[Bldg-sim] Interior window creation
Nick Caton
ncaton at smithboucher.com
Thu May 27 16:50:17 PDT 2010
I stand happily corrected!
If I could go back in time, I'd tell myself to ask more questions like
this - I sometimes feel chock-full of needlessly complicated and
drawn-out procedures!
~Nick
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: Carol Gardner [mailto:cmg750 at gmail.com]
Sent: Thursday, May 27, 2010 6:22 PM
To: Nick Caton
Cc: Jackson, Alan; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Interior window creation
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 windows should 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 interior
wall 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 window
with 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 interior
wall. 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 windows in 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 Window topic. 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
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
<http://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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