southern piedmont community college analysis
DESCRIPTION
Professional shading analysis and report.TRANSCRIPT
Southern Piedmont Community College:Schematic Daylighting Design
26 August 2009
Architect:
Morris • Berg Architects6101 Carnegie Boulevard,Suite 101Charlotte, NC 28209-4641
Contents – 2
Document SummaryBase Case
Student Commons Workplane Rendering 4Intuitive Case
Student Commons Workplane Rendering 5Base Case 6Typical Office Workplane Rendering 6
Intuitive CaseTypical Office Workplane Rendering 7
Student CommonsDaylight factor 8UDI percentage 9Glare reduction, energy cost, & emissions graphs
10Typical Office Bay
Spaces 1, 2, & 3 11Spaces 4, 5, & 6 12Glare reduction, energy cost, & emissions graphs
13Base Case
1st floor 141st floor, with shading 152nd floor 162nd floor, with shading 173rd floor 183rd floor, with shading 19
Intuitive Case1st floor 201st floor, with cupola 212nd floor 222nd floor, with cupola 233rd floor 243rd floor, with cupola 25
Table of Contents
Appendix ADirect Solar Penetration 1 26Direct Solar Penetration 2 27
Appendix BGlossary of Terms 28
Appendix CGeneral Building Energy Model Info 29
Appendix DEnergy Model Results: Percentage Improvement for Student Commons 30
Appendix EBaseline and Proposed Design Input Parameters For All Spaces 31
Appendix FSection through cupola 32
Contents – 3
AnalysisThe premise for this analysis was to achieve a minimum daylight factor of 2 within the spaces while simultaneously controlling glare and solar heat gain on the window wall. Simulating an overcast sky condition shows how well the shading would perform and affect the daylighting opportunities in the worst case scenario. Implementing the shading devices shown reduced the contrast ratio from the window wall to the back of the space significantly, while still providing daylighting opportunities within both spaces. The addition of the lightshelf along with the exterior shading devices improved the uniform distribution of light within the space, as well as blocking direct solar penetration from the top 1/3 of the window wall into the space.
With the shading devices in place, the simulation predicts an annual savings of 60% during the course of the year.
Analysis Parameters:An average overcast sky condition was simulated. The •
sky vault simulated has an output of 1800 footcandles, which is the average overcast sky condition for this region.
A typical office quadrant and a structural bay from the • student commons area were simulated. Radiance was used to perform all simulations.
A weighted average of 60% visual light transmittance • was used for all glazing types. All interior surface reflectance was based on the IES standards. The reflective values used were as follows: 60% reflective wall surfaces, 85% reflective ceilings, and 30% reflective floor materials.
A line of sight was used to diagram how the view • window would be shaded, but still allow the occupant within the space to have a visual connection to the exterior. In the shading schematic for the student commons, a slightly different approach was taken regarding the placement and number of shading devices. The scale of the window wall to the interior of the space called for more shading devices on the exterior to provide optimal sun control and glare reduction. The spacing for the lower shading devices came from the rhythm of the mullion spacings above, and the proportions of the mullions were used to determine the distance between the devices. These device fit within the facade design while providing excellent sun control.
Note:There is a reduction in the amount of area that would be equal to or greater than a daylight factor of 2 simply because the shades block about 90% of the direct solar penetration. Even though there is a reduction in overall area, this is not a negative aspect of the shading device. The benefits of glare and heat gain reduction outweigh the slight loss in daylight factor. The occupant’s visual comfort would be much better with the shading devices being suggested. Also, this analysis does not engage the LEED metric of daylighting within either of these spaces. The daylight factor of 2 is simply being used to assess the daylighting performance within the spaces, and begin to compare the base case against the intuitive case.
Document Summary
Contents – 4
Base case workplane rendering of typical office bayFigure 1:
Base Case Typical Office Workplane Rendering
Contents – 5
Intuitive case workplane rendering of typical office bayFigure 2:
Section through Figure 3: typical student commons bay. See Appendix A for more information.
