[Bldg-sim] illuminance data in TMY2 file

[eddy santosa]

 Hi Ery,

I think illumination value can't be calculated from radiation data.
Different skymodel and altitude of the sun provide different efficacy.

Thanks,

Eddy Santosa



Date: Mon, 6 Apr 2009 16:27:14 -0600
> From: Ery Djunaedy <erydjunaedy at gmail.com>
> Subject: [Bldg-sim] illuminance data in TMY2 file
> To: bldg-sim at lists.onebuilding.org,
>        radiance-general at radiance-online.org
> Message-ID:
>        <a590350904061527v7bc912e8sc0b7334daeaaeeaa at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> All,
>
> Attached is the illuminance (global horizontal) for Boise, ID, from
> TMY2 data. Note the valley in the graph on the left bottom corner
> which is caused by the very low illuminance values for January (the
> values are in the hundreds, compared to tens of thousand in February).
> I know for a fact that in Boise January is not (much) darker than
> December or February.
>
> Furthermore, the corresponding radiation data do not have that dip in
> January. The illumination values are calculated based on the radiation
> data, right? So if there is nothing wrong in the radiation data, is
> this related to the model used in converting radiation data into
> illumination values?
>
> I also checked another site in Idaho, it has the same dark January.
>
> Any thoughts?
>
> Thanks,
>
> Ery
> -------------- next part --------------
> A non-text attachment was scrubbed...
> Name: BoiseIlluminance.jpg
> Type: image/jpeg
> Size: 93828 bytes
> Desc: not available
> URL:
> http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20090406/1c2d5184/attachment-0001.jpg
>
> ------------------------------
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20090407/39d77bc8/attachment-0001.htm>