Southern Piedmont Community College: Schematic Daylighting Design 26 August 2009
Architect: Morris • Berg Architects 6101 Carnegie Boulevard, Suite 101 Charlotte, NC 28209-4641
Table of Contents Document Summary Base Case Student Commons Workplane Rendering Intuitive Case Student Commons Workplane Rendering Base Case Typical Office Workplane Rendering Intuitive Case Typical Office Workplane Rendering Student Commons Daylight factor UDI percentage Glare reduction, energy cost, & emissions graphs
4 5 6 6 7 8 9 10
Typical Office Bay Spaces 1, 2, & 3 Spaces 4, 5, & 6 Glare reduction, energy cost, & emissions graphs
11 12 13
Base Case 1st floor 1st floor, with shading 2nd floor 2nd floor, with shading 3rd floor 3rd floor, with shading Intuitive Case 1st floor 1st floor, with cupola 2nd floor 2nd floor, with cupola 3rd floor 3rd floor, with cupola
Contents – 2
14 15 16 17 18 19 20 21 22 23 24 25
Appendix A Direct Solar Penetration 1 26 Direct Solar Penetration 2 27 Appendix B Glossary of Terms 28 Appendix C General Building Energy Model Info 29 Appendix D Energy Model Results: Percentage Improvement for Student Commons 30 Appendix E Baseline and Proposed Design Input Parameters For All Spaces 31 Appendix F Section through cupola 32
Document Summary Analysis The 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.
Contents – 3
• 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.
Base Case Typical Office Workplane Rendering
Figure 1: Base case workplane rendering of typical office bay
Contents – 4
Intuitive Case Typical Office Workplane Rendering
Figure 2: Intuitive case workplane rendering of typical office bay
Figure 3: Section through typical student commons bay. See Appendix A for more information.
Contents – 5
Figure 4: Section through typical office window. See Appendix A for more information.
Typical Office Bay Spaces 4, 5, & 6
6
5
4
3
2
1
Figure 6: Diagrammatic key plan of typical office bay
N
Figure 5: 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.
Useful Daylight Indeces
%UDI
%Above
Space 4 2 3 3 9
62 84 90 82
37 13 7 9
Space 5 1 2 2 3
68 76 86 86
30 22 11 11
Space 6 100 100 100 100
0 0 0 0
0 0 0 0
Useful Daylight Indeces
100
100
90
90
80
80
Useful Daylight Indeces 120
100
70
60
UDI (%<100 Lux) UDI (%>2000 Lux)
50 40
UDI (%<100 Lux)
40 30
20
20
10
10
3
6
9
Feet from window wall
Contents – 6
12
4
UDI (%>2000 Lux)
50
30
0
80 UDI (100<%<2000 Lux)
60
Percentage of time
UDI (100<%<2000 Lux)
Percentage of time
70
Percentage of time
%Below
UDI (100<%<2000 Lux) UDI (%<100 Lux) UDI (%>2000 Lux)
60
40
20
0 3
6
9
Feet from window wall
12
5
0 3
6
9
Feet from window wall
12
6
Typical Office Bay Glare reduction, energy cost, & emissions ENERGY MODEL RESULTS: Glare Reductiongraphs Graph of Typical Office Bay
Cost Comparison 135 130
Cost ($)
125 120
Base Case Annual Cost 133.51548
115 Intuitive Case Annual Cost 116.44
110 105
Emissions Comparison
DF
3000 2900
Lbs of CO2
2800 2700 2600 2500
Base Case Annual Emissions 2943.512473
2400
Intuitive Case Annual Emissions 2567.062579
2300
Usage Comparison 1350 1300
Maximum recommended contrast ratio metric: 6:1 Glare reduced by: 58%
Maximum recommended contrast ratio metric: 6:1 Glare reduced by: 58%
kWh
1250
Distance from Window Wall (ft)
1200 1150
Base Case Annual Electricity Usage 1335.1548
1100 1050
Intuitive Case Annual Electricity Usage 1164.4
Overall Reduction (%) 100.0% 90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0%
Contents â&#x20AC;&#x201C; 7
10.0%
Base Case 100.0%
Intuitive Case 87.2%
Typical Office Bay Spaces 1, 2, & 3
5
4
3
2
1
Figure 8: Diagrammatic key plan of typical office bay
N
Figure 7: These values are shown below as the percentage of occupied time throughout the year that the simulated sensor within the space would fall inside the Useful Daylight Index (UDI) recommended range of 10-200 footcandles. The points were evenly spaced from the window wall to the back of the room.
