WK4-Salhia Shading Coeffficient

8/11/2019 WK4-Salhia Shading Coeffficient

1/17

SHADING COEFFICIENT CALCULATIONSALHIA TOWER, BAHRAIN


2/17

Precedent 1: International Energy Conservation Code (IECC)

SHGC Multipliers for Permanent Projections

The window projection factor shall be determined in accordance with Equation 5-1.

PF = A/Bwhere:

PF = Projection factor (decimal).

A = Distance measured horizontally from the furthest continuous extremity of any overhang, eave, or permanently attached shading device

to the vertical surface of the glazing.

B = Distance measured vertically from the bottom of the glazing to the underside of the overhang, eave, or permanently attached shading

device.


3/17

Precedent 2: ASHRAE

SHGC Multipliers for Permanent Projections

Shading devices such as overhangs can reduce solar gains through windows. ASHRAE

90.1 standard allows credit for permanent overhangs that provide significant shading.

The following table has multipliers that reduce the SHGC when overhangs are

present.


4/17

Precedent 3: Energy Conservation Building Code of India (ECBC)Fin Projection Factor Multiplication Method

According to ECBC, An adjusted SHGC, accounting for overhangs and/or side fins can

be calculated by multiplying the SHGC of the unshaded fenestration product times a

multiplication (M) factor.

SHGC (Window + Vertical Fin) = M x SHGC of Glasswhere M = Vertical Fin Projection Factor


5/17

Precedent 4: Building and Construction Authority of SingaporeGuidelines on ETTV for Buildings

Shading Coefficient (SC):

In general, the shading coefficient of any fenestration system can be obtained by multiplying the shading

coefficient of the glass (or effective shading coefficient of glass with solar control film where a solar control

film is used on the glass) and the shading coefficient if the sun shading devices as follow:

SC=SC1 X SC2

Where,SC= shading coefficient of the fenestration system

SC1= shading coefficient of glass or effective shading coefficient of glass with solar control film where solar control film is used on glass

SC2= effective shading coefficient of external shading devices

Where,

G = Ae/A the fraction of area exposed to direct solar radiation

SC2 = Ae x ID + A x IdA x IT

SC2 = G x ID + Id

IT


6/17

Precedent 4: Building and Construction Authority of SingaporeGuidelines on ETTV for Buildings, continued

Shading Coefficient of Shading Device:

To determine the effective SC of a shading device, theoretically, the computation has to be carried out for 12

months of the year. However, as the computation involved is rather tedious and the degree of accuracy

required is not a critical factor, it is deemed sufficient to base the SC computation on 4 representative months

of the year, viz. March, June, September and December. The representative days of these 4 months are march

21, June 22, September 23 and December 22.

Where,

M denotes March

J denotes June

S denotes September

D denotes December

But this method does not take into account the material of the shading device,

hence, a dynamic performative approach is adopted

Effective SC = M(GxID+Id) +J(GxID+Id)+S(GxID+Id)D(GxID+Id)

MIT+JIT+SIT+DIT


7/17

Effective Shading Coefficient - Performative Design Approach:

Definition and Process

Shading Coefficient (SC):

Shading Coefficient is the ratio of the solar heat gain through specific fenestration to

the solar heat gain through a 1/8 (3mm) clear glass.

By definition, the shading coefficient of 1/8 in(3mm) thick, clear, double strength

window glass is 1.0**

Effective Shading Coefficient

Step 1: Base case is run with a 3mm clear double strength glass (shading

coefficient of 1.0) with no external shading to calculate solar heat gain.

Step 2: The design case is run with the desired glass and external shading system

for the same orientation and window size as the base case to calculate

solar heat gain.Step 3: The ratio of solar heat gain through the desired glass to the base case gives

the effective shading coefficient.

Note: As the shading percentage on the window varies due to relative movement of the sun, the effective

shading coefficient also varies throughout the day and year.

