I echo that AC is quite efficient. Far more efficient than traditional heating. There's a misconception that hot areas are less environmentally friendly due to AC. The opposite is true.
Hot areas are only 25 freedom units hotter than humans prefer. Cold areas have months of 50+ temperature difference.
The misconception persists because heat uses gas, which is 5-10X less expensive per BTU of energy than electricity. So it might be cheaper to heat cold areas than run AC in hot ones, but its much more damaging to the environment. Plus, hot climates are using a lot of renewables these days which impacts the environmental friendliness of electric but not gas.
I expect migration to the sun belt to accelerate, at least in the US. It makes a lot of sense from environmental perspectives. In some southern cities there's already long stretches every summer where daytime AC use runs on 70%+ renewable energy.
So some parts of construction techniques and building materials have improved significantly. However, when comparing the framing lumber used today to what was used in the 60s, I'm shocked that new construction doesn't fall over the first time the wolf huffs and puffs.
The purpose is to prevent buildup of harmful gasses and VOCs (everything from CO2 to CO to regular out-gassing of furnitures, etc) that can become dangerous if not cycled regularly.
2120: The environment is all full of poisonous gasses from the people of 2020. Each house needs its own air purifier to make the outdoor air safe to breathe.
> the first Cordis hotel on mainland China boasts something that is genuinely rare in big Chinese cities: clean indoor air.
https://www.theguardian.com/cities/2018/mar/27/china-clean-a...
That's the case in much of the world already... I live in area where there's tons of smog in the colder months and consider installing a system for bringing in filtered air from the outside, so that I won't have to open windows for the 6+ months smog period.
One reason is efficiency. In the Bay Area, it's common when the daytime high temperature is 80–90˚F for the nighttime low to be 50–60˚F. You can set your thermostat to 76˚F until sunset, then bring in outside air to cool down to 68˚F or below by sunrise. You get cool air when you're trying to sleep and avoid running the AC in the night or morning.
I'm getting my furnace & AC replaced today and was sad to learn I couldn't get one of these. The fresh air intake has to be at least 10' from the furnace flue vent, and that isn't practical with my home's design.
But there is also typically fresh air requirements to bring in some percentage of fresh air.
And lastly the HRV/ERV mentioned in the other comment is typically more a residential thing from what I've seen but that's totally a thing I want in my next house.
I was describing my home renovation project to someone who lives in Brazil. I don't how true this is for that entire country, but she said that it's very uncommon for Brazilian homes to have insulation.
I live in a modern house in Northern Europe, and we don't even turn our heating on until it gets below freezing. Because we have good insulation, only then it starts to drop below 22C (72F) inside.
...sigh. I really hope it doesn't go this way.
Hot days are getting hotter and much more frequent. Snow is getting rare. We had a yearly ice skating event that never happens anymore because there is no ice.
Weeks of 30C weather are getting more common while not long ago, hotter than 25C was considered exceptional.
It’s like daily temperatures are just shifted +5 degrees within 2 decades.
It’s not just my gut feeling, there are plenty of statistics
The whole comment is hyperbole.
- predicting what council rates (US has Land tax I think?!?) might turn into when the town realises it will be half underwater...
They can be, and there's lots of modern construction techniques that are really good (search term "building science").
One big problem is that a lot of stuff is still built to "minimum code" which just isn't that great. On top of that, sloppy construction work can significantly undermine what is done. In my own house I've fixed several simple things, like missing insulation around vents and holes cut too big (or created by a hammer, rather than cutting).
Here's a good walkthrough of a house under construction showing lots of problems typical to any subdivision (non-custom) build: https://youtu.be/OmU2N_Q732A
1,000 cubic feet of natural gas is a bit over 1 million BTU. That converts to 297 kwh of electricity.
that 1,015,000 btu costs:
$38.61 in electric
$11.85 in natural gas
(Of course if you start with a fossil fuel, turn it into electricity, and then pipe that into an AC unit, the overall efficiency will be dropped by the efficiency of the power plant, but it's still somewhat made up for by the advantages of heat pumps)
> From 1990 to 2013, U.S. shipment-weighted efficiency for residential split-system A/Cs increased from 9.5 SEER (~2.2 COP) to 14.9 SEER (~3.8 COP).
https://www.energy.gov/sites/prod/files/2016/07/f33/The%20Fu...
