[Radiance-general] Help - Radiance / LEED

[Lars O. Grobe]

Hi!
On Apr 22, 2011, at 0:37, "Guglielmetti, Robert" <Robert.Guglielmetti at nrel.gov> wrote:

> So, assuming you are indeed calculating illuminance, in lux (lumens/m^2), then multiplying those values by 0.0929030436 will convert the values to footcandles (lumens/m^2).

Actually lm/ft2. You see what a mess the mixing of metric and imperial system leads to if these typos appear even in Rob's explanation.

If it was my office, the first thing I'd do is to establish a policy to only use metric units everywhere (geometry, results,...). The conversion to imperial units can be done on the fly when filling out a form.

By the way, it is rather important to understand the difference between Radiance W/m2sr and Irradiance W/m2. Going from radiometric (W aka Watts) to photometric (lm aka lumens) is just to match the human eye's perception according to wavelengths, and in many cases Radiance can internally do this on your behalf.

Cheers, Lars.