I have a small 5th floor flat, with high ceilings. The sash windows, which are tall, face south. There is a very busy road underneath the windows. Two rooms have these windows.

It's noticeable that I start coughing as soon as I get into the flat. And my girlfriend starts sneezing and getting a blocked-up nose. Obviously from the traffic pollution from outside.

Spring is about to start and soon it's also going to get pretty hot and uncomfortable, since the windows make it like a greenhouse.

What would be the best solution to tackle both the pollution and heat, bearing in mind that it's a small flat, and I don't think I'm allowed to mount any kind of unit on the outside of the flat.

Is there a joint aircon & purifier that I can connect with a hose, which is reasonably quiet? I'm willing to spend a bit to get a nice air environment.

Room 1: 365 X 365 X 365cm, 12 X 12 X 12 feet

Room 2: 365 X 190 X 365cm, 12 X 6 X 12 feet

                     Pollution and Heat               

              │          │          │          │      
              ▼          ▼          ▼          ▼      

 │     Window 1      Window 2    ││     Window 3     │
 │                               ││                  │
 │                               ││                  │
 │                               ││                  │
 │                               ││                  │
 │                               ││                  │
 │              Room 1           ││      Room 2      │
 │                               ││                  │
 │                               ││                  │
 │                               ││                  │
 │                               ││                  │
 │                               ││                  │
 │                               ││                  │
 │                               ││                  │
  • 1
    What do you think about window shades and a pair of desktop air filters?
    – wallyk
    Commented Mar 11, 2015 at 18:02
  • Are you looking for a how-to on converting a window unit into 'ducted and now just sits there'; In conjunction with somehow adding a filter? Or are you willing to spend great gobs of money (as I have outlined in my answer)?
    – Mazura
    Commented Mar 20, 2015 at 0:31

3 Answers 3


My wife is asthmatic and has strong allergic reactions to dust, mold and dust mites, so we deal with this very condition.

There are some 'portable' air conditioners that draw air from inside the room and cool it, while also cooling the room by blowing the heated air outside. These come with rudimentary filters, but also have the added benefit of creating a slightly negative pressure environment which can help remove allergens.

Additionally, because they are actively condensing some moisture from the room, it will additionally remove some pollutants. I know this is true anecdotally as I have to infrequently clean the condensing coils and filter regularly and they are often dark and extremely soiled.

This unit sits on the floor, and uses a plastic shroud (that must be fitted) to seal the exhaust out the window.

I believe this fits most of your requirements. Although I did not notice it at the time we purchased ours, I believe there are some models available with HEPA type filters also.


If you're not allowed window units (not even stuck mostly inside?) but could get away with an exhaust vent in the window:

Portable Server Room Air Conditioners: -uptime4u.com

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Depending on the kind you get, you're going to have to empty it occasionally or find a way to drain it. It should have a standard filter rack that will work to some degree. Or build your own thing that does all these functions. Check out 4" Media Filters if you're going to ad hoc something.

If you're serious about clean air check out this TFP (Turbulent Flow Precipitation) mumbojumbo:

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I have no affiliation with CleanAire, just personal experience that when you turn one of these on, it smells like an open window. You could completely pipe the two together, but that's unnecessarily elaborate for your install. I'd suggest a stand-alone TFP for year round use anyway. Besides, the air cleaner could be in the other room, where as you might want the AC in the bedroom.

The noise levels for both could probably be described as: (with performance to suit)

  • Low: That's not bad.

  • High: Wow, that's kinda loud.


If you have circular vents in the wall that could be replaced, kept and refitted upon leaving; look up single room heat-recovery-extractor-fan with 2 separate fans, they can filter the air with HEPA filters. For cooling down you would need big unit of A/C with internal condensation or bucket at the back or next to drain. Myself I use Ion / UV portable HEPA/Carbon filter but that is because I got it for free with spare filters, not that I needed, although I was reading on technology behind it and it is legit.

Downside of single room heat-recovery-extractor-fan is they have to be connected by electrician... You could make it on custom plug but then it is all on you.

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