1 Introduction
2 Research method
2.1 Local weather data
2.2 Building simulation program (EnergyPlus)
2.3 Simulation setup program (Java EnergyPlus (jEPlus))
3 Studied zone model
3.1 Zone model description
3.2 Investigated design parameters
Tab.1 Investigated design parameters |
Index | Variable | Type | Lower bound | Upper bound | Initial value | Increment | |
---|---|---|---|---|---|---|---|
1 | Façade orientation | Discrete | (east, west, north, and south) | ||||
2 | WWR/% | Discrete | 0.2 | 0.8 | 0.2 | 0.1 | |
3 | Glazing quality (see Table 2) | Discrete | W1 | W10 | W1 | 1 | |
4 | Overhang projection (P) | Discrete | 0 | 0.50 H | 0.00 | 0.25 | |
5 | Side-fins projection (F) | Discrete | 0 | 0.50 W | 0.00 | 0.25 |
Tab.2 Double glazing window specifications |
No. | Configuration | SHGC | U/(W·m−2·K−1) | LT | Cost /(USD·m−2) | Cost difference | Window quality |
---|---|---|---|---|---|---|---|
W1 | Low-e double sliver (6 mm-12 mm-6 mm) air | 0.20 | 1.60 | 0.28 | 53 | 23 | |
W2 | High performance (8 mm-16 mm-8 mm) xenon | 0.22 | 1.23 | 0.21 | 67 | 37 | High |
W3 | Low-e neutral (8 mm-16 mm-8 mm) xenon | 0.26 | 1.40 | 0.40 | 67 | 37 | |
W4 | Low-e neutral blue (6 mm-12 mm-6 mm) air | 0.31 | 1.60 | 0.50 | 53 | 23 | |
W5 | Super low-e neutral (6 mm-12 mm-6 mm) xenon | 0.37 | 1.15 | 0.50 | 73 | 43 | Medium |
W6 | Low-e super neutral (6 mm-12 mm-6 mm) air | 0.38 | 1.60 | 0.69 | 57 | 27 | |
W7 | Low-e clear (6 mm-16 mm-6 mm) argon | 0.56 | 1.52 | 0.76 | 67 | 37 | Low |
W8 | Reflective (6 mm-8 mm-6 mm) air | 0.64 | 1.99 | 0.76 | 30 | 0 | |
W9 | Clear (6 mm-4 mm-6 mm) air | 0.74 | 3.40 | 1.00 | 30 | 0 | |
W10 | Clear (6 mm-6 mm-6 mm) air | 0.85 | 3.06 | 0.8 | 30 | Base |
3.3 Other input parameters
3.4 Daylighting and lighting interaction
Tab.3 Fixed design parameters of the tested room |
Characteristics | Description of the studied case |
---|---|
Wall U-value without thermal bridge/(W·m−2·K−1) | 0.574 |
Roof U-value/(W·m−2·K−1) | 0.397 |
Occupancy density of the tested room/(m2·person−1) | 4 |
Lighting load/(W·m−2) | 5 |
Equipment load/(W·m−2) | 3 |
Ventilation/(L·s−1·person) | 10 |
Infiltration/Air change (ACH) | 0.5 |
Thermostat setting/°C | 24 in summer and 21 in winter |
Illuminance level/(Lux·m−2) | 300 |
Glare maximum allowable index | 19 |
Frame material of the window/(W·m−2·K−1) | 5.881 (polyvinyl chloride (PVC)) |
Window divider/(W·m−2·K−1) | 5.881 (PVC) |
