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



Title: specific energie in office buildings

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@xxxxxxxxxxxx

Prof. Emeritus of Architecture    Ph./Fax: 1-979-696-2506

Texas A&M University

=====================================

 

-----Original Message-----
From: postman@xxxxxxxx [mailto:postman@xxxxxxxx] On Behalf Of Varkie Thomas
Sent: Wednesday, January 21, 2004 3:37 PM
To: BLDG-SIM@xxxxxxxx
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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