HEAT GAINS and LOSSES : WINDOWS and SKYLIGHTS (Glass)

Energy Efficient Building Design College of Architecture Illinois Institute of Technology, Chicago HEAT GAINS and LOSSES : WINDOWS and SKYLIGHTS (G...
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Energy Efficient Building Design

College of Architecture

Illinois Institute of Technology, Chicago

HEAT GAINS and LOSSES : WINDOWS and SKYLIGHTS (Glass) The heat gain components through glass consists of solar radiation and conduction. Solar radiation is considered in two parts – direct and diffuse (or scatter). Diffuse radiation is the solar radiation that is absorbed, stored and scattered in the atmosphere. The glass can be in the sun (direct and diffuse radiation) or in the shade (diffuse or scatter radiation). Conduction heat gain occurs due to the difference in temperature on either side of the glass. Conduction heat gain is positive if the outdoor air temperature is greater than indoor air temperature and it is negative (heat loss from the space) if the indoor air temperature is greater. Solar radiation is always positive.

Window

Sun

Overhang

N Sun

WINDOW

Altitude

I

Azimuth Glass in Shade diffuse radiation

Wall-Solar Azimuth

Window

Component of Solar

Side Fin

Radiation perpendicular Glass in Sun

to Wall-Window Surface

direct and diffuse radiation

Figure ? Direct solar radiation is the vector component of the absolute (total) solar radiation that is perpendicular to the glass surface. The Solar Cooling Load (SCL) Factor for a window is based on this value. So for any given hour, the SCL values for windows with different azimuth and tilt angles will have different SCLs although the absolute solar radiation is the same for all windows. Q-solar = A * SC * SCL Q-cond = A * U * CLTD A = Glass Area , SC = Glass Shading Coefficient, U = Glass heat transfer coefficient. CLTD = Cooling Load Temperature Difference. CLTD for glass depends mainly on the difference between indoor and outdoor temperatures but as with walls and roofs it is affected by the mass and properties of the glass material. When solar radiation strikes a glass surface, some of it is transmitted, some of it is absorbed and some of it is reflected. The absorbed component increases the temperature of the glass and the heat is slowly conducted (released) to the outside and inside depending on the difference in temperature. Unlike walls that are thick and have high densities, the absorbed portion of the solar radiation is relatively small compared to transmitted and reflected components. Instructor: Varkie C. Thomas, Ph.D., P.E.

Skidmore, Owings & Merrill LLP

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003)

F13 - 1

Energy Efficient Building Design

College of Architecture

Illinois Institute of Technology, Chicago

For example, a particular tinted glass has a transmissivity of 0.6 (60% of radiation is transmitted), reflectivity of 0.3 (30% of radiation is reflected) and absorbtivity of 0.1 (10% of radiation is absorbed). The direct solar radiation value is the component of the absolute solar radiation that is perpendicular to the glass surface. Shading Coefficient (SC) is the ratio of the solar heat through a given glass type under specific conditions to the solar heat gain through a standard reference unshaded glass that was used to determine Solar Cooling Load (SCL) factors. The reference glass is one-eighth thick inch clear double strength single glass and it has an SC = 1 under the specific conditions. SC = Solar heat gain through given glass type Solar heat gain through reference glass type Solar Heat Gain Coefficient (SHGC) is the ratio of the measured solar heat through a given glass type to the incident solar heat on the glass. The measured values are affected by the air films on either side of the glass, absorbtivity and by other factors. SHGC is therefore less than SC (about 10% to 15%). SHGC values are used in manual calculations. Input to energy computer programs is usually SC, and the program calculates SHGC based on conditions on either side of the glass. ASHRAE Standard 90.1 specifies SHGC values for different climates because it is based on tested measured values of different glass types and not on theoretical values. Radiant heat entering through the glass does not directly affect the room space air through which it passes. The radiant heat is first absorbed by the interior surfaces (walls, floor, ceiling) of the space and the contents (furniture and other objects) in the space. The absorbed heat is released to the air in the space through conduction and convection due to the difference in temperature. Solar Cooling Load (SCL) factors are based on the solar radiation heat gain entering through the glass and the effect of the room surfaces and furnishings in absorbing and transmitting the radiant heat. There is therefore a time lag between the solar radiation entering the space through the glass and when it affects the temperature of the air in the space. Visible Light Transmission (VLT) factor is the ratio of amount of light (lumens) transmitted through the given glass type to the amount of light transmitted by the standard reference glass type. Visible light and radiation heat are part of the electromagnetic spectrum and vary from each other in wave length. The is therefore a correlation between SC and VLT for different glass types but they are not the same. For building energy efficiency in summer you want to reduce the SC and increase the VLT. This reduces the cooling load due to radiation heat gain and reduces it even further by reducing the heat gains from lighting. Glass manufacturing research and technology tries to develop glass that optimizes the properties of glass for building energy efficiency. In summary, energy efficient glass depends on it’s U-value, SC, SHGC and VLT. Glass manufacturer’s data provides this information. ASHRAE tables for Solar Cooling Load (SCL) factors are therefore based on approximate groups and combinations of different types of room surfaces and furnishings. It is also based on floor levels (ground, middle, top) since this affects the inside surfaces of the space.

