Transcript EnergyPlus Training Part 1

Lecture 9: Windows and
Daylighting
Material prepared by GARD Analytics, Inc. and University of Illinois
at Urbana-Champaign under contract to the National Renewable Energy
Laboratory. All material Copyright 2002-2003 U.S.D.O.E. - All rights reserved
Importance of this Lecture to the
Simulation of Buildings
 Every building is different in many ways:
 Location/exterior environment
 Construction/building envelope
 Space usage/interior environment
 HVAC system
 Building consume approximately one-third of all
energy used nationally—lighting accounts for about
one third of building energy use
 Daylighting has the potential to significantly reduce
the amount of energy spent on lighting
 Proper modeling of windows is important to both
daylighting studies and energy analysis since it has a
significant impact on both of these areas
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Purpose of this Lecture
Gain an understanding of how to


Specify windows in EnergyPlus
Specify and control daylighting features
within a zone
3
Keywords Covered in this Lecture
 Material:WindowGlass
 Material:WindowGas
 Material:WindowGasMixture
 Material:WindowShade
 Material:WindowBlind
 WindowShadingControl
 WindowFrameAndDivider
 WindowGapAirFlowControl
 Daylighting:Simple and Daylighting:Detailed
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Windows
glass
gas
5
Material:WindowGlass
Non-opaque solid layer used to
construct windows
More examples from DOE-2
library in file
WindowGlassMaterials.idf
MATERIAL:WindowGlass,
SPECTRAL PANE,
!- Name
Spectral,
!- Optical Data Type
SpectralDataSet1, !- Name of Window Glass Spectral Data Set
0.0099,
!- Thickness {m}
0.0, !- Solar Transmittance at Normal Incidence
0.0, !- Solar Reflectance at Normal Incidence: Front Side
0.0, !- Solar Reflectance at Normal Incidence: Back Side
0.0, !- Visible Transmittance at Normal Incidence
0.0, !- Visible Reflectance at Normal Incidence: FrontSide
0.0, !- Visible Reflectance at Normal Incidence: Back Side
0.0, !- IR Transmittance at Normal Incidence
0.84, !- IR Hemispherical Emissivity: Front Side
0.84, !- IR Hemispherical Emissivity: Back Side
0.80; !- Conductivity {W/m-K}
6
Material:WindowGas
Non-opaque gaseous layer used to
construct windows


Gas type can be: Air, Argon, Krypton,
Xenon, or Custom
Custom requires properties (curve fit
coefficients) for conductivity, viscosity, and
specific heat as well as the gas molecular
weight
More examples from DOE-2
library in file
WindowGasMaterials.idf
MATERIAL:WindowGas,
WinAirGap, !- Name
AIR,
!- Gas Type
0.013;
!- Thickness {m}
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Material:WindowGasMixture
Allows a custom mixture of gases to
construct a non-opaque gaseous layer
used for windows


Gas type can be: Air, Argon, Krypton, or
Xenon
User defines up to four gases in mixture
Material:WindowGasMixture,
MyWinGasMix, !- Name
0.0127,
!- Thickness
2,
!- Number of gases in mixture
Air,
!- Gas Type - Gas #1
0.5,
!- Fraction - Gas #1
Argon,
!- Gas Type – Gas #2
0.5;
!- Fraction – Gas #2
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Constructing Windows
Same as a regular construction
definition except using window glass,
window gas, and/or window gas
mixture
CONSTRUCTION,
ELECTRO-CON-DARK,
ELECTRO GLASS DARK STATE,
WinAirGap,
SPECTRAL PANE;
!!!!-
Name
Outside Material Layer
Material Layer #2
Inside Material Layer
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Material:WindowShade
Allows specification of window shades

Becomes part of window shading control
More examples from
DOE-2 library in file
WindowShadeMaterials.idf
MATERIAL:WindowShade,
MEDIUM REFLECT - MEDIUM TRANS SHADE, !- Name
0.4,
!- Solar transmittance
0.5,
!- Solar reflectance
0.4,
!- Visible transmittance
0.5,
!- Visible reflectance
0.9,
!- Thermal emissivity
0.0,
!- Thermal transmittance
0.005, !- Thickness {m}
0.1,
!- Conductivity {W/m-K}
0.05,
!- Shade-to-glass distance {m}
0.5,
!- Top opening multiplier
0.5,
!- Bottom opening multiplier
0.5,
!- Left-side opening multiplier
0.5,
!- Left-side opening multiplier
0.0;
!- Air-flow permeability
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Material:WindowBlind
Allows specification of window blinds

