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Hold on, let me translate my stupid freedom units into Science™. My exterior house walls are already ... 30cm thick? That's 15cm of insulation + structure, a th

Hold on, let me translate my stupid freedom units into Science™. My exterior house walls are already ... 30cm thick? That's 15cm of insulation + structure, a thermal gap, and then 10cm of stone facade. I only have to run the AC for a few hours at night, once the house warms up after a full day of sun. The only time of year I need "full AC" is during the high summer when the temps go above 40°C. What really kills me is that house is heated with propane, owned by a local monopoly, and the cost of propane has a 300% surcharge. The next time the HVAC packs up, I'm getting a heat pump, and adding solar panels (I only need a few); the savings in propane will pay for the HVAC/solar in a few years (in fucking TEXAS). The irony of this is not lost on me.

adrianN 1y ago
If you had a solar fence you could run the AC during max solar production for a couple of hours and not use it the rest of the day then. You might want to do the math on replacing the HVAC with a heat pump before it breaks, might be a good investment.
- thechao 1y ago
  There's an enormous premium on heat pumps in the U.S. So, there's a manufacturer of heat pumps here, in Austin; they sell a heat pump for 1600$ in Australia (installed); but the same unit is 9000$ (installed) in Austin. Part of the difference is labor (about 1000$); the rest ... I dunno? The difference in cost in electricity vs. propane runs about 1500$/yr. My current HVAC unit is good for another 5 years, or so. I'll just wait it out.
  - adrianN 1y ago
    1500 return on 9000 investment is 16%. Hard to beat that with other investments.
    - thechao 1y ago
      Understood, but the heat pump, itself, depreciates. They're good for about 10 years, out here, so you'd have to knock 900$/yr off the "investment". That takes it down to 6%, which is better than a high yield savings account, for sure. My suspicion is that the folk who make these heat pumps are well aware of the pricing structure in central Texas.

adrianN 1y ago

If you had a solar fence you could run the AC during max solar production for a couple of hours and not use it the rest of the day then. You might want to do the math on replacing the HVAC with a heat pump before it breaks, might be a good investment.

thechao 1y ago
There's an enormous premium on heat pumps in the U.S. So, there's a manufacturer of heat pumps here, in Austin; they sell a heat pump for 1600$ in Australia (installed); but the same unit is 9000$ (installed) in Austin. Part of the difference is labor (about 1000$); the rest ... I dunno? The difference in cost in electricity vs. propane runs about 1500$/yr. My current HVAC unit is good for another 5 years, or so. I'll just wait it out.
- adrianN 1y ago
  1500 return on 9000 investment is 16%. Hard to beat that with other investments.
  - thechao 1y ago
    Understood, but the heat pump, itself, depreciates. They're good for about 10 years, out here, so you'd have to knock 900$/yr off the "investment". That takes it down to 6%, which is better than a high yield savings account, for sure. My suspicion is that the folk who make these heat pumps are well aware of the pricing structure in central Texas.