Instructor: Varkie C. Thomas, Ph.D., P.E.

Skidmore, Owings & Merrill LLP

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003)

F13 - 2

Energy Efficient Building Design

College of Architecture

Illinois Institute of Technology, Chicago

ZONE TYPES The ASHRAE Cooling Load Temperature Difference (CLTD), Solar Cooling Load (SCL) and Cooling Load Factor (CLF) method was developed so that heating and cooling loads can be calculated manually. It consists of building performance tables for different latitudes and different building configurations. The tables were generated using the DOE2 computer program that used more intensive and accurate calculation procedures (example Transfer Function Method for Walls). These tables are published in the ASHRAE 1981 Handbook. Room or space zone types were developed for: Solar Heat Gain through Glass Internal Heat Gains from People, Lights, and Equipment MULTI-STORY BUILDING ROOF

BUILDING FLOOR TYPES (1) Single Story (ground floor and roof) (2) Top Floor (multi-story with roof) (3) Middle Floor (multi-story without ground & roof)

(4) Ground Floor (multi story) (5) Interior Zones (6) Exterior Zones

Ceiling

TOP Floor

Ceiling (a) None (b) With Window Glass

MIDDLE Floor without Ceiling

Inside Shades (a) None (b) Half (c) Full Lights

Number of Interior and Exterior Walls (a) one or two (b) three © four or more

Concrete Partition Equipment

People Floor Covering (a) None (b) Vinyl (c) Carpet

Floor (a) 2.5 inch concrete (b) 1 inch wood

Ceiling

Partitions (a) Gypsum (b) Concrete Block

MIDDLE Floor SINGLE-STORY BUILDING INTERIOR Zone Ceiling

GROUND Floor

Instructor: Varkie C. Thomas, Ph.D., P.E.

PLAN VIEW OF BUILDING ( ZONES )

ROOF NW

N

NE

W

INT

E

SW

S

SE

Ceiling

GROUND Floor

Skidmore, Owings & Merrill LLP

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003)

F13 - 3

Energy Efficient Building Design

College of Architecture

Illinois Institute of Technology, Chicago

ASHRAE Zones for Solar Cooling Load (SCL) Factors for Glass are based on: A. Floor Level and Room Location 1. Single Story Building (Table 8.8-A) 2. Top Floor (Table 8.8-B) 3. First / Ground Floor (Table 8.8-C) 4. Middle Floor (Table 8.8-D) 5. Interior Rooms (Table 8.8-E) B. C. D. E. F. G.

Number of Walls in the Space ( 1 & 2 or 3 & 4 or greater) Floor Type ( Concrete or Wood ) Ceiling Type ( With or Without Suspended Ceiling ) Floor Covering ( Carpet or Vinyl ) Partition Type (Gypsum or Concrete Block ) Inside Shades ( Full, Half or None )

The figure below shows space heat gain time delay.

CLTD/SCL/CLF Method

Heat Balance Method

TETD Method Convection HEAT

COOLING

GAIN

LOAD

Radiation

HEAT EXTRACTION

Convection with Time Delay Furnishings Structure and other Variable Heat Storage Plus / Minus Swing

The tables show : Direct solar radiation intensities for different vertical surface azimuths and for a horizontal surface for 24o North latitude on July 21st and January 21st. Note that solar radiation on the south surface peaks in winter. Heating energy can be reduced by increasing the percent glass on the south. how the SCL (time delayed) values vary for different vertical surface azimuths and for a horizontal surface for 24o North latitude on July 21st.

Instructor: Varkie C. Thomas, Ph.D., P.E.

