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Ventilation: Retrofitting continuous ventilation after fitting new windows

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    • CommentAuthorShevek
    • CommentTimeAug 5th 2021 edited
     
    We've fitted new windows to our flat and exceeded expectations on airtightness. So next step is to add ventilation.

    The most cost-effective method I think is to add trickle vents (easy retrofit in our case because there is a roller shutter above each window with an internal access panel they can be fitted into) and then swap the current intermittent extract fan in the bathroom for a continuous extract fan + humidity booster sensor. All internals doors have a 5-10 mm undercut.

    Am I taking the right approach?

    My main concern is noise. What is the quietest fan on the market and what can we do to make sure we minimise noise? A suspended ceiling in the bathroom to provide sound-proofing to a fan unit is definitely on the cards; it needs one anyway because it's currently a concrete soffit and attracts condensation because if it's surface temperature.

    We may also fit a hot water cylinder with integrated heat pump of some description in the little room next to the kitchen. Could that factor into a ventilation strategy?

    I did also wonder if we could fit a dMEV fan unit (e.g. Brookvent airstream) but fitting ductwork at a later date.
      layout.jpg
      existing_fan.jpeg
    • CommentAuthorMike1
    • CommentTimeAug 5th 2021 edited
     
    I wouldn't want to be cutting trickle vents - they're not readily controllable and they'll let in external noise.

    Ideally you'd want to be fitting an MVHR unit - maybe in the laundry. ICW this and your other thread on suitable heating, this thread may be worth a read: http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17129
    • CommentAuthorShevek
    • CommentTimeAug 5th 2021
     
    Thanks Mike. Agreed, but budget has been blown on new windows and there's no EU funding available for MVHR as far as I can tell.

    My intention would be to fit acoustically attenuated trickle vents like Brookvent's SM Acoustic.
    • CommentAuthorEd Davies
    • CommentTimeAug 5th 2021
     
    Shevek is the location in your profile up to date? I was under the impression you're in Portugal now which seems to be supported by the spelling on that plan. Might be relevant to people's answers, e.g., weaking the argument for MHRV a bit.
  5.  
    At our last house that I built, which was a PH, I fitted a Genvex Combi 180LS which is a combined MVHR, DHW warm air heating unit with built in EASHP. We lived in SE England near the coast at the time and the unit was very effective used in conjunction with electric towel rails in the bathrooms at keeping the house warm and providing DHW.
    •  
      CommentAuthorfostertom
    • CommentTimeAug 6th 2021 edited
     
    You can get trickle vents that have a humidity sensor that shuts them automatically when not needed. How airtight they then are, I don't know.

    Ventilation guru Peter Rickaby, who's done lots of work on IAQ in far-from-ideal housing like Thamesmead, for buildings like yours swears by centralised MEV (MRHV but without the ducted intake or heat recovery!) https://www.vent-axia.com/range/centralised-mechanical-extract-ventilation-mev, as a lot cheaper and tenant-foolproof.
    •  
      CommentAuthordjh
    • CommentTimeAug 6th 2021
     
    Posted By: fostertomYou can get trickle vents that have a humidity sensor that shuts them automatically when not needed.

    But if Shevek fits an EAHP then surely any sensor in a trickle vent will see more of the external air's properties as it is sucked in? And with an EAHP they'll need to be always open in any case?

    Ventilation guru Peter Rickaby, who's done lots of work on IAQ in far-from-ideal housing like Thamesmead, for buildings like yours swears by centralised MEV (MRHV but without the ducted intake or heat recovery!)

    "Sorry, the page or file you were looking for couldn't be found
    "We've recently redesigned the Vent-Axia.com website"

    But that's essentially how an EAHP behaves isn't it, as far as ventilation goes? It acts as an MEV unit.
    •  
      CommentAuthorfostertom
    • CommentTimeAug 6th 2021 edited
     
    https://www.vent-axia.com/range/centralised-mechanical-extract-ventilation-mev
    works for me.

    Posted By: djhsurely any sensor in a trickle vent will see more of the external air's properties as it is sucked in
    So you'd think but apparently they've solved that, whether 'sucked' in (by fan, or more usually by passive stack effect) or 'blown' in by wind. Hopefully the fan's humidistat would fairly well sync with the trickle vents' stats - at any rate you'd want to have whatever kind of air inlet open only at times of ventilation need.