Occupancy/Lighting/Equipment schedules | Schedule: Time, active fraction Weekdays: 00: 00–12: 00, 0; 12: 00–14: 00, 0.5; 14: 00–18: 00, 1; 18: 00–24: 00, 0.5 Weekends: 00: 00–12: 00, 0; 12: 00–13: 00, 0.5; 13: 00–23: 00, 1; 23: 00–24: 00, 0.5 Note: 0= zero, 0.5= half, and 1= All |
3.5 Glare index
4 Cost analysis of window types
5 Results and discussion
5.1 Combined effects of fenestration parameters
5.2 Effect of design parameters on unshaded fenestration
5.2.1 Annual energy consumption
5.2.2 Annual artificial lighting
5.3 Effect of design parameters on solar shaded fenestration
5.3.1 Annual energy consumption
Tab.4 Annual artificial lighting consumption (kWh) of the tested windows at a WWR of 0.4 on the unshaded four facades |
Window | East | West | North | South |
---|---|---|---|---|
W1 | 204.5 | 194.6 | 200.6 | 199.4 |
W2 | 209.6 | 196.1 | 204.3 | 202.3 |
W3 | 200.0 | 193.1 | 197.2 | 196.5 |
W4 | 197.7 | 192.4 | 195.5 | 195.0 |
W5 | 197.8 | 192.4 | 195.6 | 195.1 |
W6 | 195.1 | 191.6 | 193.6 | 193.3 |
W7 | 194.3 | 191.4 | 193.0 | 192.8 |
W8 | 194.3 | 191.4 | 193.0 | 192.8 |
W9 | 192.9 | 191.0 | 192.0 | 192.0 |
W10 | 194.0 | 191.3 | 192.7 | 192.6 |
Tab.5 Percentage effect of full solar shading on energy consumption of the tested window types on each facade |
Façade | East | West | North | South | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|
WWR= 0.2 | WWR=0.8 | WWR=0.2 | WWR=0.8 | WWR=0.2 | WWR=0.8 | WWR=0.2 | WWR=0.8 | ||||
W1–W3 | 0.66–1.16 | 4.05–5.86 | 1.03–1.39 | 4.60–6.34 | 0.61–0.67 | 2.22–3.34 | 0.60–0.91 | 3.22–5.35 | |||
W4–W6 | 1.51–1.75 | 7.37–8.86 | 1.70–1.94 | 7.82–9.30 | 0.86–1.01 | 4.24–4.68 | 1.17–1.36 | 7.44–9.53 | |||
W7–W10 | 2.68–4.79 | 13.13–20.88 | 2.82–5.00 | 13.43–21.04 | 1.57–2.83 | 7.69–12.14 | 2.13–5.43 | 16.53–32.39 |
Tab.6 Energy saving in kWh and percentage (%) of windows 1 and 10 at a WWR of 0.2 and 0.8 under different shading conditions |
Shading condition | WWR= 0.2 | WWR= 0.8 | |||||||
---|---|---|---|---|---|---|---|---|---|
W1 | W10 | W1 | W10 | ||||||
East facade/kWh (%) | |||||||||
Full side-fin | 8.40 (0.32) | 45.40 (1.59) | 35.75 (1.25) | 298.05 (7.80) | |||||
Full overhang | 8.80 (0.34) | 91.40 (3.20) | 79.85 (2.80) | 499.45 (13.07) | |||||
Combined (full) | 17.30 (0.66) | 136.80 (4.79) | 115.60 (4.05) | 797.50 (20.88) | |||||
West facade/kWh (%) | |||||||||
Full side-fin | 9.28 (0.36) | 46.85 (1.65) | 43.55 (1.53) | 304.90 (7.98) | |||||
Full overhang | 17.20 (0.67) | 95.25 (3.35) | 87.33 (3.07) | 499.32 (13.06) | |||||
Combined (full) | 26.48 (1.03) | 142.10 (5.00) | 130.88 (4.60) | 804.22 (21.04) | |||||
