transformation of industrial planning in singapore

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Transformation of industrial planning in Singapore: Study on themicroclimatic condition of different industrial estates

Steve Kardinal Jusuf a , * , Nyuk Hien Wong b , Zhi Ying Wong b , Erna Tan ba NUS Environmental Research Institute, National University of Singapore, 4 Architecture Drive, Singapore 117566, Singaporeb Department of Building, National University of Singapore, 4 Architecture Drive, Singapore 117566, Singapore

a r t i c l e i n f o

Article history:Received 24 January 2014Received in revised form10 April 2014Accepted 8 May 2014Available online 2 June 2014

Keywords:IndustrialMicroclimatic conditionAir temperatureUrban morphologySingapore

a b s t r a c t

Despite the progression and variation of Singapore industrial developments over time, present literaturehave yet to examine the changes in the urban morphology of local industrial estates and consequently,their impact on the microclimate.

The paper discusses the microclimatic condition and urban morphology in four different industrialdevelopments developed by JTC in Singapore, constructed in different decades, and categorized intoBusiness Park development (BPD) and B2 development (B2).

Comparisons of urban morphology and microclimatic condition among the different estates wereanalysed. In general, it is found that, compared to B2, BPD has a lower mean SVF value, more extensivegreenery, higher building height and building mass, a signi cantly larger proportion of greenery butlesser pavements and building area, and lower building density. There is a decreasing trend in the meanambient air temperature observed along with the transformation of industrial developments over time.B2 has higher mean air temperature than BPD at all times of the day. B2 has lower diurnal temperaturerange than BPD which infers that BPD is generally more effective in reducing the heat island intensity.

Finally, critical morphology parameters on ambient temperatures in industrial estates were identi ed.Within the 50 m radius, critical parameters with signi cant in uence on the minimum temperature

(T min ) and the average temperature ( T avg ) values are the green plot ratio (GnPR), the total tree leaf area(TREE) and the percentage of greenery area (GREEN), whereas the critical parameters with signi cantin uence on the maximum temperature ( T max ) are SVF, GnPR, TREE and GREEN.

2014 Elsevier Ltd. All rights reserved.

1. Introduction

The management of urban growth is a key to the spatial dis-tribution and variability, which in turn affects the environmentalquality. Differences in land-use, surface characteristics, urbanmorphology and atmospheric conditions give rise to variations inthe thermal environment within an urban area [2e 7] . The impact of land use including commercial, residential, agricultural, industrialuses has been extensively researched using remote-sensing tech-nology in United States, China and Germany [8 e 11] . More impor-tantly, several overseas studies and Singapore have found thatregions associated with industrial activities tend to exhibit highertemperatures than the surroundings [12] .

Yu [13] noted that Singapore economy has witnessed a rapidexpansion of industrial developments since independence in 1965.According to Han [14] , approximately 7000 ha of industrial landand 4 million m 2 of ready built factor space have been developed inthe last 36 years. The industrial sector is found to be the largestconsumer of electricity constituting 40.2% of the nationwide elec-tricity consumption in 2011 [15] . Currently, the industrial sectortakes up 18% of the total land mass and is projected to increase to20% by 2050 [16] . With the overall supply of industrial spaces set togrow, these trends underline the value of examining the trans-formation of existing industrial estates to help negate the adversemicroclimatic effects for future developments.

Despite the variations in forms and functionalities, Peddle [17]de nes industrial estates as a large tract of land, subdivided anddeveloped for use of several rms, distinguished by sharableinfrastructure and close proximity, bounded by the restrictions onthe lot sizes, access and utilities.

Established in 1968, the Jurong Town Corporation (JTC) is astatutoryboardin chargeof the planning, development, leasing and

* Corresponding author. Tel.: 65 65164691.E-mail addresses: [email protected] , [email protected]

(S.K. Jusuf).

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management of Singapore industrial estates. With control over 80%of the total industrial land, JTC is the largest industrial landlord andis responsible for the implementation of industrial land use policiesto meet the changing and diverse needs of businesses [18] .

