If you follow the link to the US Naval observatory, you can print out a table of solar position for any particular location, on any particular date. For my location (52N), I see the sun crosses the horizon around 7am, 4pm at this time of year, and reaches a maximum elevation of 21.5 degrees. In the middle of the summer at the same location, I get 4am, 8pm and 61 degrees elevation.
There is no simple calculation in this case. The zero points are constant as being the start and end of the day (from which you can pick earlier or later references), but the elevation does not make any correction for your location or the time of year.
Regardless of how you determine the correct angle for 'noon', you would need to repeatedly update this based on the date.
A better approach might be to determine the relevant time of day based on location, since a constant UTC time might be a close enough approximation. Here, 12:00 is good enough (but I have the meridian just a few miles away).