Monday, 15 May 2017

The western sun is strong

There is common wisdom in Japan that the western sun is strong. Of course it is not—the sun delivers just as much radiation in the West as it did in the morning in the East. And it delivers the most when it is highest and due South. In fact, less radiation may get through in the West as the air may be more hazy and dusty in the afternoon than it was in the morning.

Panels on a west-facing roof titled to the South
Some people are retrofitting solar panels onto pyramid roofs that slope four ways, and are encouraged by the wily sellers of panels to add them to the East and West sides as well as the South side. Panels facing due south will generate the most, and you could generate 20% less if the panels point East or West. The installers will charge the same wherever the panels go, and when grants are available they often do not depend on where the panels go. Orienting panels in different directions will give peak generation at different times of day which may be more useful than maximum total generation. Given a choice, people recommend the East side for panels, rather than the West side. If the western sun were stronger, they would be recommending panels on the West side.

One of my favourite local solar installations.
I wish they all had servos and tracked the sun! 
What is happening in both cases is that the temperature in the afternoon is higher, and in the normal state of affairs, the western sun is going to feel a lot hotter as the ambient temperature is already hot. In the morning it is relatively cool.

For the panels, efficiency drops as temperature rises, so the eastern panels will produce more electricity in the cool morning than the geometrically identical ones on the west that have to wait until the hotter afternoon to produce their electricity.

Friday, 12 May 2017

Shelves for an airing cupboard

My telephone sometimes tries to be smart and puts together photos I've taken into cute albums of what I have been doing. Unfortunately, I use my phone more as a note-taking device than a scrap book of life-defining events, so a significant proportion of my photos are of the dimensions and prices of items in hardware shops, as you can see here.

Five years into living in this house we still haven't reached peak shelf. The new airing cupboard presents a particular challenge to storage.

I realise that the concept of an airing cupboard may be confined to the UK, or at least to northern Europe. It's a simple enough idea though. You have a cupboard next to the hot water tank, which stays warm and is a good place to dry clothes. Hot water tanks have been standard in UK houses for a while, and damp weather has been around even longer. These hot water tanks are always inside so that any heat lost from them goes into the house, in contrast to Japan where hot water tanks are become more common but are invariably outside the house, even in areas like mine where it drops ten degrees below freezing.

Airing cupboards are particularly useful in the UK where it is often raining or damp, especially in the winter, and drying outside is not an option. I remember my Australian friend talking about hanging out washing in the summer, and the first bits being dry by the time they finished hanging out the last bits, so airing cupboards are probably not so important there. Years of cheap electricity in the US mean that people dry laundry in machines, and it has been suggested that hanging it anywhere else is a confession of poverty.

Drying outside is possible in Japan for most of the year, although the rainy season can sometimes give you few opportunities. Another problem we have is with allergies and when it is pollination season for all the now mature cedar that were planted after the war, we don't want to hang washing outside.

We have an indoor hot water tank, and I'm not really sure why we didn't make it into an airing cupboard from the start, but I have recently converted the door into it, and there are nice spaces around 30 cm wide on two sides of the tank.The door is diagonal, so you can easily get into these two sides. The one on the right is about 50 cm deep, the other on the left almost a metre. 

I was trying to work out the best way of utilising the space. The shallower gap on the right is about one hanger-width deep, so the best plan is a couple of things sticking out of the wall to hang hangers, one high and one low. There were various options available in shops, but the best things I saw were the shop fittings that their products were hanging off, and I haven't seen them for sale anywhere. As usual Japan seems to have a massive range of products that are all tailored to a very standardised set of architectural constraints. So there are hangers designed to fit on the backs of doors, or on the frames for sliding aluminium windows. Not much is available for screwing into a wall. 
Not the hangers, the thing the hangers are hanging from

I imagined some kind of drawer system to pull out racks to hang socks and things on, that would then push back into the deeper space on the left. Several sketches of ropes and pulleys, levers and pivots, and rails on rails followed, but in the end, simplicity prevailed. I got a foldaway hanger that can be screwed into the wall, but it is a little too narrow. There are also extendable poles that fit on the wall on one side and the boiler on the other. Luckily the boiler is square.

The best solution was simple brackets sticking out of the wall, with some nuts and bolts at intervals along them. Then we can hang hangers off them.

