Passive air flow in passenger compartment

[drfoto]

The i3 feels like a tomb even at expressway speeds where positive pressure should be allowing significant outside air to come in through the vents. It's absurd that in a car where efficient utilization of electrical power is paramount that you have to run the fan on a relatively high speed just to circulate air. Ridiculous design fail.

 

[ASUN]

I do find this problem too. It does get stuffy with only two bars from the fan. Three will make it sound noisy, but it's what needed.

I notice the same thing from other German cars I drove. Perhaps this is a German car common issue, since the cars are all sealed tightly? I guess it's a good and bad thing.

 

[jadnashuanh]

I wonder if it is the fact that there is a fairly efficient small particulate filter in-line that requires the fan to move some air. It is designed to filter out soot, dust, pollen particles, so has to be relatively dense. The location of the air intake is often positioned so that the speed of the vehicle doesn't change the air volume coming in, otherwise, what might be fine for around town, would be a hurricane on the high speed road. This also helps with the drag factor, otherwise, it would disrupt the air flow over the vehicle.

 

[i3atl]

As stated in the other thread you started, this isn't a "design fail" - it's a design choice they made that you disagree with. If outside air was always allowed in, then in colder temps the car's range would be affected due to the need to use the heater to offset the cold air entering the cabin. Use of the heater consumes significantly more energy than running the fan alone.

 

[alohart]

If outside air was always allowed in, then in colder temps the car's range would be affected due to the need to use the heater to offset the cold air entering the cabin./quote]
Outside air needn't always be allowed in. The owner's manual states that the automatic or manual recirculated air control has a third mode indicated by the 'A' and 'M' LED's being off which allows outside air to flow in continuously. If one doesn't want cold outside air to flow in, set this control to manual. However, I think this control is active only when the fan is on. It could have been designed to always be active which would have satisfied those of us who want fresh air flow without the fan being on.

As it stands, I frequently open the driver's window to allow outside air in. That works fairly well except in rainy weather. Our Honda Insight has the option of flow-through ventilation without the fan being on, but the cabin air outlet is so small that not much air will flow through unless a window is opened slightly to exhaust some air. So in practice, this isn't much better than opening a window in our i3 to get some fresh air.

 

[jadnashuanh]

FWIW, per the user's manual, the car will not stay in recirculate mode forever to allow fresh air to come in and exhaust stale, humid air from breathing or evaporation from an enclosed space. Even in the Eco modes, if the car detects the windows fogging up, it will turn on the heat and maybe the a/c to help dry the air out.

There are few (if any) details in the car that were not reviewed, and a decision made to execute them the way they did. The Germans are very detail oriented, and rarely make a decision for an arbitrary reason. You may not agree with them, or understand why, but it is not arbitrary.

 

[ASUN]

The owner's manual states that the automatic or manual recirculated air control has a third mode indicated by the 'A' and 'M' LED's being off which allows outside air to flow in continuously.

I just found out yesterday too through trial and error.

I usually just keep it at A anyways, but will give the no light option a try to see if it will help with drawing fresh air in. I do find the car a bit stuffy if I don't turn the fan on to the third light. The fan is quite loud at the third light imo.

FWIW, per the user's manual, the car will not stay in recirculate mode forever to allow fresh air to come in and exhaust stale, humid air from breathing or evaporation from an enclosed space.

I did notice this too. I swtiched to M, but notice it switched back to A after a short while.