Monday, December 29, 2008

"we want these detainees broken"

  • Former Navy General Counsel Alberto Mora: “there are serving U.S. flag-rank officers who maintain that the first and second identifiable causes of U.S. combat deaths in Iraq – as judged by their effectiveness in recruiting insurgent fighters into combat – are, respectively the symbols of Abu Ghraib and Guantanamo."
  • Jonathan Fredman, chief counsel to the CIA’s CounterTerrorist Center: "If the detainee dies you’re doing it wrong."
  • In mid-August 2003, an email from staff at Combined Joint Task Force 7 headquarters in Iraq requested that subordinate units provide input for a “wish list” of interrogation techniques, stated that “the gloves are coming off,” and said “we want these detainees broken.”
  • JPRA Commander Colonel Randy Moulton’s authorization of SERE instructors, who had no experience in detainee interrogations, to actively participate in Task Force interrogations using SERE resistance training techniques was a serious failure in judgment.
  • Secretary of Defense Donald Rumsfeld’s authorization of aggressive interrogation techniques for use at Guantanamo Bay was a direct cause of detainee abuse there.
I think at this point I'm just sick of all the damage that has been done to my country by Bush and his team.  I doubt that throwing many of them in jail will do much to improve the behavior of similarly-minded people, but I'm all for prosecutions so long as they don't shift attention from the job at hand, which is to fix the economy.

Thursday, December 18, 2008

Insulating the pool

Since this is my first posting about the pool, let me show you around a bit.  South is to the left.  You can see all along the south side of the pool there is a two-foot-wide shelf.  The water over that shelf will be 12 inches deep in the shallow end and 18 inches deep in the deep end.  In the middle of the south side you can see where the hot tub will go.  At the far end (west), you can see the shelf that will eventually support the automatic cover vault.  To the left of the pool, at the far end, you can see the pump vault that will hold the pumps below ground, behind baffles, which should make them completely silent.  The top of the wooden form will be about three inches below the coping around the pool, so you can see that the coping is about 18 inches above grade on the near side.  That coping will be about 16 inches wide, and will form a sort of bench seat most of the way around the pool.  At the far end, the grade level will be raised to match the coping height, which because of the slope of the back yard will only be about six inches.

The blue stuff you are looking at is the 2 inch thick Dow Styrofoam Highload 40 insulation, most of which is glued (yes glued, with polyurethane foam) to the soil behind it.  On the bottom of the pool, the insulation sits on 4 inches of crushed drain rock, which sits on a geotextile fabric membrane.  The next thing to go into the pit is the plumbing and rebar grid, and after that we shoot gunite.

Heat losses for most pools are dominated by evaporation. We're going to be getting a safety cover, and one of the side effects of these covers is that they are close to vapor-tight. We'll keep it closed for most of the day and only open it to go swimming. As a result, I'm expecting evaporative losses to be quite small -- perhaps a half inch a month or so.  On our 18x46 foot pool, that's 260 gallons/month. Multiply by 2270 kJ/kg (water's heat of vaporization), and that's 70,000 BTU/day.  [Update: this evaporation estimate was dead on.]

Direct heat loss through the cover will be the largest remaining heat loss.  The 24-hour average outside temperature in spring is around 60 degrees, and the safety cover will be something like R-1, so loss from a 85 degree pool would be 520,000 BTU/day.  During the early spring and late fall, we'll probably lower this loss by putting a bubble-type cover over the safety cover.  (I wasn't able to find an automatic safety cover which insulates.)  The combination of the two covers will be around R-3, so losses will be around 180,000 BTU/day.

Most contractors tell me that the dirt under the pool is a fine insulator, but I think they really don't know what they're talking about. Houses use under-slab insulation to insulate their 70 degree interiors from the 55 degree earth heat sink. The pool will be at 85 degrees, which is twice that temperature gradient, so I think insulation will matter even more for the pool. In particular, I'm most concerned about the water table contacting the bottom of the pool in the spring and sucking all the pool's heat into an underground plume of warm water headed towards the San Francisco Bay.  [Update: the water table never gets to the bottom of the pool, as our dirt is well drained.]

Let's suppose that concrete conducts 1.7 W/m-K. To convert that to more familiar units, 8 inches of concrete would be R-0.68 (which is terrible -- single-paned windows are better). I'll guess that the dirt, even when wet, insulates a bit as well, so that the bottom of the pool is about R-2. My pool will have an average depth of 7 feet (it has a 10.5 foot deep diving area), so it'll have an exposed area of about 1790 feet. If the pool temp is 85 degrees, and the ground temp is 60 degrees, that's 537,000 BTU/day, about three times my expected loss through the top in the spring. That's why I'm insulating the pool.

