Sunlight control and daylight distribution analysis: the KOMTAR case study PDF

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Available online at www.sciencedirect.com Building and Environment 39 (2004) 713 – 717 www.elsevier.com/locate/buildenv Sunlight control and daylight distribution analysis: the KOMTAR case study Sharifah Fairuz Syed Fadzila;∗ , Sheau-Jiunn Siab a Department of Architecture, School of Housing, Buildi...

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Sunlight control and daylight distribution analysis: the KOMTAR case study Sharifah Fairuz Syed Fadzil Building and Environment

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Available online at www.sciencedirect.com

Building and Environment 39 (2004) 713 – 717 www.elsevier.com/locate/buildenv

Sunlight control and daylight distribution analysis: the KOMTAR case study Sharifah Fairuz Syed Fadzila;∗ , Sheau-Jiunn Siab a Department

of Architecture, School of Housing, Building and Planning, University Science Malaysia, Penang 11800, Malaysia b ML Design Pte. Ltd., 18-1 Jalan Sri Hartamas 8, Kuala Lumpur 50480, Malaysia Received 22 April 2003; received in revised form 6 August 2003; accepted 9 December 2003

Abstract Direct sunlight penetration and daylight distribution analyses were carried out at KOMTAR Penang which is a near-circular oce building with 12 bays of continuous orientation. Unlike rectangular plan buildings where one sun shading design device will protect one facade, this cylindrical building requires variations in sun shading devices around the whole perimeter. Daylight data were collected in overcast conditions and compared well with computer simulations, and further simulations were carried out to see the daylight reduction with calculated shading. ? 2004 Published by Elsevier Ltd. Keywords: Sunlight control; Daylight factor; Shading

1. The KOMTAR case study The KOMTAR building is the landmark of Georgetown, Penang, consisting of a tower block 68 storey high and a huge shopping mall below. The KOMTAR building, designed by Dato’ Lim Chong Keat in the 1970s is made of 12 similar-sided polygons that looked almost circular from afar. The exterior facade is almost all glass curtain wall cladding except for the reinforced concrete columns and oor slabs. The lifts, stairs, toilets and service core is located at the center of the building and it has one oor completely vacant. One can walk around the perimeter of the building and see magni cent views of Georgetown, Butterwoth, the Penang Bridge, the ferry terminal and much more. Despite the various orientations each side of the polygon is facing, the tower block has got no external shading device to control direct sunlight penetrating inside or to minimize solar heat gain (Figs. 1 and 2). 2. Analysis of sunlight penetration and shading depths of KOMTAR Through days of observation, it was found that without any exterior shading device, direct light penetration on clear

and cloudy days was quite extensive due to the amount of glass area surrounding the building. However, depending on the time, the sun’s altitude and the orientation of each bay, it was found that only 3– 4 bays were aected at a time with dierent degrees of the extent of sunlight penetration. (Fig. 3). Most of the oces that are in operation in the KOMTAR tower have vertical and horizontal blinds installed throughout the glass interiors to prevent these direct sunlight penetration, glare problems and the excess heat gain. Daylighting potential and views through the glass area are then neglected or ignored. What KOMTAR needs is a kind of exterior shading device that will help control some of these direct light penetration, glare and heat gain problems. The question then arises: how can designers know the right extent of shading width to put in each side intelligently and exactly? The established way of doing this is by using the appropriate sunpath diagram of Penang along with the shading mask. Several computer programs, for example, SUNTOOL [1] developed by the University of Western Australia, also does exactly the same thing with more sophisticated details that can tell designers the extent of sunlight penetration in whatever orientation, location and time of the year. 2.1. Methodology

Corresponding author. Tel.: +604-6533-888 Ext. 3184; fax: +604-657-6523. E-mail address: [email protected] (S. Fairuz Syed Fadzil). ∗

0360-1323/$ - see front matter ? 2004 Published by Elsevier Ltd. doi:10.1016/j.buildenv.2003.12.009

All 360-day simulations were carried out per orientation using SUNTOOL for the critical times from 10 am to

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S. Fairuz Syed Fadzil, S.-J. Sia / Building and Environment 39 (2004) 713 – 717

Fig. 3. Level 35 KOMTAR showing the extent of direct light penetration at 1 bay at 2:30 pm.

