I've only ever visited Phoenix but when I did it was mid July and being outside genuinely did not feel hospitable to human life. That statement doesn't surprise me at all. Unless you're employed in, I dunno, the solar power industry I really feel like you shouldn't be living there. It should be like living on an oil rig.
Do you think people shouldn't be living in Chicago (or most of Canada and the US midwest for that matter) because without heating it's just completely inhospitable to human life during the winter?
I haven't formed an opinion on the matter yet, but I do think there's a large difference between it being too cold and too hot.
If I'm too cold and my power goes out I have a lot of options to survive. I can put on more clothes, get under a blanket, light my furniture on fire, etc
If I'm too hot and my power goes out, I die. Once the wet bulb temperature gets above a certain level in shade, there's nothing that can be done to stop me from dying except Air Conditioning.
What? That doesn't make any sense at all. The whole point of wet bulb temperature is to adjust for humidity. Also only 33% of Phoenix homes have a pool. Using a pool as a solution to prevent people from dying is a "let them eat cake" idea
The wet bulb temperature of Phoenix still gets very high. Last July, there was an average wet bulb temperature of 73 degrees Fahrenheit. 95 degrees will kill a healthy human, it takes much less to kill a vulnerable person or someone performing manual labor. Climate change is only going to raise that number.
Like the other commenter who already corrected you, it makes perfect sense if you actually understand how wet bulb works, here’s a calculator for you: https://www.omnicalculator.com/physics/wet-bulb
Hint: Phoenix is at 17% humidity today, even their all time high of 122 doesn’t push the wet bulb temp out of the safe range.
I understand how wet bulb temperature works just fine. You didn't need to write a snarky response to engage in this discussion.
Now include climate change raising the temperature and changing the length and severity of monsoon season, continued development raising the heat island effect.
It doesn't matter what the average wet bulb temperature over the entire coty over a long period of time. It matters what the peak wet bulb temperature is for significant number of vulnerable people. The wet bulb temperature only has to get very high once to kill a large swath of people.
I understand just fine the wet bulb temperature has been within safe levels for the vast majority of people so far. My concern is about the future.
Relying on a coat for survival is very different from relying on an HVAC system. One has no moving parts, requires no external inputs, and is routinely handed out for free to those who can’t afford them.
Heating is considerably more energy efficient than having to run ACs all over the place. And if you need to go outside when it's cold you can: you add layers of clothing.
In Arizona, in the middle of summer, you could be buck naked and you'd still overheat (and get burnt, to boot).
Heating takes considerably more energy than cooling. Especially since most heating is done with natural gas, if homes were heated with a heat pump it would already 2-4x more efficient. Then if you look at the temperature delta between outside and room temp, the cold climates have a much larger difference. Taking 100 degree air down to 75 takes less energy than bring 20 degree air up to 65.
> Heating is considerably more energy efficient than having to run ACs all over the place.
That's actually incorrect. Heating takes considerably more energy.
When you're cooling you're looking at a temperature delta of at most 20 degrees C/45 degrees F between outside and inside. When you're heating, it can be easily be twice that. Or even more, in parts of Canada or the Great Lakes states.
Air conditioning is a heat pump and can achieve up to 300% efficiency. Whereas most houses in cold climates use furnaces, which have at most 98% efficiency.
Now that we have more efficient cold-climate heat pumps all of this may gradually change. But as of right now, what you're saying is wrong.
Heating under usual winter conditions would consume more energy than cooling under practical conditions. Yes.
But that's very different than claiming than cooling is more efficient than heating. In A/Cs the ratio of energy (in the form of heat) removed to energy consumed is very low, around 10-15%.
In furnaces the ratio of energy added to energy consumed is around 90%, which was pretty good until the emergence of heat pumps. There almost all the energy consumed is added to the output in addition to all the energy removed from the other side. That's why the efficiency in heat pumps is beyond 200%.
In summary, no. Cooling is not more efficient than heating. But given the temperature differential when cooling the energy consumption is usually higher.
> Air conditioning is a heat pump and can achieve up to 300% efficiency. Whereas most houses in cold climates use furnaces, which have at most 98% efficiency.
No. You can't directly compare "efficiency" numbers across different energy sources. My understanding is that the efficiency of gas powered electricity generation is around 33%, meaning that powering a heat pump with a COP of just under 3 will be of similar end-to-end efficiency as burning the gas directly in a condensing boiler/furnace.
Sure, but that doesn't mean you can throw your hands up and make an argument comparing nameplate efficiencies of things with different energy sources.
I'm well aware the figure in my above comment could be off by a decent amount due to transmission efficiency, what specific plants are generating marginal power, etc. But it's at least framing the comparison right.
Even in your worst case scenario, heat pumps are about as efficient end-to-end as a natural gas furnace. And renewable power is only going to become more common over time so it could get better.
To a consumer, comparing nameplate efficiencies as you say makes the most sense. I can easily find out how much a joule of electricity and a joule of natural gas cost me. Then multiply those with efficiency to see which is cheaper.
I did not put forth a worst case scenario. I put forth an example of doing proper comparison.
Based on a figure I just saw from someone else describing their setup (1.75 COP at 5 deg F), and taking into account transmission losses etc, the worst case would seem to be significantly less efficient than burning natural gas directly in a condensing furnace.
This isn't meant as some sort of knock against heat pumps! In fact I'm tentatively planning to add a heat pump to my own home within the next several years. Focusing on a worst case is still not an overall comparison of performance, but rather just one data point in the evaluation of a given design.
Multiplying the cost of the energy source by the nameplate efficiency is indeed another sensible way of comparing across technologies. But that isn't what you did in your original comment, where you juxtaposed two different types of efficiency numbers. That was my only point in my original comment.
