5 ms·

But having the whole cabin be at a cooler temperature allows the heat transfer to happen uniformly across your whole body, which is a lot more comfortable than

But having the whole cabin be at a cooler temperature allows the heat transfer to happen uniformly across your whole body, which is a lot more comfortable than having a vent pointed at yourself.

datameta 5y ago
One method optimizes for energy efficiency and the other for comfort. This material is a passive method that I think rather soon recoups any extra energy expended during manufacturing.
clairity 5y ago
no, that's just rationalizing. you're sitting uncomfortably for 10-15 minutes waiting for that temperature to be reached[0], and even then, heat transfer is maximized by having the air flow over you. the edge case might be when there are like 4+ people in a car for which there are not enough vents, but even then, pointing the vents at people, even somewhat indirectly, is better. heat transfer is what makes you feel cool/warm, not temperature, and air flow promotes convection (as well as conduction). it's why metal feels cooler (or warmer) than plastic at the same temperature (e.g., differing heat transfer coefficients). [0]: note that most car trips are less than ~15 minutes, at which point, all that heating/cooling is wasted as you flush it out the door.
- nicoburns 5y ago
  > note that most car trips are less than ~15 minutes, at which point, all that heating/cooling is wasted as you flush it out the door. Talking about energy efficiency: if your car trip is <15 minutes, then ideally you shouldn't be using a car at all!
  - clairity 5y ago
    if only we could collectively realize this and reconfigure our urban spaces according to that consideration! for instance, adding many, many more street trees everywhere, replacing street parking with protected bike lanes, and converting a lane on major streets to dedicated bus lanes with synchronized/sensored lights. but yes, for those majority short trips, the wind in your hair on a (electric) bike/scooter is likely just as cooling, and the trip likely no longer.
  - oblib 5y ago
    > Talking about energy efficiency: if your car trip is <15 minutes, then ideally you shouldn't be using a car at all! That depends on where you live. It take me about 5-7 minutes to drive to the nearest store (a "Dollar General" store). That store is about 2.5 miles away, so about a 5 mile round trip. Average walking speed is about 3.2 mph, so a +2 hour trip walking it. The next nearest store is about 10-12 miles away (a grocery store). Most of those miles are on a road with a 55mph limit but these are curvy hilly roads so probably closer to a 40-45 mph average. That's a +6 hour walk. Riding a bicycle is akin to death wish on those 2 lane roads with no shoulder.
    - ajuc 5y ago
      This sounds so weird. Like a place that has no general store in walking distance implies end of the world but then you say it has bad traffic too. And 2-lane road with no shoulder implies it's not a highway in the middle of nowhere but a place where people live. Why has nobody opened a shop closer? Seems like easy money.
      - URSpider94 5y ago
        He didn’t say it has bad traffic, he said it’s dangerous. I grew up in a place like this - isolated houses along a 2-lane road through the countryside with no shoulder. It’s a local road, but the speed limit is typically 55 mph because the housing density is very low. There’s not much traffic, but the traffic that is there is flying down the curvy road just trying to hang on. All of the stores are centralized in small towns and villages spaced 20 miles apart or so.
        ajuc 5y ago
        Yeah I just have no reference. Here villages spaced 30 km from each other doesn't happen. It's usually walking distance.
        crooked-v 5y ago
        To get a better idea of that sort of context, look at Texas or Montana in Google Maps and zoom in on one of the low-population areas. You'll see plenty of little towns with no public transit that would be literally days away from each other if walking.
  - Tarsul 5y ago
    I wonder how improved traffic could be if we somehow had managed that people driving alone would be driving in a vehicle that is suited for exactly 1 person. (although now I'm having pictures in my head of the insane traffic in India's cities... :)) Maybe electric vehicles could be an incentive to downsize vehicles?
    - clairity 5y ago
      for sure. on top of energy taxes, we could assess escalating maintenance fees on cars by size and weight, to encourage right-sized vehicles, especially in metro areas where it really matters.