Section through Figure 4: typical office window. See Appendix A for more information.
Intuitive CaseTypical Office Workplane Rendering
Contents – 6
Typical Office BaySpaces 4, 5, & 6
Diagrammatic key plan of typical office bayFigure 6:
Useful Daylight Indeces
0
10
20
30
40
50
60
70
80
90
100
3 6 9 12
Feet from window wall
Perc
enta
ge o
f tim
e UDI (100<%<2000 Lux)
UDI (%<100 Lux)
UDI (%>2000 Lux)
Useful Daylight Indeces
0
10
20
30
40
50
60
70
80
90
100
3 6 9 12
Feet from window wall
Perc
enta
ge o
f tim
e
UDI (100<%<2000 Lux)
UDI (%<100 Lux)
UDI (%>2000 Lux)
Useful Daylight Indeces
0
20
40
60
80
100
120
3 6 9 12
Feet from window wallPe
rcen
tage
of t
ime UDI (100<%<2000 Lux)
UDI (%<100 Lux)
UDI (%>2000 Lux)
4 5 6
These values are shown below as the percentage of Figure 5: time throughout the year that the simulated sensor within the space would fall inside the UDI recommended range of 20-200 footcandles. The points were evenly spaced from the window wall to the back of the room.
%Below %UDI %Above
Space 42 62 373 84 133 90 79 82 9
Space 51 68 302 76 222 86 113 86 11
Space 6100 0 0100 0 0100 0 0100 0 0
6 15 234
N
Contents – 7
ENERGY MODEL RESULTS: Glare Reduction Graph of Typical Office Bay
DF
Distance from Window Wall (ft)
Maximum recommended contrast ratio metric: 6:1 Glare reduced by: 58%
19 of 21
Typical Office BayGlare reduction, energy cost, & emissions graphs
Maximum recommended contrast ratio metric: 6:1Glare reduced by: 58%
Base Case Annual Cost133.51548
Intuitive Case Annual Cost
116.44
105
110
115
120
125
130
135
Cost
($)
Cost Comparison
Base Case Annual
Emissions2943.512473
Intuitive Case Annual
Emissions2567.062579
2300
2400
2500
2600
2700
2800
2900
3000
Lbs
of C
O2
Emissions Comparison
Base Case Annual
Electricity Usage
1335.1548Intuitive Case
Annual Electricity
Usage1164.4
1050
1100
1150
1200
1250
1300
1350
kWh
Usage Comparison
Base Case100.0% Intuitive Case
87.2%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
Overall Reduction (%)
Contents – 8
Typical Office BaySpaces 1, 2, & 3
Useful Daylight Indeces
0
20
40
60
80
100
120
3 6 9 12 15 18
Feet from window wall
Perc
enta
ge o
f tim
e UDI (100 % 2000 Lux)UDI (%<100 Lux)UDI (%>2000 Lux)
Useful Daylight Indeces
0
20
40
60
80
100
120
3 6 9 12 15 18
Feet from window wall
Perc
enta
ge o
f tim
e
27 83 96 94 92 90UDI (%<100 Lux)UDI (%>2000 Lux)
Useful Daylight Indeces
0
20
40
60
80
100
120
3 6 9 12
Feet from window wallPe
rcen
tage
of t
ime UDI (100<%<2000 Lux)
UDI (%<100 Lux)UDI (%>2000 Lux)
1 2 3
Diagrammatic key plan of typical office bayFigure 8:
These values are shown below as the percentage of Figure 7: occupied time throughout the year that the simulated sensor within the space would fall inside the Useful Daylight Index (UDI) recommended range of 10-200 footcandles. The points were evenly spaced from the window wall to the back of the room.
