4 ms·

Ventilation is energetically expensive, and can be even impossible to retrofit (windows that don't open, ...) Purification however is energetically very cheap

• koheripbal 5y ago
  Most office buildings also do not have windows that open at all.
  • jhugo 5y ago
    These office buildings usually have automated ventilation which if specced properly can provide equivalent or more air exchanges per hour than open windows. As a bonus, automated ventilation can include a heat exchanger, while an open window can't.
• newaccount74 5y ago
  Heat exchangers can recover a large fraction of the energy lost through ventilation. Modern systems can even recover humidity from the air leaving the building. Air purifiers are very loud and mostly effective at removing particulates. If you want to remove VOCs, formaldehyde and CO2 then ventilation is a lot more effective. A well designed ventilation system can be completely inaudible.
  • jhugo 5y ago
    > Air purifiers are very loud and mostly effective at removing particulates. If you want to remove VOCs, formaldehyde and CO2 then ventilation is a lot more effective. Modern air purifiers are basically silent in normal operation, and there are models that remove VOCs and formaldehyde. CO2 is still best removed with ventilation.
    • newaccount74 5y ago
      > Modern air purifiers are basically silent in normal operation Maybe on the lowest setting, but I doubt you'll actually have clean air on the lowest setting. Especially if you want to filter VOCs.
      • jhugo 5y ago
        > Maybe on the lowest setting, but I doubt you'll actually have clean air on the lowest setting. Especially if you want to filter VOCs. Have you actually used a decent air purifier or are you just guessing? There are plenty of models that do a good job filtering VOCs (as measured by a separate VOC sensor) and are almost silent in normal operation. A lot of the innovation in this space seems to be happening in Asian brands, I remember when I lived in London it was very hard to find good air purifiers.
        • newaccount74 5y ago
          I don't have an air purifier myself, but I've talked to people who own air purifiers and read lots of online reviews. All I've heard is that on the lowest setting they are very silent, but on "auto" mode they start up regularly and are not silent at all, and if your room is anywhere close to the recommended size the lowest setting doesn't do much at all. I was mostly researching about the Mi brand air purifiers, since they are readily available in Europe and a lot cheaper than European brands, but if you have suggestions for a brand that makes purifiers that are actually silent AND effective I'd be curious to hear about them.
          • jhugo 5y ago
            The Mi 3H is a decent model (fairly significant improvement on the earlier models). I have one in my bedroom, and it really only cranks up the volume if I fry something in the kitchen and forget to run the extractor. VOC levels (as measured by a separate sensor) were up around 400 μg/m^3 when we moved in — somewhat high, probably because the apartment was new — and after a week, during which the Mi 3H was on auto mode and always silent, I tested again and they were down around 120 μg/m^3. It also deals with moderate spikes in PM — like someone smoking on the balcony outside, or opening a dusty moving box in the room — without increasing the noise levels noticeably.
• legulere 5y ago
  Automated ventilation saves energy. You don’t need to open windows anymore which leads to less heat or cold coming in. If your ventilation system has a heat exchanger it’s performing even better. It’s impossible to build highly efficient houses without automated ventilation.