AC Upgrade Part 1 Results – 24 % Better!

Wow! It looks like adding a second hose to my AC unit reduced my power usage by 24%!

Here’s how I did the experiment:

First, I picked two days in a row that were going to be very close to each other weather-wise. In Texas summers, that’s pretty easy.

Monotonous Texas summer weather is great for AC A-B testing!In this case I chose Saturday, with a high of 97 o F and a low of 76 o F, and Sunday, with a high of 94 o F and a low of 77 o F. These two days aren’t identical, but I’m mainly looking for solid proof adding the second hose changed things. Naturally if I were being real stickler, I would want to run each configuration for at least three days, average the results, etc, etc. However, that would mean both having to *live* in the yurt at 83 o F for at least another week, having that many days in a row that were pretty close, delaying additional upgrades for the sake of data integrity, etc. If I can show a significant difference in testing each for one day, I’m willing to call it done.

Next I set up the AC with both hoses and set the thermostat to 83 o F. Why that temperature? Because I need something that the AC can actually *achieve* without running the compressor 24/7. I’m *not* recording the actual temperatures in the yurt while I’m doing this, so I need to pick a setting where I will *know* the temperature because the AC is able to reach it. I want the compressor to come on and off to maintain that temperature. Then the *only* thing I need to measure to do the comparison is how many electrons were eaten by the AC unit.
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I started with the two-hose configuration because it was already set up, and because I would be home most of the day and two hoses is *way* more comfortable! I started the AC at 7 AM Saturday morning, reset my Kill-A-Watt power meter, and let it run. I ended up at a fabulous party that was hard to leave and didn’t get home until 2 AM. While I was at the party, I *knew* that every minute I stayed was another minute I was committing to be up on Sunday night. Actually, the Kill-A-Watt meter *does* have a timer, so if I just want to have the unit turn off automatically at a certain time, I think I could do that. But the risk of screwing up the measurement was too high, and I only needed one more day.

Here are the results for Saturday:
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So I used a total of 9.34 KWHs keeping the yurt at 83 o F on a 97 o F day.

I was going to be gone most of the day Sunday, so that was a great day to go back to *one* hose, which makes the yurt feel depressurized and uncomfortable. I woke blearily at 7 AM after not going to bed until 3:30 AM, grabbed the second AC hose, which is right next to the bed, and started pulling and tugging until I got all 9 feet coiled on the floor. Luckily there were no wasps this time. At that level of hangover, I would *not* have been willing to get out of bed simply because it was full of angry wasps, and the resulting contest for territory would likely have gotten ugly. I mumbled a prayer to Past Angry Scott for taking the time to annihilate Inconvenient Nature the night before. The second hose I added was now inside, which is what I started with. I reset the Kill-A-Watt, then collapsed back into bed and tried to sleep as the pressure in the yurt dropped and the temperature rose. Sometimes you have to suffer for science!

After getting back from an exhausting day of eating beignets at The G’ral Majal and swimming with hot naked people at Hippie Hollow, I barely managed to keep myself awake long enough to get my second reading, seen here:

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What a change! A total of 11.91 KWH on a day that the forecast said was 3 o F *cooler* than the day before! Plugging those numbers into the Percent Difference calculation, we see that adding the second hose provides at *least* a 24% improvement.

So adding the hose has drastically reduced my power usage in addition to equalizing the pressure in the yurt!

From a strict science perspective, there are a lot of things wrong with this methodology. I would be a lot more valid if I kept track of real-time temperatures and humidities inside and outside the yurt, etc. But, I’m happy with the improvement it demonstrates and am ready to move onto the next step.

The two remaining major upgrades are plugging the roof ring, which is currently still partially open, and adding the Relectix radiant barrier bubble wrap. At each phase I’ll try a similar test and see how much they help. What I’d eventually like to get is a measurement of how much power I’m using for climate control inside the yurt. From an absolute perspective, I want the bragging rights of knowing how much less power I’m using than an average American. From a relative perspective, I want to see how much it’s costing me on a cubic-foot basis for similar comparisons to, say, an average suburban home.

These kinds of discoveries are a big part of what makes this experimental lifestyle worthwhile!

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