International standards

Wednesday, 17 February 2010

Three months after the first post, things seem to have been very busy, but I'm not sure how fast they have been moving.

We've decided to make a Passive House. This means it must follow strict standards for insulation and airtightness. It will need a mechanical ventilation system that will transfer the heat leaving the building to the heat coming in, so it will maintain ambient temperature.

Whenever I talk about insulation, people seem to automatically say how hot it's going to be in the summer. This seems intuitive but not completely logical. After all, thermos flasks can keep cold things cold, and fridges and freezers are insulated too.

Just like the old joke from the days when David Beckham played for England and Wayne Rooney still had his own hair:
They were stopping for lunch at the England training ground and took out their packed lunches
Rooney: What's that you got there Becks?
Beckham: It's a thermos flask. Posh Spice bought it for me for my birthday
Rooney: Ooh that's good. What's it do?
Beckham: Well, it keeps hot things hot, and cold things cold
Rooney: Sound. What you got in it?
Beckham: Three cups of tea and a choc ice!

There's also a very strong sense in Japan that this country is completely different to the rest of the world, and what happens in Germany cannot be used here. As far as I can tell the same laws of thermodynamics apply, and water and air have more or less the same chemical composition in both places. The climate is certainly a bit different though.

Summer temperature is about five or ten degrees warmer in Matsumoto than in Germany, and five or ten degrees colder in the winter. Also there is a difference between average monthly highs and lows of over ten degrees every month, with August having average highs of 30.5 and lows of 19.8. January swings from 4.9 to -5.5. As well as looking at averages, the extremes are also interesting. In 1987 there were two days when nighttime temperatures stayed above 25 degrees. This was a record. In other words, on pretty much every day of every year, opening the windows at night is going to let in air below 25 degrees.

1943 saw 155 days where the temperature fell below zero. This makes me think that the cold is a more serious problem than the heat!

There are places in Austria with a similar temperature range, for example Eisenstadt or Baden. Searching for "passive house" on the internet in English, you find lots of people making them in the US and talking about making them in the UK. Searching for Passivhaus in Eisenstadt, I found most of the hits were estate agents selling those that have been built over the past twenty years!

Building a house

(Reposted from September, 2009, with pictures added. )

We're now heading fairly surely towards actually building a house. People keep asking me what kind of house it's going to be, and I'm not really sure how to answer. I wonder if they want me to say that I'm building an igloo, or a fourteenth century Venetian palace or a brick Victorian end terrace. Certainly they want some short answer and not a long description of what colour each wall will be and what the doorknobs will be made of.

It certainly seems like I should have a short answer for this question. As building is much more of a philosophical journey than a technical one I'm just going to set out what I want to do and what that means.

I want to build a house that has an energy consumption of less than zero.

An explanation of why I'd like to build a house that produces energy should not be necessary, and in my opinion in a developed country you should not be allowed to build to consume when you can build to conserve.

Following from this basic condition for building are four topics: Energy efficiency, thermal inertia, generation of electricity and collection of heat. They are of course interconnected, but I'll try to explain each one.

When it's going to be ten below zero outside, a big part of energy efficiency is thermal efficiency. First of all, this depends on the size and shape of the building. The bigger it is, the more heat it will need. The bigger the surface area, the more heat it will lose in the winter, also, the more heat it will gain in the summer when it's over thirty outside. As well as the design and layout of the house and the rooms, the materials used are important. It must be well insulated. A lot of the heat is lost through windows, so these are very important.

Thermal inertia will keep the building at a constant temperature. The more heat the building can contain, the better. This can be both active and passive. The air in rooms contains a certain amount of heat, and it will make a difference how this air moves by convection and how it is forced and fanned where it might not otherwise go, and whether heat can be recuperated from air as it leaves the building. Water, or other liquids, can also store heat and can be moved around the house to where heat is needed. In addition, building materials can store heat. While wood is a good insulator, stone can store a lot more heat. Another possibility is phase change materials: for example floor panels containing a liquid that freezes at 19 degrees. Because of the latent heat of freezing, this can absorb a lot of heat as it is melted, and release a lot of heat as if freezes, all at the ideal temperature of 19 degrees.

Photovoltaic solar cells are pretty much the only practical way of generating electricity in a small plot in the middle of an urban area. The amount of solar energy that falls on the earth in one hour is the same as the amount used by the human race in a year, so some kind of harnessing of this power is very feasible. In fact most kinds of energy production come indirectly from the sun, whether you're burning wood, using fossilised wood in the form of coal or prehistoric microbes in the form of oil, or even using wind and waves that have been generated ultimately by temperature changes and the evaporation of the oceans. Only nuclear power and tidal generation are not originally solar. The sun is, of a course, a large nuclear reactor so I suppose you could say that all energy is ultimately nuclear. Solar cells are not highly efficient, perhaps only converting 10 to 20% of the sun's energy that hit them into electricity, but that's worth a whole new blog.

