[Virtual-sim] Daylight control and electric lighting energy saving

Paul Carey paul at zed-uk.com
Mon Jan 4 05:59:45 PST 2010

Dear Seo,


Well, as far as I know it doesn't do it directly like EnergyPlus does for
example.  I believe (unless it's changed in v6) that what you have to do is
to carry out a daylighting calculation in Radiance for each space and then
link the results of that to the Apache-Sim calculations so that the daylight
level reductions are accounted for correctly.  Personally I'm not entirely
convinced of it's accuracy, as you have to make sure the "area of interest"
is assigned correctly and very slight changes in this selection can have
profound effects on the daylight factor results.   I prefer using Flucs Pro
for doing the daylight calculations and then making a judgement on a
diversity factor to utilise in the simulations.  It makes the simulations
much simpler but takes daylight control into account to some extent.  


Another issue to consider, is that if you did this calculation/simulation
with EnergyPlus it uses the climate file data to work out the daylight
control savings, but if you want to use IES then you have to use the CIE
overcast sky within Radiance.  There is much debate as to which approach is
more accurate and both have their pro's and con's.  In that respect it would
also be worth looking at the work of Dr John Mardaljevic at De Montfort
University.  His PhD thesis and some interesting reading is available online
here :





From: virtual-sim-bounces at lists.onebuilding.org
[mailto:virtual-sim-bounces at lists.onebuilding.org] On Behalf Of Donghyun Seo
Sent: 30 December 2009 23:42
To: virtual-sim at lists.onebuilding.org
Subject: [Virtual-sim] Daylight control and electric lighting energy saving


Dear All,

I'm a relatively newbie of IES VE.
I would like to know how IES VE calculates electric lighting energy use with
daylight control simulation.

I checked FlucsDL and FlucsPro User Guides but there are general explains
about input.
If you can direct me good references for my question, it would be very
helpful to me.

Thank you and Happy New Year!


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