Passive Solar window awnings or shades
smokey11106
| Posted in Energy Efficiency and Durability on
Hi. I live in NY, zone 4 and I have a number of windows and two sliding glass doors facing almost south. Most are not directly south, but a few degrees off to the east and a few a liitle off to the West. I am considering retractable window awnings for those windows so as to be able to help cooling in the summer. My question is whether this is still a good idea and are there other alternatives that I might not know about that I can use that are durable, easy to use and hopefully less expensive than some of the retractable awnings I’ve been seeing? Thanks and Happy New Year.
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Replies
Eric,
You can build (or hire a builder to install) small roofs or shading shelves above your south windows. These can be attached to your wall, and if they are carefully designed and installed, can be integrated with the architectural style of the house and can look attractive.
If you install fixed overhangs, make sure they are engineered for your latitude to allow full winter sun while shading the summer noontime sun.
Thank you both. 1) to Martin: Are there any designs you could recommend that I can give to my contractor? Are they simple enough to build and not complicated degree/angle wise and in construction. 2) To Robert: Are there semi-fixed types that are removeable, so I can maybe take them down in the winter? And how do I make sure they are built for my latitude and do you recommend any?
Eric,
You need to find a competent local carpenter who understands solar angles and passive solar shading. This is not something that can be designed from afar.
You don't need them at all. Look at my blog on this site 'A contrarian view of passive solar design"
And then make sure you read the many critical comments that follow.
I like this economical solution, and of course don't get the striped ones.
http://greenbuildingindenver.blogspot.com/2009/09/solar-shading-contd.html
Has anyone tried out the design recommendations from http://www.susdesign.com/overhang_recs/index.php? Obviously, the most basic of these recommendations does not take into account things like site occlusions, etc. I am also trying to decide between retractable vs. fixed awnings vs. external vertical hanging shades for summer for my south-facing windows.
I like the plantable trellises we've been making from treated six by six and four by six posts with heavy duty galvanized hat channel for shade screen. When we need more strength we use Mac Girt structural hat channel from Macelroy Metals. It has span tables so inspectors will allow us to glaze it.
The SusDesign overhang ratios are reasonable, but I prefer a somewhat different set of standards.
They say "the ideal overhang would provide 90 to 100% shading mid-day during July and August (northern hemisphere), and 70%+ shading in September when there can still be very warm days. The recommended overhang would provide nearly complete sun exposure in the typically coldest months of December and January, and very good sun exposure in February."
In my cold climate designs, I prefer to get 100% of the noontime winter solstice sun to maximize passive solar gain and 100% noontime summer solstice shading to control overheating. In the swing seasons, windows can be opened for natural ventilation and nighttime cooling.
If you use the SusDesign chart, use the depth:height ratios rather than the absolute numbers to adjust overhang depth according to your header height.