Skidmore, Owings & Merrill LLP

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003)

F13 - 4

Energy Efficient Building Design

College of Architecture

Illinois Institute of Technology, Chicago

EXAMPLES OF ZONE TYPES for Glass SCL and People, Equipment & Lights CLF No. of

Mid-Flr Type

Walls

Ceiling

Floor

Partition

Inside

Glass

People

Type

Cover

Type

Shade

Solar

Equipt

ZONE TYPE

TOP FLOOR 1 or 2

2.5" Concrete

Lights

With

Carpet

Gypsum

Full

A

A

B

3

A

B

B

4

A

A

B

ZONE TYPE

GROUND FLOOR 1 or 2

2.5" Concrete

With

Carpet

Gypsum

Full

A

C

B

3

A

C

B

4

A

B

B

ZONE TYPE

MIDDLE FLOOR 1 or 2

2.5" Concrete

With

Carpet

Gypsum

Full

B

B

C

3

B

B

C

4

B

C

C

No. of

Mid-Flr Type

Walls

Ceiling

Floor

Partition

Inside

Glass

People

Type

Cover

Type

Shade

Solar

Equipt

ZONE TYPE

TOP FLOOR 1 or 2

2.5" Concrete

Without

Vinyl

Cncr Blck

None

3 4

Gypsum

B

A

C

B

A

B

A

A

B

ZONE TYPE

GROUND FLOOR 1 or 2

2.5" Concrete

Without

Vinyl

Cncr Blck

None

3 4

Gypsum

D

D

D

C

D

C

B

C

C

ZONE TYPE

MIDDLE FLOOR 1 or 2

2.5" Concrete

Lights

Without

Vinyl

Cncr Blck

3 4

Instructor: Varkie C. Thomas, Ph.D., P.E.

Gypsum

Skidmore, Owings & Merrill LLP

None

C

C

C

C

C

C

B

A

C

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003)

F13 - 5

Energy Efficient Building Design

College of Architecture

Illinois Institute of Technology, Chicago

Building

Direct Solar Radiation Intensities on Vertical & Horizontal Surfaces o

JANUARY 21st

Latitude : 24 North

Rad = Absolute Solar Radiation BTUH

Month/Day : January 21st

Glass

NW W SW

N Inter S

NE E SE

Direct Solar Radiation Intensities for Hours 7:00 AM to 6:00 PM

Azim

7

8

9

10

11

12

13

14

15

16

17

18

N

2

12

18

23

26

27

26

23

18

12

2

1

NE

21

41

23

24

26

27

26

23

18

12

2

1

E

62

190

190

144

73

29

26

23

18

12

2

1

SE

63

218

253

245

211

160

95

38

19

12

2

1

S

25

114

166

200

220

227

220

200

166

114

25

12

SW

2

12

19

38

95

160

211

245

253

218

63

31

W

2

12

18

23

26

29

73

144

190

190

62

31

NW

2

12

18

23

26

27

26

24

23

41

21

10

Horiz

5

55

121

172

204

214

204

172

121

55

5

2

Rad

71

239

288

308

317

320

317

308

288

239

71

25

NW W SW

N Inter S

NE E SE

Building

Direct Solar Radiation Intensities on Vertical & Horizontal Surfaces JULY 21st

Latitude : 24o North

Rad = Absolute Solar Radiation BTUH

Month/Day : July 21st

Glass

Direct Solar Radiation Intensities for Hours 7:00 AM to 6:00 PM

Azim

7

8

9

10

11

12

13

14

15

16

17

18

N

45

41

37

39

41

42

41

39

37

41

45

26

NE

168

176

150

104

58

42

39

36

32

26

18

6

E

190

213

195

149

83

43

39

36

32

26

18

6

SE

101

128

129

108

73

45

40

36

32

26

18

6

S

18

27

34

39

44

46

44

39

34

27

18

6

SW

18

26

32

36

40

45

73

108

129

128

101

50

W

18

26

32

36

39

43

83

149

195

213

190

95

NW

18

26

32

36

39

42

58

104

150

176

168

85

Horiz

73

141

198

243

270

278

270

243

198

141

73

13

Rad

186

241

265

278

284

286

284

278

265

241

186

81

Instructor: Varkie C. Thomas, Ph.D., P.E.