    This is an alternative to
    Posted By: djhShevek fits an EAHP
    •  
      CommentAuthordjh
    • CommentTimeAug 6th 2021
     
    Posted By: fostertomhttps://www.vent-axia.com/range/centralised-mechanical-extract-ventilation-mev
    works for me.

    It works for me too, but that isn't what you posted. It was another example of including a trailing punctuation mark in the URL :cry:
    •  
      CommentAuthordjh
    • CommentTimeAug 6th 2021
     
    Posted By: fostertom
    Posted By: djhsurely any sensor in a trickle vent will see more of the external air's properties as it is sucked in
    So you'd think but apparently they've solved that, whether 'sucked' in (by fan, or more usually by passive stack effect) or 'blown' in by wind. Hopefully the fan's humidistat would fairly well sync with the trickle vents' stats - at any rate you'd want to have whatever kind of air inlet open only at times of ventilation need.

    Have you got a link (without a comma :bigsmile:) to such a product?

    This is an alternative to
    Posted By: djhShevek fits an EAHP

    Sorry, I don't understand this at all. The whole discussion is in the context of Shevek's "We may also fit a hot water cylinder with integrated heat pump of some description in the little room next to the kitchen." or even his continuous extract fan.
    • CommentAuthorbxman
    • CommentTimeAug 6th 2021
     
    Can you fit outside insulation and avoid that condensation on the concrete soffit ?


    How many occupant and what volume is the flat ?

    how many months is it necessary to keep the windows closed .

    Are you able to dry any washing outside the envelope ?

    How much moisture is generated by cooking ?

    if you were on your own you might find you could control the R H and have an acceptable air quality without the need for any forced air movement

    My experience is that if you can eliminate air movement you will feel 2 degrees warmer than before .
    •  
      CommentAuthorfostertom
    • CommentTimeAug 6th 2021
     
  13.  
    An EAHP could handle this and your heat question. I have a Bosch Compress, and previously hade a Nibe Fighter - both very good - do hot water, heating and ventilation; in your climate you could run it without hardly ever needing the immersion. You're welcome to contact me if you want to discuss more
    • CommentAuthorShevek
    • CommentTimeAug 8th 2021 edited
     
    You're right Ed, thanks for that. I've updated my info to Portugal.

    - Occupancy is currently 2 but could be 4 when rented out. Or 3 if we have a little one :confused:
    - Volume is approx. 170 cu m
    - Windows needed to be closed, at least at night, for 2-3 months if I recall correctly (lows and highs of 6Ă‚Âş to 15Ă‚Âş Dec to Feb)
    - Washing is dried outside the envelope for most of the year, but in winter needs to be brought in at night to finish off.
    - We do cook a lot but moisture hasn't been a problem, although that was probably because the laundry window next to the kitchen used to have a large vent grill at the top (because of the gas boiler). We removed that when we fitted new windows.

    Thanks for the heads up on the trickle vents with humidity sensors Tom. Pretty cool how they work without electricity. No more expensive than acoustically attenuated vents too (€32 on that second link of yours). Is shutting off trickle vents based on humidity alone a good idea though? Could that lead to build up of CO2 in bedrooms over night?

    An exhaust air heat pump is an option. Open to suggestions. I think from listening to MEP seminars I've also had it drummed into my head that MEV with trickle vents in this context will be the simplest, most cost-effective and healthy option. I've got to keep in mind that there's €2500 EU funding available for a heat pump system but not a ventilation system for whatever reason, but if I could combine the two then the funding is probably available for the heat pump element.
    • CommentAuthorShevek
    • CommentTimeAug 8th 2021
     
    Posted By: minisaurusAn EAHP could handle this and your heat question. I have a Bosch Compress

    Is that a system with an external fan unit?
  16.  
    Posted By: Shevek
    Posted By: minisaurusAn EAHP could handle this and your heat question. I have a Bosch Compress

    Is that a system with an external fan unit?


    No, internal fan, and you can regulate the flow to suit.
    • CommentAuthorShevek
    • CommentTimeAug 10th 2021 edited
     
    I was looking into this Aquapura Monobloc unit from Energie. The first configuration is air source heat pump.

    But the second configuration? Exhaust air heat pump?

    https://energie.pt/en/products/aquapura-monobloc
      energie2.jpg
    • CommentAuthorminisaurus
    • CommentTimeAug 10th 2021
     
    Posted By: ShevekI was looking into this Aquapura Monobloc unit from Energie. The first configuration is air source heat pump.