North facade/kWh (%) | |||||||||
Full side-fin | 11.3 (0.44) | 58.3 (2.13) | 44.8 (1.62) | 284.7 (8.31) | |||||
Full overhang | –2.25 (–0.09) | 19.4 (0.71) | 16.5 (0.60) | 131.3 (3.83) | |||||
Combined (full) | 9.0 (0.35) | 77.7 (2.83) | 61.3 (2.22) | 415.9 (12.14) | |||||
South facade/kWh (%) | |||||||||
Full side-fin | 7.9 (0.31) | 59.6 (2.21) | 39.9 (1.47) | 481.5 (14.21) | |||||
Full overhang | 5.9 (0.23) | 86.8 (3.22) | 47.7 (1.75) | 616.1 (18.18) | |||||
Combined (full) | 13.8 (0.55) | 146.4 (5.43) | 87.6 (3.22) | 1097.6 (32.39) |
5.3.2 Annual artificial lighting
Tab.7 Increase in energy consumption (kWh) due to the increase of WWR from 0.2 to 0.8 of W1 or W10 under different shading conditions |
Overhang condition | Side-fin condition | East | West | North | South | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
W1 | W10 | W1 | W10 | W1 | W10 | W1 | W10 | |||||
Full | Full | 248.5 | 965.3 | 267.7 | 978.2 | 199.4 | 684.5 | 181.3 | 695.3 | |||
Half | Full | 285.5 | 1143.3 | 301.7 | 1153.0 | 209.6 | 732.1 | 195.2 | 873.3 | |||
Zero | Full | 317.1 | 1358.4 | 337.2 | 1368.3 | 217.8 | 799.4 | 220.3 | 1184.9 | |||
Full | Half | 261.8 | 1079.5 | 285.9 | 1095.5 | 214.5 | 782.9 | 193.6 | 852.6 | |||
Half | Half | 300.6 | 1262.4 | 320.0 | 1274.3 | 224.7 | 825.9 | 208.5 | 1051.9 | |||
Zero | Half | 333.5 | 1485.2 | 356.0 | 1497.8 | 233.3 | 893.2 | 235.7 | 1385.2 | |||
Full | Zero | 273.4 | 1203.0 | 301.3 | 1222.3 | 232.7 | 913.9 | 210.6 | 1077.6 | |||
Half | Zero | 313.3 | 1394.6 | 336.0 | 1409.6 | 243.6 | 959.0 | 227.4 | 1302.0 | |||
Zero | Zero | 346.9 | 1626.0 | 372.1 | 1640.3 | 251.6 | 1022.8 | 255.0 | 1646.6 |
Tab.8 Percentage effect of full solar shading on the artificial lighting consumption for the tested window types on each facade |
Facade | East | West | North | South | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
WWR=0.2 | WWR=0.8 | WWR=0.2 | WWR=0.8 | WWR=0.2 | WWR=0.8 | WWR=0.2 | WWR=0.8 | |||||
W1–W3 | 2.36–4.78 | 4.53–8.12 | 0.54–0.75 | 1.25–1.84 | 1.64–4.36 | 3.51–6.52 | 1.32–2.26 | 3.05–3.96 | ||||
W4–W6 | 1.44–1.87 | 2.92–3.79 | 0.38–0.48 | 0.84–1.06 | 1.03–1.32 | 2.23–2.94 | 0.94–1.15 | 1.94–2.59 | ||||
W7–W10 | 1.08–1.35 | 2.03–2.65 | 0.28–0.36 | 0.57–0.75 | 0.77–0.96 | 1.51–2.01 | 0.73–0.89 | 1.30–1.79 |
5.4 Cost analysis
5.4.1 Cost analysis for windows without solar shading
5.4.2 Cost analysis for windows with solar shading
Tab.9 Economical evaluation of windows on various facades at a WWR of 40% without shading |
