Thanks for sharing Alex =).

Regarding that concern I voiced between visible and other wavelengths... I dug a little and found a resource supporting the notion. See the color chart near the bottom of the following link that plots water absorption coefficients against the electromagnetic wavelength spectrum - visible light is absorbed by water much less than other wavelength ranges. http://www.lsbu.ac.uk/water/vibrat.html

Again, I brought this up for two purposes: To suggest a reason why the DOE2 help files list an albedo of 0.05 for the ocean (unqualified with a frequency range like "visible light," 'albedo' generally refers to the full electromagnetic spectrum), and as a reason to caution that a majority of the sun's energy which might otherwise produce a solar heat gain on a building envelope may fall outside the visible range, and thus would be subtracted out of what's reflected to your building if you're talking about a body of water. Again, I'm no physicist but I know enough to suggest caution.

If you're modeling daylighting controls, the lake could certainly be modeled as a surface with a reflectance in the 90%+ range at low incident angles (sunrise/sunset), but if you're trying to account for additional envelope thermal loads reflected from a lake, I think your albedo figure should never fall in that range (unless, again, the lake is covered with snow), and that figure further might not vary appreciably with the incident angle...

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Calculating seasonal sun angles for a specific latitude/longitude as a separate topic can be a tricky business - but there a number of free and for-cost tools that do all the legwork for you.

Here's one example of a free, simplistic tool to get angles at a specific time/location: http://solardat.uoregon.edu/SolarPositionCalculator.html

A tangent tip: you can right-click anywhere in google maps and select "what's here" from the context menu to get the exact latitude and longitude for your location.

NICK CATON, E.I.T.