**Definition from ASHRAE 90.1


8/17


Window Details


9/17


Validation: Base Case -East Orientation

A test cell with a glazing and shading system similar to that of the project was

modeled in Ecotect.

Base case with 3mm clear glass:

Material and Layers properties input in Ecotect


10/17


Validation: Case 1-East Orientation

Validation case with Viracon VE 1-40 glass

The validation case is run for the 4 representative days as described on slide 7

Product VE 1-40

Transmittance

Visible Light 36%

Solar Energy 21%

Ultra-Violet* 10%

Reflectance

Visible Light-Exterior 15%

Visible Light-Interior 19%

Solar Energy 25%

ASHRAE U-Value

Winter Nighttime 0.31 Btu/(hr x sqft x F)

Summer Daytime 0.29 Btu/(hr x sqft x F)European U-Value 1.6

Shading Coefficient 0.32

Relative Heat Gain 68 Btu/hr x sqft

Solar Factor (SHGC) 0.28

LSG 1.3

1. Product Information 2. Material and Layers properties input in Ecotect


11/17



March 21 June 22

HOUR

SOLAR

SHADE

INCIDENT

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTED (T)

(W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADING

COEFFICIEN

T (Y/X)

3mm V1-40 3mm V1-40 3mm (X) V1-40 (Y)

700 0% 442 36 74 322 41 115 358 0.32

800 0% 533 43 89 389 50 139 432 0.32

900 0% 364 30 61 268 35 96 298 0.32

1000 0% 471 38 77 338 44 121 376 0.32

1100 0% 323 24 49 214 28 77 238 0.32

1200 0% 128 7 15 65 8 23 72 0.32

1300 100% 114 10 20 89 11 31 99 0.31

1400 100% 103 9 18 81 10 28 90 0.31

1500 100% 85 7 15 66 9 24 73 0.33

1600 100% 63 5 11 49 6 17 54 0.31

1700 100% 47 4 8 37 5 13 41 0.32

Daily Avg. = 0.32

HOUR

SOLAR

SHADE

INCIDENT

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTED (T)

(W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADING

COEFFICI

ENT (Y/X)

3mm V1-40 3mm V1-40 3mm (X) V1-40 (Y)

600 0% 457 37 76 332 43 369 119 0.32

700 0% 668 54 111 486 63 540 174 0.32

800 0% 683 55 114 497 64 552 178 0.32

900 0% 492 40 82 357 46 397 128 0.32

1000 0% 365 28 59 256 33 284 92 0.32

1100 0% 302 23 47 204 26 227 73 0.32

1200 0% 159 13 26 114 15 127 41 0.32

1300 100% 129 11 23 101 13 112 36 0.32

1400 100% 114 10 20 89 11 99 31 0.31

1500 100% 83 7 15 65 8 72 23 0.32

1600 100% 59 5 11 47 6 52 17 0.33

1700 100% 45 4 8 35 5 39 13 0.33

Daily Avg.=0.32

HOUR

SOLAR

SHADE

INCIDENT

(W/m2) ABSORBED(A) (W/m2)

TRANSMITTED (T)

(W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADING

COEFFICIEN

T (Y/X)

3mm V1-40 3mm V1-40 3mm (X) V1-40 (Y)

700 0% 518 42 86 377 49 419 135 0.32

800 0% 611 49 102 445 57 494 159 0.32

900 0% 588 47 98 427 55 474 153 0.32

1000 0% 459 35 73 317 41 352 114 0.32

1100 0% 270 18 36 158 20 176 56 0.32

1200 100% 61 5 11 47 6 52 17 0.33

1300 100% 67 6 12 53 7 59 19 0.32

1400 100% 65 6 12 51 7 57 19 0.33

1500 100% 46 4 8 36 5 40 13 0.33

1600 100% 36 3 6 28 4 31 10 0.32

1700 100% 17 1 3 13 2 14 5 0.36

Daily Avg. = 0.33

September 23 December 22

HOUR

SOLAR

SHADE

INCIDENT

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTED (T)