Yes, the hot side will spit out all of the heat extracted from inside, plus the energy from the compressor operation, so indeed energy is conserved.
In the case of the house I'm currently at, it is pretty good at retaining heat in "winter" (in quotes, because it's Bay Area winter). However, in the summer it will be quite warm late at night. So sometimes I want it the other way around, I want it to radiate excess heat away as fast as possible, but I can't control that. We should be able to deploy "heatsinks" at night.
That's for a house. Modern office buildings are built like greenhouses, even when they are otherwise insulated.
We can't really roll out solar panels fast enough. They would help offsetting the cooling energy costs by a lot. After all, it's during warm sunny days where the air-conditioning needs are the greatest. They also provide shade.
Technology Connections has a good video about this: https://youtu.be/_-mBeYC2KGc?t=355
If we go by the DOE SACC ratings, this single-hose toshiba [0] has a 14% higher SACC rating than this dual hose whynter [1], for the same BTU/hr rating. If we go by the wattage ratings (note: these are usually peak rather than average), the toshiba does use 13% more power than the whynter, so let's assume it cancels out and they both have the same energy efficiency. The toshiba is still $144 cheaper than the whynter. That's hard to justify for "dual hoses seem like they should be more efficient" without any actual evidence.
Please prove me wrong, before it's too late for me to return the single-hose one.
[0] https://www.toshiba-lifestyle.com/us/Room-Air-Conditioners/P...
[1] https://www.whynter.com/product/whynter-elite-12000-btu-dual...
That air has to come from somewhere, so it's going to pull warm air from everywhere it can, door, windows, any creaks/holes/openings, etc. And the fans have some serious airflow/CFM.
Dual hose designs pull air from outside and expel it back outside.
So technically it should be capable of getting your room colder and keeping it that way with less compressor usage.
The cold part of the A/C just circulates air around the room on any model.
Looking at my model, I could turn it into a dual hose design - it pulls air from the rear, right below the exhaust vent. That seems to be the case for a lot of these. Creating an attachment/adapter to connect another hose seems easy enough.
I went years without any AC and my bedroom wall faces south. My room would get so hot in the summer I couldn't get any sleep. Tried an evaporative cooling unit because they're cheap which did absolutely nothing for me. Eventually broke down and got a portable AC which unfortunately was a single hose unit. You really need to look carefully at what you're buying because the whole single/dual tube thing doesn't seem to be something the sellers put out there. Even though it it was a single it still made a world of difference. On really hot days it doesn't get super cold but cool enough that I don't notice the heat.
The dual hose unit will likely outperform significantly if the temperature delta is high, but if the temp delta is low then the single-hose unit is probably better as it likely has a more efficient compressor.
It looks like DOE SACC tests assume the outdoor air temp is 83 degrees for 80% of your usage and 95 degrees for 20% of your usage.
In case anyone is interested, I did not end up returning my single-hose unit, but I did end up buying a dual-hose Whynter ARC-122DHP [0] for another room. It came with a yellow energy guide card listing a cooling capacity of 12000 BTUs and an EER of 11.1, which indicates an average power draw of just 1081 watts (EER=BTU/watt). Unfortunately no SACC or CEER rating was listed. Actually measuring power shows that it draws the full 1200 watts on startup, quickly drops to around 1100 watts, and then slowly drops to 900 watts as the room temperature falls. For comparison, my 8000 BTU (unknown EER, 6000 SACC, 6.5 CEER) single-hose Toshiba RAC-PD0812CRRU [1] also draws 1200 watts on startup, quickly drops to around 900 watts, and then slowly drops to 800 watts as the room temperature falls. So it seems like the dual-hose is around 20-30% more efficient (in a different room under arbitrary conditions) based off the BTU rating, but no better based off the SACC rating. I also noticed that it did not come with foam seals for the window bar like the single-hose unit did, so there is probably room for some efficiency gain there.
[0] https://www.whynter.com/product/whynter-elite-12000-btu-dual...
[1] https://www.toshiba-lifestyle.com/us/Room-Air-Conditioners/P...
Their efficiency is based on thermodynamics, so there's not much you can do to break the physical barriers.
Air conditioners are actually pretty fantastically efficient for what they do. The problem with air conditioners is that there's no way to move a ton of heat without using a lot of energy. So, they do use a lot, but they make the most of it.
What's truly bad are our buildings that have the minimal insulation and sealing possible, leaking all that cold air right back out into the environment.