FW: modeling hourly daylight illuminance/daylightfactor values for a year


Thanks for the pointers John and Christoph.

I did manage to install DAYSIM and model an office space. When I ran the
simulation I got the 'uncommented lines in the dc file' error which I looked
up in the tutorial and fixed the PATH and RAYPATH environmental variables. I
am using Windows XP on my notebook (the tutorial points these fixes for
Windows 2000, I tried them nevertheless).

I encountered the same error even then. I was trying to fix it and in the
process uninstalled and installed the program 2 to 3 times. Now the program
doesn't start after installation. I can't get it to start despite some
effort. It would help my thesis a lot if I can make it work.

Need your help.

Thanks again,


On 3/27/06, Reinhart, Christoph <[email protected]> wrote:

Hi Ramana,

To further convince you that Daylight Coefficients are 'the way to go',
you can have a look at the attached paper.

Christoph Reinhart, Ph.D.
Associate Research Officer National Research Council Canada
Institute for Research in Construction
Adjunct Professor McGill University
School of Architecture
1200 Montreal Road M-24, Ottawa Ontario K1A 0R6, Canada
tel: (613) 993-9703 fax: (613) 954 3733
Lightswitch Wizard (initial design) www.buildwiz.com
DAYSIM (expert software) www.daysim.com

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of John
Sent: Sunday, March 26, 2006 4:57 AM
To: [email protected]
Subject: [Radiance-general] modeling hourly daylight
illuminance/daylightfactor values for a year


A brute-force approach (i.e. a new simulation for every hour) can be
done, but it is computationally very inefficient. A better approach is
to use daylight coefficients. Background, theory and implementation are
described in chapter 6 here:
[Web pages seem to be down at the moment - try again later/tomorrow]

An end-user DC version called DAYSIM is available from here:
DAYSIM is different in detail from the description noted above, but does
more or less the same thing.


Dr. John Mardaljevic
Senior Research Fellow
Institute of Energy and Sustainable Development De Montfort University
The Gateway Leicester
+44 (0) 116 257 7972
+44 (0) 116 257 7981 (fax)

[email protected]

Radiance-general mailing list
[email protected]

Venkata Ramana Koti
1137 E Orange St Apt #35
Tempe AZ 85281 USA
Tel: 480.326.9275

MS in Building Design (Energy/Climate)
School of Architecture and Landscape Architecture
College of Design
Arizona State University, Tempe AZ 85287