(W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADING

COEFFICI

ENT (Y/X)

3mm V1-40 3mm V1-40 3mm (X) V1-40 (Y)

700 0% 3 0 1 2 0 2 1 0.50

800 0% 71 6 12 53 7 59 19 0.32

900 0% 383 31 64 278 36 309 100 0.32

1000 0% 388 29 60 263 34 292 94 0.32

1100 0% 247 16 33 143 18 159 51 0.32

1200 0% 104 6 13 58 7 64 20 0.31

1300 100% 52 5 9 41 5 46 14 0.30

1400 100% 71 6 13 56 7 62 20 0.32

1500 100% 44 4 8 34 4 38 12 0.32

1600 100% 22 2 4 17 2 19 6 0.32

Daily Avg.= 0.34

Ecotect test cell oriented East with

Viracon VE1-40 window glass


12/17



Validation Case with Viracon VE 1-42 glass

Product VE 1-42

Transmittance

Visible Light 37%

Solar Energy 24%

Ultra-Violet* 16%

Reflectance

Visible Light-Exterior 19%

Visible Light-Interior 14%

Solar Energy 21%

ASHRAE U-Value

Winter Nighttime 0.31 Btu/(hr x sqft x F)

Summer Daytime 0.29 Btu/(hr x sqftx F)

European U-Value 1.6Shading Coefficient 0.36

Relative Heat Gain 77 Btu/hr x sqft

Solar Factor (SHGC) 0.31

LSG 1.2

1. Product Information 2. Material and Layers properties input in Ecotect


13/17


14/17

Shading Coefficient - Performative Design Approach:

Validation Case Results

Case 1: Shading Coefficient of VE 1-40 (0.32)= Average of (SCM + SCJ + SCS + SCD)

= 0.32

Case 2: Shading Coefficient of VE 1-42 (0.36)= Average of (SCM + SCJ + SCS + SCD)

= 0.36

Where,

M denotes March

J denotes June

S denotes September

D denotes December


15/17


Viracon V1-40 + Opaque Shading Device

HOUR

SOLAR

SHAD

E

SOLAR

SHADE

INCIDEN

T

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTED

(T) (W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADING

COEFFICIE

NT (Y/X)

3mm

V1-

40+Fin 3mm

V1-

40+Fin 3mm

V1-

40+Fin 3mm (X)

V1-40+Fin

(Y)

700 0% 10% 442 36 65 322 37 358 102 0.28

800 0% 14% 533 43 74 389 41 432 115 0.27

900 0% 30% 364 30 40 268 23 298 63 0.21

1000 0% 44% 471 38 43 338 24 376 67 0.18

1100 0% 92% 323 24 12 214 7 238 19 0.08

1200 0% 99% 128 7 8 65 5 72 13 0.18

1300 100% 100% 114 10 11 89 6 99 17 0.17

1400 100% 100% 103 9 10 81 6 90 16 0.181500 100% 100% 85 7 8 66 5 73 13 0.18

1600 100% 100% 63 5 6 49 3 54 9 0.17

1700 100% 100% 47 4 5 37 3 41 8 0.20

Daily Avg.= 0.19

HOUR

SOLAR

SHADE

SOLAR

SHADE

INCIDE

NT

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTE

D (T) (W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADING

COEFFICIEN

T (Y/X)

3mm

V1-

40+Fin 3mm

V1-

40 +F in 3 mm

V1-

40+Fin 3mm (X)

V1-40+Fin

(Y)