      - conk 5y ago
        There are several studies on the relationship between vehicle weight and road wear and tear. 1 fully loaded semi does more damage than nearly 10,000 cars. The reality is if costs were assigned appropriately large aspects of life would become unworkable.
  - lotsofpulp 5y ago
    In the US, that frequently involves crossing 6 to 8 lane roads with 40mph+ speed limits, and 200ft setbacks to allow for huge parking lots. Or an actual highway where only motorized vehicles are allowed.
- chmod600 5y ago
  You are arguing too technically here. How people feel and what they like is very subjective. If people don't like air blowing unnaturally at them, no amount of arguing will change that.
  - clairity 5y ago
    you're implying that there is something incorrigible about such feelings, and that it's useless to point out other, objective factors that can impact decision-making (and habits). if that were true, we'd be a way more predictable, and boring, species than we are.
    - wvenable 5y ago
      The purpose of air conditioning in comfort -- so arguing that people can make themselves slightly less comfortable by doing something different is moot. It's even more energy efficient to not run the AC at all so why argue about vent position?
    - drdeca 5y ago
      I don’t think they are implying that. If someone’s preferences are based on metric A, and another method provides better results with regards to metric B, even if metrics A and B are correlated, this needn’t be a reason for the person to prefer the proposed alternate method, because the current method may still provide results with regards to metric A. Telling someone that tomato is a more vibrant red than chicken, will not compel them to prefer the taste of a tomato to the taste of chicken. (In this example the “correlation” bit doesn’t apply, but, whatever.)
    - deleted 5y ago
      [deleted]
- Dylan16807 5y ago
  > that's just rationalizing That's not called for. > you're sitting uncomfortably for 10-15 minutes waiting for that temperature to be reached It doesn't take that long, and you can compromise by hitting yourself with some of the full-power cooling until the cabin reaches a comfortable temperature. > heat transfer is what makes you feel cool/warm, not temperature, and air flow promotes convection (as well as conduction). Heat transfer yes, but everywhere on the body. You can't just look at the total.
easygenes 5y ago
I find having a vent on my hands or face MUCH more comfortable. I’ve lived in some of the hottest places on earth and indeed on the worst days there would never be a point where you’d feel cool enough without blowing the vents directly at you. Even in more temperate climates the airflow over my face is just refreshing, and helps keep my hands completely dry for a better grip.
- comex 5y ago
  > I’ve lived in some of the hottest places on earth and indeed on the worst days there would never be a point where you’d feel cool enough without blowing the vents directly at you. Surely if an air conditioner brings an indoor area to a given temperature (and humidity), it doesn't matter what the temperature is outside. So what gives? Is the air conditioner not powerful enough? Do people not want the inside to be as cold as in other locales, since they're used to the heat? The latter would make sense, but then I don't understand why you'd need to be blowing the vents directly at you.
  - galangalalgol 5y ago
    It happens in houses too. People will run their heater warmer than they cool their house to in summer. My theory is that the wall temperature is causing more or less radiant heating and the thermostat gets adjusted to compensate. So if the car body is much hotter it will feel hotter even with the same air temp.
  - easygenes 5y ago
    Well the topic is car A/C and indeed if the outside temperature is 45C (113F), and the air conditioner only produces a difference of 20C, and your target is 22C then you’ll fall short of that by a few degrees. Also with car A/C (or indoor spaces which take in a lot of direct sunlight), hotter days tend to be the result of greater insolation. If direct sunlight is hitting your skin on a clear summer day it has a significant warming effect which you would want to offset with more ambient or active cooling.
- IgorPartola 5y ago
  That’s because you have good blood circulation. Blood acts as your body’s coolant and transfers heat to your hands. Lots of people don’t have this so what they would get is the sensation of being very hot except their hands which will get very cold. Not a pleasant combo.