Faced with the constraints of limited land, strong physicalplanning framework and administration are essential to optimizeland use in view of various competing uses [13] . To prevent urbansprawl and achieve an orderly distributed land use, boundaries,zoning regulations and maximum plot ratio were set out in theMaster Plan. Although the Master Plan has undergone several re-visions since its inception in 1960s, the emphasis on environmentalmanagement is evident in the detailed planning of industrial areas.Heavy industrial areas are concentrated southwest to the centralbusiness district and the remaining areas are located along bordersof island, away from the cleaner commercial and residential estates[19] .

The emergence of different industrial developments since the

inception of Master Plan in 1960s can be categorized into threedifferent time frames.

During the period of 1960s e 1970s, ready-built standard fac-tories and light industrial estates were constructed to facilitate theef cient set up of labour-intensive industries. These were typicallylocated in suburban areas and near high density housing estates.Flatted factories, small workshop complexes and landed factorieswere the predominant forms of industrial infrastructure [20] .

During the period of 1970s e 1980s, industrial restructuring wasnecessary to retain global economic competitiveness. The switch tocapital and technology intensive industries promoted the growth of high-value industrial businesses, thus the emergence of ScienceParks and Business Parks. The high land cost and land scarcitynecessitated land intensi cation. With reclamation, en-bloc rede-

velopment and higher plot ratios set out in JTC 's Industrial LandPlan for 21st Century (IP21), multi-storey premises such as stack upand ramp up factories emerged, raising the plot ratio from 0.5 to2.5. Specialized clusters also housed and promote knowledge-based activities [19] .

During the period of 2000s e 2010s, an integrated planningapproach was adopted to realize the concept of live-work-play-learn hub, in pursuit of holistic development and sustainability of industrial developments, with an emphasis on environmentalquality and aesthetics [20] .

Under the Master Plan 2008, the industrial land use is catego-rized into different zones according to the potential environmentalpollution. Lands zoned as Business 1 (B1) and Business 2 (B2) areindustrial developments with at least 60% of gross oor area used

for light manufacturing or warehousing purposes, leaving a

maximum of 40% for ancillary activities such as of ces and show-rooms [14] . Another category is the Business Parks, set aside fornon-pollutive industries and businesses with at least 85% of thetotal oor area used for its operations. This predominantly includeshigh-technology, value-added and knowledge-intensive activities[21] .

The aim of this study is to evaluate the microclimate withrespect to the urban morphological characteristics for the differentforms of industrial estates developed by JTC in Singapore.

2. Methodology

2.1. Object of study

The paper is con ned to the study of microclimatic conditionand urban morphology changes in four different industrial de-velopments constructed in different decades. These include an in-

dustrial estate with single-user landed factories, and one estatecomprising of a mix of landed and ready-built multiple-users

atted factories, which both are categorized as B2 development.Two different forms of business parks categorized as Business ParkDevelopment (BPD), i.e. a pioneer development and an integratedindustrial hub are included. They are located at Loyang IndustrialEstate (Loyang), Woodlands Industrial Park (Woodlands), Interna-tional Business Park (IBP) and one-north. The general site locationsare highlighted in Fig. 1. All four sites chosen are owned by JTC tominimize hidden factors and allow a common basis for comparisonto study the transformation of industrial infrastructure over time.

Background information for the various sites has been obtainedfrom JTC.

Loyang Industrial Estate was developed in 1974 e 1977. Approx-

imate site study gross oor area (GFA) is 1.16sqkm with gross plotratio of 2.5. It is located on the eastern of Singapore. This devel-opment is categorized as B2 development under Master Plan(2008). Single-storey landed factories were built for aviation in-dustrial centre, manufacturing, repair, overhaul, aviation works andprecision parts manufacturing.

Woodlands Industrial Park was developed in 1995 e 1999.Approximate site study GFA is 1.78sqkm with gross plot ratio of 2.5.It is located on the northern of Singapore. This development iscategorized as B2 development under Master Plan (2008). Proto-type factories (standalone/semi-detached factories) were built forfood production and manufacturing from raw materials, assemblyof plants and machinery, and treatment of waste oil/solvents.

