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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

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    • CommentAuthorHoveTom
    • CommentTimeSep 5th 2019
     
    Hi All,

    I’m converting a bungalow with major renovation and a new roof. I’m installing several Velux windows upstairs as planning dictated I can’t have dormers.

    Has anyone tried Velux Active home monitoring and ventilation? For those that don’t know it’s an add on to electric Velux windows. It comes with a sensor which monitors humidity, CO2 and Air Temperature and regulates them to your settings through the Velux. Apparently recovering up to 75% of the heat from the out going air in the process. It’s £180 odd for the first kit and then £70 odd for further rooms.

    This price seems very reasonable and much cheaper and easier to install that all the ducting involved in other MVHR systems. I have ruled out ducted MVHR as my property isn’t being built with strict air tightness in mind and due to difficulty running the ducts with it being a bungalow conversion. I am however very interested in Aereco products.

    Does anyone have Aereco house ventilation? If so what kit and how do you find it, is there a noticeable difference? I appreciate this Velux system would only do the bedrooms and the Aereco system does the whole house but for the cost it can’t be ignored..

    Any help or thoughts much appreciated.

    Tom.
    • CommentAuthorandyman99
    • CommentTimeSep 5th 2019
     
    I've a solar powered Velux and I'm very pleased with it. However from their website:

    "The smart ventilation unit is installed above the VELUX roof window on the outside of your home, is invisible from inside and delivers over 75% heat recovery of the exhaust air"

    I'm a little sceptical how it can do that when the outside temperatures start to drop?
    •  
      CommentAuthordjh
    • CommentTimeSep 5th 2019
     
    I'm confused by the content on https://www.velux.com/products/ventilation/velux-smart-ventilation They say 'Fits most MK sizes of our top-operated roof windows'. What does that mean? I take it to mean top-hinged but there's a picture of a woman accessing the unit with the top of the window outside the frame? And the schematic of a man installing it seems to imply the sash has to be removed altogether?

    I'm impressed by the low price, but I don't understand why subsequent units would be so much cheaper than the first?
    • CommentAuthortony
    • CommentTimeSep 5th 2019
     
    I cannot see any way that they could justify the claim about recovering heat. As far as I can see all the do is let (hot) air out in greater or lesser amounts.

    ???
    •  
      CommentAuthordjh
    • CommentTimeSep 5th 2019 edited
     
    Posted By: tonyAs far as I can see all the do is let (hot) air out in greater or lesser amounts.

    The page I linked to explains the mechanism. It's the same idea as an enthalpy wheel, though less efficient. I've seen other devices using the same idea but I don't remember which.
  1.  
    Interesting idea, and distributed mhrv could well be cheaper than ducted, especially if a brand like velux get involved. The other similar products (DJH referred to) use a pair of ventilators, one sucks while the other blows (so to speak), but the velux website described both being in the same box, which could cause short circuits perhaps.

    'MK' is velux's product code for their range of 78cm wide windows - MK06, MK08 etc - the width that fits the MHRV.

    'Top operated' means the handle is at the top and the hinges are in the middle, also called 'centre pivot', like in the picture. Their 'top hung' ones open at the bottom for greater headroom or escape, but wouldn't work with the mhrv.

    Confusingly, the 'velux active' name in the UK seems to be used for a completely different product, an internet controller that interfaces with their electric window openers to open the windows if the room is too hot, as Tony said. The first room needs a temperature sensor and an internet gateway. Subsequent rooms just need a temperature sensor so cost less.

    I couldn't immediately spot the mhrv on sale in the UK despite it having the same name 'velux active' on their international website... Anyone?
    • CommentAuthorRex
    • CommentTimeSep 6th 2019
     
    I am very suspicious of wonderful graphics; a designer can draw any air-flow graphic that the client wants.

    As far as I understand things, MVHR is designed to provide a cross-flow of air in a room. Surely this will only supply / extract air in a very limited space and most of the room will not benefit from fresh air as eddy currents will establish.

    Additionally, I assume that this require power. How many roof lights have a power source close by?
  2.  
    So, search on VELUX SMART, not ACTIVE. Utube clips of it and installation. Obviously very new, as I can't see a price anywhere on the net - The £180 quoted above, I believe relates to the ACTIVE, which is just a smart vent.