But having the whole cabin be at a cooler temperature allows the heat transfer to happen uniformly across your whole body, which is a lot more comfortable than having a vent pointed at yourself.

datameta 5y ago

One method optimizes for energy efficiency and the other for comfort. This material is a passive method that I think rather soon recoups any extra energy expended during manufacturing.

clairity 5y ago

no, that's just rationalizing. you're sitting uncomfortably for 10-15 minutes waiting for that temperature to be reached[0], and even then, heat transfer is maximized by having the air flow over you. the edge case might be when there are like 4+ people in a car for which there are not enough vents, but even then, pointing the vents at people, even somewhat indirectly, is better. heat transfer is what makes you feel cool/warm, not temperature, and air flow promotes convection (as well as conduction). it's why metal feels cooler (or warmer) than plastic at the same temperature (e.g., differing heat transfer coefficients). [0]: note that most car trips are less than ~15 minutes, at which point, all that heating/cooling is wasted as you flush it out the door.

nicoburns 5y ago
> note that most car trips are less than ~15 minutes, at which point, all that heating/cooling is wasted as you flush it out the door. Talking about energy efficiency: if your car trip is <15 minutes, then ideally you shouldn't be using a car at all!
- clairity 5y ago
  if only we could collectively realize this and reconfigure our urban spaces according to that consideration! for instance, adding many, many more street trees everywhere, replacing street parking with protected bike lanes, and converting a lane on major streets to dedicated bus lanes with synchronized/sensored lights. but yes, for those majority short trips, the wind in your hair on a (electric) bike/scooter is likely just as cooling, and the trip likely no longer.
- oblib 5y ago
  > Talking about energy efficiency: if your car trip is <15 minutes, then ideally you shouldn't be using a car at all! That depends on where you live. It take me about 5-7 minutes to drive to the nearest store (a "Dollar General" store). That store is about 2.5 miles away, so about a 5 mile round trip. Average walking speed is about 3.2 mph, so a +2 hour trip walking it. The next nearest store is about 10-12 miles away (a grocery store). Most of those miles are on a road with a 55mph limit but these are curvy hilly roads so probably closer to a 40-45 mph average. That's a +6 hour walk. Riding a bicycle is akin to death wish on those 2 lane roads with no shoulder.
  - ajuc 5y ago
    This sounds so weird. Like a place that has no general store in walking distance implies end of the world but then you say it has bad traffic too. And 2-lane road with no shoulder implies it's not a highway in the middle of nowhere but a place where people live. Why has nobody opened a shop closer? Seems like easy money.
    - URSpider94 5y ago
      He didn’t say it has bad traffic, he said it’s dangerous. I grew up in a place like this - isolated houses along a 2-lane road through the countryside with no shoulder. It’s a local road, but the speed limit is typically 55 mph because the housing density is very low. There’s not much traffic, but the traffic that is there is flying down the curvy road just trying to hang on. All of the stores are centralized in small towns and villages spaced 20 miles apart or so.
      - ajuc 5y ago
        Yeah I just have no reference. Here villages spaced 30 km from each other doesn't happen. It's usually walking distance.
        crooked-v 5y ago
        To get a better idea of that sort of context, look at Texas or Montana in Google Maps and zoom in on one of the low-population areas. You'll see plenty of little towns with no public transit that would be literally days away from each other if walking.
- Tarsul 5y ago
  I wonder how improved traffic could be if we somehow had managed that people driving alone would be driving in a vehicle that is suited for exactly 1 person. (although now I'm having pictures in my head of the insane traffic in India's cities... :)) Maybe electric vehicles could be an incentive to downsize vehicles?
  - clairity 5y ago
    for sure. on top of energy taxes, we could assess escalating maintenance fees on cars by size and weight, to encourage right-sized vehicles, especially in metro areas where it really matters.
    - conk 5y ago
      There are several studies on the relationship between vehicle weight and road wear and tear. 1 fully loaded semi does more damage than nearly 10,000 cars. The reality is if costs were assigned appropriately large aspects of life would become unworkable.
- lotsofpulp 5y ago
  In the US, that frequently involves crossing 6 to 8 lane roads with 40mph+ speed limits, and 200ft setbacks to allow for huge parking lots. Or an actual highway where only motorized vehicles are allowed.
chmod600 5y ago
You are arguing too technically here. How people feel and what they like is very subjective. If people don't like air blowing unnaturally at them, no amount of arguing will change that.
- clairity 5y ago
  you're implying that there is something incorrigible about such feelings, and that it's useless to point out other, objective factors that can impact decision-making (and habits). if that were true, we'd be a way more predictable, and boring, species than we are.
  - wvenable 5y ago
    The purpose of air conditioning in comfort -- so arguing that people can make themselves slightly less comfortable by doing something different is moot. It's even more energy efficient to not run the AC at all so why argue about vent position?
  - drdeca 5y ago
    I don’t think they are implying that. If someone’s preferences are based on metric A, and another method provides better results with regards to metric B, even if metrics A and B are correlated, this needn’t be a reason for the person to prefer the proposed alternate method, because the current method may still provide results with regards to metric A. Telling someone that tomato is a more vibrant red than chicken, will not compel them to prefer the taste of a tomato to the taste of chicken. (In this example the “correlation” bit doesn’t apply, but, whatever.)
  - deleted 5y ago
    [deleted]
Dylan16807 5y ago
> that's just rationalizing That's not called for. > you're sitting uncomfortably for 10-15 minutes waiting for that temperature to be reached It doesn't take that long, and you can compromise by hitting yourself with some of the full-power cooling until the cabin reaches a comfortable temperature. > heat transfer is what makes you feel cool/warm, not temperature, and air flow promotes convection (as well as conduction). Heat transfer yes, but everywhere on the body. You can't just look at the total.

easygenes 5y ago

I find having a vent on my hands or face MUCH more comfortable. I’ve lived in some of the hottest places on earth and indeed on the worst days there would never be a point where you’d feel cool enough without blowing the vents directly at you. Even in more temperate climates the airflow over my face is just refreshing, and helps keep my hands completely dry for a better grip.

comex 5y ago
> I’ve lived in some of the hottest places on earth and indeed on the worst days there would never be a point where you’d feel cool enough without blowing the vents directly at you. Surely if an air conditioner brings an indoor area to a given temperature (and humidity), it doesn't matter what the temperature is outside. So what gives? Is the air conditioner not powerful enough? Do people not want the inside to be as cold as in other locales, since they're used to the heat? The latter would make sense, but then I don't understand why you'd need to be blowing the vents directly at you.
- galangalalgol 5y ago
  It happens in houses too. People will run their heater warmer than they cool their house to in summer. My theory is that the wall temperature is causing more or less radiant heating and the thermostat gets adjusted to compensate. So if the car body is much hotter it will feel hotter even with the same air temp.
- easygenes 5y ago
  Well the topic is car A/C and indeed if the outside temperature is 45C (113F), and the air conditioner only produces a difference of 20C, and your target is 22C then you’ll fall short of that by a few degrees. Also with car A/C (or indoor spaces which take in a lot of direct sunlight), hotter days tend to be the result of greater insolation. If direct sunlight is hitting your skin on a clear summer day it has a significant warming effect which you would want to offset with more ambient or active cooling.
IgorPartola 5y ago
That’s because you have good blood circulation. Blood acts as your body’s coolant and transfers heat to your hands. Lots of people don’t have this so what they would get is the sensation of being very hot except their hands which will get very cold. Not a pleasant combo.