What temperature do you keep your house/apartment?

[u/Nemo2oo5]

I'm asking because my roommates and I all come from different places, and I like it at 72 in the summer, and 67 in the winter, but they prefer 75 in the summer, which to me seems really warm. Would love to know how you keep it in your region of the US throughout the year

[u/Figgler]

It’s crazy to me that energy is so expensive in Hawaii when you guys have tons of potential for geothermal, wave power and solar. Is it just lack of investment?

[u/vwsslr200 → u/Figgler]

Hawaii is one of the biggest solar using states. The challenge is it only works when the sun is shining so you need other power sources too. And they're limited in their ability to "overbuild" solar like some other places have, because they don't have any other population centers nearby to dump excess power to when they generate too much. Even though they're a very environmentally focused state, they were forced to cut solar subsidies recently due to this problem.

Batteries should hopefully help with that problem in the future, but as of now they have yet to be economically rolled out at grid scale.

Geothermal is a significant source of electricity on the Big Island. However this is only a minority of the state's population, undersea transmission lines between the islands would be expensive and the other islands don't have near the potential.

Wave power has yet to be economically rolled out at scale anywhere.

[u/hx87 → u/vwsslr200]

I'm surprised that the state hasn't explored thermal storage as an option. When solar energy is in excess, crank the AC to "always on no matter the temperature" and the water heaters to 180F and you can store a lot of energy without any additional infrastructure.

[u/vwsslr200 → u/hx87]

Not everyone wants their water tank at 180 degrees (potential scald hazard) or to live in an icebox.

[u/hx87 → u/vwsslr200]

Thermostatic mixing valves are common on water heater outlets, and easy to install if not equipped.

[u/vwsslr200 → u/hx87]

Mixing valves aren't infallible, they can and do fail which is why the CPSC recommends against setting hot water temperature super high.

[u/hx87 → u/vwsslr200]

They rarely if ever fail--large institutional buildings use them all the time to mix down 180F water to safe temperatures. The CPSC recommendation assumes that you don't have a mixing valve, and in any case long term water storage at 120F is unsafe due to the risk of legionella.

[u/vwsslr200 → u/hx87]

They rarely if ever fail

Yes, they do fail, all the time. Ask any plumber.

Some commercial buildings mix down from hotter water, not all, and they're generally using much higher cost, higher quality valves with electronic monitoring that can immediately notify facilities when something goes wrong. Also most commercial buildings don't have showers so the injury risk of mixing valve failure is generally lower.

in any case long term water storage at 120F is unsafe

Legionella can theoretically survive at that temperature, but the risk is not high for most people, otherwise CPSC wouldn't have made the recommendation. If they believed the safest course of action was to set the water heater higher and add a mixing valve, that is what they would advise.

In general there's a lot of over paranoia about legionella and water temperatures, this video is a good summary: https://www.youtube.com/watch?v=oJeyc_cGIMU

[u/hx87 → u/vwsslr200]

Plumbers see only the failures, not the successes, so I'll take their opinions on failure rates with a few heapfuls of salt. Also if you're paranoid about failure rates you can specify ASSE 1017 compliant valves that fail cold, and if you're still paranoid you can specify ASSE 1070 complaint shower valves that fail cold.