    Looks like a great idea, essentially an MVHR using an existing structural opening. We (the wife) often have our velux vents open, so this would help ameliorate my naval gazing obsession with drafts.

    People often have lights in their ceiling, (if there's a flat area of ceiling), which would likely be near the head of the velux, so getting power to it retro. might not be such a big deal.

    BUT...an MVHR outside of the thermal envelope? Do we take the over 75% heat recovery at face value? What's the cost per unit? What are the flow rates?

    If it's sub £300 say, I would deff suggest it for any clients with velux in a bathroom, and poss in a bedroom. On the subject of flowrates, it would need to be around 8 litre/min, for a const running, to replace an intermittent for BRegs, and this theoretically should be better than an intermittent, for "cleaning" the room.

    Looking forward to understanding more...
    •  
      CommentAuthordjh
    • CommentTimeSep 6th 2019 edited
     
    Posted By: RexAs far as I understand things, MVHR is designed to provide a cross-flow of air in a room. Surely this will only supply / extract air in a very limited space and most of the room will not benefit from fresh air as eddy currents will establish.

    That's how things like Fresh-R work though, isn't it? and they seem to get by. I suppose there's more mixing with the rest of the air inside takes place than we expect.

    Additionally, I assume that this require power. How many roof lights have a power source close by?

    Is it not solar-powered?

    Posted By: GreenPaddyBUT...an MVHR outside of the thermal envelope? Do we take the over 75% heat recovery at face value? What's the cost per unit? What are the flow rates?

    I worry about the outside location as well, but I suppose we just have to trust they've insulated it sensibly. Ditto with the 75% claim; it's not outrageous, since the best units claim over 90%, but Velux would be staking their good name if they don't have any evidence. I didn't immediately see a cert on the website though.

    TBH, the web page looks like a pre-announcement (aka vapourware). Trying to find it in the shop seems to be impossible. There don't seem to be any documentation links, nor customer references etc. It's all a bit new.
  3.  
    Didn't see anything about it being solar powered... You can get solar powered window openers, but they use much less power over a day.

    Would really be great for retrofits, velux have been selling that size window for decades so there must be a huge number installed and waiting for an easy retrofit mhrv solution.
    • CommentAuthorHoveTom
    • CommentTimeSep 9th 2019
     
    I’ve spoken with Velux about this product. I think the figure of 75% heat recovery is disingenuous at beat. It seems there isn’t a heat exchanger of any sort. It’s just an automatic window opener and closer, but it won’t allow the window to open if the outside air temp is below a pre set temp. This is how they claim heat is recovered within the system.

    I asked what would happen for three quarters of the year at night when the outside air temp is below what most would desire in the bedroom if the C02 levels become high? Answer - The window stays shut. Same for humidity. So basically nothing happens. I asked if I could do without a bathroom extractor if I had one of these in a bathroom Velux and the answer was no, for the above reason that it wouldn’t be practical.

    It can open a vent instead of the whole window at times but this is basically just a trickle vent so without any sort of fan to assist it could take a while to clear the air from a room.

    Hope this helps someone considering this. I may have understood the system wrong so do double check yourself.
  4.  
    Either velux have told you about the wrong product, or they don't even know what's on their own website...

    Cut/paste this link.
    https://www.velux.com/products/ventilation/velux-smart-ventilation

    This clearly discusses fans, fan speeds, heat recovery, etc. There are other UTube vids too.

    Velux "Active" is the simple vent opener. This is something quite different, by description, even if it's just a twinkle in velux's supply chain eye.
    • CommentAuthorHoveTom
    • CommentTime5 days ago
     
    I’ve spoken with Velux again and it would seem it was a bit of both. The product isn't for sale in the UK, yet it is on their website. So the sales team only know what it says on the website and no more.

    They can however take your order for it. Prices are for the 780mm frame size £644, 942mm £643 and for 1140mm £702 all plus vat.

    Difficult to buy when they can’t answer any questions on it at this stage. You’d have to get In touch with Velux in a mainland European country which sell it to get technical (or even fairly basic) answers.
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