[bldg-sim] Multiple windows for DF% calculation in Energy-10

[Rob Hitchcock]

Caroline,

A description of the method used by the Daylighting EES Apply is given 
in the Energy-10 Help under the Daylighting section.  You should pay 
particular attention to the "Lighting Zone Default Geometry" section, 
which describes how this Apply method establishes a small daylighting 
zone module on each orientation that is used to calculate daylight 
factors for each orientation.  This means that only those apertures that 
are part of a daylighting zone module will affect the daylight factors 
for that orientation.  Changing the glazing type in other apertures on 
the orientation will not change the daylight factors within the 
established daylighting zone, but WILL change the overall thermal 
gains/losses within the building.  This will result in a mis-match 
between the daylighting and thermal calculation results.

The Apply should only be used for building geometries that have been 
created by the default building generator.  This is not a suitable 
approach for the type of daylighting specific studies you are attempting 
to undertake.  You should manually input your own daylighting zones for 
buildings that are different from the default building, and for 
buildings in which you want to use different glazing types on the facade 
of each orientation.

Rob Hitchcock
===========
Caroline Prochazka wrote:

>I am a graduate student of architecture at the
>University of Waterloo. I am using Energy-10, Ecotect
>and Desktop Radiance to study the role of daylighting
>with respect to heating and cooling energy for two
>existing Canadian 'green' buildings. This posting is
>only one of my many questions, which recently arose
>from closer examination of my models.
>
>ENERGY-10: When applying daylighting, I can only
>specify one window type per orientation for the
>'apply' Daylight EES. This tends to give me reasonable
>DF% values. Once I change the glazing to include more
>than on window type per orientation, the DF% drops
>dramatically, and the trend in the one building I've
>worked on shows heating energy decreasing and lighting
>energy increasing. Cooling is very similar between the
>two cases. How does Energy-10 know WHERE to place the
>windows for daylighting? As the overall glazing:wall
>ratio is roughly the same, I would tend to trust the
>'apply' case more, as it seems to make better use of
>the daylighting information, although this is at the
>cost of a more precise representation of the true
>glazing condition. Is there something I may be
>missing? 
>
>=====
>t.    519.822.3832
>e.    cjprocha at yahoo.com
>web:  http://www.geocities.com/cjprocha
>
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