[BLDG-SIM] Day-Lighting and DOE2.1E

[Larry Degelman]

Just a side note of interest (with no judgment inferred):
 
ASHRAE/IESNA Standard 90.1-1999 no longer allows lighting control
credits.  Compliance is based on connected lighting power alone.  With
the 1989 Standard, credits could be taken for automatic controls/sensors
and daylighting controls.  (Inference about the dependability of
lighting sensors/controls??? - I don't know.)
 
Furthermore, VLT (Visible Light Transmittance) is not considered in the
Prescriptive Envelope Option, but it is considered in the Envelope
Trade-off Option, a la Chapter 5 (Sect. 5.3.2.4 and 5.4).
 
Regards,
===================================== 
Larry O. Degelman, P.E.                  larry at taz.tamu.edu 
Prof. Emeritus of Architecture    Ph./Fax: 1-979-696-2506
Texas A&M University
=====================================
 
-----Original Message-----
From: postman at gard.com [mailto:postman at gard.com] On Behalf Of Varkie
Thomas
Sent: Wednesday, January 21, 2004 3:37 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Day-Lighting and DOE2.1E
 
Can day-lighting controls be considered for LEED certification under
"Energy & Atmosphere - Optimize Energy Performance"?  If so where should
the light sensor be located in the space?  Is there any energy code that
allows credit for day-lighting controls? The DOE2 program allows two
light sensors per space.  Supposing the two sensors are located 5 ft and
10 ft from the window.  Is the average daylight at these two points used
in determining the reduction in artificial lighting?
 
The DOE2 program expects zones to have 6 surfaces defined with X,Y,Z
coordinates and reflectance values for day-lighting analysis.  Ignoring
this produces warning messages but the results show a reduction in
artificial lighting energy.  For day-lighting analysis we only enter
into DOE2 the X,Y coordinates of the window origin relative to the wall
and also the wall and window dimensions.  Can we assume that the energy
savings results from the DOE2 program are on the safe side (the actual
energy saved is more) when we use the program without all the surfaces
and coordinates?
 
Are there any rules for day-lighting analysis for establishing energy
savings and for comparing the results from different studies?
 
Varkie Thomas
Skidmore, Owings & Merrill LLP
Tel: (312) 360-4467 (direct)
 
 
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