The blue Styrofoam has an R value of R-10. It is designed to deflect 5% at 40 psi, and is rated for continuous (dead) load of 13.3 psi. 10.5 feet of water plus 8 inches of concrete will be 5.25 psi, well within the dead load rating of the Styrofoam. The stuff should compress 0.33 mm when the pool is filled, which I don't think will cause cracking anywhere (thermal expansion is probably more than that).

The insulation changes the bottom of the pool from R-2 to R-12, so now I expect to lose 90,000 BTU/day, which is a savings of 447,000 BTU/day.  To put that in perspective, on an average day my solar panels will deliver around 40,000 BTU each.  I think I can squeeze 12 of them up onto the roof.  The insulation is saving about as much heat flow as the panels put in!

To attach the insulation to bare dirt on the walls and shelves, I glued them on with Tap Plastics X-30 two-part expanding polyurethane foam, which I sprayed on with a pair of Wagner power sprayers.  The trick here was to hold the panels firmly (with a few hundred pounds of force) against the dirt while the polyurethane expanded, which takes about 30 minutes.  Once we did that the panels really stuck on well.

Note: I wore complete face covering, goggles, and breathed through an activated charcoal filter to take out the volatile organics.  It was impossible to get the crew to wear the same protective gear.  In the end, everything that was exposed got coated in a fine mist of polyurethane.  The warning label says skin will develop an allergy to the stuff with repeated exposure.  If you try this yourself, be careful, and be careful with your crew!

The soil at the bottom of the pool is firm clay, covered with filter fabric, covered with drain rock.  Initially I tried gluing the insulation to the drain rock, but this doesn't work well.  The insulation does not sit flat against the drain rock, and it rocks around a bit.  Worse still, the polyurethane is quite springy, and was deflecting about a quarter inch under my body weight.  This made me realize that the combinations of shelves, drain rock, and insulation is very bad, because the insulation on drain rock might settle, which would cause the pool to hang from the shelves, which would cause the gunite shell to crack.  If I had it to do over again, I would eliminate the soil shelves, which are only there to reduce the cost of the gunite by $1500 or so.

Instead, I ripped up all the bottom insulation that the crews had installed and reinstalled it myself.  I had already compacted the soil, first with the Bobcat, then with my feet (the crew were actually laughing at me), then with a heavy roller.  Then I compacted the drain rock with the heavy roller.  Then I cut the insulation into 15" x 24" squares and hand placed each one, tweaking the rock placement and vibrating the panel so that the rocks settled into a configuration which was flat for each panel.  That took about four partial days, and only got finished because Martha got into the pit with me.  I read later that a skilled laborer with one assistant is expected to place 100 square feet of under-slab insulation per hour, so I was about two times slower than that.

I'm still paranoid about settling, so I'm going to have the south and west walls of the pool done with #5 40 ksi vertical rebar on 6 inch centers.  #5 is strong enough to actually support the entire pool weight (450,000 pounds filled) on the soil shelves, should the shelves not creep under that load.  I also put a 1 foot chamfer on the edge of the shelf under the cover vault.  The fillet of gunite that fills that chamfer, along with the rebar, will spread the torque from the pool wall hanging on that shelf.

[Update: I ended up with a mix of #3 40 ksi and #4 60 ksi rebar, with about half the strength necessary to hold up the whole pool. I figured I only had to hold up one end, and the rebar guy objected strongly to #5 -- he bent most of the rebar with his right knee!]

Another issue is the bond strength between the XPS insulation and the gunite.  I've since built the pump vault, which is insulated as well, and the XPS/concrete bond there is perhaps only 1 to 3 pounds per square inch shear strength.  If I assume 1 psi for the pool shell, then it will take about 140,000 pounds of shear, which is substantially less than the 450,000 pound filled weight of the pool.  This shear strength is comparable to the shear strength of the polyurethane bond to the soil.  This pool shell will be sitting on its bottom.  The polyurethane is substantially more springy than the polystyrene, and I think it will deflect the 0.3mm in shear that will happen when we fill the pool.

I did not predict the cost well.  I used 130 2 foot by 8 foot panels, with a small amount left over that I am using to insulate the pool piping.  These cost $2800.  I used 30 gallons of the X-30, which cost me about $1500.  It took me and a crew of three guys four days to glue on the side panels, and I think that labor cost me $2500.  The bottom I did myself, but the labor for that would probably have been another $1000 or so.