Skidmore, Owings & Merrill LLP

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003)

F13 - 6

Energy Efficient Building Design

College of Architecture

Illinois Institute of Technology, Chicago

Building

ZONE Type A : SOFT Rad = Absolute Solar Radiation BTUH

Latitude : 24o North

Standard Glass with NO Shades

Month/Day : July 21st

Inside Surfaces and Furnishings : Soft

NW

N

NE

W

Inter

E

SW

S

SE

Glass

Solar Cooling Load (SCL) Factors for Hours 7:00 AM to 6:00 PM

Azim

7

8

9

10

11

12

13

14

15

16

17

18

N

35

36

36

38

40

42

42

40

38

39

43

32

NE

124

150

144

115

78

58

49

44

38

32

25

14

E

130

177

180

154

107

68

54

46

40

33

25

14

SE

74

104

114

106

83

59

50

44

38

32

25

14

S

15

23

30

35

40

43

43

40

37

32

24

14

SW

15

23

30

35

39

42

61

88

110

118

105

62

W

15

23

30

35

39

41

67

116

160

186

184

118

NW

15

23

30

35

39

41

51

83

122

151

158

106

Horiz

55

113

170

218

253

271

273

258

225

176

115

54

N Inter S

NE E SE

Building

ZONE Type B : MEDIUM SOFT Rad = Absolute Solar Radiation BTUH

Latitude : 24o North

Standard Glass with NO Shades

Month/Day : July 21st

NW W SW

Inside Surfaces and Furnishings : Medium Soft

Glass

Solar Cooling Load (SCL) Factors for Hours 7:00 AM to 6:00 PM

Azim

7

8

9

10

11

12

13

14

15

16

17

18

N

30

32

32

35

37

39

40

39

37

39

42

33

NE

105

128

126

106

78

62

55

50

44

38

31

20

E

118

151

158

141

105

74

63

55

48

41

33

22

SE

63

89

100

95

78

60

53

48

43

37

30

20

S

13

20

26

31

36

39

40

38

36

32

26

17

SW

13

20

26

31

35

38

55

79

98

106

98

63

W

14

21

27

32

35

38

61

102

141

165

167

115

NW

14

21

27

32

35

38

47

75

108

134

142

102

Horiz

48

97

146

190

224

244

251

243

219

181

130

78

Instructor: Varkie C. Thomas, Ph.D., P.E.

Skidmore, Owings & Merrill LLP

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003)

F13 - 7

Energy Efficient Building Design

College of Architecture

Illinois Institute of Technology, Chicago

Building

ZONE Type C : MEDIUM HARD Rad = Absolute Solar Radiation BTUH

Latitude : 24o North

Standard Glass with NO Shades

Month/Day : July 21st

Inside Surfaces and Furnishings : Medium Hard

NW

N

NE

W

Inter

E

SW

S

SE

Glass

Solar Cooling Load (SCL) Factors for Hours 7:00 AM to 6:00 PM

Azim

7

8

9

10

11

12

13

14

15

16

17

18

N

31

31

30

32

35

36

36

35

34

36

39

31

NE

104

120

114

92

65

53

50

47

43

38

32

23

E

117

143

143

123

88

62

56

51

47

42

35

26

SE

64

85

92

85

68

51

47

44

40

36

30

21

S

14

20

25

29

33

36

36

34

32

29

24

15

SW

17

23

28

32

34

37

53

75

92

97

87

53

W

20

25

30

34

36

38

60

99

132

152

150

97

NW

19

24

29

33

35

37

45

72

103

125

129

87

Horiz

57

102

145

181

208

223

226

217

194

160

115

71

N Inter S

NE E SE

Building

ZONE Type D : HARD o

Rad = Absolute Solar Radiation BTUH

Latitude : 24 North

Standard Glass with NO Shades

Month/Day : July 21st

NW W SW

Inside Surfaces and Furnishings : Hard

Glass

Solar Cooling Load (SCL) Factors for Hours 7:00 AM to 6:00 PM

Azim

7

8

9

10

11

12

13

14

15

16

17

18

N

27

27

27

29

31

33

33

33

33

34

37

30

NE

86

100

97

82

63

54

52

49

46

42

37

29

E

97

118

121

108

83

64

59

56

52

47

41

33

SE

53

71

77

74

62

50

47

45

42

38

33

26

S

13

18

22

25

29

32

32

31

30

28

24

18

SW

18

22

26

29

31

34

47

64

79

84

78

53

W

22

26

29

32

34

36

53

84

112

130

130

91

NW

20

24

28

31

33

34

41

63

88

106

111

80

Horiz

55

90

124

154

178

193

199

196

181

156

122

88

Instructor: Varkie C. Thomas, Ph.D., P.E.

