in the 1930s; goodness knows what he would have made of the country more recently. He adds that "so benumbed are we nowadays by electric light that we have become utterly insensitive to the evils of excessive illumination." He talks about establishments that are "lit far too extravagently" admitting that "some of this may be necessary to attract customers."  He talks of the waste of lighting before it is dark in the summer, "and worse than the waste is the heat . . . Outside it will be cool, but inside it will be ridiculously hot, and more often than not because of lights too strong or too numerous. Turn some of them off and in no time at all the room is refreshingly cool. Yet curiously neither the guests nor the owner seem to realise this. A room should be brighter in winter, but dimmer in summer; it is then appropriately cool, and does not attract insects. But people will light the lights, then switch on an electric fan to combat the heat. The very thought annoys me." (p 36-37)

If only he were still alive and working as an electrician in Matsumoto.

"Light is used not for reading or writing or sewing," he says later, "but for dispelling the shadows in the farthest corners, and this runs against the basic idea of the Japanese room." So when we're asking what went wrong with Japanese architecture and looking for a culprit, we can add electric lights to aluminium windows in the line up of usual suspects. And I suppose the Japanese obsession with imitating the West. 

Joshua Sowin writes more about Tanizaki's essay here . I've been reading a 1977 translation by Thomas J Harper and Edward G Seidensticker, published by Leete's Island Books of Stony Creek, CT. 

No LEDs on display, but what is on display is being lit by LED...

We went to a few showrooms the other day to look at stuff for the house. We're interested in LEDs, for reasons explained here. One problem is knowing how bright the LEDs will actually be. Everybody used to know what a 60 Watt bulb was like, but to compare incandescents, fluorescents and LEDs, wattage has little meaning, and it's not so helpful to compare different LEDs. Light manufacturers have now started putting lumen values on their products, rather than just wattage, so there is some way of comparing, but the angle at which the light comes out can also be an issue in terms of how bright it is. 

We saw lots of LEDs in the Bathroom shop, Takara, where they have recently changed all their display lights into 60-watt halogen-style bulbs (around 7 watts) in lighting rails for the displays. They even have extra LED spotlights inside the bathrooms on display, to supplement the standard light fittings inside their bathrooms, which puts aside previous concerns that LEDs aren't bright enough.

We asked them to switch off the fitted lights in one bathroom, and just switch on the two LED spotlights to get an idea of how bright they were. They were certainly bright enough, especially under the relatively large area under the spot, but it was definitely less bright on the ceiling and higher up on the walls. Not very good, for example, if we invite a vampire round for a bath, and they turn into a bat and hang from the ceiling. Or perhaps they would prefer to be in the dark, and even for our vampire friends LEDs may be better. Anyway, as a whole the room seemed less bright, as it contained darkness, but it was bright enough where needed.

They are putting LEDs in one of their display bathrooms next week, and the bathroom we're getting has LED downlights as an option to the standard bracket-lights. This will cost us 39,000 yen extra. Obviously they're charging over the odds for this, but the design is superior, with down-lights rather than bracket lights, and it will claw back some of the cost in electricity bills in the next few decades, and should reduce some extra heat in the summer. It's best to write it off as an early adopter tax. 

In the tile shop they had several larger LED display units on the ceiling, like these from Toshiba. Much bigger units.

We asked about LEDs in the home fittings showroom of Panasonic, the electrical manufacturer, and got a rather blank look. They were using some for lighting their own displays of other fixed furnishings, but it obviously hasn't seriously crossed their minds to try to get people to put them in new houses. 

It seems in these, and many other shops that putting LEDs in makes a great deal of financial sense as they can get the same light output for a lower running cost, both in terms of electricity and bulb replacement. There seems to be much less effort getting them into new builds, although they are probably still working on the loss-leader concept that Gillette developed with their razor blades. Buy an LED fitting and you will have light for the rest of your life.  Buy a normal fitting and you'll be buying light bulbs for the rest of your life. Why get people to buy one thing when you can get them to buy two?

LED light bulb... this should be a contradiction in terms.

Just read is-this-the-ultimate-green-led-light-bulb. And it makes me wonder what's going on. It talks about "solving the problem of uni-directionality in older LED bulbs". I wonder whether Edison was concerned with the "problem" of his lightbulb not having an open flame...

Another thing that doesn't make sense is the idea of a replacable LED bulb.  LEDs have rated lifespans of over 40,000 hours. That's three hours a day for forty years. Form most domestic uses, the only reason for replacing the bulb would be if you wanted to change the fitting and keep the bulb. 

