# Site Standard Meridian argument in genrsky

Hello!

I just wish to confirm about the Site Standard Meridian (-m) argument for
genrsky. Is it the following:

Local longitude of Standard Time Meridian (LSTM):
LSTM = 15 deg x (Longitude/15 deg)round to integer

Best regards,
Vaib

Hi Vaib,

I just wish to confirm about the Site Standard Meridian (-m) argument
for genrsky. Is it the following:

Local longitude of Standard Time Meridian (LSTM):
LSTM = 15 deg x (Longitude/15 deg)_round to integer

What you are describing is a special case that is true for most, but not all, time zones.

Most time zones in Radiance notation are given in multiples of 15 degrees. Exceptions to this are the countries marked on this map
http://www.icsm.gov.au/mapping/images/time_zones.jpg
with a star.

Countries that have a TZ of GMT +/- X.5 hrs or -(X*15) + 7.5 deg include:
- India
- a bit of Australia
- Iran
(there are more...)

Finally, there is Nepal which is at GMT +5:45 hrs or -5.75*15 = -86.25 deg in Radiance notation.

In other words: the 'round to integer' part of your equation is correct in most, but not all, cases. You might end up with a floating point number if your project is located in exotic places.

FYI: This integer bug existed in epw2wea which just recently made it into Radiance HEAD. It was fixed just before Christmas.

Regards

Axel

Best regards,
Vaibhav

···

On 5 January 2014 17:18, Axel Jacobs <[email protected]> wrote:

Hi Vaib,

I just wish to confirm about the Site Standard Meridian (-m) argument

for genrsky. Is it the following:

Local longitude of Standard Time Meridian (LSTM):
LSTM = 15 deg x (Longitude/15 deg)_round to integer

What you are describing is a special case that is true for most, but not
all, time zones.

Most time zones in Radiance notation are given in multiples of 15 degrees.
Exceptions to this are the countries marked on this map
http://www.icsm.gov.au/mapping/images/time_zones.jpg
with a star.

Countries that have a TZ of GMT +/- X.5 hrs or -(X*15) + 7.5 deg include:
- India
- a bit of Australia
- Iran
(there are more...)

Finally, there is Nepal which is at GMT +5:45 hrs or -5.75*15 = -86.25 deg

In other words: the 'round to integer' part of your equation is correct in
most, but not all, cases. You might end up with a floating point number if
your project is located in exotic places.

FYI: This integer bug existed in epw2wea which just recently made it into

Regards

Axel

_______________________________________________
[email protected]

A Wikimedia map with detailed annotation. Political boundaries are probably much more important than the geographic longitude value. A very high proportion of countries span multiple 15 degree longitude zones. In nearly all countries, cities near certain borders might round off to a different time zone by geographic location, but are grouped into the country's primary time zone by political boundaries.

···

-----Original Message-----
From: Axel Jacobs [mailto:[email protected]]
...
Most time zones in Radiance notation are given in multiples of 15
degrees. Exceptions to this are the countries marked on this map
http://www.icsm.gov.au/mapping/images/time_zones.jpg
with a star.
...
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I agree with Chris, you're better off looking up the time zone and setting
-m accordingly. The equation you propose will give the wrong meridian for
many cities. For example: Indianapolis, Knoxville, Boise, all of Spain and
almost all of France.

Andy

···

On Mon, Jan 6, 2014 at 5:59 AM, Christopher Rush <[email protected]>wrote:

A Wikimedia map with detailed annotation. Political boundaries are
probably much more important than the geographic longitude value. A very
high proportion of countries span multiple 15 degree longitude zones. In
nearly all countries, cities near certain borders might round off to a
different time zone by geographic location, but are grouped into the
country's primary time zone by political boundaries.

-----Original Message-----
From: Axel Jacobs [mailto:[email protected]]
...
Most time zones in Radiance notation are given in multiples of 15
degrees. Exceptions to this are the countries marked on this map
http://www.icsm.gov.au/mapping/images/time_zones.jpg
with a star.
...
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses

_______________________________________________