Useful Daylight Indeces
100
Percentage of time
Percentage of time
Space 1 3 2 2 2 2 3
93 92 98 96 92 97
4 5 0 2 6 0
Space 2 0 2 4 6 8 10
27 83 96 94 92 90
73 16 0 0 0 0
Space 3 4 7 6 10
96 93 94 90
0 0 0 0
Useful Daylight Indeces
120
120
100
100
80
UDI (100 % 2000 Lux) UDI (%<100 Lux) UDI (%>2000 Lux)
60
%Above
Useful Daylight Indeces
120
80
%UDI
80 27 83 96 94 92 90 UDI (%<100 Lux) UDI (%>2000 Lux)
60
Percentage of time
6
%Below
UDI (100<%<2000 Lux) UDI (%<100 Lux)
40
40
40
20
20
20
0 3
6
9
12
Feet from window wall
Contents – 8
15
18
1
0 3
6
9
12
Feet from window wall
15
18
2
UDI (%>2000 Lux)
60
0 3
6
9
Feet from window wall
12
3
Student Commons Glare reduction, energy cost, & emissions graphs
ENERGY MODEL RESULTS: Glare Reduction Graph for the Student Commons Cost Comparison 400 350 300
Cost ($)
250 Base Case Annual Cost 368.877
200 150 100
Intuitive Case Annual Cost 82.44
50 0
DF
Emissions Comparison 9000 8000 7000 Lbs of CO2
6000 5000 4000 3000
Base Case Annual Emissions 8132.345782
2000 1000 0
Intuitive Case Annual Emissions 1817.490888
Usage Comparison 4000 3500 3000
Maximum recommended contrast ratio metric: 6:1 Glare reducedrecommended by: 68% Maximum contrast ratio metric: 6:1
2500 kWh
Distance from Window Wall (ft)
2000 1500 1000
Base Case Annual Electricity Usage 3688.77
500 0
Glare reduced by: 68%
Intuitive Case Annual Electricity Usage 824.4
Overall Reduction (%) 100.0% 90.0% 80.0% 70.0% 60.0% 50.0%
Base Case 100.0%
40.0% 30.0% 20.0%
Contents â&#x20AC;&#x201C; 9
10.0%
Intuitive Case 22.3%
Base Case Student Commons Workplane Rendering
Figure 9:â&#x20AC;&#x201A; Base case workplane rendering of student commons. Percentage of DF at or above 2: Student Commons- 65% Typical office bay- 75%
Analysis â&#x20AC;&#x201C; 10
Intuitive Case Student Commons Workplane Rendering
Figure 10:â&#x20AC;&#x201A; Intuitive case workplane rendering of student commons Percentage of DF at or above 2: Student Commons- 35% Typical office bay- 40%
Analysis â&#x20AC;&#x201C; 11
Student Commons Daylight factor 5.914973 2.884423 2.090326 2.234863 1.616089 Figure 11: Diagrams showing the contrast ratio reduction due to shading devices
1.315138 1.107564 1.050896 Figure 13: Daylight factors shown in plan view for the student commons
Figure 12: Diagrams showing the contrast ratio reduction due to shading devices
Analysis – 12
Student Commons UDI percentage Useful Daylight Indeces
UDI (100 < % < 2000 Lux) UDI (%<100 Lux) UDI (%>2000 Lux)
100
Percentage of time
90 80 70 60 50 40 30 20 10 0 0
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 Feet from window wall
Analysis â&#x20AC;&#x201C; 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 20200 footcandles. The points were evenly spaced from the window wall to the back of the room.
