3 ms·

Digging into the article, it's a hypothetical home and they are only testing fully off versus ideal temperature blasting. I don't think it's always true, which

Digging into the article, it's a hypothetical home and they are only testing fully off versus ideal temperature blasting. I don't think it's always true, which is why I listed the factors that can influence it. But I am also getting into home automation and just watched a video where some one ran through the numbers on their specific house after getting electricity monitoring connected to their heating and Home Assistant. It's not that clear cut and really depends on your specific home. https://youtube.com/watch?v=Dn8NRC1XrrA https://youtube.com/watch?v=Dn8NRC1XrrA

tadfisher 3y ago
I don't see how this could be possible, because it should always cost more energy to maintain a higher temperature gradient, assuming a non-zero R-value. If there are other factors you're optimizing for, such as energy cost rather than overall usage, then I could see how avoiding peak pricing could net savings in cost, but the laws of thermodynamics are pretty absolute if you're optimizing for energy consumption.
- regularfry 3y ago
  You're assuming that the system is the same in both cases. It's not. 1. You run the A/C all day: the gas stays both cold, and dry. Cold, dry air is, it turns out, ok as an insulator. Not very good thermal conductivity at all. 2. You turn the A/C on at the end of the day in a warm, humid environment. The air is moist, which causes two compounding problems: first, the volume of air you need to cool just holds more energy than it would if it was dry. But second, because moist air is more thermally conductive, it's better at coupling heat in from the outside, so more energy is coming into the system as you're trying to cool it. At least, that's the argument. I haven't run the numbers to check orders of magnitude or anything. I wasn't expecting the difference in thermal properties of dry and moist air to be that significant, but there are some very interesting numbers at https://www.engineeringtoolbox.com/moist-air-properties-d_1256.html https://www.engineeringtoolbox.com/moist-air-properties-d_12....

tadfisher 3y ago

I don't see how this could be possible, because it should always cost more energy to maintain a higher temperature gradient, assuming a non-zero R-value. If there are other factors you're optimizing for, such as energy cost rather than overall usage, then I could see how avoiding peak pricing could net savings in cost, but the laws of thermodynamics are pretty absolute if you're optimizing for energy consumption.

regularfry 3y ago
You're assuming that the system is the same in both cases. It's not. 1. You run the A/C all day: the gas stays both cold, and dry. Cold, dry air is, it turns out, ok as an insulator. Not very good thermal conductivity at all. 2. You turn the A/C on at the end of the day in a warm, humid environment. The air is moist, which causes two compounding problems: first, the volume of air you need to cool just holds more energy than it would if it was dry. But second, because moist air is more thermally conductive, it's better at coupling heat in from the outside, so more energy is coming into the system as you're trying to cool it. At least, that's the argument. I haven't run the numbers to check orders of magnitude or anything. I wasn't expecting the difference in thermal properties of dry and moist air to be that significant, but there are some very interesting numbers at https://www.engineeringtoolbox.com/moist-air-properties-d_1256.html https://www.engineeringtoolbox.com/moist-air-properties-d_12....