There is some incorrect information in
this post. “U-value” per se does have a well-defined meaning
in the context of fenestration product rating (e.g. vertical orientation, solar
at normal incidence, standard winter/summer conditions), but during the EnergyPlus’s
timestep calculations, the tilt and solar incidence angles make a big a
difference. In E+, window performance is a function of tilt for
convection calculations both inside the glazing cavities (see ISO 15099) and
along the room-siden of the window or skylight. The implications of tilt
and solar beam incidence angle are as documented in the engineering reference
section “Calculation of Angular Properties”.
From:
EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Tasos Ioannou
Sent: Monday, February 16, 2009
12:02 PM
To:
EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support]
Heat transmittance question
|
The U value has got nothing to do with the
position of the window. The U value is always the same regardless of the
position of the window since it has got to do with the material of the glass
pane and the nature of the air gap of the window. The position of the window
though, has a different effect in the zone's heating or cooling demand since
it has an effect on the solar gains but apart from that the U value is always
the same. If you make a window the U value will be stored from the EnergyPlus
or DesignBuilder and the different positions of this window mayindeed have a
different effect in your simulation but not due to the change in the
U-value. From: Michele
Martinello <michele.martinello@
Passa a Yahoo! Mail. |
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