I am planning to build a shed atop my terrace. I was analyzing the sun path to determine the overhang length, facade height etc, but got stuck with a conflict as below.

The summer sun's location peaks are on Northern side of a location (or a plot or house), while its winter sun, is at lower angle, on Southern side as shown below, referred from here.

enter image description here

My conflict is as follows. I see in multiple websites, for a glass of a fixed direction (ex, South), they show both summer and winter sun angles. How can that be the case?

Case 1: For ex, let us look at below diagram from here

enter image description here

They have shown both Jun Sun and Dec Sun for a South facing Glass! But, if we look at sun path, only Dec sun may be on South side. Here are 2 months' sun orientation from this wonderful tool.

Jun on northern side of building: enter image description here

Dec on southern side of building: enter image description here

So strictly speaking, for south side glass, shouldn't we only consider winter months? And similarly, summer for northern side? Similarly this should not be applicable at all to E-W side right, because there, Sun appears also at ultra low angles, so no point unless a vertical shading (thus recommendations to minimize glass on E-W, as I am from tropical region).

Here is another image with same conflict in same website.

enter image description here

Case 2: Here is another image from another website. Here too, for a single direction glass (presumably North or South), they illustrate both Summer and Winter as below.

enter image description here

How can that be the case??

Case 3: And then another from here

enter image description here

What am I missing?

My understanding is that, if we take North for example, through out the day, Sun's altitude changes, but the maximum of that incidence is at Summer solstice as below.

enter image description here

So in Northern side, if I want to avoid Sun's direct incidence altogether, say from 8 AM to 4 PM and I do not mind the time afterwards as anyway its morning or evening, I should only see for Northern Side, at Summer Solstice (around Jun), from 8 AM to 4 PM what is the min and max altitudes. For my location, that happens to be around $30^{\circ}$ to $78^{\circ}$, which after further calculations gives me a guideline that, my overhang length $l$ could be $1.732h$, where $h$ is height of my glazing, for example. There is no need of Dec calculation on Northern Side.

enter image description here

If my understanding is correct, then it is wrong for those websites to illustrate both Summer and Winter solstice angles on a glass of single direction. Or please correct me where I am going wrong here.

This is blocking my design phase of my shed.


As Roger pointed out, in some locations, sun always tend to be in north or south. For ex, in northern hemisphere, as you go northwards, sun becomes more and more only available in south, through out the year. For ex, the sun path for Hamburg, Germany is shown below.

enter image description here

  • $\begingroup$ Did you realize that these figures use different target points for the sun rays, is that perhaps a source of confusion? I would find it clearer if they would use e.g. always a couch in your shed, or always the same point on the fassade. Instead, sometimes the rays target the front yard and sometimes the back yard, I find that gets confusing. $\endgroup$
    – rfl
    Mar 21 at 9:35
  • 1
    $\begingroup$ Perhaps I misunderstand the question: if we live in nothern hemisphere (Europe or North America), then the Sun is always in the south - in winter and in summer; the only thing that changes is how high it is (i.e., the angle). This is certainly not true for anywhere in the world, but some of the materials that you cite were probably designed for the northern audience. $\endgroup$ Mar 21 at 14:37
  • $\begingroup$ @RogerVadim that is a wonderful hint, which I think clarified my doubt. Indeed, as we go north wards in norther hemisphere, this seems to be the case (that sun is always in south all the year both in winter and summer). I checked for Hamburg, and its the case. :) $\endgroup$ Mar 25 at 8:16
  • $\begingroup$ I live in Normandy, where the standard orientation of houses is towards South-West. Since it's a relatively cold region, one installs on this side of a house large bay windows to capture maximum of heat, whereas the other side the house usually has only small windows or none at all. Of course, big apartment buildings are less concerned about this - but one usually prefers to rent an apartment on the sunny side. This is nearly opposite of the Mediterranean region, where one favors small windows on the sunny side and favors living in a shade. $\endgroup$ Mar 25 at 8:32


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