600 0% 25% 457 37 56 332 49 369 105 0.28

700 0% 25% 668 54 82 486 71 540 153 0.28

800 0% 14% 683 55 95 497 73 552 168 0.30

900 0% 4% 492 40 72 357 52 397 124 0.31

1000 0% 3% 365 28 49 256 37 284 86 0.30

1100 0% 10% 302 23 34 204 30 227 64 0.28

1200 0% 13% 159 13 14 114 17 127 31 0.24

1300 100% 100% 129 11 13 101 15 112 28 0.25

1400 100% 100% 114 10 11 89 13 99 24 0.241500 100% 100% 83 7 8 65 9 72 17 0.24

1600 100% 100% 59 5 6 47 7 52 13 0.25

1700 100% 100% 45 4 4 35 5 39 9 0.23

Daily Avg.= 0.27

HOUR

SOLAR

SHADE

SOLAR

SHADE

INCIDE

NT

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTED

(T) (W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADIN

G

COEFFI

CIENT

(Y/X)

3mm

V1-

40+Fin 3mm

V1-

40+Fin 3mm

V1-

40+Fin 3mm (X)

V1-40+Fin

(Y)

700 0% 10% 518 42 76 377 43 419 119 0.28

800 0% 14% 611 49 85 445 48 494 133 0.27

900 0% 30% 588 47 67 427 38 474 105 0.22

1000 0% 52% 459 35 35 317 20 352 55 0.16

1100 0% 99% 270 18 5 158 3 176 8 0.05

1200 100% 100% 61 5 6 47 3 52 9 0.17

1300 100% 100% 67 6 7 53 4 59 11 0.19

1400 100% 100% 65 6 6 51 4 57 10 0.18

1500 100% 100% 46 4 5 36 3 40 8 0.20

1600 100% 100% 36 3 3 28 2 31 5 0.16

1700 100% 100% 17 1 2 13 1 14 3 0.21

Daily Avg.= 0.19

HOUR

SOLAR

SHADE

SOLAR

SHADE

INCIDE

NT

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTED

(T) (W/m2)

SOLAR HEAT

GAIN (W/m2)

(A+T)

SHADIN

G

COEFFI

CIENT

(Y/X)

3mm V1-40+Fin 3mm V1-40+Fin 3mm V1-40+Fin 3mm(X) V1-40+Fin(Y)

700 0% 34% 3 0 0 2 0 2 0 0.00

800 0% 41% 71 6 7 53 4 59 11 0.19

900 0% 56% 383 31 29 278 16 309 45 0.15

1000 0% 97% 388 29 6 263 3 292 9 0.03

1100 0% 96% 247 16 6 143 3 159 9 0.06

1200 0% 97% 104 6 7 58 4 64 11 0.17

1300 100% 100% 52 5 5 41 3 46 8 0.17

1400 100% 100% 71 6 7 56 4 62 11 0.18

1500 100% 100% 44 4 4 34 2 38 6 0.16

1600 100% 100% 22 2 2 17 1 19 3 0.16

Daily Avg.= 0.13

March 21 June 22

September 23 December 22

Ecotect test cell oriented East

with Viracon VE1-40 window

glass and Opaque fin


16/17


Viracon V1-40 + VNE1-63 (Insulating Silkscreen)

HOU

R

SOLAR

SHADE

SOLAR

SHADE

INCIDEN

T

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTED

(T) (W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADING

COEFFICI

ENT

(Y/X)

3mm

V1-

40+Fin 3mm

V1-

4 0+ Fin 3 mm

V1-

4 0+ Fin 3 mm ( X)

V1-40+Fin

(Y)

700 0% 8% 442 36 67 322 38 358 105 0.29

800 0% 10% 533 43 78 389 44 432 122 0.28

900 0% 20% 364 30 46 268 26 298 72 0.24

1000 0% 28% 471 38 54 338 30 376 84 0.22

1100 0% 57% 323 24 24 214 14 238 38 0.16

1200 0% 62% 128 7 9 65 5 72 14 0.19

1300 100% 100% 114 10 13 89 7 99 20 0.20

1400 100% 100% 103 9 12 81 7 90 19 0.21

1500 100% 100% 85 7 10 66 5 73 15 0.21

1600 100% 100% 63 5 7 49 4 54 11 0.20

1700 100% 100% 47 4 5 37 3 41 8 0.20

Daily Avg.= 0.22

HOUR

SOLAR

SHADE

SOLAR

SHADE

INCIDEN

T

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTED (T)