Becomes part of window shading control

Example on next slide…

More examples from DOE-2 library in file
WindowBlindMaterials.idf
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Material:WindowBlind
MATERIAL:WindowBlind,BLIND WITH HIGH REFLECTIVITY SLATS,
HORIZONTAL, !- Slat orientation
0.025, !- Slat width [1"] (m)
0.01875, !- Slat separation [3/4"] (m)
0.001, !- Slat thickness (m)
45.0, !- Slat angle (deg)
0.9,
!- Slat conductivity (W/m-K)
0.0,
!- Slat beam solar transmittance
0.8,
!- Slat beam solar reflectance, front side
0.8,
!- Slat beam solar reflectance, back side
0.0,
!- Slat diffuse solar transmittance
0.8,
!- Slat diffuse solar reflectance, front side
0.8,
!- Slat diffuse solar reflectance, back side
0.0,
!- Slat beam visible transmittance
0.8,
!- Slat beam visible reflectance, front side
0.8,
!- Slat beam visible reflectance, back side
0.0,
!- Slat diffuse visible transmittance
0.8,
!- Slat diffuse visible reflectance, front side
0.8,
!- Slat diffuse visible reflectance, back side
0.0,
!- Slat IR (thermal) hemispherical transmittance
0.9,
!- Slat IR (thermal) hemispherical emissivity, front side
0.9,
!- Slat IR (thermal) hemispherical emissivity, back side
0.050, !- Blind-to-glass distance
0.5,
!- Blind top opening multiplier
0.5,
!- Blind bottom opening multiplier
0.5,
!- Blind left-side opening multiplier
0.5,
!- Blind right-side opening multiplier
,
!- Minimum slat angle (deg)
;
!- Maximum slat angle (deg)
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WindowShadingControl
Referenced by exterior window surface
definitions
Shading types:



Shade (interior, exterior, or between
glass)—WindowShade
Blind (interior, exterior, or between glass)—
WindowBlind
Switchable glazing
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WindowShadingControl (cont’d)
 Reference to either a construction or a
material name
 Many shading control variations:





Always on or off or on as per schedule
On if high solar, glare, air temperature, cooling
load, or combinations of these
Meet daylighting illuminance setpoint
On at night if heating required or low
temperatures with various daytime controls
Off at night while on during daytime for cooling
conditions and high solar on windows
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WindowShadingControl (cont’d)
Other controls

Various setpoints

Glare control

Several control options for blind slat angles
WINDOWSHADINGCONTROL,
WIN-CONTROL-GLARE,
SwitchableGlazing,
ELECTRO-CON-DARK,
OnIfHighGlare,
,
0.0,
NO,
YES,
,
,
;
!!!!!!!!!!!-
User Supplied Shading Control Name
Shading Type
Name of construction with shading
Shading Control Type
Schedule Name
Solar/Load/Temp SetPoint {W/m2, W or deg C}
Shading Control Is Scheduled
Glare Control Is Active
Material Name of Shading Device
Type of Slat Angle Control for Blinds
Slat Angle Schedule Name
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WindowFrameAndDivider
Used to define information about
frames and dividers
Can be significant portion of heat
transfer characteristics of window
Includes physical properties (width,
projections, number of dividers) as well
as thermal properties
Example on next slide…
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WindowFrameAndDivider
(cont’d)
WindowFrameAndDivider,
TestFrameAndDivider, !- User Supplied Frame/Divider Name
0.05, !- Frame Width {m}
0.05, !- Frame Outside Projection {m}
0.05, !- Frame Inside Projection {m}
5.0, !- Frame Conductance {W/m2-K}
1.2, !- Ratio of Frame-Edge Glass Conductance to Center-Of-Glass Co
0.8, !- Frame Solar Absorptance
0.8, !- Frame Visible Absorptance
0.9, !- Frame Thermal Hemispherical Emissivity
DividedLite, !- Divider Type
0.02, !- Divider Width {m}
2,
!- Number of Horizontal Dividers
2,
!- Number of Vertical Dividers
0.02, !- Divider Outside Projection {m}
0.02, !- Divider Inside Projection {m}
5.0, !- Divider Conductance {W/m2-K}
1.2, !- Ratio of Divider-Edge Glass Conductance to Center-Of-Glass
0.8, !- Divider Solar Absorptance
0.8, !- Divider Visible Absorptance
0.9; !- Divider Thermal Hemispherical Emissivity
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WindowGapAirFlowControl
Used to allow ventilation of air gap in
windows with either inside or outside air
Air can be vented to inside or outside
Can be scheduled
WindowGapAirflowControl,
!!Zn001:Wall001:Win002, !InsideAir,
!OutsideAir,
!0.008,
!!AlwaysOnAtMaxFlow,
!No,
!;
!-
Used to control forced airflow through a gap
between glass layers
Name of Associated Window
Airflow Source
Airflow Destination
Maximum Airflow (m3/s per m of glazing width)
(5.2 cfm for 1m x 1m window)
Airflow Control Type
Airflow Has Multiplier Schedule?
Name of Airflow Multiplier Schedule
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Daylighting
DAYLIGHTING:SIMPLE

Specify useful fraction of solar gain
DAYLIGHTING:DETAILED

Calculates illuminance
Only one type per zone
May use different types in same run
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Daylighting:Simple
Effectiveness method

Fraction beam usable

Fraction diffuse usable

Schedule
LIGHTS

Fraction replaceable

All lights on one control
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Daylighting:Simple
Light
Control
Sensible and Latent
Beam Solar
Sky
Diffuse
Ground
Diffuse
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Daylighting:Detailed
Methodology
Calculated illuminance level
External factors

