2.  The axis of the Earth’s rotation makes an angle of about 23.5 degrees with the plane of its orbit  Because of this, there is more sun on the northern part of the Earth during summer and less in winter  The transition between these occurs on the first days of spring and fall

3.  It might help to rotate the image of the Earth’s orbit so that the North and South poles are pointing up and down, as shown here  If you imagine yourself in the Northern hemisphere, you can see that in December you’d be looking down towards the south to see the sun  Likewise, in June, you’d have to look almost directly overhead  You can see the sunlight falling on Earth throughout the year in this NASA videoNASA video

4.  In the summer the sun is more overhead than it is in the winter  For passive solar homes, you want to maximize winter sun input to a home to get the most heat  You also want to minimize summer sun input to prevent overheating

5.  Controlling seasonal solar input can be achieved using a roof overhang, awning, or other horizontal feature to provide summer shade  The image on the right shows how the summer sun is blocked by the awning but the winter sun is not

6.  Imagine an existing 2-story house that faces south and which has a window on the first floor and none on the second.

7.  The owner wishes to improve its passive solar features by adding a window to the second floor and an awning above the window on the first  The owner wants to use the existing roof overhang on the second floor for summer shading the second story window  What should be the size of the second-story window and the first-floor awning?

8.  The image to the right shows the suns rays during the summer (orange) and winter (blue) on the southern wall of the house  Note which rays enter the window and which reach the wall of the second story

9.  An ideal window on the second floor would capture all the winter sun but be shaded from the summer sun by the overhang.  The top of the window is where the top ray of winter sun hits, and the bottom of the window should be where the top ray of the summer sun hits  The new window is shaded in the summer but lets in the winter sun

10.  The awning on the first floor needs to provide shade from the summer sun but let in the winter sun  The location of the outermost tip of the awning is identified by ◦ Find the top-most winter ray that enters the window. ◦ Find the bottom-most summer ray that enters the window. ◦ Where they intersect is the edge of the awning.

11.  Page Border  Title box in corner ◦ Title ◦ Name ◦ Drawing # ◦ Scale ◦ Date ◦ Approval  Heavy lines for edges of objects  Lighter lines for showing dimensions and some features

12.  The scale tells you how big a feature should be on the drawing based on its actual size ◦ Example: If the scale is 1” = 4’, then a wall that is 8 feet high would be drawn 2 inches high  The scale is set so that the largest dimension will fit on the paper. If a building is 35 feet tall and there is 6 inches of vertical space, a scale of 1” = 6’ or 1”=8” might work  The scale is the same vertically and horizontally

13.  It is important to ◦ Be neat ◦ Show important dimensions ◦ Use labels to identify key features ◦ Ensure the drawing communicates what you want to show  Using graph paper is helpful  Use a straight-edge, rule, and protractor  Use a light pencil at first, then go over the final lines with a heavier pencil or a pen

14. You will create a drawing similar to the one shown in this presentation. Using the drawing, you will determine the size of a new window on the top story and a new awning on the bottom story. You will be able to determine their actual sizes by measuring their size on the drawing and using the drawing scale.