%Below %UDI %Above
Space 13 93 42 92 52 98 02 96 22 92 63 97 0
Space 20 27 732 83 164 96 06 94 08 92 010 90 0
Space 34 96 07 93 06 94 010 90 0
6 15 234
N
Contents – 9
Student CommonsGlare reduction, energy cost, & emissions graphsENERGY MODEL RESULTS: Glare Reduction Graph for the Student Commons
DF
Distance from Window Wall (ft)
Maximum recommended contrast ratio metric: 6:1 Glare reduced by: 68%
9 of 21
Maximum recommended contrast ratio metric: 6:1Glare reduced by: 68%
Base Case Annual Cost
368.877
Intuitive Case Annual Cost
82.440
50
100
150
200
250
300
350
400
Cost
($)
Cost Comparison
Base Case Annual
Emissions8132.345782
Intuitive Case Annual
Emissions1817.490888
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
Lbs
of C
O2
Emissions Comparison
Base Case Annual
Electricity Usage
3688.77Intuitive Case
Annual Electricity
Usage824.4
0
500
1000
1500
2000
2500
3000
3500
4000
kWh
Usage Comparison
Base Case100.0%
Intuitive Case22.3%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
Overall Reduction (%)
Analysis – 10
Base case workplane Figure 9: rendering of student commons.
Percentage of DF at or above 2:Student Commons- 65%Typical office bay- 75%
Base CaseStudent Commons Workplane Rendering
Analysis – 11
Intuitive CaseStudent Commons Workplane Rendering
Intuitive case Figure 10: workplane rendering of student commons
Percentage of DF at or above 2:Student Commons- 35%Typical office bay- 40%
Analysis – 12
Diagrams showing the contrast ratio reduction due to Figure 11: shading devices
Diagrams showing the contrast ratio reduction due to Figure 12: shading devices
5.914973
2.884423
2.090326
2.234863
1.616089
1.315138
1.107564
1.050896
Student CommonsDaylight factor
Daylight factors shown in plan view for the student Figure 13: commons
Analysis – 13
These values are shown below as the percentage of time throughout the year that the simulated sensor within the space would fall inside the UDI recommended range of 20-200 footcandles. The points were evenly spaced from the window wall to the back of the room.
Student CommonsUDI percentage
%Below %UDI %Above
1 68 323 97 04 96 05 95 05 95 06 94 07 93 07 93 00 3 97
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46
Perc
enta
ge o
f tim
e
Feet from window wall
Useful Daylight IndecesUDI (100 < % < 2000 Lux)
UDI (%<100 Lux)
UDI (%>2000 Lux)
Analysis – 14
Base Case1st floor
Figure 14:
Analysis – 15
Base Case1st floor, with shading
Figure 15:
Analysis – 16
Base Case2nd floor
Figure 16:
Analysis – 17
Base Case2nd floor, with shading
Figure 17:
Analysis – 18
Base Case3rd floor
Figure 18:
Analysis – 19
Base Case3rd floor, with shading
Figure 19:
Analysis – 20
Intuitive Case1st floor
Figure 20:
Analysis – 21
Intuitive Case1st floor, with cupola
Figure 21:
Analysis – 22
Intuitive Case2nd floor
Figure 22:
Analysis – 23
Intuitive Case2nd floor, with cupola
Figure 23:
Analysis – 24
Intuitive Case3rd floor
Figure 24:
Analysis – 25
Intuitive Case3rd floor, with cupola
Figure 25:
Analysis – 26
Shading EffectivenessStudent Commons
100.00 100.00 100.00 100.00 100.00 100.00
21.86
0.76
35.73
19.36
65.12
6.91
0.00
20.00
40.00
60.00
80.00
100.00
120.00
Window Transmitted Solar
Window Transmitted Beam Solar
Window Transmitted Diffuse Solar
Window Heat Gain Window Heat Loss Total Heat Gain
Cooling Season Comparison
Base Case Intuitive Case
Analysis – 27
Shading EffectivenessStudent Commons
Base Case Annual Cost
4.409276425
Intuitive Case Annual Cost0.3046614
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Cost
($)
Cost Comparison
Base Case Annual
Emissions97.20790544 Intuitive Case
Annual Emissions
