Joe,
That seems to work just as well and is maybe somewhat clearer. Are you sure no other instances than sun position calculation in E+ uses the time zone information?
But you should subtract, not add 0.5 to the time zone. I think it is best shown with the equations used by software like E+.
HourAngle = (15 deg)*(LocalSolarTime - 12 + TimeHourOffset)
LocalSolarTime = LocalTime + (Longitude / (15 deg) ? TimeZone) + EoT
Longitude and TimeZone are positive in eastward direction. The LocalTime is the time given in the .epw file. HourAngle should be 0 deg at solar noon for data in -0:30-0:30 and -7.5 deg (equals time 11:30) for data in -1:00-0:00 convention.
For data in -0:30-0:30 you need to neutralise that E+ sets TimeHourOffset=-0.5. This is done by adding 7.5 to the Longitude or adding -0.5 to the TimeZone, as can be seen from the equations above.
This half hour discrepancy doesnâ??t make much difference for common simulation purposes. But there are cases when it is important. In hygrothermal simulation solar heat and the hour angle are important parameters. And in some building certifications/regulation system thereâ??s a max limit on allowed solar heat gain through windows, a faulty hour angle calculation would affect this.
Regards,
Lukas