Alcun Atirutan BBS

It's stupid hot out today (pushing 100°F/~38°C) and my strategy of using the house and its contents as a thermal battery is being pushed to the limit.

But, it's still working! My air conditioner has been off for 8 hours and I'm still decently comfortable. 76°F is 24.4°C

Now, I live in a very new home built to recent codes. But I have very little shade, and in any case it shows what's possible!

Demand-side energy management has a ton of potential when combined with a little brainpower.

@TechConnectify Ugh. Not like that here. How exactly are you achieving that? I'm guessing also that your home is fairly modern, or at least modern enough to have up to date windows, etc.

@smallerdemon the air conditioner runs basically non-stop from 8:30 PM until I wake up.

I like to sleep in the cold, and we have a lot of nuclear baseload power here in Illinois. So power is cheap and clean in the overnight hours.

And yes, my home is new but not built far beyond code minimums as far as I can tell. Standard six-inch stud exterior walls and plain jane windows (though they have a Low-e coating, I think)

@TechConnectify are you "supercooling" bringing down the temperature as much as possible during cheap power times and then off during peak cost times?
We replaced our central AC with a variable speed heat pump last year and supercooling doesn't seem to work as well ($$$ wise) as just keeping the house a constant temperature with it. I think this is because of the way the heat pump tries to stay "on" as much as possible and adjusts the compressor "power" down as it gets closer and closer to the requested temperature.
Note: I do live in the desert and keeping a house 76F when it is 110F is a challenge in and of itself.

@asjimene yes that's exactly what I'm doing!

And you're right about newer equipment - often it runs more efficiently at lower outputs, so shifting demand around may actually take more energy (but of course if the cost difference is substantial that may not matter)

I've just got your bog standard 13 SEER one-way air conditioner, though. It's either running or it's not, so it doesn't have any efficiency tricks up its sleeve

@TechConnectify how cool did you get your house 8 hours ago?

@dbloom it was holding at 67 until I turned it off at 10:00. That was about as cold as it could possibly get with the temperature outside what it was - about a 20° split

@TechConnectify That's the perfect temperature! But the average American still wants the indoor temperature to be 68°F in summer and 82°F in winter.

@pepemapache keep in mind humidity, though. 76 with 70% RH (which it currently is inside) is quite a lot less pleasant than 80° at 25% RH

In the Midwest you basically cannot get below 50% RH in the summer, despite having air conditioning. Hell, even after the AC was running for 10 hours straight, it was still 55% indoors.

@TechConnectify True, here in northern California we're blessed

@pepemapache my Default Preferred Temps™ are 68° in the winter and 74° in the summer. However, I don't sleep well when it's above 70 so I run AC more at night.

Makes me the perfect candidate for moving most/all cooling demand to off-peak hours. 80% of the time it's exactly what I'd be doing anyway

@TechConnectify My family absolutely refuses to do this even though we live in a new home in a place with semi-regular rolling blackouts...

@TechConnectify Oh and they also hate the idea of power companies being able to delay AC/heat by a few minutes for grid management because "they'll never let you use it" even though that's something that's easy to prevent client side...

@gudenau cooperation is a slippery slope!

@TechConnectify I presume better than burning 4000+ kWh from the grid, like David a.k.a. 8-Bit Guy

@TechConnectify @smallerdemon Nice that you have 6" exterior walls. 4" is still the norm in Ohio.

@tnarg42 @smallerdemon what.

Y'all're basically in the same climate. I don't think I've ever been in a home around here with four inch walls.

@TechConnectify @smallerdemon Exactly. I don't get it. Wish I had 6" exterior walls.

@tnarg42 honestly, this is really surprising to me. My brother has a home in San Diego and when I visited him I couldn't put my finger on what was off about the house.

Then I realized it was the window sills that were weirdly shallow.

I completely thought that was exclusively a California thing

@TechConnectify the real question is, why is your phone not brown?

@TechConnectify When do you open the windows to let fresh air in?

(I spend the whole summer with windows opened)

@Arcaik this is not the kind of weather you open windows for.

But, I also have some forced ventilation providing air exchange 24/7

@TechConnectify Interesting, how many degrees does it increase by per hour?

I may have to try it the other way around and heat the place to 26 or so when there's plenty of solar and have it cool down in the evenings, although uninsulated brick veneer walls and aluminium frame single pane windows aren't great for heat retention.

@deanstyles if it's sunny, pretty close to 1°F per hour. Less if it's cloudy, of course.

It's also unsurprisingly warmer upstairs than downstairs, but I'll work from my laptop in the living room when it gets this hot rather than in the office/bedroom

@TechConnectify

I am curious if this strategy saves money?

I'm in a 70+ years old house but have a new 20 SEER heat pump for ~1450 sq ft with an ecobee maintaining 75F during the day.

ComEd lets me see my costs by day (and hour) and when I zero in on Aug 23 (Hi 99F/Lo 77F) it cost $3.42. This is not imo, excessive when my average daily cost is about $1.05 for electricity on a "normal" day.

@Totorose Well, it's hard to tell concretely.

I am definitely saving money monthly compared to their flat rates, about $15/month in the summer according to what ComEd tells me, however I am probably using the air conditioner more with this strategy than I would otherwise. Perhaps not much more, though, as I would want to drop the temperature significantly at night anyway. I can't stand sleeping in warm temps.

@Totorose This is even harder to figure out when you have a fancy heat pump.

Your system probably only attains 20 SEER when it's running at a modest load. At max output, efficiency drops. So as long as it can maintain your setpoint while staying within its efficiency sweet-spot, it will almost certainly use less energy keeping things consistent.

When energy costs don't vary over the course of the day, that's obviously the smarter move. When they do, the math is harder to figure out.

@Totorose Now I could do a test on two days with similar weather conditions. Let the AC maintain ~72 one day, then do my time-shifting the next. See what the difference in overall energy consumption was, then solve for whether my strategy is actually saving money. Then again, having an EV, I would want to be on the time-of-use plan anyway.

I suppose it's worth doing that test, but that might have to wait until next year.

@danbrotherston Oh, I try to do this when I can. But from June through August you're lucky if it gets down to 20°C at night 'round these parts.