Bay orientation 0°

Horizontal shading depth (mm)

330°

2000

30°

1500

300°

1130

1520 1280 1000 500 710

Fig. 1. The KOMTAR tower block taken from afar.

0

270° 1960

60° 1300

90°

1330 1630

1980

1140

240°

1540

120°

1790

150°

210° 180°

Fig. 4. Results of the SUNTOOL simulations showing the extent (i.e. maximum) of shading needed for each bay. Fig. 2. The KOMTAR tower (dashed line shown above)—indicating no shading devices.

3 pm to nd out the maximum depth of horizontal exterior shading device needed for all the 12 bays at KOMTAR. The 10 am to 3 pm duration was chosen as the critical period in this context and climate, where solar gain is usually at its peak making exterior shading a must. Furthermore, shading for the period before 10 am and after 3 pm showed depths that are too wide (the worst being almost parallel to the window sills) and impractical to construct as permanent devices. Only the maximum depth is graphed (Fig. 4) as had the maximum been constructed it would also have solved a year’s shading needs/requirements of all bays. To get the appropriate sunpath for the location of Georgetown, Penang, the latitude of 05◦ 28′ North and the longitude of 100◦ 20′ East of Greenwich was input to the SUNTOOL program. 2.2. Results As can be seen from the results in Figs. 5 to 6: • The usual practice of having similar shading devices regardless of orientation is inappropriate if the intention of having them is for direct sunlight penetration control. • The extent of horizontal shading pattern should follow the appropriate sunpath if designers want to avoid them

Fig. 5. Schematic oor plan of Level 35 at KOMTAR.

to be insucient (satisfying less than 50% of the yearly shading needs); or in excess (providing more shading than is needed). • Designers can also use these exterior shading requirements if their designs have the same opening heights and orientations similar to the bays at KOMTAR, and if the critical hours are the same, i.e. from 10 am to 3 pm. With the suggested maximum shading depths given, designers can also develop alternatives in the design of their shading device, for example, by dividing the depth into several segments, curving them, etc.

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Fig. 6. Schematic oor plan as Fig. 5 with the shading depths of each bay inserted.

• It can also be deduced that the best bay with the least sunlight penetration is with orientation 0◦ and the worst is with 240◦ ; those with orientations 30◦ , 180◦ , 330◦ , 60◦ , 90◦ , 300◦ , 150◦ , 120◦ , 210◦ and 270◦ are the next one’s ranking them in order. In this context, the bay with the least direct sunlight penetration is considered the best as it receives the least heat gain thus reducing the cooling load and saving energy. It is also the best bay with regard to minimum glare problems. 3. Analysis of KOMTAR in overcast sky Section 2 discusses KOMTAR in a clear sky, but situations would be dierent for an overcast sky. Since cloudy to overcast skies occur more often here in Malaysia, analysis must take the most extreme case of a completely overcast sky into consideration as well. Overcast sky means that the sun is completely hidden above the clouds and thus problems of direct light penetration do not occur. The daylight factor (DF) is used to study light distribution in an overcast sky, where natural light comes from 3 components; and they are the sky component, the internal re ected component and the external re ected component. 3.1. Methodology There are no illuminance data at any meteorological stations in Penang or in the whole of Malaysia. On 25 July 2001 which was observed to be very cloudy to overcast, daylight measurements and illuminance data (Ei ) were taken at several points in the building which were compared with the outdoor illuminance (Eo ). Measurements used ve light metres or probes that had been calibrated and connected to a data logger. Probes 1– 4 were suitable for light measurements in the interiors and were taken 1 m from the oor as the working plane, while probe 5 was suitable to measure exterior light up to 100; 000 lux. All ve probes were moved from axis to axis three rounds to get the average %DF. The locations of the measured points and axis could be seen in Fig. 7 and the averaged %DF achieved in Table 1.

