[Bldg-sim] Interior window creation
Carol Gardner
cmg750 at gmail.com
Thu May 27 16:22:04 PDT 2010
Sunspace Elements
<spaceasasunspaces.htm> <airflowcontrol.htm>
Sunspace Elements
Interior Windows
Interior windows can be specified by following an INTERIOR-WALL command by
one or more WINDOW commands. Interior walls can have windows. The keywords
for interior windows are the same as those for exterior windows, with some
exceptions:
1. The following keywords are unused:
FRAME-WIDTH SETBACK
GLARE-CTRL-PROB SHADING-DIVISION
GLASS-TYPE-SW SWITCH-CONTROL
GND-FORM-FACTOR SWITCH-SCH
INF-COEF SWITCH-SET-HI
LEFT-FIN-A, etc. SWITCH-SET-LO
OVERHANG-A, etc. VIS-TRANS-SCH
RIGHT-FIN-A, etc. WIN-SHADE-TYPE
2. SKY-FORM-FACTOR multiplies the total diffuse radiation incident on an
interior window. If the interior window has a setback (relative to the
sunspace) or there are obstructions inside the sunspace that shade the interior
window, a value of SKY-FORM-FACTOR less than 1.0 should be specified (the
default value is 1.0).
Shading devices on interior windows, like Venetian blinds, drapes, or
pull-down shades, can be simulated via the keywords SHADING-SCHEDULE and
MAX-SOLAR-SCH. Movable insulation on interior windows can be modeled using
keywords CONDUCT-SCHEDULE and CONDUCT-TMIN-SCH.
For an accurate calculation of the solar radiation transmitted by a sunspace
interior window, it is important to specify the X and Y coordinates of the
window. These coordinates are measured with respect to the lower-left hand
corner of the INTERIOR-WALL as viewed in the NEXT-TO space (see “INTERIOR-WALL
Command” in the *DOE-2.2 Dictionary*). The position of exterior
windowsshould also be carefully specified. The program will only
recognize interior
windows in an interior wall between a sunspace and a non-sunspace.
Sliding glass doors can be modeled as interior windows. If the
interiorwall containing the glass door has AIR-FLOW-TYPE =
FREE-DOORWAY (see
WALL-PARAMETERS, below), the door will be assumed to be open and convection
through the opening will be calculated if T(sunspace) - T(adjacent space) >
AIR-FLOW-CTRL-DT.
Additional control of the opening and closing of the door can be obtained by
using SS-FLOW-SCH (see description of ZONE keywords, below).
An unglazed opening in a sunspace interior wall can be input as a
windowwith GLASS-TYPE-CODE = 0. The program will calculate the solar
radiation
passing through the opening by using a transmittance of 1.0 for all angles
of incidence. WALL-PARAMETERS data, described below, would be entered for
the INTERIOR-WALL to specify the convective air flow through the opening.
Interior Doors
Unlike exterior walls, interior walls in cannot have doors. However, an
opaque interior door with a conductance significantly different from the
sunspace interior wall containing it can be input as a separate
interiorwall. Alternatively, the door can simply be ignored if the
conduction
across it is small compared to the overall conduction across the wall. The
program will calculate convection through a fully or partially open door if
AIR-FLOW-TYPE = FREE-DOORWAY and appropriate values of DOORWAY-H and
DOORWAY-W are specified (see WALL-PARAMETERS, below).
Use Glass Type not Shading Coefficient for Sunspaces
You should use GLASS-TYPE-CODE rather than SHADING-COEF for sunspace
exterior windows. This allows the program to accurately calculate the hourly
direct and diffuse radiation transmitted by the glazing. This is not
possible with SHADING-COEF except for standard 1/8" clear glass.
Use Custom Weighting Factors for Sunspaces
Custom Weighting Factors (CWFs) should be used for sunspaces for several
reasons:
1. For high conductance spaces, the precalculated (ASHRAE) weighting
factors overestimate heating and cooling loads. The overestimate can be as
high as 25-30% for heavily glazed spaces.
2. CWFs account for loss of solar gain due to reflection of sunlight
back out of exterior windows.
3. CWFs give a more accurate calculation of the generally large
temperature swings in a solar-driven space.
4. CWFs will automatically be calculated for any space with FLOOR-WEIGHT
= 0 (the default value). Otherwise, the program will use ASHRAE weighting
factors.
Positioning Surfaces
For an accurate calculation of solar radiation falling on the interior walls
of a sunspace, the bounding surfaces of the sunspace need to be
geometrically positioned. This applies to the exterior walls and roofs and
their associated windows, and the interior walls and their associated
windows. We recommend that a sunspace interior wall be defined in the
sunspace rather than in the adjacent room. Otherwise, the adjacent room
must be properly located with respect to the sunspace. If this is not done,
the interior walls and windows will be mispositioned relative to the
sunspace exterior windows, and the projection of solar radiation from the
windows onto the interior walls will be incorrect. This will give a wrong
calculation of the solar radiation transferred from sunspace to room. Even
in this case, there will be no fictitious overall solar gain or loss since
the solar that stays in the sunspace plus that transferred to adjacent rooms
is constrained by the program to equal that entering the sunspace. There
will, however, be an error message if the transferred solar exceeds the
entering solar, which would give a net negative solar gain in the sunspace.