Window | NPV/USD | SPPwt/a | |||||||
---|---|---|---|---|---|---|---|---|---|
East | West | North | South | East | West | North | South | ||
W1 | 2249.2 | 2277.1 | 1408.6 | 1987.9 | 1.48 | 1.46 | 2.27 | 1.66 | |
W2 | 2153.2 | 2195.0 | 1342.6 | 1920.1 | 2.38 | 2.34 | 3.60 | 2.64 | |
W3 | 2023.3 | 2040.1 | 1248.6 | 1815.3 | 2.52 | 2.50 | 3.83 | 2.77 | |
W4 | 1969.0 | 1983.3 | 1308.2 | 1864.8 | 1.67 | 1.66 | 2.43 | 1.76 | |
W5 | 1862.9 | 1873.8 | 1146.6 | 1698.0 | 3.09 | 3.08 | 4.65 | 3.35 | |
W6 | 1815.5 | 1824.1 | 1136.1 | 1723.4 | 2.09 | 2.08 | 3.17 | 2.19 | |
W7 | 1319.8 | 1327.9 | 855.8 | 1362.9 | 3.65 | 3.63 | 5.20 | 3.55 | |
W8 | 1122.3 | 1125.9 | 781.7 | 1188.1 | 0 | 0 | 0 | 0 | |
W9 | 248.5 | 238.3 | 75.7 | 303.5 | 0 | 0 | 0 | 0 |
Tab.10 Economical evaluation of windows at various WWR on the west facade without shading |
Window | NPV/USD | SPPwt/a | |||||||
---|---|---|---|---|---|---|---|---|---|
20% | 40% | 60% | 80% | 20% | 40% | 60% | 80% | ||
W1 | 1082.5 | 2277.1 | 3273.6 | 4404.8 | 1.53 | 1.46 | 2.85 | 2.83 | |
W2 | 1039.4 | 2195.0 | 3012.8 | 4052.4 | 2.46 | 2.34 | 4.58 | 4.55 | |
W3 | 972.3 | 2040.1 | 2772.4 | 3728.6 | 2.61 | 2.50 | 4.90 | 4.86 | |
W4 | 957.0 | 1983.3 | 2799.3 | 3734.5 | 1.72 | 1.66 | 3.27 | 3.27 | |
W5 | 895.6 | 1873.8 | 2457.1 | 3299.3 | 3.20 | 3.08 | 6.04 | 6.01 | |
W6 | 875.0 | 1824.1 | 2535.6 | 3403.3 | 2.16 | 2.08 | 4.08 | 4.05 | |
W7 | 645.0 | 1327.9 | 1647.3 | 2169.1 | 3.72 | 3.63 | 7.24 | 7.30 | |
W8 | 548.0 | 1125.9 | 1694.9 | 2235.5 | 0 | 0 | 0 | 0 | |
W9 | 95.3 | 238.3 | 411 | 600.9 | 0 | 0 | 0 | 0 |
5.5 Concluding discussion of the fenestration characteristics
Tab.11 Economical evaluation of solar shading of the windows at a WWR of 40% on various facades |
Window | NPV/USD | SPPws/a | |||||||
---|---|---|---|---|---|---|---|---|---|
East | West | North | South | East | West | North | South | ||
W1 | −124.1 | −89.9 | −194.6 | −170.9 | 46.06 | 36.75 | 96.10 | 70.41 | |
W2 | −117.8 | −67.4 | −194.7 | −155.2 | 44.00 | 32.45 | 96.34 | 59.80 | |
W3 | −47.2 | −22.5 | −148.6 | −102.2 | 29.36 | 26.30 | 56.22 | 39.63 | |
W4 | 60.6 | 81.9 | −84.3 | −6.0 | 19.46 | 18.25 | 35.59 | 24.59 | |
W5 | 13.5 | 35.8 | −113.8 | −42.0 | 22.83 | 21.10 | 42.78 | 28.66 | |
W6 | 41.2 | 56.4 | −92.1 | −42.9 | 20.72 | 19.73 | 37.24 | 28.78 | |
W7 | 242.3 | 258.3 | 22.8 | 184.8 | 12.42 | 12.03 | 22.07 | 14.02 | |
W8 | 362.4 | 380.5 | 82.3 | 354.5 | 10.02 | 9.73 | 18.23 | 10.15 | |
W9 | 545.6 | 560.2 | 178.1 | 646.0 | 7.74 | 7.60 | 14.24 | 6.88 | |