Skidmore, Owings & Merrill LLP

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003)

F13 - 8

Energy Efficient Building Design

College of Architecture

N

Illinois Institute of Technology, Chicago

WINDOWS and SKYLIGHTS

100 ft

24oN Latitude

Example

Building: 100'L x 100'W x 300'H (100% Glass)

E

300 ft

Calculate Solar Heat Gain for:

S

(1) Zone Type A ( SOFT Interior ) (2) Zone Type D ( HARD interiors )

100 ft

July

ZONE TYPE A (SOFT)

July

ZONE TYPE D (HARD)

Hour

Solar Cooling Load (SCL) Factors

Hour

Solar Cooling Load (SCL) Factors

No.

N

E

S

W

RF

No.

N

E

S

W

RF

6

19

57

5

5

10

6

17

46

7

17

29

7

35

139

15

15

55

7

27

97

13

22

55

8

36

177

23

23

113

8

27

118

18

26

90

9

36

180

30

30

170

9

27

121

22

29

124

10

38

154

35

35

218

10

29

108

25

32

154

11

40

107

40

39

253

11

31

83

29

34

178

12

42

68

43

41

271

12

33

64

32

36

193

13

42

54

43

67

273

13

33

59

32

53

199

14

40

46

40

116

258

14

33

56

31

84

196

15

38

40

37

160

225

15

33

52

30

112

181

16

39

33

32

186

176

16

34

47

28

130

156

17

43

25

24

184

115

17

37

41

24

130

122

18

32

14

14

118

54

18

30

33

18

91

88

19

11

6

6

44

24

19

17

27

13

50

71

20

6

3

3

21

12

20

15

24

11

42

62

21

3

1

1

11

6

21

13

21

10

36

56

Instructor: Varkie C. Thomas, Ph.D., P.E.

Skidmore, Owings & Merrill LLP

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003)

F13 - 9

Energy Efficient Building Design

College of Architecture

Length (ft) =

Building

100

Width (ft) =

Illinois Institute of Technology, Chicago

100

Height (ft) =

300

Wall Glass (ft2) =

30,000

Roof Glass (ft2) =

10,000

Wall Glass SC =

1.0

Roof Glass SC =

1.0

Calculate Solar Gains at: (1) 8:00 AM (2) 12:00 Noon (3) 4:00 PM (4) 8:00 PM (5) 12:00 Midnight Heat Gain (btu/hr) = Area * SC * SCL

July Hr.No.

NORTH SCL

MBH

EAST SCL

MBH

MBH = 1000 btu/hr

SOUTH

WEST

ROOF

TOT

SCL

MBH

SCL

MBH

SCL

MBH

MBH

ZONE TYPE A (SOFT) 8

36

1080

177

5310

23

690

23

690

113

1130

8900

12

42

1260

68

2040

43

1290

41

1230

271

2710

8530

16

39

1170

33

990

32

960

186

5580

176

1760

10460

20

6

180

3

90

3

90

21

630

12

120

1110

Peaks at 4 PM

ZONE TYPE D (HARD) 8

27

810

118

3540

18

540

26

780

90

900

6570

12

33

990

64

1920

32

960

36

1080

193

1930

6880

16

34

1020

47

1410

28

840

130

3900

156

1560

8730

20

15

450

24

720

11

330

42

1260

62

620

3380

Envelope

Solar Radiation BTUH

Solar

Heat Gain

Zone Type A (Soft Interior)

Radiation

MBH

Zone Type D (Hard Interior)

BTUH

Peaks at 4 PM

10000 MBH 300 BTUH 8000 MBH

6000 MBH

200 BTUH

4000 MBH 100 BTUH 2000 MBH

8:00

12:00

4:00

8:00

AM

Noon

PM

PM

Instructor: Varkie C. Thomas, Ph.D., P.E.

Skidmore, Owings & Merrill LLP

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003) F13

- 10

Energy Efficient Building Design

College of Architecture

Illinois Institute of Technology, Chicago

Conduction Heat Gain through Glass (Windows and Skylights) Q = A * U * CLTD Q = conducted heat gain through glass A = glass surface area U = U-value of glass CLTD = Cooling Load Temperature Difference for glass CLTD for Glass

AM

Hour

1

2

3

4

5

6

7

8

9

10

11

12

CLTD

1

0

0

0

0

0

0

0

2

4

7

9

CLTD for Glass

PM

Hour

13

14

15

16

17

18

19

20

21

22

23

24

CLTD

12

13

14

14

13

12

10

8

6

4

3

2

The glass CLTD values in the table above are for based on the following conditions: Indoor Room Temperature = Outdoor Design High Temperature = Average Outdoor 24-Hour Day Temperature = Daily Temperature Range =