This guy at My LED lighting guide gives a list of eight reasons why LEDs are better than compact fluorescants, and Eternaleds asks if LEDs are brighter than CFLs and finds that no, they aren't really brighter. 

The point is that the light all comes out in the same direction, so if you know what you want to be bright, and can point the light there, then the LED is going to use a lot less power, not because it's producing light more efficiently, which it isn't, but because it's going to the right place.

If there's a chance that you're going to be doing something behind the lightbulb, in that bit of the wall where small dead insects accumulate, and you want to make sure it's not dark there, then CFLs or incandescants are for you. If you don't even want a space there, you should probably consider LEDS. If a light is not going to be used very much, and if you're not sure which part of a large area you're going to be using, then fluorescents will probably do as good a job as LEDs, and currently cost less to buy and fit, although LEDs use less resources and as they work out how to manufacture them in bulk, and once they pay back the retooling costs, LEDs will be cheaper.

A practical example in the house is a store room that may be used a few minutes a day. Rather than putting LEDs all around, we'll just put one fluorescent tube in the middle. This will brighten up the whole room in one go, and should still last a few decades. The other low-energy option would be to have a couple of head torches left on a hook at the entrance and turn a trip to the basement into a caving expedition!

But anyway, I wish people would stop talking about LED light bulbs. The whole point of a light bulb is that Edison's elements needed a vacuum, or an inert gas, so that they wouldn't burn away. Rather sensibly, with glass being transparent and easy to blow or suck into bulbs, he put them into a glass bulb. LEDs are semiconductors, typically produced on a flat wafer. They don't need a bulb. It may be a good idea to put a lens in front of them.

Putting LEDs into bulbs is like using a keyboard designed for typewriters over a hundred years ago when you're inputting words into a computer...

Slits in the envelope

In most places we have walls interrupted by occasional windows. The wall is a more-or-less uniform structure with three layers of insulation. Although the middle layer has a lot of wood in it, the first degree estimate (10% wood, 90% insulation) is near enough. We have data for the windows of the U values of glass and frame, and the thermal bridge "psi" value between glass and frame, and between frame and structure. U values come in W/m2K, in other words the heat flow per area per temperature difference. The psi value is in W/mK, so gives the heat flow along a line. A square window with one metre for each side will have an area of one square metre, but for the thermal bridge, the length is 4 metres. As window get smaller and less square, the relative effect of the thermal bridge gets bigger. 

A rather wonderful piece of software called Therm can answer the question of how much heat is going to be lost from an actual wall structure, so we can see how close the actual U factor is of a wall with a wooden pillar running down it, compared to the prediction from the U values of 10% wood and 90% insulation.

You start by drawing the structure and setting each polygon to the appropriate material from the library of data the system has. In this picture, you can see the three layers of glass wool insulation in blue, a wooden pillar in the middle in orange, and a couple of layers of structural board in the other colour. Is that puce?

Next you set the boundary conditions. You can tell the software whether each surface is inside or outside, or whether to ignore it. You can consider a surface it adiabatic, in other words that heat is not going to flow through it at all. It would be very time consuming, and not particularly helpful, to model the whole house, and you usually want to find out about a particular bit of wall, or a boundary between roof and wall, or some kind of junction. 

To model a wall, you can slice it in two places and put in an adiabatic surface in each, so you can get some meaningful estimation of what's going on. The main concern is heat flowing from inside the house out, so once you get far enough away from the part you're interested in, you can ignore any heat flowing along the walls. 

In this case, the left side is outside, the right side is inside, and the top and bottom are adiabatic, so we're just looking at heat flowing from inside (where the temperature is assumed to be 20 degrees C) to outside (where it's assumed to be very cold - 18 degrees below zero). Of course the temperature will be changing all the time, as will the humiditiy, but this is just looking at a steady state in the worst case. Another piece of software called Wufi http://www.wufi.de/index_e.html will simulate the humidity conditions over a year or two, and show where moisture could build up in a wall or roof structure. That's not avaiable as a free download though!

To find out the thermal bridge effect of the wooden pillar running through an insulated wall, I compared three different structures. First, I made an ideal wall with a 50mm insulation on the inside, 120 mm in the middle, 12 mm of structural board, then 100 mm of insulation on the outside (1). Ideal, but of course it would not hold up very well! This has a U value of about 0.131 W/m2K. 

