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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.

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    • CommentAuthordelprado
    • CommentTimeJan 29th 2018
     
    What does everyone think? My understanding is that solar gain doesn't quite work in this country, except perhaps for east facing elevations to warm a house up.

    Anywhere else just doesnt really achieve much in the shoulder seasons and becomes overpowering during the summer (when there is no option for large soffit, expensive external blinds or deciduous trees, etc to provide shading)
    • CommentAuthordelprado
    • CommentTimeJan 29th 2018
     
    Sorry, and my conclusion is therefore that we should consider using solar control glass to stop summertime overheating?
    • CommentAuthorsam_cat
    • CommentTimeJan 29th 2018
     
    It works for us, just takes some maths...
    South west facing patio with large patio doors. This resulted in massive overheating in the summer.
    Built a veranda that sticks out enough that the summer shadow falls 'just' outside the patio door from 11am - 3pm, evening side has a trellis and plants to help cut down on the late day solar gain. And its covered in solar panels ;)

    In the winter the sun is low and the plants are leafless, so sun gets in and heats the house.
    Summer the sun is high and the heat doesnt get in, plants are leafy so dapple/cut down the light when we need it to.

    Result is it works pretty well, just takes a bit more though/planning.
    • CommentAuthorTimSmall
    • CommentTimeJan 29th 2018
     
    Sketchup is pretty good for modelling solar shading (use the last Google version instead of the Trimble versions to get the full solar shading functionality in the free version). You can also use something like a "Sun Sail" or other temporary shading methods if you like.
    • CommentAuthordelprado
    • CommentTimeJan 29th 2018
     
    Thanks guys. I dont think solar shading will work in my case as its four big bays at the front of the house. Just not really a realistic aesthetic solution I dont think?
    • CommentAuthorgyrogear
    • CommentTimeJan 29th 2018 edited
     
    Posted By: delprado

    What does everyone think? My understanding is that solar gain doesn't quite work in this country, except perhaps for east facing elevations to warm a house up.

    Anywhere else just doesnt really achieve much in the shoulder seasons and becomes overpowering during the summer (when there is no option for large soffit, expensive external blinds or deciduous trees, etc to provide shading)


    What direction does your house face ?
    (Aristotle thought it was a wise thing to orient one's house so it would be warmed by the sun... :smile: )

    If your house is overheating in the summer, it might be for other reasons (such as low mass...) and insufficient overhangs.

    AFAIU, over the year, in your location, your windows should be producing a net heating gain, therefore saving you money and giving you nice views and good quality of life etc.

    cf.

    ... the size and positions of your windows was presumably calculated in relation to your floor area and quantity and distribution of thermal mass
    .. and the general building designed with window aspects in mind (such as overhangs etc.).
    exactly in order to prevent the sort of problem you describe...

    (Regarding your east-facing elevations, I'd be surprised if they were doing much warming of a winter morning - I imagine that by 9:30 (? 90 minutes after sunrise ?), your sun ought to be getting south-eastish already, still any ought to be welcome; and in summer, ought not to be a problem if you have been tempering the house overnight...

    Do you have a basement ? Was any of your low-E glass installed back-to-front for your location?

    Perhaps your solution is to use summer heat to cool your house, thus removing the hot-window issue...

    Or provide shading from other sources (planters, roller awnings...) or install a water feature (swimming pool, spa etc., or spray system for evaporative cooling).
    etc.

    maybe take a look at this !
    https://www.builditsolar.com/Projects/Cooling/passive_cooling.htm

    ========
    For info, we are on the French channel coast (not a million miles from S. England). We have high mass and south-facing aspect, sun windows with zero overhangs and certainly in heating season could not manage without our solar gain.

    We do have a limited area of roof glass therefore solar-control for summer, with internal box-blinds .

    Our bedrooms are all north, two of them being semi-buried. We have electric window blinds. Of a summer night, nocturnal heat is not a problem, as we temper the house on external air, and in the day we use partial south curtains and generate through-drafts using a certain basement-window regime.

    Good luck,

    gg
    •  
      CommentAuthorfostertom
    • CommentTimeJan 29th 2018
     
    delprado, can you re-title the thread? Solar control glazing means it blocks incoming solar a little or a lot. Do you mean selective coated glazing, as typically in 2G/3G windows, which aims to let solar gain in but prevent it being lost by re-radiation?

    How well the latter works, and the attendant danger of summer overheating, is at the core of Passive House calculation, as well as something we need to understand and utilise when not going the full PH route. Given that, we shouldn't need to use solar-blocking glass.

    This certainly can and does work throughout UK.
    •  
      CommentAuthordjh
    • CommentTimeJan 29th 2018
     
    Posted By: fostertomdelprado, can you re-title the thread? Solar control glazing means it blocks incoming solar a little or a lot. Do you mean selective coated glazing, as typically in 2G/3G windows, which aims to let solar gain in but prevent it being lost by re-radiation?

    I thought he meant exactly what he wrote, as evidenced by the second post. i.e. the hypothesis is "if there isn't much benefit from solar gain, is it better instead to optimise overheating behaviour by using solar control glass: discuss"

    But I generally agree with you that solar control glass shouldn't ordinarily be needed for new-build dwellings in the UK, whereas solar gain is very much worth having. Retrofit is as always a more difficult decision.
    • CommentAuthorgravelld
    • CommentTimeJan 29th 2018
     
    Regarding retrofit and obviously after modelling, I tend to think it is best to optimise for solar gain as much as possible and have external "hacks" to avoid over heating, e.g. over shading, pergolas stopping summer sun.

    Still potential for over heating on worst case days in e.g April, October but overall, on average through the year, it might be for the best.
    • CommentAuthordelprado
    • CommentTimeJan 30th 2018
     
    From some research, it appears internal blinds (the right kind), offer a decent degree of solar rejection, because they bounce it back to be absorbed in the glass. Not as good as external but cheaper. Anyone got any thoughts on that?

    My other thought is to have solar control glass in the bedrooms, but solar gain (normal) downstairs. I think that could be a very good compromise?
    •  
      CommentAuthordjh
    • CommentTimeJan 30th 2018
     
    Posted By: delpradoFrom some research, it appears internal blinds (the right kind), offer a decent degree of solar rejection, because they bounce it back to be absorbed in the glass. Not as good as external but cheaper. Anyone got any thoughts on that?

    We have honeycomb blinds inside the sash, next to the glass, on our full-height bedroom windows. It definitely makes a big difference, since it stops the sun getting any further into the room and warming the carpet and walls. The ventilation gets rid of the excess heat, sometimes with help from open windows. Because of our large roof overhangs, we typically only need to cover the bottom half of the windows to keep the sun out of the room during summer.
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