You can try to compare that cost to the cost of the panel array.  The problem with the comparison is that the panels deliver the most heat when its warm, when you don't need it.  The second problem is that the panel array is limited by the size of my roof, so I can't just spend an arbitrarily large sum on panels.

That said, standard FAFCO-type panels are something like $300 each, and produce 25,000 BTU/day.  To generate the same amount of heat saved, you'd need 18 panels, which would cost $5400.  However, the panels don't really work at all in November and April, when you need the heat most.  The panels I'm using are SunEarth EP40s, which are glazed and insulated copper panels, and cost around $1100 each.  These will deliver around 35,000 BTU/day, and will work in November and April.  But I'd need 13 to match the insulation's savings.  And that would cost $14,000!  So I'm pretty confident the insulation will be a win.

I'm not quite done with the insulation.  You can see a pile of pink insulation at the southeast corner of the pool.  This is standard XPS, and it will be going around all the pool piping.  I tried to find XPS pipe insulation, but the stuff is hideously expensive because it is all custom cut from large billets, usually for municipalities who are insulating their sewer pipes against frost.  So instead I'm gluing together a little box of 2" XPS around all my pipe runs.  Because the pool pump will be running 24 hours a day, the heat losses from the pipes can actually be comparable to the pool shell itself if not insulated.  If you are building a pool, you might want to consider insulating your pipe runs even if you don't insulate the shell, because insulated pipe runs don't suffer any of the structural and installation issues that come with the shell.

Side note: I had a hell of a time finding a Highload 40 distributor. I ended up calling Dow directly, who referred me to White Cap Insulation in San Francisco, who sold me the stuff for $21.58 per 2" x 2' x 8' sheet. Note that standard 20 psi extruded polystyrene has a dead load rating of over 6 psi, so it would have been technically okay for my 5.25 psi of dead load. If I wanted to save around $600, I would probably have gone for the thinner stuff. It would also be easier to buy. I'm hoping that the extra-sturdy foam is buying me a little margin, which is nice to have because I don't have examples of other pools that have been built this way.  [Update: somehow I miscalculated the amount of gunite in the pool, and it's a bit larger than my estimate here.  So, I'm glad I have lots of extra margin on the load carrying capacity of the insulation.]

Side note two: the space down at the bottom of the deep end experiences really wild temperature swings right now.  Because it is down low, it is radiatively coupled to the sky and not much else.  When the sun is shining down there, it can get well over 100 degrees.  As soon as the sun goes down, the temperature plummets, and because the pool is a depression, chilled air tends to stay down there.

Side note three: If you read this post and insulate your pool, or know of a pool that's been insulated, you might leave a comment so that there is some repository of success stories on the internet for this idea. And please please post if there has been a problem with an insulated pool.

Sunday, December 14, 2008

The World's Underwriter

This graph, from the New York Times, shows the extent of U.S. financial commitments made over the last year to deal with the credit crisis.

From December 2007 through September 2008, we committed $537 billion.  That is not money spent, but it is money put at risk by guaranteeing various financial instruments, and by loaning to banks that could not otherwise get loans.

But in September 2008 the Fed went nuts, nearly doubling the commitment to $1097 billion, or around $5500 per taxpayer.  (There are around 200M taxpayers, right?)

And then in October, the FDIC joined the Fed, and, according to the NYT, together they upped the commitment to $5069 billion.  I am not following the NYT very well here, however, since it appears that $1600 billion of this refers to the size of the commercial paper pool, and not the size of the projected government purchases within that pool.  So it's not like the government is actually selling $5 trillion of T bills.

It appears the Fed has become the world's underwriter.  The commercial paper thing appears pretty transparent, for instance.  The Fed sells T bills at 1% interest, and buys commercial paper at 5 to 10% interest.  So long as the default rate is lower than the spread, the Fed makes money.  Given the size of the money flow here, it is possible that the Fed could either make or lose amounts similar to the size of the national debt over the next couple of years.

Of course the problem is that someone at the Fed has to decide what rate they want for paper from which companies.  Since the decisions required are vast -- they have to price the entire commercial paper market -- one presumes the same people are doing this that just presided over the credit default swap implosion.  So, it seems like we might be more likely to headed for the "likely to double the national debt" outcome and less likely to end up at the "paid back the national debt" outcome.

This is Macroeconomics, for real.  Wow.  It really makes you wish there were a way to get off this train.

