• (Edited )

Read the Heating Cooling Lighting Appendix for detailed explanations to understand this.

• (Edited )

Merilyn,

You can go through this blog to understand this Sun Path Chart.

The sunrise is the first time during the day when the altitude is 0. So on this chart you can find the sunrise time from the right-side. For example - For March/September 21st, the sunrise time will be 6am.

Hope this helps,

Rajan

• Thank you so much for the response Rajan! that was super helpful!

• Let's do another example together. . . What time is sunrise on February 21st in Columbus, Ohio (48 degrees north latitude)?

scroll down for the answer.  . . .

A: a bit before 7am

Start with the month, in red. February is the 2nd month, so look for the line labeled II in Roman numerals. (The sun follows the same path on February 21st as on October 21st, labeled X in Roman numerals on the right-hand side of the same line because October is the 10th month.).

I depicted the altitude line in green. This measures the angle the sun sits as measured up from the horizon. You can see the 10-degrees, 20-degrees, 30-degrees labels above the green box, but we are looking for 0-degrees above the horizon--because the sun is at the horizon, not above it, at sunrise. There is no 0-degrees label, but you can intuit that. The 0-degrees altitude line meets the February-October line twice: once at sunrise on the right-hand side of the chart, and once at sunset on the left-hand side of the chart.

Once you've found the intersection of the red and green lines, you've found sunrise on February 21st. To find the time, move along the orange line upward until you hit the time number labels. In our example, that falls between 6am and 7am, but much closer to 7am so we'll call it 6:50am. There's your answer!

The sun path follows a complex geometry based on latitude, time, and season and is measured by azimuth and altitude. It then requires a complex set of charts to take all of those inputs and outputs into account. These charts are especially confusing because: (1) all of the lines are in the same (black) color so it's sometimes difficult to follow just one of them, (2) the months are in Roman numerals (presumably so you can more easily invert the chart if you were calculating for the southern hemisphere. . . but that's a stupid system because it doesn't make it easier), (3) the months are inexplicably on opposite sides of the same line, making it seem like the left-hand side is for February and the right-hand side is for October (even though the whole line represents both months), (4) since we read left-to-right, it seems like the sunrise should be on the left and the sunset on the right--but it's the other way around because the sunrise is in the east and convention puts the east on the right, and (5) each month's line represents the 21st of the month, which may seem arbitrary, but makes more sense when you give it some thought--the summer and winter solstice, and spring and fall equinoxes fall on the 21st.

Bonus question: what is the azimuth of the sun at sunrise on that same day? Scroll way down to check your answer.

A: 72 degrees east of south

• thank you so much Michael Ermann! I've been watching Amber books and it's my go tos to gain solid background knowledge for the exams. But through my recent experiences with PPD / PDDs, I felt like the exam questions do not relate closely with the study contents. Any advice on how to improve study schemes to catch up with the recent exam question bank updates?

• Ben of Hyperfine has a good video on it.  https://www.youtube.com/watch?v=lJVEubm9Ja8

I teach it live in my courses.

There is also a really cool tool online - just type in your longitude & latitude and it'll chart your location/date for you.  http://andrewmarsh.com/apps/releases/sunpath2d.html

Compare Summer & Winter is Juneau AK and Florida Keys.

Florida:  27.6648° n, 81.5158° w

Juneau:  58° 18' 20.8836'' N and 134° 25' 59.8944'' W

Hope this helps!

Rebekka O'Melia, Registered Architect, NCARB, B. Arch, M. Ed, Step UP, Step UP ARE 5.0 Courses