xpitxbullx
Member
In Las Vegas, it would be insane to test this theory in the summer. I’ll sit back and see how the northern states chime in.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Windows Down? or Air Conditioner? Whats more efficient?
- Thread starter Garlan Garner
- Start date
The video that I have posted have been realized with outside temperature near 100F. AC was set at 70F.
That's because there's offset: higher temperatures decrease air temperature and reduce rolling resistance through increased tire pressures.
Why bother caring about energy use. It's not like our energy use makes people sick, or kills people or anything. And it's not like BEV have any refueling limitations that impact journey capability and duration.
But, whether we care of not, some of us prefer outside air to AC, and live in places where the air is OK, and the temperature is amenable to opening the windows half the time. Added to the refueling limitations, it'd be nice if there were real data for the Model 3.
And of course, the OP's poll is pretty useless, since the answer will be "Depends on speed".pointless
Indeed: I have a cousin that can't stop coughing when AC depletes the air of humidity as it naturally does.
There are so many variables at play on my regular commute, but I typically see about 15-20 wH/MI improvement without AC running. This would be windows open on city roads, and just the fan running while on the highway.
All the windows down. Follow this guy to work all the time
Feels like the eye of a hurricane. Everything just stands still.
Feels like the eye of a hurricane. Everything just stands still.
Nice. Very nice post. Thanks for the information.All the windows down. Follow this guy to work all the time
View attachment 317674
I have real world data for Model 3. New England here. In the vast majority of situations, windows down is way more efficient, even on the highways. I've actually tested this extensively in various speeds and weather, using the car's efficiency reading as my guide. The following is just for my commute (I've tested on various other recurring trips as well).
Baseline measurement: daily commute is 80mi round trip. First let's look at temperature effects only (HVAC off, windows rolled up). Ideal efficiency happens when temps are between 70-80F. Here, I get around 165Wh/mi for the round trip. The reason for this insanely good efficiency is due to intermittent traffic that keeps my average speed down. If the same commute was performed with no traffic, efficiency would be around 190Wh/mi @ around 70mph. At around 50F, efficiency drops to around 180-190Wh/mi. And at 90F and above, efficiency drops to around 205Wh/mi (I suspect because the A/C compressor kicks on to cool the battery).
Now, with the A/C running for cabin conditioning, and ideal temp range (70-80F), that same round trip jumps to 210Wh/mi. Without A/C is 165Wh/mi. That's a huge penalty. What's worse, the firmware doesn't seem to be smart enough to shut off the A/C if outside temps are already below the set point. In other words, if you set cabin temp to 72, and it's 70 outside, and you put the HVAC settings on Auto, it will still run the A/C, presumably for dehumidifying purposes. In these scenarios, I always set to manual and shut off A/C compressor and just let outside ambient air keep the cabin cool. Running just the HVAC fan uses negligible energy. not enough to show up in measurements.
I've also kept windows down for this same commute, no HVAC, and I average around 170Wh/mi. I have yet to measure the effect of going 70mph the whole way with the windows down. I suspect that will have worse efficiency. But at that speed, I'd likely just crack the window, which would drastically reduce drag. Windows all the way down at highway speeds is not comfortable, and it's really noisy.
Test for yourselves. If you can bear it, given it's the dead of summer and it's hot, turn off the HVAC for any of your drives. You should see a pretty huge increase in efficiency. I haven't found a situation where windows down can cause an equivalent drop in efficiency.
Also FWIW, I grew up in the suburbs of Atlanta GA, so I consider myself very heat tolerant. I also grew up riding in econoboxes with no A/C, so it doesn't faze me at all to test out no A/C in 90+ weather. Kinda nostalgic, actually. Now if only the Model 3 had a choke.
Baseline measurement: daily commute is 80mi round trip. First let's look at temperature effects only (HVAC off, windows rolled up). Ideal efficiency happens when temps are between 70-80F. Here, I get around 165Wh/mi for the round trip. The reason for this insanely good efficiency is due to intermittent traffic that keeps my average speed down. If the same commute was performed with no traffic, efficiency would be around 190Wh/mi @ around 70mph. At around 50F, efficiency drops to around 180-190Wh/mi. And at 90F and above, efficiency drops to around 205Wh/mi (I suspect because the A/C compressor kicks on to cool the battery).
Now, with the A/C running for cabin conditioning, and ideal temp range (70-80F), that same round trip jumps to 210Wh/mi. Without A/C is 165Wh/mi. That's a huge penalty. What's worse, the firmware doesn't seem to be smart enough to shut off the A/C if outside temps are already below the set point. In other words, if you set cabin temp to 72, and it's 70 outside, and you put the HVAC settings on Auto, it will still run the A/C, presumably for dehumidifying purposes. In these scenarios, I always set to manual and shut off A/C compressor and just let outside ambient air keep the cabin cool. Running just the HVAC fan uses negligible energy. not enough to show up in measurements.
I've also kept windows down for this same commute, no HVAC, and I average around 170Wh/mi. I have yet to measure the effect of going 70mph the whole way with the windows down. I suspect that will have worse efficiency. But at that speed, I'd likely just crack the window, which would drastically reduce drag. Windows all the way down at highway speeds is not comfortable, and it's really noisy.
Test for yourselves. If you can bear it, given it's the dead of summer and it's hot, turn off the HVAC for any of your drives. You should see a pretty huge increase in efficiency. I haven't found a situation where windows down can cause an equivalent drop in efficiency.
Also FWIW, I grew up in the suburbs of Atlanta GA, so I consider myself very heat tolerant. I also grew up riding in econoboxes with no A/C, so it doesn't faze me at all to test out no A/C in 90+ weather. Kinda nostalgic, actually. Now if only the Model 3 had a choke.
I'm going to have to wait for it to cool down before doing real "no AC" testing.
Driving to work this morning at 6:15AM and it was already 85F
Slightly OT, but....one thing I've really noticed while trying the window up/down thing is the effectiveness of the cabin air filters.
Following a stinking, clattering diesel truck for a while and couldn't smell it at all inside the cabin.
I wound the window down and was hit by the wall of toxic stench from outside
Driving to work this morning at 6:15AM and it was already 85F
Slightly OT, but....one thing I've really noticed while trying the window up/down thing is the effectiveness of the cabin air filters.
Following a stinking, clattering diesel truck for a while and couldn't smell it at all inside the cabin.
I wound the window down and was hit by the wall of toxic stench from outside
Similar threads