IBP was developedin 1992 e 2009. Approximatesite study GFA is

0.37sqkmwith gross plot ratio of 1.0e

2.5. It is located on the south-

Nomenclature

JTC Jurong Town CouncilBPD Business Park developmentB2 B2 developmentSVF sky view factorT min minimum temperatureT avg average temperatureT max maximum temperatureGnPR Green Plot Ratio within 50 m radius areaTREE total tree leaf area within 50 m radius areaGREEN percentage of greenery area within 50 m radius areaIP21 Industrial Land Plan for 21st CenturyLTA Land Transport AuthorityGIS Geographic Information System

BDG percentage of building footprint area within 50 mradius area

PAVE percentage of pavement area within 50 m radius areaHBDG average height to building area ratioWALL total wall surface areaAvgHT average building heightTURF turf area within 50 m radius areaTotalGreen total green area within 50 m radius areaDTR diurnal temperature rangeGross oor area all covered oor areas of a building, except

otherwise exempted, and uncovered areas forcommercial uses [1]

Gross plot ratio the ratio of the gross oor area of a building(s) toits site area [1]

S.K. Jusuf et al. / Building and Environment 80 (2014) 48 e 60 49


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western of Singapore. This development is categorized as BusinessPark Development (BPD) under Master Plan (2008). Purpose-builthigh rise buildings were built for information technology (IT),software development, research and development (R & D), high-tech manufacturing, laboratory testing and data processingactivities.

One-north is developed in 2005 e 2025. Approximate site studyGFA is 2.36sqkm with gross plot ratio of 3.3 e 7.5. It is located on the

south-western of Singapore. This development is categorized asBPD under Master Plan (2008). Mixed-use development (high rise)are built for educational institutions, residences and recreationalamenities, research facilities and of ces.

Several measurement points were chosen to cover differenturban morphology in each area. In Loyang, there were 11 mea-surement points. In Woodlands, there were 12 points. In IBP, therewere 10 points. In one-north, there were 30 points. Locations of measurement points can be referred to in Fig. 1.

2.2. Climate predictor parameters

On each measurement point, U12-011 HOBO temperature/RHdata logger and solar cover were used to measure the ambient air

temperature. Wind speed smart sensor S-WSA-M003 and HOBOmicro station H21-002 were used to measure the wind speedcondition. All sensors were installed on lamp posts at 2.1 mabove ground in compliance to Land Transport Authority (LTA)regulations. For Loyang and Woodlands, data logging wascon gured at 1-min interval, while IBP and one-north werecon gured at 10-min and 5-min interval respectively, whichwere all averaged into hourly means. The sensors were factorycalibrated.

As the reference point, each area had one weather stationinstalled as shown in Fig. 1 for Loyang, Woodlands and IBP. Analysisfor one-north used meteorological data from nearby weather sta-tion in National University of Singapore (managed by Departmentof Geography) [23] . HOBO Weather Station H21-001 was used to

collect data of solar radiation (W/m2

), ambient air temperature ( C),

relative humidity (%), wind direction (degree), wind speed (m/s)and rain fall (mm).

2.3. Urban morphology parameters

To obtain the urban morphology data, master plan drawings of the four industrial estates were input into the Geographic Infor-mation System (GIS) system to extract the relevant morphology

information. In quantifying the morphology parameters, a buffer of 50 m radius with respect to each the measurement point waschosen. Kruger and Givoni [24] examined three radii, 56 m, 125 mand 565 m, and found 56 m to be most effective in producing sig-ni cant correlation between land use patterns and local tempera-tures. Similarly, in a local study, Jusuf and Wong [25] concluded that50 m radius had the most signi cant in uence amongst the 4 radii(25 m, 50 m, 75 m and 100 m) based on the correlation strengthbetween building area and T min , T avg and T max .

Using ArcGIS, the two dimensional area of greenery (GREEN),building (BDG) and pavement (PAVE) within the radius is quanti-

ed. The quantity of trees on site within the bound area is veri edby site survey. The total leaf area is then obtained according to theweightage assigned as set out in the equation developed by Ong

[26] for the calculation of green plot ratio (GnPR).The average height to building area ratio (HBDG) and total wall

surface area (WALL) can also be calculated based on the heightattribute data in BDG extracted from the GIS measurement. Ac-cording to Giridharan et al. [27] , the thermal mass of built envi-ronment within the area of in uence radius is a function of HBDG,derived by dividing the average height of buildings over the oorarea.