6.7166341390
20
40
60
80
100
120
Lbs
of C
O2
Emissions Comparison
Base Case Annual
Electricity Usage
44.09276425Intuitive Case
Annual Electricity
Usage3.046614
0
5
10
15
20
25
30
35
40
45
50
kWh
Usage Comparison
100.0%
6.9%
0.0%
20.0%
40.0%
60.0%
80.0%
100.0%
120.0%
Usage Comparison
Base Case Intuitive Case
Analysis – 28
Shading EffectivenessPlan and Section
Analysis – 29
Shading EffectivenessPerspective
Analysis – 30
Shading EffectivenessStudent Commons
Clear Sky Condition
Overcast Sky Condition: 1800 fc
Analysis – 31
Shading EffectivenessStudent Commons
Analysis – 32
Shading EffectivenessStudent Commons
Analysis – 33
Line of Sight
Appendix ADirect Solar Penetration 1
Base Window Diagram March 1 – March 21, 9am
This set of images speaks about the impact of the proposed shading device on the window wall. These images show the shading device’s effectiveness beginning on March 1st at 9am and continuing until April 1st at 9am. The shading devices are shown to work in conjunction with an automated shade screen system that would counteract the extreme low angle solar penetration in the winter months. The shading devices
march 21
march 1
Line of Sight
35 Degree Sun angLe
30 Degree Sun angLe
are designed to decrease the amount of direct solar radiation on the window wall during the cooling season, and the automated shading device is implemented to reduce glare at the window wall during the heating season. Careful thought was placed into the depth and angle of the shading device to maximise the occupant’s view outward while minimizing harsh glare at the window wall. These shades block roughly
80% of direct solar penetration on the view window by March 1st and 90% by on the view window by April 1st while still allowing for a comfortable view to the exterior.
Analysis – 34
Direct Solar Penetration 2
March 21 – April 1, 9am December 21, 8am
Line of Sight
December 2110 Degree Sun angLe
march 21
apriL 1
Line of Sight
35 Degree Sun angLe
40 Degree Sun angLe
Analysis – 35
Daylight Factor (DF):The daylight factor is a ratio of the measured interior illuminance to the exterior luminance of a uniform sky vault. For example, a DF of 2 means that the interior space has a value that is 2% of the exterior luminance.
Potential Daylit Area:In this case, the potential daylit area is amount of total floor area that would be easily daylit using only the window wall.
Energy Cost Formula:This formula is used to estimate the cost savings of using daylight to illuminate the space. The formula is as follows:(Total kWh) (Cost per kWh) (Yearly Occupancy Hours)= Total Cost
Contrast Ratio:The contrast ratio is used to quantify issues of glare within the space. The contrast ratio is the DF at the window wall compared to the DF at the back of the space. Ratios greater than 10:1 should be avoided; the metric used for these simulations was 6:1.
Daylight Autonomy:Daylight autonomy is the percentage of time of the year that a specific space has sufficient enough daylighting, and does not require electric lighting. Percentages between 50 and 70 are excellent.
Usable Daylight Index (UDI):The usable daylight index shows the percentage of occupied time containing of a certain range of illuminance
Appendix BGlossary of Terms
values. A range of 100-2000 lux (10-200 footcandles) is used for the simulations.
Window to Floor Area Ratio:The window to floor area ratio measures the percentage of floor area that is glazed on the window wall. For example, if the floor area was 100 ft2 and there was a 5’x8’ window perpendicular to the floor, the window to floor area ratio would be 40%.