    But the second configuration? Exhaust air heat pump?


    Could be EAHP - input air isn’t shown? You’d want some input air hole(s) somewhere.

    Only does hot water, no radiators? Don’t forget that the “Nordic” EAHPs give you radiator and/or underfloor heating, as well as hot water :)

    Why do you get wine bottles with the second configuration?
    • CommentAuthorgravelld
    • CommentTimeAug 10th 2021 edited
     
    I like Aereco's demand controlled units. If you're under 5m3/hm2 you'll need vents.
    •  
      CommentAuthordjh
    • CommentTimeAug 10th 2021
     
    Posted By: minisaurusWhy do you get wine bottles with the second configuration?

    The label says it is also indoors, so presumably it's a chilled wine cellar. Well spotted!
    • CommentAuthorShevek
    • CommentTimeAug 11th 2021
     
    Presumably trickle vents are expected? I’m expecting a call from them today to discuss.

    Exhaust air heat pump to heat water only and refresh air internally seems like a strange concept to me. Basically cooling your house down whenever you heat your water.
    • CommentAuthorShevek
    • CommentTimeAug 11th 2021 edited
     
    Posted By: gravelldI like Aereco's demand controlled units. If you're under 5m3/hm2 you'll need vents.

    That an interesting company, thanks. They even have trickle vents designed for exactly where I was thinking of putting them:
    https://www.aereco.com/products/air-inlets/eah2/
    • CommentAuthorShevek
    • CommentTimeAug 12th 2021 edited
     
    Here's a thought I have about trickle vents with humidity sensors. What happens when it's foggy, as it can often be along the Portuguese coast where we're situated?

    I would typically close the windows when this happens to stop the damp coming inside, especially if it's also a cold morning. But trickle vents with humidity sensors are likely to just increase their aperture as the moisture laden air creeps inside.
    • CommentAuthorShevek
    • CommentTimeAug 27th 2021
     
    Having lived here for a over a year now it’s occurred to me that there’s one other thing we seriously need to consider: fog.

    Very often a fog rolls in off the Atlantic. Summer and winter (it’s foggy most mornings at the moment). In warm weather it can mean waking up sweaty but it dries up soon enough. In cold weather it’s really problematic and clearly contributes to a small mould problem in the flat (coupled with significant thermal bridges at the floor slabs).

    The problem with the extract + trickle vent method is that this just pulls the fog inside (and at the moment just windows cracked open for ventilation, resulting in same problem). The only option being to get a separate dehumidifier.

    So unless there are dehumidifying trickle vents out there we should be looking at a solution with integrated dehumidifier.
    •  
      CommentAuthordjh
    • CommentTimeAug 27th 2021
     
    Hang a fog net outside the windows to condense some of the fog? :bigsmile:

    https://en.wikipedia.org/wiki/Fog_collection
    • CommentAuthorShevek
    • CommentTimeAug 27th 2021
     
    😂
    •  
      CommentAuthordjh
    • CommentTimeAug 27th 2021
     
    FWIW, I just bought a robotic lawnmower that has a 'smart' rain detection feature. Unfortunately it also thinks morning dew is rain and refuses to start up in the morning! Duh! Grr! :devil:
    • CommentAuthorbxman
    • CommentTimeAug 29th 2021
     
    maybe the mower is intelligent enough that you do not cut damp grass
  29.  
    Coastal areas of East Scotland get a cold, thick "haar" fog off the North sea in summer, it happens because the sea temperature is much cooler than the land. Warm air blows off the land, gets cooled by the sea and condenses fog, then blows back onto the land later.

    Fortunately the foggy air isn't any wetter than normal, just colder, so it isn't bringing any extra moisture into the indoors. It is easily evaporated by warming up the air again by a few degrees above sea temperature, so once it's at indoor temperatures it doesn't make things damp. Is this what you are finding, or is it different that far south?

    We used the radical solution of moving house a few miles inland, the haar rarely gets that far inland before evaporating.
    • CommentAuthorShevek
    • CommentTimeAug 31st 2021 edited
     
    Posted By: bxmanmaybe the mower is intelligent enough that you do not cut damp grass

    ha, yes, cutting damp grass will clog up the mower!

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