This may occur if interior walls or windows on them overlap, if a multiplier
is used on an interior window, or if a multiplier is used on rooms adjacent
to a sunspace.
Massive Interior Walls
Sunspace interior walls are often fairly heavy, leading to a significant
time delay in the heat transfer across them by conduction. Such walls
should be described by response factors, i.e., with a delayed-type
construction.
The order of defining layers in a delayed interior wall is from "outside" to
"inside", where "outside" is the side of the wall in the NEXT-TO space, and
"inside" is the side in the space in which the wall was defined. If, as
recommended, the interior wall is defined in the sunspace, then the outside
of the wall is the side in the adjacent room.
Delayed conduction through interior walls is calculated only for sunspace
interior walls. For other interior walls the hourly conduction is quick.
Delayed conduction through an interior between two non-sunspaces can be
obtained simply by assigning SUNSPACE = YES to one of the spaces, even
though the space is not actually a sunspace. In this case, If the solar
flux on the "sunspace" side of the wall is small, it is recommended that
INSIDE-SOL-ABS = (0,0) be input for the wall in order to zero out absorption
of solar radiation. Otherwise, all interior and exterior walls and
windowsin the "sunspace" should be geometrically positioned as
described above in
"Positioning of Sunspace Surfaces".
Moisture from Plants and Trees
Atriums often have plants and trees. Moisture transpiring from leaves and
evaporating from soil can produce a significant latent load. You can model
this load using the source keywords in SPACE as follows:
SOURCE-TYPE = PROCESS
SOURCE-LATENT = 1.0
SOURCE-SENSIBLE = 0.0
SOURCE-POWER = [latent load in Btu/hr or W]
SOURCE-SCHEDULE = U-name of schedule
Baffles and Louvers
Baffles and louvers on sunspace exterior windows, which block and/or diffuse
incoming beam radiation, can be modeled as blinds using the WINDOW-LAYERS
keyword in the WINDOW command. See “Window Layers Method” in the
Windowtopic. The blinds can be
interior, exterior or between pane. They can be controlled in different ways
to manage solar gain.
On Thu, May 27, 2010 at 3:54 PM, Nick Caton <ncaton at smithboucher.com> wrote:
> Alan,
>
>
>
> To my understanding, you simply cannot put a window on an interior wall.
> The best approximation may be as follows:
>
> 1. Keep the internal wall in it’s entirety – this will model heat
> transfer to the adjoining space correctly… if it’s a large internal window
> consider adjusting the internal partition’s properties to match the
> effective thermal mass/U-value.
>
> 2. Create a new external wall, of any construction layers, on top of
> the interior wall with the exact (maybe rounded) area of the window
>
> 3. Create a window on that exterior wall with that exact area and
> with matching properties to the real glazing with one exception: Give it a
> ridiculously low U-value to effectively eliminate what would be the modeled
> thermal transfer interactions with the exterior.
>
> 4. Assign window shades to model the solar shading effects of the
> adjacent space (ceiling/walls).
>
>
>
> Best of luck!
>
>
>
> ~Nick
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> *Check out our new web-site @ *www.smithboucher.com* *
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Jackson, Alan
> *Sent:* Thursday, May 27, 2010 5:47 PM
>
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] Interior window creation
>
>
>
> I am attaching the pd2 and inp, just so someone can confirm they get the
> same error. I am on a 64-bit machine so I have been getting weird warnings
> and error to begin with back when I was using the wizard.
>
>
>
> Alan Jackson, LEED AP
> KlingStubbins
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Jackson, Alan
> *Sent:* Thursday, May 27, 2010 6:43 PM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] Interior window creation
>
>
>
> I am attempting to create an interior window to allow solar gains to pass
> through a sunspace to an adjacent space. I am getting to the following
> warning when attempting to create a window component on the interior wall.
>
>
>
>
>
> As a work around I changed the wall to EXTERIOR-WALL in order to add the
> windows then planned on changing back to INTERIOR-WALL but when I open the
> project I get a warning saying “A PARENT EXTERIOR-WALL must be defined
> before ..”
>
>
>
> I know you can create interior windows and use them in conjunction with
> sunspaces as the DOE2 manual specifically calls out this scenario.
>
>
>
> What am I doing wrong?
>
>
>
>
>
> Alan Jackson, LEED AP
> KlingStubbins
>
>
>
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>
--
Carol Gardner PE
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