Similar to the methodology detailed by Svensson and Eliasson[28] , the photographical method involving sh-eye lens and NikonDigital camera is used to capture the sky view factor (SVF) for eachmeasurement point. The images are then imported into the Ray-Man 1.2 software and converted into black-and-white form, withthe sky in white and buildings or trees are black for SVF calculation

[29] .

Fig. 1. Locations of Loyang, Woodlands, IBP and one-north Industrial Estates mapped onto URA Master Plan 2008 [22] and the corresponding measurement points.

S.K. Jusuf et al. / Building and Environment 80 (2014) 48 e 6050


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Nikon D80 Digital camera with Nikon AF DX 10.5 F2.8G IF EDsheye lens was used to capture the SVF.

2.4. Data selection for analysis

The eld measurements were conducted in different timeframes. They were 1 July 2012 e 31 December 2012 for Loyang andWoodlands; 1 December 2010 e 30 April 2011 for IBP; and 1November 2007 e 31 March 2008 for one-north.

Using the meteorological data, the data analysis focuses onfairly clear, calm (wind speed less than 3 m/s) and hot weathercondition, selected by analysing the pro le of daily solar radia-tion which exhibits a bell curved shape with a peak exceeding700 W/m 2 , wind speed less than 3 m/s, air temperature and norain.

Based on the selection criteria, dates were selected from therespective measurement periods for which the corresponding airtemperatures were further analysed. Loyang used total of 29 daysdata which 11 days were from July 2012, 4 days were from August2012, 3 days were from September 2012, 8 days were from October2012, 2 days were from November 2012 and 1 day was fromDecember 2012. Woodlands uses total of 23 days data which 7 days

were from July 2012, 6 days were from August 2012, 3 days werefrom September 2012, 5 days were from October 2012, 1 day wasfrom November 2012 and 1 day was from December 2012. IBP usestotal of 23 days data which 2 days were from December 2010, 6days were from January 2011, 8 days were from February 2011, 3days were from March 2011, and 4 days were from April 2011. One-north uses total of 36 days data which 6 days were from November2007, 7 days were from December 2007, 6 days were from January2008, 15 days were from February 2008, and 2 days were fromMarch 2008.

2.5. Data analysis

From the eld measurement data, the urban morphology pa-rameters were compared for the industrial estates. The urbanmorphology parameters discussed were SVF, GnPR, averagebuilding height (AvgHT) and total wall surface area (WALL),average building height to oor area ratio (HBDG) and composi-tion of pavement (PAVE), greenery (GREEN) and building footprint(BDG).

From the urban morphology analysis, comparison of ambient airtemperature among estates and comparison of average ambient air

Fig. 2. SVF measurement results.



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temperatures between categories of industrial were made. Thedistribution of ambient air temperature was analysed. Daytimerefers to 08:00 to 19:00 h, whereas nighttime refers to 20:00 to07:00 h.

Kruskal e Wallis test was used to see if there is any statisticaldifference for each parameter among the four industrial estates,while Mann e Whitney U test was used to nd signi cant differencefor each parameter between the two categories of industrialdevelopment. Post-hoc pair-wise test was further used to revealany difference for each parameter between two of the industrialestates.

Finally, critical morphology parameters affecting the ambienttemperatures in industrial estates were analysed. Pearson correla-

tion was used to measure the linear correlation between air tem-perature and each parameter.

3. Urban morphology of industrial estates

3.1. Comparison of SVF measurement results

Fig. 2 shows the sky view factor (SVF) measurement resultsobtained.

As shown in Fig. 3a, Loyang exhibits a moderately high SVFrange from 0.65 to 0.85, which concurs with the fact that it is arelatively open area with short buildings located apart. The pres-ence of foliage is consistently observed across all the measuredspots, which indicates well spread greenery despite the generally

sparse canopy. Shading is provided mainly by trees from the

immediate surroundings, with minimal sky obstruction by build-ings; exceptPoint 7 where the lowest SVF of 0.37 is observed due tothe extensive crown of a single tree with dense canopy with mul-tiple overlapping leaves.

