retro

Hi all, very informative place for ventilation info here! Most of the discussion I've seen of PIV is re houses, where it seems it usually lives in the loft. How does it work out in a flat? I've seen there are some units designed for flats, but for example I don't know: - Where are they typically installed? - There's typically no ducting with PIV, correct? - What sort of noise levels do you get with PIV units suitable for a flat? I can look up dB / SPL numbers, but experiences of people here probably would tell me more! - Any other experience with specific units in a flat, or listing of different ones on the market would of course be very useful My situation: - Purpose-built concrete London flat, no ceiling void or loft for ducting - Next to fairly busy (noisy) road - No trickle vents. Good thing too because of the road noise (at least I can close the windows when I want quiet/comfort). - In my flat the obvious MVHR unit siting is high on a kitchen wall next to the window (bathroom is tricky because of pipework blocking venting in/out). Would that make sense for PIV too? I had a vague notion to fit a door on the kitchen to keep down fridge/washing machine noise, presumably not a problem for PIV? The spare room is the other possible choice I think. That room is currently kept colder by a few degrees in the winter so I keep the door closed most of the time, I guess that makes little difference to PIV? What I want to achieve / thoughts: - Lower CO2 levels in living room and bedrooms in the colder months. This is the main issue in my mind (especially in the living room as it's also a home office). Currently the windows are open both too much (noise, me forgetting to close them, heat loss) and too little (still days, me forgetting to open them). - No significant increase in noise levels in bedrooms or living room, either from transmission through holes made in exterior walls, or from ventilation units themselves (especially not intermittent noise like those suck/blow every 70 seconds dMVHR units). Also I'd rather not have increased transmission of sound (talking etc.) between bedrooms/living room - this is one thing putting me off full ducted MVHR (though maybe false ceilings in every room would help that?). - Lower humidity would be great: I dry clothes indoors and have to run a dehumidifier. Also my bay windows have cold bridges causing a lot of condensation, costs me 15 minutes of most of my winter mornings mopping it up, big pain. Plus the bathroom seems almost impossible to fit proper extraction fan due to pipework blocking all direct routes out through the wall, the tile grouting and sealant slowly gets mouldy even with window open a lot and me squeegeeing off the tiles after using the shower. - I do get moderate hayfever and my flat is next to a fairly busy road so any reduction in pollen and pollution from cars is very welcome too - Of course energy efficiency is a draw too. I've been considering MVHR but for dMVHR noise is a problem I think. For ducted MVHR the ducting is of course a big thing (probably false ceilings needed) and as I understand it also lack of airtightness likely causing short-circuiting of the heat exchanger. Plus I don't see myself realistically doing MVHR this year. So I'm leaning toward PIV not MVHR, at least as a first step. - While I'm doing this, if there's any benefit to doing aircon/air-to-air heat pump at the same time, I'd certainly consider it. Cooling would only be for very peak of hot summers (but great to have then), heating air-to-air might be useful in the winter for energy efficiency even if the financial payoff is too long to make sense on its own. All comments very welcome, thanks!