78oF 95oF 85oF 21oF

ASHRAE design weather conditions give T-maximum and T-daily_range. T-average can be calculated from: T-average = T-maximum - (T-daily_range) / 2 CLTD values have to be corrected for location conditions other than the values shown above. CLTD (corrected) = CLTD (table) + ( 78 – T-room ) + (T-average – 85 ) T-room = Actual design temperature of the room T-average = Actual average summer design temperature of the location. Example: Location = Dubai. Design outdoor temperature = 115oF, Daily range = 20oF , T-average = 115 – 20/2 = 105 Design indoor temperature = 72oF, CLTD (corrected) for hour 3:00 PM = CLTD(table) + ( 78 – 72 ) + ( 105 – 85 ) = 14 + 6 + 20 = 40oF

Instructor: Varkie C. Thomas, Ph.D., P.E.

Skidmore, Owings & Merrill LLP

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003) F13

- 11

Energy Efficient Building Design

College of Architecture

Illinois Institute of Technology, Chicago

EXAMPLE: Cooling Load through Building Envelope (Walls and Windows) Cooling Load Temperature Difference (CLTD) for Light Construction

Solar Cooling Load (SCL) Factors for Soft Zone

HR

N

Qw-N

E

Qw-E

S

Qw-S

W

Qw-W

HR

N

Qgs-N

E

Qgs-E

S

Qgs-S

W

Qgs-W

8

5

800

16

2,560

0

0

1

160

8

32

7,680

151

36,240

20

4,800

21

5,040

9

8

1,280

29

4,640

2

320

3

480

9

32

7,680

158

37,920

26

6,240

27

6,480

10

11

1,760

39

6,240

5

800

6

960

10

35

8,400

141

33,840

31

7,440

32

7,680

11

14

2,240

45

7,200

9

1,440

9

1,440

11

37

8,880

105

25,200

36

8,640

35

8,400

12

16

2,560

46

7,360

13

2,080

13

2,080

12

39

9,360

74

17,760

39

9,360

38

9,120

13

19

3,040

43

6,880

18

2,880

17

2,720

13

40

9,600

63

15,120

40

9,600

61

14,640

14

21

3,360

40

6,400

22

3,520

24

3,840

14

39

9,360

55

13,200

38

9,120

102

24,480

15

24

3,840

37

5,920

25

4,000

34

5,440

15

37

8,880

48

11,520

36

8,640

141

33,840

16

26

4,160

35

5,600

26

4,160

46

7,360

16

39

9,360

41

9,840

32

7,680

165

39,600

17

29

4,640

33

5,280

26

4,160

56

8,960

17

42

10,080

33

7,920

26

6,240

167

40,080

18

30

4,800

30

4,800

26

4,160

62

9,920

18

33

7,920

22

5,280

17

4,080

115

27,600

Example Glass Conduction Heat Gain HR

Table

Corrct

Qgc

HR

N

E

Building : 120'L x 120'W x 20'H

Latitude : 24oN

Total for Walls and Windows S

W

Month/Day : July 21st

8

0

16

5,120

8

13,600

43,920

9,920

10,320

Room Temp (Tr oF)

9

2

18

5,760

9

14,720

48,320

12,320

12,720

o

Outside Temp (To F)

105

10

4

20

6,400

10

16,560

46,480

14,640

15,040

Daily Range (DR oF)

20

11

7

23

7,360

11

18,480

39,760

17,440

17,200

Avg Temp (Ta oF)

95

12

9

25

8,000

12

19,920

33,120

19,440

19,200

CLTD (corr) = CLTD(table) + (78-Tr) + (Ta-85)

13

12

28

8,960

13

21,600

30,960

21,440

26,320

14

13

29

9,280

14

22,000

28,880

21,920

37,600

Qw =A*U*CLTD

Aw =

1600

Uw =

0.1

15

14

30

9,600

15

22,320

27,040

22,240

48,880

Qgs = A*SC*SCL

Ag =

800

SC =

0.3

16

14

30

9,600

16

23,120

25,040

21,440

56,560

17

13

29

9,280

17

24,000

22,480

19,680

58,320

Zone

N

E

S

W

18

12

28

8,960

18

21,680

19,040

17,200

46,480

HR

17

9

15

17

Instructor: Varkie C. Thomas, Ph.D., P.E.

Skidmore, Owings & Merrill LLP

72

Peak Envelope Loads

N W

E S

Qgc = A * Ug * CLTD

Ug =

ARCH-551 (Fall-2002) ARCH 552 (Spring-2003) F13

0.4

- 12

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