As shown in Fig. 2b, Woodlands exhibits either a high SVF of above 0.90 or below that of 0.70. The observed values indicate anuneven distribution of greenery across the various spots in theindustrial park. In Points 3, 6, 7, 8 and 10, majority of the shading iscaused by dense tree canopies with some encroachment of sur-rounding buildings into the sky visibility as shown from thecompletely black portions of SVF images. As for Points 1, 2, 4, 5, 9,11and 12, the obvious lack of adjacent building structures and sparseleafage barely provides any effective shade, thus contributing to

high SVF value.As shown in Fig. 2c, IBP displays a narrower range of SVF values

between 0.65 and 0.85 as compared to Woodlands. The effective-ness of shade is relatively consistent across all the spots. Whilesimilar values are found in Loyang, the distinct difference is thatinstead of well-spread sparse foliage, the dark parts here arecompletely shaded and highly concentrated around the perimetersof the hemisphere captured. A large part of shading in IBP is due tothe buildings from the immediate surroundings rather than thetree canopy, as inferred from the evident polygonal shaded outline.This implies that the building masses are generally taller and moreclosely arranged in the estate layout.

As shown in Fig. 2d, a wide range of SVF values from 0.15 to 0.99are observed in one-north, with an equal number of spots with

values above and below 0.50. For points where SVF value falls

Fig. 2. (continued ).



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below 0.50, the shaded cover is either completely due to thebuildings that ank the sides of the measured spot as in Points 3and 4, orthe canopyof mature trees as in Points 7,17, 24 and 28. Theexceptions with a combination of both are at Points 21 and 22. Amix of the multi-storied industrial complexes and foliage fromtrees lining the streets reduce the overall sky visibility.

Table 1 show the comparison of the SVF values observed acrossthe four industrial estates. The variation in SVF values is the least inIBP with a standard deviation of 0.072, whereas the values vary themost in one-north with 0.302.

Comparing the mean value of the SVF results, the largest dif-ference of 0.172 is again noted between IBP and one-north, thus,although both are business park developments, the former isgenerally less shaded throughout the site.

Although the SVF values vary quantitatively, the Kruskal e Wallistest results show insuf cient evidence to conclude any statisticaldifference among the four industrial estates.

The Mann e Whitney U test results reveal no signi cant differ-ence between the SVF values for B2 and BPD. Nonetheless, BPD hasa lower mean SVF value (0.622) than B2 (0.725). This implies thaton average, any spot within BPD receives a greater extent of shadethan that of B2.

3.2. Comparison of greenery condition

In the evaluation of greenery condition for the four industrialestates, the total tree leaf area (TREE) and turf area (TURF) are thetwo key components used to quantify the Green Plot Ratio (GnPR).

The GnPR is derived from Equations (1) and (2) .

Total Tree Leaf Area No : of Trees Canopy Area LAI(1)

GnPR Total Tree Leaf Area Turf Area

Area of Circle r 50 m (2)

Table 2 provides the descriptive statistics summarizing thecomparison of the three parameters. Total green area (TotalGreen)is the total of TREE and TURF within an area of 50 m radius.

As shown in Table 2 , one-north has the largest total green areafor an average spot, followed by IBP, Woodlands and Loyang withthe least. Interestingly, the composition that adds up to the totalgreenery for each estate is different.

Although one-north does not have the most extensive turf area,it possesses the largest total tree leaf area, which hence attains thehighest total greenery area. It can be inferred that the main con-tributors of foliage are trees, possibly due to the presence of forested parks within the estate. The high density of leaves is inagreement with the low SVF values detailed earlier.

Conversely, for IBP, the predominant greenery on site is turf andits extensiveness compensates for the small tree leaf area to bringthe total greenery to the second highest. Similar to one-north,Woodlands has limited turf area, thus the total tree leaf areaplays the key role in contributing to the overall green condition.

Loyang has equally low proportion of turf and tree leafage, thuscomparatively it has the poorest greenery condition among thefour. Comparing Woodlands and Loyang, the former has an

evidently higher tree leaf area yet smaller turf, which implies the




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on-site presence of more trees with extensive leafage than thelatter.

As expected, since it corresponds with the total greenery, the

highest average GnPR is observed in one-north, followed by IBP,Woodlands and Loyang. Comparing the two estates with thegreatest difference for average GnPR, one-north has 25.17% moregreenery than Loyang for every square metre on site.

Both the highest and lowest GnPR values are observed in one-north; with GnPR of 3.73 measured at Point 29 located within apark where dense clusters of trees are found, whereas the GnPR of 0.26 is found at Point 4 within a high-rise built-up area. Such lowvalues are the result of the high concentration of built structures

and larger building footprint, which proportionately reduces theturf area.

