[Equest-users] How does eQuest know initial FootcandlesforDaylighting Calc?

Matutinovic, Luka LMatutinovic at halsall.com
Thu Jan 7 06:09:14 PST 2010


Does this mean that there is some "baseline" fc that is provided by the
electrical lighting?  That is to say, eQuest will determine how many fc
daylight provides and satisfy the rest with some fraction of the
installed LPD?  This implies that there is a relationship between LPD
and fc, is that true and if so what is it or where could I find it?

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-----Original Message-----
From: Nick Caton [mailto:ncaton at smithboucher.com] 
Sent: Wednesday, December 30, 2009 10:27 AM
To: R B; John Aulbach
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] How does eQuest know initial
FootcandlesforDaylighting Calc?

The DOE2 help files suggest, if not directly, that the sensor you are
placing is measuring ONLY "illuminance due to daylight," in isolation of
any electrical lighting in the project.  When you define a "target"
illumation level (say 30fc) at a specific point/orientation, that sensor
will plot the daylight measured in the same vector against a curve
(specified when you select dimming control options) to determine a
factor to apply to the zone's Lightig Watts/SF.

To my knowledge, eQuest in no manner whatsoever is attempting to perform
the operations of photometric software (AGI32/Visual/LightPRO/etc).


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-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of R B
Sent: Monday, December 28, 2009 4:44 PM
To: John Aulbach
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] How does eQuest know initial Footcandles
forDaylighting Calc?

My guess is that the tool assumes the lighting wattage that you have
gives the amount of footcandles specified. If 50% of this is from
daylight, then remaining is from 50% of the installed lighting
(translating into 50% wattage usage).

On 12/28/09, John Aulbach <jra_sac at yahoo.com> wrote:
> LIke the Phantom of the Opera.."A mystery never fully explained.."
> I have performed Daylighting savings EEMs in eQuest, where one places
> sensor in the space, one deliniates a minimum footcandle requirement,
> runs a Parametric run to determine how much lighting energy may be
> What is NOT clear to me is how eQuest determines what the inital
> level is. It obviously knows the lighting fixture height (Ceilling or
> syspended) and the geometry of existing windows, etc. But I cannot
> where the information lies that says "eQuest assumes so many
lumens/watt of
> certain lighting."
> Can anyone "ILLUMINATE" me, please?
> Hope all had a great Christmas.
> John Aulbach
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