Change your perception of, and attitude toward, discomfort

The prospect of staying longer in the house of Jack and Dah, on the occasion of their travels in the country, seemed agreeable to a degree that was even enhanced as the dew point declined during this week, and I found myself spending less time in the pub and looking forward, as a man might in the morning shower look forward to an anticipated departure or an encounter with a certain lady that promised to end in a pleasant conclusion, to my evening cigar and a cold bottle of Singh, and a profitable review of the basic equations of gaseous heat transimission. And yet, as the week went on, I found myself to an increasing degree drawn to reading Swann's Way, from which I began to learn slowly a new manner of perceiving everyday events, as in reading the passage in which Proust's father, remarks to his son's visiting friend, who is visibly wet on the occasion of his visit to the house at Combray: "Why, Mr. Bloch, is there a change in the weather? Has it been raining?" Which drew from Bloch nothing more instructive than: "Sir, I am absolutely incapable of telling you whether it has rained. I live so resolutely apart from physical contingencies that my senses no longer trouble to inform me of them." This bringing to mind the teachings of the eminent Thai monk Buddhasa Bhikkhu who told of his many solitary months living in the forest near the current monastery of Suan Mokh, in the province of Surat Thani, and his conquest of mosquito bites in the evening by strict adherence to the precepts of the Dhamma. "Not using mosquito nets...was very beneficial. It helped us xpand our thinking, to feel unburdened, to wake up better, and to consider sleep as a temporary rest rather than a pursuit of or indulgence in comfort. It also helped us practice wakefulness to the best."

Cool night sky

I got a giant case of ptomaine from eating a giant hot dog at the Robin Hood and while bedridden began to read a copy of Proust that I found at Jack's place, he and Dah were upcountry. A few days in the world of Combray put me in a contrarian frame of mind and I began to imagine that much of what I believed about roof insulation could be wrong, that rusty tin roofs might be the best of all. Thai country folk lived under them. They just stayed under the house, not in the house, in the daytime when the uninsulated roof created oven-like heat in the room. But at night maybe the outward radiation would cool the simple metal roof below air temperature.

An email from technology innovator Steve Baer reminded me of work by the solar master Harold Hay who invented and promoted a roof pond concept in California that relied on night radiative cooling to store "coolness" for the day use.

I built a "upcountry" room with a metal roof and zero ventilation and let it sit on my roof for a couple of days. Of course not a real room, but one of about a cubic foot size with a sheet of mat black aluminum foil for a roof and the room itself a foam picnic box that I bought for a buck at the Chinese shop down the street. Into which I put a brick for thermal mass and a hobo to measure temp and dew point.

You can see the temp history of the country room in red and the temps of Jack's bedroom and the outside temp (last two almost the same) over several days. The country room is impossible in the daytime but gets really cool at night. At least toward the end of the test period when the dew point got fairly low and the night sky temp fell to as low as -5 degrees C. So you might be very happy with a simple tin roof at night -- though not at day. And, this being a dryish night, note that the suppresssed temp is still way above the dew point, so there will be no problematical condensation. The question being, how about during the hot season, when the dew points are a lot higher, maybe 18 C instead of 10 C? Would you get any radiative night cooling then? If so, would water start to drip from the ceiling?

By the way, I say test boxes--there were two of them. One had foil with shiny side down (the blue line) the other had the bottom surface of the foil spray painted mat black (red line). The shiny foil reduces the peak heat of the day but also slightly reduces the cooling effect of night radiation.

In the cool of the pub

Sometimes the only place that seemd tolerable was a pub, so I spent time working in those fine places sipping Heinekens and sketching out my ideas on paper napkins. Sometimes I'd lose interest in thermodynamics -- I did poorly in it at college --and then I'd draw little pictures of the action around me, older guys like myself thinking and drinking or watching TV with their bored girlfriends picking at the fahlang food or patiently waiting, like rice farmers waiting for the rains.
















I noticed that many of these girls had remarkably large hands.

A one-watt air conditioner

Air conditioning for your pet mouse

Jack and Dah have a goal: no house air conditioning.

Air conditioning is notoriusly inefficient in Thailand, with typical split room-size air conditioners churning out 12000 BTU per hour (3000 watts) of cooling per room, mainly energy spent on cooling sun-heated walls and vaporizing moisture that freely enters the room from outside sources, all at a cost equal to 35 percent of a Thai college graduate's salary. Tankers of oil steam into the Gulf to meet this wasteful demand.

And of course with the light, leaky construction of a traditional Thai house an off-the-shelf machine would be even more inefficient.

So...while hanging around the pub one day I set out to reinvent the air conditioner.

Let's start not with a 3000 watt machine, or even a (say) 300 watt machine that would be arguably sufficient to cool Jack and Dah when they are sleeping. Let's start with the bench machine above, which I built for a couple of hundred baht, a one-watt air conditioner, which meets the following specifications:

cooling capacity (mostly latent): 1 watt
condensate, cc/hr: 1
unconditioned air water vapor entering machine: 20 g/cubic meter
conditioned air water vapor exiting machine: 8 g/cubic meter

Operation of this machine requires about 3600 joules of energy per hour, which can be easily provided by only about 10 grams of ice.

The question: can we effectively scale up, say by a factor of about 300? This would require about 3 kg of ice per hour--seems doable.