Quiet ventilation solution for windowless room.

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AlphaAlfalfaSprout

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#324705 15-May-2026 15:23

I have a room with no windows and just one internal door. It's half of the original basement rumpus room, which was subdivided to create a bedroom, and the bedroom inherited all of the windows. The other room needs ventilation. I started looking into the cost of adding a window, but this seems like it would cost a fortune, especially as it will require consent.

As I understand it, you can put up to a 300mm hole in the concrete block wall before consent is needed. What is a good, quiet forced airflow solution I could attach to a 100-300mm penetration? None of the residential extractor fans I've ever heard have been even remotely acceptable in terms of noise levels.

The actual volume of airflow will not need to be high. Basically the equivalent of a window ajar, but it would be nice to have headroom for emergency airing A fan with full speed control (not a handful of fixed steps) would be ideal.

I'm also wondering whether I should be pushing air out or sucking it in through a filter. The filter would probably necessitate a louder fan.

johno1234

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#3491263 15-May-2026 15:44

Sorry this is not an answer to your question, but I don't think habitable windowless rooms are permitted under NZ building rules - sounds like this alteration is not consented and a possible red flag if you wanted to sell the house.

Dynamic

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#3491265 15-May-2026 15:57

I've never lived in a home with one, but the forced air fans in HRV / DVS / SmartVent systems might be an option to consider. Quiet and low pressure but designed for long term use.

You might be able to find a secondhand system from one of the above or an equivalent that someone has ripped out in a renovation and DIY install it.

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MikeAqua

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#3491269 15-May-2026 16:06

johno1234:

Sorry this is not an answer to your question, but I don't think habitable windowless rooms are permitted under NZ building rules - sounds like this alteration is not consented and a possible red flag if you wanted to sell the house.

I'm not sure exactly what habitable means but you can definitely get consent for windowless rooms for some applications. Media rooms, butler's pantries, actively ventilated bathrooms and walk in wardrobes come to mind.

Mike

johno1234

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#3491272 15-May-2026 16:26

MikeAqua:

johno1234:

Sorry this is not an answer to your question, but I don't think habitable windowless rooms are permitted under NZ building rules - sounds like this alteration is not consented and a possible red flag if you wanted to sell the house.

I'm not sure exactly what habitable means but you can definitely get consent for windowless rooms for some applications. Media rooms, butler's pantries, actively ventilated bathrooms and walk in wardrobes come to mind.

Habitable means a room that is normally occupied. E.g. bedrooms, living rooms, dining rooms and kitchens. Non habitable includes bathrooms, store rooms, hallways.

https://www.building.govt.nz/building-code-compliance/g-services-and-facilities/g7-natural-light

I think you can have a windowless room if you call it an office, but you can't if you call it a bedroom or living room.

Eva888

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#3491278 15-May-2026 16:40

Why not put a high horizontal window that opens in the wall of the adjoining bedroom and some vents low down in the wall. Still gives privacy to both rooms but allows air to circulate. Also consider a half glass door with obscure glass. Adding light will make it more usable and then a fan might be enough to circulate some air.

SnoopyDo

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#3491280 15-May-2026 16:49

something like

VL-100EU5-E : Single Room Fresh Air Ventilation with Lossnay Energy Recovery // Mitsubishi Electric

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SnoopyDo

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#3491281 15-May-2026 16:49

something like

VL-100EU5-E : Single Room Fresh Air Ventilation with Lossnay Energy Recovery // Mitsubishi Electric

tweake

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#3491290 15-May-2026 18:13

AlphaAlfalfaSprout:

I have a room with no windows and just one internal door. It's half of the original basement rumpus room, which was subdivided to create a bedroom, and the bedroom inherited all of the windows. The other room needs ventilation. I started looking into the cost of adding a window, but this seems like it would cost a fortune, especially as it will require consent.

As I understand it, you can put up to a 300mm hole in the concrete block wall before consent is needed. What is a good, quiet forced airflow solution I could attach to a 100-300mm penetration? None of the residential extractor fans I've ever heard have been even remotely acceptable in terms of noise levels.

The actual volume of airflow will not need to be high. Basically the equivalent of a window ajar, but it would be nice to have headroom for emergency airing A fan with full speed control (not a handful of fixed steps) would be ideal.

I'm also wondering whether I should be pushing air out or sucking it in through a filter. The filter would probably necessitate a louder fan.

plenty of ventilation products around. but getting one that suitable for a small room might be tricky.

but you can make your own. you will not need a big hole. plenty of small variable speed ES fans around. set it for slow speed. add filter box and a bit of ducting etc. noise is a bit tricky as most rely on the fan being in ceiling etc where you can't hear it.