Based on the Kruskal e Wallis test results, there is a statisticallysigni cant difference in the GnPR values across the four industrialestates. The post-hoc pair-wise test further revealed a real differ-ence in the greenery condition between Loyang and one-north, andLoyang and IBP.

The Mann e Whitney U test results verify that the GnPR of twotypes of development are signi cantly different. As inferred fromthe higher average rank of BPD than B2, it can be concluded that ingeneral BPD has more extensive greenery than B2 development.

3.3. Comparison of average building height

Among the four estates, IBP has the highest average buildingheight of 20.13 m, which is 2.41 times taller than that of Loyang. Asdetailed in Table 3 , compared to Woodlands and Loyang, one-northand IBP have a much higher standard deviation, which translate toa wider range of building heights observed.

Hence it can be inferred that Loyang is characterized by build-ings of generally similar heights between 6 m and 10 m, whereas

for Woodlands, IBP and one-north, some buildings are twice theheight of others, which verify the different types of facilities foundon site, such as multi-storeyed ready-built factory and single-storeylanded factories.

The Kruskal e Wallis test results con rm that there is a signi -cant difference in average building height (AvgHT) in the four es-tates, but the post-hoc pair-wise test results show insuf cientevidence to distinguish the statistically different pairs of industrialestate.

Nonetheless, the quantitative difference in the average buildingheight within the same development category is minimal. Thedisparity between Loyang andWoodlands, as well as one-north andIBP is only 1.69 m and 1.11 m respectively. This is relatively insig-ni cant considering that a typical oor-to- oor height for an in-

dustrial building is 3.8 me

5.0 m [30] .Comparing the average building height of BPD and B2 devel-opment, a substantial difference of 52.07% is noted. The Man-ne Whitney U test results con rm that the BPD has a signi cantlyhigher median height than B2 developments.

Interestingly, there appears to be a positive relationship be-tween maximum height of buildings and the transformation of industrial developments over time, with increasingly taller build-ings are developed in the recent years. A driving factor could be theneed to maximize industrial land use, through the allocation of higher Gross Plot Ratio achievable under the planning policy. Also,along with the shift in the economic focus to high value industrialbusinesses and operations, the change in function also necessitatesa change in the building form.

3.4. Comparison of total wall surface area

The total wall surface area (WALL) increases when the buildingsget higher, as it is computed as a function of the building height and

Table 2Comparison of greenery condition among the four industrial estates.

N Minimum Maximum Mean Std.

deviationLoyang Turf 11 2791.72 5524.73 4220.29 823.40

Trees 11 2199.96 17,220.98 4647.82 4310.30TotalGreen 11 5901.33 22,745.71 8868.11 4755.89GnPR 11 0.75 2.89 1.13 0.61

Woodlands Turf 12 1278.76 4620.55 3063.19 869.43Trees 12 2829.75 15,470.00 6335.58 4158.28TotalGreen 12 4108.51 20,090.55 9398.78 4837.37GnPR 12 0.52 2.56 1.20 0.62

IBP Turf 10 4737.68 6375.44 5638.67 586.30Trees 10 1611.32 6701.98 4736.95 1887.50TotalGreen 10 7876.00 12,037.12 10,375.62 1774.64GnPR 10 1.00 1.53 1.32 0.22

One-north Turf 29 470.84 6867.29 4766.95 1841.44Trees 29 0.00 22,476.95 7059.01 5768.42TotalGreen 29 2070.17 29,268.76 11,825.96 7085.15GnPR 29 0.26 3.73 1.51 0.90

Table 3Comparison of average building height among the four industrial estates.

N Minimum Maximum Mean Std. deviation

Loyang 11 7 15.75 8.37 2.76Woodlands 12 0 31.5 10.06 9.79IBP 10 0 45.5 20.13 14.08One-north 29 0 108 19.02 19.94The value 0 indicates absence of buildings.

Fig. 3. Comparison of building, pavement and greenery percentage composition.

Table 1Comparison of SVF results among the four industrial estates.