Monday, 8 May 2017

Could Passivhaus be cheaper?

Passivhaus, Herefordshire, 2016 
I don't just mean cheaper than it is now, but could Passive House be cheaper than a regular building. And I don't mean cheaper in the long term, but cheaper to build.

Low energy buildings, Pennyland, 1979
When we were building, we found in most cases the extra demands of passive house provided extra opportunities for builders and contractors to charge us more money. I think this was partly our fault for not finding people who were interested in changing the way they work, so rather than seeing our house as an opportunity to learn how to build better houses in the future, they saw it as a diversion from their usual practice. Where we did work with people who were used to working to rigorous energy specifications, I got a strong sense that they were able to charge more because they thought nobody else could do what they were doing, or because they were aiming for rich customers who just judged value by the price tag.

The theory behind Passivhaus is that increasing insulation means massively reducing the heating system, so extra costs insulating are balanced by lower costs installing a heating system. Since Passivhaus also required a ventilation system, and rather than removing the heating system it just scales it down, this seems like a challenge. The cost of extra insulation, structural changes to accommodate and support the insulation, airtightness barriers, increased window specs and ventilation system all need to add up to less than a fraction of the heating system. 
State of the art building, Lavenham Wool Hall, UK, 1464 

According to this report from the Passive House Trust, sponsored be AECOM, passive houses cost 3-8% more in Germany, where many are built to the standard. In the UK they typically cost 15-20% extra, although the extra costs are less for large projects, terraces, north-south oriented buildings, and projects where the design can change after tender.

But some people are saying that Passivhaus can, and will cost no more, for example Passivehouse Plus in Ireland give the builder's view on why passive house doesn't cost extra.


Low cost, zero maintenance house, Japan
Twentieth century
And there is a best practices document developed in collaboration with EEBA, and Proud Green Building that asks this question: Can you build a high performance home without additional cost?

And they answer: YES!
Bird Table, Huddersfield,
Turn of millenium

You can Download your copy today! Which will tell you about putting a value on high performance, how to shift costs where they matter most, opportunities in green remodeling, builders' perspectives on achieving high performance, high performance home ratings and certifications, case studies and financial considerations.

Friday, 5 May 2017

What percentage of climate denial is driven by fossil fuels?

Although some people claim denial of climate change is not happening, there is a clear consensus among scientists that denial is real, and that it presents severe and long-lasting risks to humanity. There is also a clear consensus that a large proportion of this denial has come from fossil fuel industry emissions.

Actually just a drained rice field in late summer
Some claim that the observed climate change denial is due to other sources, for example scientific research. However, it is difficult to find evidence of understanding of the scientific process within these claims. This is an important markers that we would expect to see if climate change denial actually had anything to do with science.

"But how much of the climate change denial we see recently can be attributed the fossil fuel industry?"
This is a question than often confuses scientists, since it is obvious that if there were no fossil fuel industry, there would be negligible anthropogenic climate change, and no denial. However, it is helpful to look more closely at this question. 

Winter, in case you forgot how it looked
Climate change denial is a complex phenomenon, and it is often difficult to separate primary causes from secondary and tertiary feedback. For example fossil-fuel generated denial can have a knock-on effect on coverage in the scientifically illiterate media and in right-wing blog posts. These can act as amplifiers, so a single fossil-fuel source that leaks into the media can result in thousands of pages on the internet, each of which can generate hundreds of comments.  

Reduction in fossil fuel industry-generated denial is an essential step to stopping denial. However, many of these secondary and tertiary effects are likely to continue long after the fossil-fuel industry has stopped the emission of denial.

Denial has other drivers including extreme libertarianism, religious dogmatism, contrarianism, and people just being stupid. While fossil industry denial is the biggest driver, some of these other forms can be much more potent. For example, libertarian denial can activate a broad spectrum of people skeptical about the power of government. 

There is also a strong danger of irreversible denial tipping points. Once people have denied scientific method and the media, they may permanently lose a reasoned understanding of the world they live in. This will not only make them pose a greater risk to the environment, but may also put them at a greater risk from an environment that will change around them because of their actions and in spite of their words

Clearly the fossil fuel industry must put in place policies and procedures to reduce denial, with a timeline for reaching zero denial. However, this will not be sufficient on its own, and we must also be wary of other sources of denial. 