%Below
%UDI
%Above
1 3 4 5 5 6 7 7 0
68 97 96 95 95 94 93 93 3
32 0 0 0 0 0 0 0 97
Base Case 1st floor
Figure 14:
Analysis – 14
Base Case 1st floor, with shading
Figure 15:
Analysis – 15
Base Case 2nd floor
Figure 16:
Analysis – 16
Base Case 2nd floor, with shading
Figure 17:
Analysis – 17
Base Case 3rd floor
Figure 18:
Analysis – 18
Base Case 3rd floor, with shading
Figure 19:
Analysis – 19
Intuitive Case 1st floor
Figure 20:
Analysis – 20
Intuitive Case 1st floor, with cupola
Figure 21:
Analysis – 21
Intuitive Case 2nd floor
Figure 22:
Analysis – 22
Intuitive Case 2nd floor, with cupola
Figure 23:
Analysis – 23
Intuitive Case 3rd floor
Figure 24:
Analysis – 24
Intuitive Case 3rd floor, with cupola
Figure 25:
Analysis – 25
Shading Effectiveness Student Commons
Cooling Season Comparison 120.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
80.00 65.12 60.00
35.73
40.00 21.86
19.36
20.00
6.91 0.76 0.00 Window Transmitted Solar
Window Transmitted Beam Solar
Window Transmitted Diffuse Solar Base Case
Analysis â&#x20AC;&#x201C; 26
Window Heat Gain
Intuitive Case
Window Heat Loss
Total Heat Gain
Shading Effectiveness Student Commons
Cost Comparison 5
Usage Comparison
4.5 4
120.0%
3.5
100.0%
Cost ($)
3 2.5 2
80.0% Base Case Annual Cost 4.409276425
60.0% 40.0%
1.5
20.0%
1
Intuitive Case Annual Cost 0.3046614
0.5 0
Base Case
50 45
100
40 35
0
Analysis â&#x20AC;&#x201C; 27
30 Base Case Annual Emissions 97.20790544
kWh
Lbs of CO2
80
20
Intuitive Case
Usage Comparison
120
40
6.9%
0.0%
Emissions Comparison
60
100.0%
25 20
Intuitive Case Annual Emissions 6.716634139
15 10 5 0
Base Case Annual Electricity Usage 44.09276425
Intuitive Case Annual Electricity Usage 3.046614
Shading Effectiveness Plan and Section
Analysis â&#x20AC;&#x201C; 28
Shading Effectiveness Perspective
Analysis â&#x20AC;&#x201C; 29
Shading Effectiveness Student Commons Clear Sky Condition
Overcast Sky Condition: 1800 fc
Analysis â&#x20AC;&#x201C; 30
Shading Effectiveness Student Commons
Analysis â&#x20AC;&#x201C; 31
Shading Effectiveness Student Commons
Analysis â&#x20AC;&#x201C; 32
Appendix A Direct Solar Penetration 1 Base Window Diagram
March 1 – March 21, 9am
30 D
eg
s ree
35 Line of Sight
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
Analysis – 33
De
un
e gr
a
march 1
le ng
march 21
es
u
n na
gl
e
Line of Sight
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.
Direct Solar Penetration 2 March 21 â&#x20AC;&#x201C; April 1, 9am
December 21, 8am
march 21
e 5D
3
gr
e
u es
na
40
Line of Sight
Analysis â&#x20AC;&#x201C; 34
ng
De
le April 1
g
e re
su
n na
gl
e
10 Degre
Line of Sight
e sun an
gle
December 21
Appendix B Glossary of Terms 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
Analysis – 35
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%.