Location Mean N Std. deviation Minimum Maximum Range

Loyang 0.722 11 0.140 0.37 0.9 0.53Woodlands 0.728 12 0.238 0.32 0.96 0.64IBP 0.751 10 0.072 0.66 0.89 0.23One-north 0.579 29 0.302 0.00 0.99 0.99Total 0.660 62 0.250 0.00 0.99 0.99



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length within the radius of in uence. It does not take into accountallowances or deduction for openings or extensions here.

As shown in Table 4 , one-north has the largest average wallsurface area, followedby Woodlands, Loyang and IBP. Although one-north has a taller average building height than Woodlands, theWALL values are comparable with a small difference of only 6.37%.This implies that the large wall surface area is mainly due to its tallbuilding height. In contrast, the morphology in Woodlands is char-acterized by shorter but more numberof buildings, which addon tothe building lengths on the two-dimensional foot print or buildingperimeter within radius of in uence. Despite the quantitative dif-ference, the average WALL values across the four estates were notsigni cantly different based on the Kruskal e Wallis test results.

Comparing average WALL values, BPD has a slightly largeraverage total wall surface area at 2718.52 m 2 than that of B2 at2405.97 m 2 by 11.50%, due to generally taller buildings more closelylocated to each other. This results in higher building density.

The Mann e Whitney U test results reveal no signi cant differencein theaverageWALLvalues betweenthe twocategories. However, themaximum WALL value found in one-north is 3.08 times that of IBP,whereas Woodlands is only 1.35 times that of Loyang. The variationsin maximum WALL values observed within the BPD category is thusmuch larger than within the B2 developments.

Interestingly, Loyang has a higher maximum WALL value at5107.96 m 2 than that of IBP at 3943.71 m 2, but a correspondingbuilding height half that of IBP at 9.8 m compared to 21 m. Thisindicates that the two dimensional footprint occupied by thebuildings are bigger, which implies higher building density thanthe latter at the corresponding points measured. One-north showsthe highest maximum WALL value and height of all at 12,136.58 m 2

and 38 m respectively. The highest maximum WALL value andheight in Woodlands are 6913.62 m 2 and 31.5 m respectively.

3.5. Comparison of average building height to building area ratio

The average height to building area ratio (HBDG) is an importantindication of the thermal mass in the estate. This has implicationson the ambient air temperatures [27] .

IBP has the highest value, followed by one-north, Loyang andWoodlands. As deduced from Table 5 , on average for every squaremetre, the building height in IBP is 1.66, 6.57 and 12.28 times that of one-north, Loyang and Woodlands respectively.

Statistically, a distinct difference in the HBDG is observed fromthe Kruskal e Wallis test results. The paired-wise test further showsthat the signi cant differences are located between the pairs of Loyang and Woodlands versus one-north. Through the Man-ne Whitney U test, a real difference is noted between the B2 andBPD HBDG values. This is in line with the visual observations fromthe site surveys where BPD have signi cantly higher building massthan that of B2 developments.

3.6. Comparison of composition of building, pavement and greenery

From Fig. 3, comparing the building footprint area (BDG),Woodlands appears to have the highest value percentages, fol-lowed by Loyang, one-north and IBP. A similar order is observed in

the case of pavement (PAVE) percentages. However, for greenery(GREEN) percentage, a reverse trend is noted, with the highestvalues noted in IBP, one-north then Loyang and Woodlands.

The Kruskal e Wallis test results prove that there is a signi cantdifference among the percentage compositions for all building,pavement and greenery. From the post-hoc tests, it is inferred thaton average compared to Woodlands, one-north has a signi cantlysmaller proportion of the estate occupied by buildings in terms of two-dimensional footprint by 9.41%. Woodlands also has a signi -cantly larger proportion of estate occupied by roads and sidewalksthan that of IBP by 23.23%.

However, IBP and one-north have signi cantly greater propor-tion of their sites occupied by turf, such as grass, by a difference of 32.76% and 21.67% respectively than Woodlands.

Summarizing the Mann e Whitney U test results, a staticallysigni cant difference in the composition between the B2 and BPDcan be concluded. Generally, BPD sites comprise of a signi cantlylarger proportion of greenery but lesser pavements and buildingarea than B2 developments.