Next I made a wall with the 120 mm middle layer completely made of wood (2). This has a U value of  0.187 W/m2K. In both cases 1 and 2, the U factor can be calculated directly from the U values of each component part. To do this you have to add up the R values (the reciprocals of the U values) which measure thermal resistance. There are also surface effect factors to account for convection, inside and outside, and factors to account for radiation. When you get to the surface, convection is the biggest cause of heat loss, but across the wall the heat is conducting. 

Next, I made a wall with a 120x240 wooden beam in the middle. This is close to the real situation. As there is 240 mm of wood and 760mm of insulation, we would assume that the U factor of this bit of wall is 0.24 x  U1 + 0.76 x U2, or 0.145 W/m2K. The Passive house spreadsheet also assumes this. In fact, the wall is conducting 0.147 W/m2K. This represents a difference of 0.002W/m2K. This corresponds to 0.002 W/mK along the length of the beam, and is the thermal bridge effect. This is small enough that we need not worry about it. Larger thermal bridge effects need to be added to the passive house spreadsheet. You can see the isotherms on this picture, showing how the temperature is distributed. 

This picture, much more pretty, shows the temperature by colour, as you'd see from an infrared camera. 

The next picture, perhaps even prettier still, shows the heat flux, with white representing the highest flux. So we can see which parts of the wall the heat is rushing through. 

This software uses what's called a finite element grid, which I can remember hearing about in my lectures at university. I think I nodded off shortly after them, only to wake up just before my finals, but along with the thermodynamics, I realise now that at least something stuck from those days, and at least in some tiny way I can call myself an engineer. I'm not sure whether it was the result of my university study, or whether it was instilled in me from earlier by my father. Perhaps the essence of engineer goes further back, and courses through my veins from generations living in the harsh and unyielding environment of the North of England, with nothing but their ingenuity, which the word engineer probably came from before they ever got around to making engines. I digress.

Calculating heat flow over complex shapes with different materials is tricky, but if we imagine a small rectangle or triangle with a constant temperature along each side, we can easily work out how temperature is going to flow through it. Therm breaks any structure up into such polygons, then goes from one end to the other working out how much heat is going through each part until it reaches some kind of equilibrium. 

Therm can be downloaded for free from here. http://windows.lbl.gov/software/therm/6/index.html

A big batsu for Japanese architecture?

Batsu is the Japanese word for a cross, and it means that something is wrong or not allowed.  I noticed a few of them on the pillars and beams of the house as it was going up. Perhaps I'm reading too much into it, but I can't help seeing it as someone putting red crosses where something is wrong.  And it seems to be a little critical of Japanese architecture.

I learnt in first-year engineering classes that squares and rectangles are not a good idea for a structure, as they create a mechanism. The top can swing from side to side, turning from a rectangle into a parallelogram. If it keeps swinging, as it well might in a strong earthquake, the parallelogram turns into a horizontal straight line with the ceiling meeting the floor. To stop this, you need triangles. 

Our first-year engineering project, as I remember, was to design a structure--basically a bridge-- that would hold one tonne across a span of one metre. Most people built a square-based pyramid, with a hook at the top to hold the weight, and a beam diagonally across the square base to turn the square into two triangles and avoid the mechanism. My group made a tetrahedron: a triangular-based pyramid, so there were no squares to start with. This is the basis of the geodesic dome, which is a very light structure. Our "bridge" weighed a little over half the next heaviest design, fulfilling the goal of the engineer to build something that will do the job using the least necessary resources.

Anyone can build a bridge, we were told, but an engineer will build a bridge that is strong enough for its purpose, using as few resources as possible. 

I really don't know very much beyond first-year engineering, but I can't help feeling that there's just far too much wood in the structure of the house, and it's all in mechanisms. When we're talking about shelves and internal woodwork, I'm constantly being told that solid wood is really expensive, and we need to use laminated wood, or fibreboard. Then I see huge chunks like this being used where the roof meets the walls: 

The lateral strength is coming from kenaf board, imported from Malaysia and made from a baste fibre. A package was left on the balcony the other day, which alarmed me somewhat as it has a "No wet" sign and an umbrella. The architect assured me that this just meant the contents should not get wet, and it would be fine to leave the palate out in the rain.

The kenaf board is being put around the outside of the pillar and beam structure, then the batsu can all be removed. It doesn't look very rigid, but according to this paper it seems to be strong along its length.