The collection of heat is most simply achieved by facing windows to the south. As the winter sun is low and the summer sun high, eaves can easily be extended to allow heat in in the winter and keep it out in the summer. This, on its own, is not going to be enough to heat the whole house and of course the more windows there are, the more heat is lost. Solar walls, developed to dry grain in Canadian barns, can absorb heat from the winter sun and convert it to hot air inside the house. Roof mounted solar thermal panels can be used to heat air or water. Combined with photovoltaics these can greatly increase efficiency, also worthy of a whole new blog. Heat pumps are another way of getting heat. They use a small amount of power to defy the second law of thermodynamics and get heat from a colder body.

I'll come onto the colour of the walls and the doorknobs later, but these will probably be influenced by the points above.

original post: http://minuszeroeco.blogspot.jp/2009/09/building-house.html

Built to last or built to lose

There have been articles about this on treehugger.com and in the Guardian recently, so here is a re-post from August 2011, embellished by a graph from a paper they cite.

It is sometimes hard for me to come to terms with the disposable nature of house building in Japan. Apparently the average life time of a house in Japan is 17 years. In the UK, it would take 1700 years to replace the entire building stock. Although those two numbers are not equivalent, it gives some idea of the difference. I come from a country where houses are built to last. I grew up in a house that was a couple of hundred years old, which was not particularly unusual. The house we rent here now is about a hundred years old, and it's a constant surprise that it is still here.

(This shows the value of buildings dropping to zero after 15 years, from this paper by Richard Koo and Masaya Sasaki.)

It is easy to write this off as bad workmanship or see it in terms of a nation that loves new things and is obsessed with the disposal of the old. It has been suggested that Japan must have a large construction industry as there are periodic needs for mass rebuilding after natural disasters. It seems that the construction industry is a powerful lobby and they can veto any suggestions to improve building standards. There is also, no doubt, something left over from the post-war rebuilding of Japan where fast, cheap building was the only option. I think there is no simple reason.

But there is a vicious circle, as I found when I was asking the bank about loans. As far as they are concerned, and as far as the taxman is concerned too, a house is worth nothing after twenty-five years. The biggest drop in value is the moment you move in. In most cases, the house is worth less than you paid for it as soon as you turn the key and walk over the threshold.

The people at the bank weren't particularly interested in the building specs when they were valuing the property, instead they look at the houses in the neighbourhood and take an average per floor area. In fact as far as collateral, they don't really take the house into consideration but just look at the value of the land. So unless you're building with cash, and have lots of it, you're at the mercy of a bank that is going to encourage you to reduce the spec. There is little incentive to build something that will last more than 25 years, although one glimmer of hope is a recent standard for a hundred-year house that can open the door to lower mortgage rates.

Houses in the UK, and probably the rest of Europe, the US and Australia, steadily increase in value. From when they are built, they start to get more valuable. After a while, when they hit an unfashionable or unserviceable age they stop getting more valuable, but even then they will hold their value. A little later they start to go up again. There are certainly stories of people with negative equity and people who lose out, but that's usually short term and a combination of local conditions and some measure of extra bad luck for the house owners, forcing them to buy and sell at the wrong times.

As we were looking around Matsumoto for houses and land, we often saw old houses for sale that were very reasonable. If they weren't sold after a year or two, they were knocked down, and the price of the land, without a house, would go up. There is a common wisdom here that renovating old houses is more expensive than building new ones, and I think it may be true if you're comparing a low-cost new-build with restoring a ruin to its ancient form. I think it's more likely to be propaganda by the building trade, a symptom of few people or businesses that renovate, and the prevailing trend of not looking after houses, but letting them wear out until they are knocked down, which is all part of the vicious cycle.

Having said that, if I look at the house we are in now and if we were to bring it up to a comfortable level to live in, we'd have to replace the roof, replace the windows that make up the north and south walls, and pull up the floors and do some work on what's underneath. By the time we'd taken all the bits off that need changing, we'd be left with a wooden frame, and that probably would have to be made earthquake proof as their are no diagonal supports and the whole thing is a mechanism. Also, I'd want to raise all the horizontal beams so the doorways are at least twenty or thirty centimetres above my head rather than two or three centimetres below, just where there is a permanent bruise on my forehead.

One way of looking at this difference is in terms of agriculture. The UK traditionally has pastoral farming, so buildings have been essential to provide shelter for people and animals, so that animals can feed off the surrounding land. Buildings have intrinsic value in this sense. Japanese agriculture is arable, so that land itself is valuable for intensive planting of crops. Any building is going to reduce this value by stopping the production of crops.

Another consequence is in the notion of "home". For the British, a home is a solid thing. An Englishman's home is his castle. For Japanese people, any building seems arbitrary and the sense of belonging is to a community of people.

So while I see what I am doing as an investment, and put myself on a mission to make a small change to the way houses are built and treated here, I'm probably just pouring cash into a hole in the ground, and the main interest of most of the people involved is to catch some of that cash as it falls. I'm sure the house could be built to a similar specification for less cost, and hopefully everyone involved will learn something on the way, so if another idiot comes along asking for a house that doesn't consume, it'll be easier for everyone concerned.

Original post: Built to last or built to lose
Thank you PJ for sending the treehugger article.