From Table6 , the morphology parametersthat differ statisticallyacross the four estates and B2 and BPD are the GnPR, the averagebuilding height, the average height to building area ratio, andpercentage composition of building, pavement and greenery. Thus,it can be inferred that there is a distinct change in the urbanmorphology of industrial estates with its transformation over time.

4. Comparison of microclimatic condition within industrialestates

4.1. Comparison of ambient air temperature results among estates

The diurnal temperature pro le for each estate was plot usingthe mean hourly temperatures, by averaging the hourly readingsfrom all measurement points for the selected days. Fig. 4 shows thecomparison of the average air temperatures among four industrialestates.

It is observed that Loyang generally exhibits the highest averagetemperatures, followed by Woodlands, IBP and one-north. Themaximum temperatures during daytime occur at around 14:00 to15:00 h. The highest average temperature of 32.70 C at Loyang is0.13 C slightly higher than that of Woodlands and 1.68 C higher

Table 4Comparison of average wall surface area among the four estates.


Loyang 11 384.09 5107.96 1996.10 1318.59Woodlands 12 0 6913.62 2781.69 2134.68IBP 10 0 3943.71 1986.39 1443.48One-north 29 0 12,136.58 2970.97 2573.22

Table 5Comparison of HBDG values among the four estates.


Loyang HBDG 11 0.26 3.72 0.859 0.992Woodlands HBDG 12 0 1.45 0.456 0.434IBP HBDG 10 0 42 5.649 12.869One-north HBDG 29 0 23.34 3.297 4.902

Table 6Summary of statistical conclusions for morphology parameters compared.

Morphology parameters Statistically different at a 0.05 level

Loyang, Woodlands IBPand one-north

B2 and BPD

SVF No NoGnPR Yes YesAverage Building Height Yes a YesAverage Total Wall Surface area No NoAverage Height to Building Area Ratio Yes YesBuilding Area Percentage Yes YesPavement Percentage Yes YesGreenery Percentage Yes Yesa

But insuf cient to distinguish signi cantly different pairs.



10/13

than that of IBP. The largest difference of 1.87 C is noted whencompared to one-north.

During nighttime, the lowest air temperatures are observed at06:00 to 07:00 h. Among the four estates, one-north is the coolestestate with the lowest average temperature recorded at 24.39 C.This is 0.35 C, 1.89 C and 1.99 C less than that of IBP, Woodlandsand Loyang respectively.

IBP has the highest diurnal temperature range value of 6.49 C(DTR maximum minimum temperatures) whereas Woodlandshas the smallest DTR of 6.22 C. DTR in Loyang and one-north are6.32 C and 6.36 C respectively. Such thermal behaviour is mainlyin uenced by the surrounding morphology properties. Accordingto Gallo and Owen [31] , a lower DTR is an indication of extensiveurbanization change in land cover. Earlier in Fig. 3, Woodlands has

the highest percentage of estate occupied by buildings and pave-ment. The extensive concrete and impervious surfaces result ingreater absorption of solar radiation, while proportionally reducingthe green surfaces for evapotranspiration, thus contributing tohigher air temperatures.

The smallest and largest temperature differences among theestates are noted between Loyang and one-north, at 13:00 h and16:00 h respectively. Interestingly, this occurs right before and afterthe period where the maximum temperatures are observed. Sinceone-north has a much higher mean GnPR value than Loyang, thepresence of extensive foliage helps to effectively lower the ambientair temperature via the evaporative cooling of surface moisture,thus attaining a lower and more gradual peak compared to Loyang.

As shown in Fig. 4, one-north typically has the lowest mean

temperature throughout the day, except from 08:00 to 13:00 h,where temperatures are 0.49 Ce 0.93 C higher than IBP. Althoughit receives extensive shading based on the low SVF values, thecooling effects seem to be outweighed by heat gain from othersources. This is possible since the differences among the SVF valuesare not statistically signi cant.

A Kruskal e Wallis test is used to determine if there is a groupdifference among the average ambient air temperatures found inthe four industrial estates. The null hypothesis is that the distri-bution of average ambient air temperature values is the same forLoyang, Woodlands, IBP and one-north.

The results in Table 7 suggest that at 95% con dence level, thereis a statistically signi cant difference among the ambient air tem-perature distribution for the four estates, with H(3) 323.93,

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transformation of industrial planning in singapore

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