W10 | 729.8 | 744.0 | 274.0 | 649.0 | 6.30 | 6.21 | 11.68 | 6.86 |
Tab.12 Economical evaluation of solar shading of the windows on the west facade for various WWRs |
Window | NPV/USD | SPPws/a | |||||||
---|---|---|---|---|---|---|---|---|---|
20% | 40% | 60% | 80% | 20% | 40% | 60% | 80% | ||
W1 | −54.3 | −89.9 | −113.7 | −135.8 | 40.29 | 36.75 | 33.59 | 32.25 | |
W2 | −44.7 | −67.4 | −73.6 | −78.0 | 35.97 | 32.45 | 29.45 | 28.14 | |
W3 | −25.2 | −22.5 | −0.8 | 24.3 | 29.57 | 26.30 | 24.07 | 22.97 | |
W4 | 17.6 | 81.9 | 178.1 | 291.4 | 21.24 | 18.25 | 16.60 | 15.52 | |
W5 | −0.4 | 35.8 | 96.3 | 164.7 | 24.09 | 21.10 | 19.34 | 18.34 | |
W6 | 7.4 | 56.4 | 130.6 | 217.5 | 22.77 | 19.73 | 18.09 | 17.05 | |
W7 | 92.2 | 258.3 | 492.5 | 756.4 | 14.25 | 12.03 | 10.75 | 9.91 | |
W8 | 144.5 | 380.5 | 700.5 | 1050.9 | 11.58 | 9.73 | 8.71 | 8.07 | |
W9 | 224.5 | 560.2 | 983.2 | 1421.4 | 9.00 | 7.60 | 6.93 | 6.54 | |
W10 | 295.5 | 744.0 | 1309.0 | 1901.7 | 7.51 | 6.21 | 5.61 | 5.25 |
Tab.13 Energy saving due to replacing a low-performance window (W10) with a high-performance window (W1) |
WWR/Façade | Energy saving/kWh | Energy saving/unit area of window/(kWh·m−2) | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
0.2 | 0.4 | 0.6 | 0.8 | 0.2 | 0.4 | 0.6 | 0.8 | Mean | STD (%) | |
(a) Without shading for W1 and W10 | ||||||||||
East | 366.3 | 791.9 | 1220.6 | 1645.5 | 114.5 | 123.7 | 127.1 | 128.6 | 123.5 | 6.3 (5.1) |
West | 382.1 | 801.1 | 1227.7 | 1650.3 | 119.4 | 125.2 | 127.9 | 128.9 | 125.3 | 4.3 (3.4) |
North | 247.2 | 514.1 | 770.6 | 1018.4 | 77.3 | 80.3 | 80.3 | 79.6 | 79.4 | 1.4 (1.8) |
South | 287.2 | 705.6 | 1184.0 | 1678.7 | 89.7 | 110.2 | 123.3 | 131.2 | 113.6 | 18.1(15.9) |
(b) With full shading for W1 and W10 | ||||||||||
East | 246.8 | 509.7 | 745.5 | 963.6 | 77.1 | 79.6 | 77.7 | 75.3 | 77.4 | 1.8 (2.3) |
West | 266.4 | 525.5 | 757.6 | 976.9 | 83.3 | 82.1 | 78.9 | 76.3 | 80.2 | 3.1 (3.9) |
North | 178.6 | 359.3 | 522.8 | 663.7 | 55.8 | 56.1 | 54.5 | 51.9 | 54.6 | 1.9 (3.6) |
South | 154.6 | 329.7 | 502.2 | 668.7 | 48.3 | 51.5 | 52.3 | 52.2 | 51.1 | 1.9 (3.6) |
(c) Without shading for W1 and full shading of W10 | ||||||||||
East | 229.5 | 465.1 | 660.9 | 848.0 | 71.7 | 72.7 | 68.8 | 66.2 | 69.9 | 2.9 (4.2) |
West | 240.0 | 469.5 | 663.3 | 846.0 | 75.0 | 73.4 | 69.1 | 66.1 | 70.9 | 4.0 (5.7) |
North | 169.5 | 337.9 | 477.9 | 602.4 | 53.0 | 52.8 | 49.8 | 47.1 | 50.7 | 2.8 (5.5) |
South | 140.8 | 300.4 | 443.2 | 581.1 | 44.0 | 46.9 | 46.2 | 45.4 | 45.6 | 1.3 (2.7) |