The TST function calculates the True Solar Time (TST) according to DIN EN 17037 from UTC (Coordinated Universal Time). At 12:00 TST the sun is at \alpha_S = 180\degree. The default geographical settings are set in the file “LT_location.mat”. Change the settings to your preferred location and set the file to read-only in order to prevent your settings from being overwritten with the default values in future versions.
Usage:
t = TST(date,utc,geolength,geowidth)
Where:
| Parameter | Description |
t | Returns the True Solar Time in |
date | Specifies the date in 'dd.mm.yyyy' format, default: current day. |
utc | Specifies the UTC time in 'hh:mm:ss' format, default: current time. |
geolength | Specifies the geographic length, default: 13.326 (Berlin). You can change the preference in the “LT_location.mat” file. |
geowidth | Specifies the geographic width, default: 52.514 (Berlin). You can change the preference in the “LT_location.mat” file. |
Examples
True Solar Time in Berlin at ‘21.05.1987’ – ’11:03:22‘ UTC:
t = TST('21.05.1987','11:03:22')
Result:
t = 12:00:00
Note: to determine noon UTC time, use the south function.
True Solar Time in Athens at ‘21.05.1987’ – ’11:03:22‘ UTC:
t = TST('21.05.1987','11:03:22',37.978,23.728)
Result:
t = 13:38:37
Reference
Daylight in buildings. 2019.