Let’s Blow this Joint

I have a confession to make. When we moved into our current house three years ago, we had to sell our clothes dryer due to gas/electric incompatibility (happens every time we move!). So we lived without a dryer for three years, hanging clothes out to dry, and generally being frugal about washing vs. re-wearing clothes. Well, after several weather-induced trips to the laundromat this winter, we (or can I lay this all at my wife’s feet?) finally broke down and bought a used washer/dryer set on Craigslist. We’ll still let the sun dry our clothes 95% of the time, but have other options now.

Even though this little vignette does relate to the common Do the Math theme of low-energy lifestyles, the actual point of bringing it up is that the washer/dryer came from a house that had just been on display as a model for energy efficiency—including the washer and dryer. At the house, we met Jason Beckman, of Classic Residential, Inc., who had carried out many of the efficiency upgrades to the house. I thought it would be instructive to have him perform an energy audit at our home—especially a blower door test to expose ventilation issues.

As a bonus, after the nominal audit activities were over, I was able to spend some quality time with the blower door, doing extensive tests in virtually every room in the house. What I found was certainly instructive for me, and hopefully will be useful to a broad audience as well.

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Death of a Battery

Four 150 A-h 12-V golf-cart batteries

Four golf-cart batteries used in my off-grid home PV system. Each is 12 V, 150 A-h, thus 1.8 kWh of storage.

All the metrics looked great. The 2.7-year-old lead acid batteries in my off-grid photovoltaic system appeared to have settled into a consistent mid-life performance. Monthly maintenance (equalizing, adding distilled water) promised to keep the batteries in prime condition for some time to come. Based on cycle depth, I expected another 2.5 years out of the present set of batteries. Life was good.

Then, during my absence over the course of Thanksgiving weekend, one of the batteries expired. No forewarning. Just gave up. A previous post expressed an overall disappointment in batteries, now reinforced by this sudden nosedive.

In this post, I’ll show the metrics on my system detailing the demise of “Battery E.” The gruesome graphics are intended for mature audiences.

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This Thermal House

If you want to make your house more efficient at repelling the unpleasantness outdoors (whether hot or cold), what should you do first? Insulate the walls? Insulate the ceiling? The roof? Better windows? Draft elimination? What has the biggest effect? While I have regrettably little practical experience tightening up a house (it’s on my bucket list), I at least do understand heat transfer from a physics/engineering perspective, and can walk through some insightful calculations. So let’s build a fantasy house and evaluate thermal tradeoffs at 1234 Theoretical Lane.

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