Monday, 1 May 2017

Things we didn't do but maybe should have - Solar Thermal

I wrote a bit about hybrid photo voltaic thermal panels in April 2011. We looked into this, and even found a manufacture, Solimpeks in Turkey, and an importer, but in the end we didn't use these panels, and did not use solar water heating. The basic reasons were the uncertainty of maintenance costs, impacting the return on investment, and increased complexity leading most seriously to an ugly roof. In the case of the PV/T panels, which deliver both electricity and hot water, we would not have been able to connect them to the grid and sell the electricity, since the panels were not licensed in Japan. 

Photovoltaics have been pretty much a no-brainer to install on new builds here, as in many cases they have no moving parts and will still be producing electricity when the house is knocked down. Photovoltaics can literally be plugged in. 

Solar thermal, on the other hand, needs to store heat when there is more than you need, supplement it when there is less than you need, and deliver the heat where you need it. 

The most obvious worry is what to do when there is not enough sun, but the three big threats for solar thermal are freezing, overheating and hygiene. Overheating seems the most serious problem. When it gets hot nothing magical happens; water turns to steam, volume expands and pressure goes up. Watt solved similar problems for the steam engine in the nineteenth century, so it should be fairly predictable in a solar collector.

Although Watt is usually credited with having invented the steam engine, like many great inventors, he did not create it out of thin air, but innovated existing ideas to make them practical. Before Watt, the steam was thrown away after pushing the piston around in the cylinder. This was fine for a static engine by a big pool of water, and in the case of mining there were often big pools of water to get rid of. In the case of textile mills, irrigation was already in place to get water there. These engines wouldn't go very far without running out of water. Watt great innovation was to turn the steam back into water, and keep it in the system. When you are collecting heat from the sun, if you cannot guarantee that the heat will be taken away from the water, then it will inevitably turn to steam, and it needs a system like the one Watt invented all those years ago. It's not rocket science—that was Stevenson—but steam in your system could be explosive, and if any air bubbles get in there after it condenses, water may stop flowing. 

Unless your system can handle overheating, you either need a much smaller system than your needs, or you need to be able to store the heat for a rainy day. Heat storage strategies are a rabbit hole you can get lost in. Adding a supplementary heater will increase the cost, but it shouldn't be so complicated to add an electrical immersion heater, fixed up to a thermostat to switch on when the tank is too cold, and a timer to check that it's night time. Electricity is an expensive way to heat, but if you are getting most of your heat from the sun, and you are rarely using this heater, then it's not a big issue. In Japan systems are typically undersized, so and electrical heater would become very expensive, and effectively the solar panels are supplementing a regular heater system, which you need to spend more on to increase the efficiency.

There are seven different ways of getting heat from the panels into your hot water tank (according to Rob Harlan interviewed on Back Woods Home). Drain back systems are perhaps the most simple. Water is sent up to the panels when the sun comes out. When the water gets hot enough, or at the end of the day, it is all sent into a tank in the house to be used. No water is left out in the cold, so there is no chance of freezing. An alternative is a continuous circuit, either open-loop heating water directly, or closed-loop using a refrigerant that will transfer heat into water in the tank. Running domestic water through a solar panel is probably bad news, since there are risks of freezing, and of water standing at a lukewarm temperature that is ideal for legionnaires disease. The continuous circuit should probably have a closed loop, which will be slightly less efficient. Since you are not using the water directly, you can use a coolant instead, and make sure it has a freezing point below your minimum temperature.

The solar collectors can either be flat panels or vacuum tubes. An interesting twist on the storage problem is to add phase change materials into vacuum tubes, so heat is stored by melting one or two materials with a high melting point. Water can be passed through the panels any time, and it will be heated up from the phase change materials. There used to be commercial models here on Made in China,com, but all Google will find me now are research papers and patents.


References

Papadimitratosa, A., Sobhansarbandib, S., Pozdina, V., Zakhidovc, A. & Hassanipour, F. (2016).
Evacuated tube solar collectors integrated with phase change materials. Solar Energy, 129, 10-19. Available from: https://www.researchgate.net/publication/294111899_Evacuated_tube_solar_collectors_integrated_with_phase_change_materials [accessed Apr 21, 2017].