Friday, December 12, 2008


That white paper got me thinking: what if the government made a bunch of other sensible decisions?
  • They might shut down Yucca Mountain, and require that all nuclear waste be stored on the site of the reactor for 300 years. Nah, won't happen. [Update: They did it!]
  • They might just have NASA cancel Ares-I and Ares-V, and leave it to SpaceX to provide a launcher. This might actually happen. All those folks in Florida and Utah that used to work for NASA contractors? Learn to build windmills. Some of you can learn to build Dragons and Falcons. [Update: Holy crap! They did it!]
  • They might require all air conditioners and heat pumps to have short-term demand management controls. As the newer air conditioners got deployed, we'd have a lot less need for online throttled-down combustion gas turbines to back up all these new wind farms. I've not seen any rumblings of this yet.
  • They might even standardize form factors for rechargable batteries... [Update: Um, they sort of did it! (Europe hsa standardized cellphone recharging plugs)]

Going Nuclear

Stephen Chu, the current director of the Lawrence Berkeley National Lab, and the guy that Obama just fingered to be the new Secretary of Energy, signed this paper in August of this year.  The paper is a short, very high level, but clear and broad statement of why and how we should invest heavily in nuclear power.  Usually, statements like this come from people with no clout.

Holy crap.  This Barack Obama guy seems to be making at least some decisions I agree with.  I'm confused and unused to this feeling, but I think I like it.


Monday, December 01, 2008

Spend, spend, spending our way out of recession

We have a consensus among politicians in this country that we must spend our way out of this recession.  Of course, there are many things to spend money on:
  • For the last six years, the neocons within the Bush Administration have spent around 700 billion dollars of our money on wars, and committed another trillion or so to the aftermath of those wars (caring for the permanently maimed American soldiers).
  • This March, the idea that everyone jumped at was spending money on consumer goods, so every American got a check for $400 from the government, and was exhorted to spend it on consumables.  Pfft!  Just like that, $80 billion gone.
  • In just the last month, the Federal Reserve has spent hundreds of billions by buying stock in badly run banks whose value is justly plummeting as people realize how stupid their management was.
All of these have been colossal failures from an economic point of view.  And I do mean colossal.  The U.S. economy is about $13 trillion a year, and has a historic growth rate of about 3% per year.  It is the most awesome generator of wealth ever.  The economy usually generates about $400 billion a year in growth.  And our government is now throwing away money at a rate which entirely negates the economy's ability to grow at all.  The current trends guarantee that our children will be worse off than we are.  We are within a single order of magnitude of blowing away the entire output of the U.S. economy, which would reduce us to hunter-gatherers amid fancy energy-starved infrastructure within a year or two.  Lest you think that an order of magnitude increase in government spending is preposterous, consider that one department, the Fed, is now spending more than 1% of the U.S. GDP per month propping up just one industry.  The auto industry is lining up at the trough, and others aren't far behind.

Although the things the government spends money on now are crippling the economy, this is actually a good time for government spending to grow, so long as we spend money on the right things.  Private sector returns on investment are low, so the cost of borrowing has dropped, which means investments have longer to make a return.  This is a great time for the government to spend money on things that will cause the economy to grow in the long term:
  • Domestic power infrastructure, like wind farms and nuclear powerplants.  These will make the cost of future energy more predictable.  Predictability means less risk, so that the cost of capital for energy-intensive manufacturing, like fertilizers and aluminum and steel and plastic, will be lower in the U.S. than in other countries without the same infrastructure.  That will give our descendants decades of competitive advantage, which is enough time for not just businesses but industries to grow.
  • Health care efficiency.  I'm not suggesting we spend more on health care itself -- we're spending too much on health care.  I suspect that a huge amount of operational expense can be slashed from health care through radical restructuring without large amounts of investment.  The restructuring will be radical though.  Imagine the number of people put out of work if drug advertising stopped.
  • Electrified transportation.  Hydrocarbon-based transport will always rely on imported fuels subject to ever-more volatile price swings.  The value of real estate depends in part on the cost of transportation (if you drive 40 miles to work at 20 mpg and $4/gallon and 3% discount, that's $100k present value), and so volatility in energy prices causes volatility in housing prices which caps the house value that people can afford.  Worse still, we get situations like the current housing bubble, caused by just 2 million people simulaneously finding out they bought way too much house.  (That's just 1.7% of the 116 million homes in the U.S.!)
At least the president-elect seems to have the right idea.  I heard him refer to investment spending as a "two-fer".  I was disappointed at his notion that half the good idea of a "two-fer" is just spending the money at all.  But at least he's looking for the right kind of thing to spend on.