Sky condition

Sun position

Ground reflectance

External shading and obstructions
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Daylighting:Detailed
Methodology (cont’)
Window factors
 Size
 Position
 Transmittance
 Shades
Internal factors
 Interior surface visible absorptance
 Position of daylighting reference point
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Daylighting:Detailed
Light
Control 1
Light
Control 2
Uncontrolled
Sensible and Latent
Beam Solar
Sky
Diffuse
Reference Pt 2
Ground
Diffuse
Reference Pt 1
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Daylighting Calculation
Daylight factors






Ratios of interior illuminance or luminance to
exterior horizontal illuminance
Contribution of direct light from each window to
each reference point
Contribution of reflected light from walls, floor
and ceiling
Window luminance and window background
luminance used to determine glare
Factors calculated for hourly sun positions on
sun-paths for representative days of the run
period
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Daylighting Calculation (cont’d)





Daylighting calculation performed each heatbalance time step when the sun is up
Daylight factors at each reference point
interpolated using the current time step’s sun
position and sky condition
Illuminance found by multiplying daylight factors by
exterior horizontal illuminance
If glare control, then automatically deploy window
shading, if available, to decrease glare below a
specified comfort level
Similar option uses shades to control solar gain
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Electric Lighting Control





Electric lights full-on assumed to provide the
setpoint illuminance – regardless of schedule
Electric lighting control system simulated to
determine fraction of lighting for each lighting zone
Based on daylighting illuminance level regardless of
actual electric lighting input power
Zone lighting electric reduction factor passed to
thermal calculation
Heat gain from lights and power input reduced
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Continuous Dimming
1.0
Increasing daylight
illuminance
Zero daylight
illuminance
Fractional
light output
Minimum light
output fraction
0
0
1.0
Fractional input power
Minimum input power fraction
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Stepped Lighting Control
Step 1
1.0
Step 2
Fractional
input power
Step 3
0
0
Daylight illuminance
Illuminance set point
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Daylighting:Detailed Inputs
 1 or 2 illuminance reference points
 Specific point(s) in zone (X,Y,Z position)
 Zone coordinate system – relative to zone origin
 If zone origins are all 0,0,0, then equivalent to
world coordinates
 1 to 3 lighting zones
 Controlled by reference point 1
 Controlled by reference point 2
 Uncontrolled
 Specify fraction of lighting power for each zone
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Daylighting:Detailed Inputs
(cont’d)
Illuminance setpoint(s) [lux]
Lighting control type

Continuous – stay on at minimum

Continuous – turn off at minimum

Stepped – automatic

Stepped – manual with probability

Minimum lighting output and power levels
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Daylighting:Detailed Inputs
(cont’d)
Glare control of window shades

Direction of view

Maximum glare level
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Daylighting:Detailed Example
DAYLIGHTING:DETAILED,
Zone 2,
1,
2.5, 2, 0.8,
2.5, 8, 0.8,
0.4,
0.4,
!!!!!!-
Zone Name
Total Daylighting Reference Points
X,Y,Z-coordinates of first reference point {m}
X,Y,Z-coordinates of second reference point {m}
Fraction of zone controlled by first ref. point
Fraction of zone controlled by second ref. point
500,
500,
1,
0,
0,
22,
0.3,
!!!!!!!-
Illuminance setpoint at first reference point {lux}
Illuminance setpoint at second reference point {lux}
Lighting control type
Azimuth angle of view direction clockwise from
zone y-axis (for glare calculation) {deg}
Maximum allowable discomfort glare index
Minimum input power fraction for continuous control
0.2,
1,
1;
!- Minimum light output fraction for continuous control
!- Number of steps (excluding off) for stepped control
!- Probability lighting will be reset in manual control
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Ground Reflectance
GroundReflectance
12 monthly values
Affects:

Solar gains

Daylighting
Snow Ground Reflectance Modifiers
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Daylighting Modeling Guidelines
Do not use window multipliers
 Different window positions would be lost
Zone multipliers
 Beneficial to get room proportions correct
 Can only use if external shading not
affected by zone position
Interior surfaces within a zone do not
block direct light for daylighting calcs
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Representative Room
with Zone Multiplier
Zone Multiplier = 4
IW-3
IW-1
IW-2
Room-1
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Model Unique Rooms as
Individual Thermal Zones
A
C
D
B
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Multiple Lighting Zones
Second Reference Point
Fraction of Zone Controlled by
Second Reference Point = 0.5
First Reference Point
Fraction of Zone Controlled by
First Reference Point = 0.5
38
Daylighting in
Part of a Thermal Zone
B
A
C
D
Interior window –
no daylighting
passes through
First Reference Point
Exterior window
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Shading Surfaces for Daylighting
 Opaque
 No daylight transmitted
(according to manual, I/O ref. pp 191-192)
 However, shadowing surface transmittance
schedule does impact daylighting currently in
some cases (may be a bug)
 Black
 Do not reflect light
 For example, reflection from top of overhang onto
window above not calculated
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Summary
Windows are a means of providing solar
heat gain and natural lighting to spaces
within a building
EnergyPlus requires specification of the
composition of window components as
well as any shading strategy being used
Daylighting calculations can show the
possible reduction in electric lighting
41