Appendix C General Building Energy Model Information GENERAL 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) 552-5800
Contact Person: Todd Berg City: Charlotte
Telephone: (704) 552-5800
Weather Data: Overcast Sky (1800 footcandle output) Climate Zone: Humid sub-tropical
Typical Space Summary
Building Use Office (Open Plan) Office (Executive/Private) Lobby Restrooms Conference Rooms Classrooms Laboratories Assembly Areas Dormitories Other (Student Commons) TOTAL (sf) Note: All spaces above are typical bays and spaces
Potential Daylight Area (sf at or above DF of 2)*
Total Area (sf)
Percentage (%)
267
742
36
1148
2050
56
1415
2792
51
Simulation Programs Radiance DAYSIM
*See Glossary in back Analysis â&#x20AC;&#x201C; 36
* See Appendix B
Appendix D ENERGYModel MODEL RESULTS: Improvement for Student Commons Energy Results: Percentage Percentage Improvement for Student Commons Performance Rating for Student Commons Energy and Daylight Control Summary Base Case Analysis
Analysis Type Daylit area (30-50 footcandles)* Area below DF of 2 Area at or above DF of 2 Daylight Autonomy* Useable Daylight Index* Contrast Ratio* Glare Reduction
Area (ft2)
Ratios
800
717.5 1332.5 <19:1
Window-to-Floor Area (%)*
Intuitive Case Analysis
Percentage (%)
Area (ft2)
Ratios
717.5
1332.5 717.5
95 88
6:1
0 26.5
Percentage (%)
90 76 68 26.5
7091.05 1817.49 Emissions Produced lbs lbs (CO2) All parameters used for the simulations that resulted in the conclusions above and below can be found on page 5. Base Case
Type Energy Use (Regulated and Unregulated)* Electricity
Total Emissions Saved (CO2)
Energy Use kWh
2050
Energy Cost [$/yr]
$321.64
Intuitive Case
Energy Use kWh
824.4
Energy Cost [$/yr]
$82.44
% Improvement Energy (%)
60%
Cost (%)
$239.20
5273.56 lbs
Percentage Improvement = 100 X [1 â&#x20AC;&#x201C; (proposed Building Performance / Baseline Building Performance)]
* See Appendix B
*See Glossary in back Analysis â&#x20AC;&#x201C; 37
5 of 21
Appendix E Baseline and Proposed Design Input Parameters For All Spaces BASELINE AND PROPOSED DESIGN INPUT PARAMETERS FOR ALL SPACES Simulation Parameters Comparison of Multiple Design Scenarios Base Case Scenario
Building Scenarios Envelope Components
SB 70 XL
SB 50
SB 50
30%
30%
60%
60%
85%
90%
Yes
Yes
Yes
Yes
3.5 to 1
3.5 to 1
.63
.70
.26
.29
.38
.27
.52
.52
.29
.29
.32
.32
0%
0%
Yes
Yes
1.0 kWh/ft2
1.0 kWh/ft2
1.0 kWh/ft2
N/A
Stepped
Dimming
N/A
Yes
Yes
N/A
N/A
Yes
N/A
View Glazing Type
SB 60
Floor Reflectance
20%
Wall Reflectance
50%
Ceiling Reflectance
70%
Exterior Shading Devices
N/A
Automated Interior Shade Screens
N/A
Window-to-Floor Area (%)*
3.5 to 1
Daylight Glazing Visual Light Transmittance
N/A
Daylight Glazing U-factor
N/A
Daylight Glazing SHGC
N/A
View Glazing Visual Light Transmittance
.70
View Glazing U-factor
.29
View Glazing SHGC
.44
Reduction in Glazing Area (%)
0%
Interior Light Shelves
N/A
Lighting Power Density Daylighting Controls Occupancy Sensor Controls Dimmable Ballasts
Advanced Case Scenario
SB 70
Daylight Glazing Type
Control Systems
Intuitive Case Scenario
* See Appendix B
Analysis â&#x20AC;&#x201C; 38
Appendix F Section through cupola
Analysis â&#x20AC;&#x201C; 39
Analysis â&#x20AC;&#x201C; 40
Analysis â&#x20AC;&#x201C; 41
Analysis â&#x20AC;&#x201C; 42