(W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADING

COEFFICI

ENT

(Y/X)

3mm

V1-

40+Fin 3mm

V1-

40+Fin 3mm

V1-

40+Fin

3mm

(X)

V1-40+Fin

(Y)

600 0% 25% 457 37 56 332 32 369 88 0.24

700 0% 25% 668 54 82 486 46 540 128 0.24

800 0% 14% 683 55 96 497 54 552 150 0.27

900 0% 4% 492 40 73 357 41 397 114 0.29

1000 0% 3% 365 28 50 256 28 284 78 0.27

1100 0% 10% 302 23 36 204 20 227 56 0.25

1200 0% 13% 159 13 16 114 9 127 25 0.20

1300 100% 100% 129 11 15 101 8 112 23 0.21

1400 100% 100% 114 10 13 89 7 99 20 0.201500 100% 100% 83 7 9 65 5 72 14 0.19

1600 100% 100% 59 5 7 47 4 52 11 0.21

1700 100% 100% 45 4 5 35 3 39 8 0.21

DailyAvg. 0.23

HOUR

SOLAR

SHADE

SOLAR

SHAD

E

INCIDENT

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTED

(T) (W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADIN

G

COEFFI

CIENT

(Y/X)

3mmV1-

40+Fin3mm

V1-40+Fin 3mm

V1-40+Fin

3mm(X) V1-40+Fin (Y)

700 0% 8% 518 42 79 377 44 419 123 0.29

800 0% 10% 611 49 90 445 50 494 140 0.28

900 0% 20% 588 47 77 427 43 474 120 0.25

1000 0% 34% 459 35 48 317 27 352 75 0.21

1100 0% 63% 270 18 16 158 9 176 25 0.14

1200 100% 100% 61 5 7 47 4 52 11 0.21

1300 100% 100% 67 6 8 53 4 59 12 0.20

1400 100% 100% 65 6 7 51 4 57 11 0.19

1500 100% 100% 46 4 5 36 3 40 8 0.20

1600 100% 100% 36 3 4 28 2 31 6 0.19

1700 100% 100% 17 1 2 13 1 14 3 0.21Daily Avg.= 0.22

HOUR

SOLAR

SHADE

SOLAR

SHADE

INCIDE

NT

(W/m2)

ABSORBED(A)

(W/m2)

TRANSMITTED

(T) (W/m2)

SOLAR HEAT GAIN

(W/m2) (A+T)

SHADIN

G

COEFFI

CIENT

(Y/X)

3mm

V1-

40+Fin 3mm

V1-40+Fi

n 3mm

V1-

40+Fin

3mm

(X)

V1-40+Fin

(Y)

700 0% 21% 3 0 0 2 0 2 0 0.00

800 0% 25% 71 6 8 53 5 59 13 0.22

900 0% 34% 383 31 42 278 23 309 65 0.21

1000 0% 58% 388 29 27 263 15 292 42 0.14

1100 0% 57% 247 16 16 143 9 159 25 0.16

1200 0% 58% 104 6 8 58 5 64 13 0.20

1300 100% 100% 52 5 6 41 3 46 9 0.20

1400 100% 100% 71 6 8 56 5 62 13 0.21

1500 100% 100% 44 4 5 34 3 38 8 0.21

1600 100% 100% 22 2 2 17 1 19 3 0.16Daily Avg. 0.17

March 21 June 22

September 23December 22

Ecotect test cell oriented East

with Viracon VE1-40 window

glass and VNE1-63 fin


17/17


Results

Effective Shading Coefficient of

Viracon V1-40 (0.32) + Opaque Fin = Avg.(SCM + SCJ + SCS + SCD)

= 0.19

Effective Shading Coefficient of

Viracon V1-40(0.32) + VNE1-63 (0.24) = Avg.(SCM + SCJ + SCS + SCD)

= 0.21

Documents

WK4-Salhia Shading Coeffficient