Fig. 7. The four station points with respect to each bay’s orientation. Table 1 Average DF(%) at respective grid/axis Bay orientation

000◦ 030◦ 060◦ 090◦ 120◦ 150◦ 180◦ 210◦ 240◦ 270◦ 300◦ 330◦

Measured Points (away from window equally) 1

2

3

4

1.23 3.53 3.44 3.84 4.44 4.11 3.49 1.56 1.97 1.98 1.69 1.06

1.01 2.68 3.10 2.95 3.75 3.34 2.62 1.19 1.61 1.65 1.37 0.78

0.86 2.14 2.31 2.52 2.87 2.47 2.20 0.88 1.18 1.09 0.93 0.60

0.78 2.02 2.10 2.57 2.79 2.48 1.89 0.75 0.87 0.92 0.82 0.53

A series of simulations using the software ADELINE 2.0 [2] was carried out for comparison with the eld measurements as can be seen in Figs. 8, 9 and 10. 3.2. Results The results compare well between simulations and measured eld work (Fig. 10). Figs. 9 and 10 were the exact output of the simulations carried out using ADELINE 2.0 NT model. Due to the complicated polygonal shape of the building, it was found that the simulations also produced contours outside the building parameter but analysis only focused on the contours within the building parameter. The inverted numbers on the plan similarly are the outcome from the ADELINE model design. Generous distribution of DF were achieved due to the huge amount of glass surrounding the oor area which contributes to the increase in the internal re ected component.

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Fig. 10. Longitude section of DF pattern.

Fig. 8. Model of combined physical parameters for typical oor (generated by SUPERLITE input les).

Fig. 12. Model of combined physical parameters for typical oor with shading devices (generated by SUPERLITE input les).

3.3. Daylight distribution analysis of KOMTAR with shading device

Fig. 9. ISO DF plan of typical oor plan.

The DF were found to range from 6.0% (near the windows) to 2.0% further away from the windows, so one can conclude, on a ne and bright day, daylighting alone is sucient for working comfortably in an open oce space (Fig. 11). If supplementary arti cial lighting is required they must be placed further away from the windows where DF were found to be in the range of 1.2%– 0.5%.

Natural light distribution at KOMTAR with overcast sky would be reduced if exterior shading devices (discussed in Section 2.1) were implemented and constructed. Since eld measurements and simulations were found to correlate quite well, simulations using ADELINE 2.0 were carried out again, this time with the input of the calculated shading devices as can be seen in Fig. 12. It was found that with the shading devices in place, the average %DF dropped by almost 50%. Qualitatively, however, with the newer range of %DF made smaller with the shading devices, natural light distribution can be predicted to be improved because the problems of glare and contrast will be minimized. Initially, glare can cause immediate discomfort to people which can lead to potential fatigue and danger [3]. Glare, a

Fig. 11. Daylight distribution for a typical oor in KOMTAR during overcast sky.

S. Fairuz Syed Fadzil, S.-J. Sia / Building and Environment 39 (2004) 713 – 717

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Figs. 13 and 14 show a plan and sectional view of %DF distribution of the oce space with shading. 4. Conclusion

Fig. 13. ISO DF plan of typical oor plan.

This paper dwelt on the fact that daylighting should be utilized in the built environment particularly in oce spaces that are in operation in daylight hours, and particularly in Malaysia where daylight is available in abundance and for free. Since sunlight, which is also common in cloudy to clear days, comes also with heat and glare problems, some kind of control is necessary, and designers must make intelligent decisions through research and thorough analysis. Careful orientation, planning and calculated shading device are all found to be of utmost importance if the target is an energy conscious and environment friendly design. Acknowledgements The authors would like to acknowledge University Science Malaysia and research funds from IRPA, the cooperation given by Penang Development Corporation and Pen-Urus Harta Sendirian Berhad which is the Management of KOMTAR. References

Fig. 14. Longitudinal section of DF pattern.

signi cant urban problem, is not comfortable if it accidentally or improperly falls within a person’s visual cone and intrudes upon his/her work.

[1] Marsh AJ. SUNTOOL, 1998. http://arch.uwa.edu.au/software. [2] ADELINE 2.0NT (SP9). Advanced daylighting and electric lighting integrated new environment, IEA 1989 –98. [3] Pang YK, Peng MY, Zhang SG, Goa LT. Evaluating discomfort from lighting glare. Building Research and Practice 1983;11(5): 317–21....