Analysis – 36
Appendix CGeneral Building Energy Model InformationGENERAL BUILDING ENERGY MODEL INFORMATION
Project Information Project Name: Southern Piedmont Community College SCO ID #: Project Address: Date: 7/27/09 Designer of Record: Morris+Berg Architects Telephone: (704) 552-5800Contact Person: Todd Berg Telephone: (704) 552-5800City: Charlotte
Weather Data: Overcast Sky (1800 footcandle output) Climate Zone: Humid sub-tropical
Typical Space Summary
Building Use
Potential Daylight Area
(sf at or above DF of 2)*
Total Area (sf)
Percentage (%)
Office (Open Plan) Office (Executive/Private) 267 742 36 Lobby Restrooms Conference Rooms Classrooms Laboratories Assembly Areas Dormitories Other (Student Commons) 1148 2050 56
TOTAL (sf) 1415 2792 51 Note: All spaces above are typical bays and spaces
Simulation Programs
Radiance DAYSIM
*See Glossary in back
4 of 21
* See Appendix B
Analysis – 37
Appendix DEnergy Model Results: Percentage Improvement for Student CommonsENERGY MODEL RESULTS: Percentage Improvement for Student Commons
Performance Rating for Student Commons
Energy and Daylight Control Summary
Base Case Analysis Intuitive Case Analysis
Analysis Type Area (ft2)
Ratios Percentage (%)
Area (ft2)
Ratios Percentage (%)
Daylit area (30-50 footcandles)*
800 717.5
Area below DF of 2 717.5 1332.5 Area at or above DF of 2 1332.5 717.5 Daylight Autonomy* 95 90 Useable Daylight Index* 88 76 Contrast Ratio* <19:1 6:1 Glare Reduction 0 68 Window-to-Floor Area (%)* 26.5 26.5
Emissions Produced (CO2)
7091.05 lbs
1817.49 lbs
All parameters used for the simulations that resulted in the conclusions above and below can be found on page 5.
Base Case Intuitive Case % Improvement
Type Energy
UsekWh
Energy Cost [$/yr]
Energy UsekWh
Energy Cost [$/yr]
Energy (%)
Cost (%)
Energy Use (Regulated and Unregulated)*
Electricity 2050 $321.64 824.4 $82.44 60% $239.20
Total Emissions Saved (CO2)
5273.56 lbs
Percentage Improvement = 100 X [1 – (proposed Building Performance / Baseline Building Performance)] *See Glossary in back
5 of 21
* See Appendix B
Analysis – 38
Appendix EBaseline and Proposed Design Input Parameters For All SpacesBASELINE AND PROPOSED DESIGN INPUT PARAMETERS FOR ALL SPACES
Simulation Parameters
Comparison of Multiple Design Scenarios
Building Scenarios Base Case Scenario
Intuitive Case Scenario
Advanced Case Scenario
Envelope Components
Daylight Glazing Type N/A SB 70 SB 70 XL
View Glazing Type SB 60 SB 50 SB 50
Floor Reflectance 20% 30% 30%
Wall Reflectance 50% 60% 60%
Ceiling Reflectance 70% 85% 90%
Exterior Shading Devices N/A Yes Yes
Automated Interior Shade Screens N/A Yes Yes
Window-to-Floor Area (%)* 3.5 to 1 3.5 to 1 3.5 to 1
Daylight Glazing Visual Light Transmittance N/A .63 .70
Daylight Glazing U-factor N/A .26 .29
Daylight Glazing SHGC N/A .38 .27
View Glazing Visual Light Transmittance .70 .52 .52
View Glazing U-factor .29 .29 .29
View Glazing SHGC .44 .32 .32
Reduction in Glazing Area (%) 0% 0% 0%
Interior Light Shelves N/A Yes Yes
Control Systems
Lighting Power Density 1.0 kWh/ft2 1.0 kWh/ft2 1.0 kWh/ft2
Daylighting Controls N/A Stepped Dimming
Occupancy Sensor Controls N/A Yes Yes
Dimmable Ballasts N/A N/A Yes
6 of 21
* See Appendix B
Analysis – 39
Appendix FSection through cupola
Analysis – 40
Analysis – 41
Analysis – 42