Field Observation on Thermal Environment of an Urban Street with Roadside Trees in a Tropical Climate

Transcription

1 Field Observation on Thermal Environment of an Urban Street with Roadside Trees in a Tropical Climate Hai Jian Toh¹, Sheikh Ahmad Zaki¹, Aya Hagishima², Mohamed Sukri Mat Ali¹ 1 Universiti Teknologi Malaysia, Jalan Semarak, Kuala Lumpur, Malaysia, haijian89@gmail.com, sheikh.kl@utm.my, sukri.kl@utm.my 2 Kyushu University, 6-1 Kasuga-koen, Kasuga-shi, Fukuoka, , Japan, ayahagishima@kyudai.jp 22 nd July

2 Urban Environment 2

3 CLIMATE CONDITION IN MALAYSIA East Coast N Equator, hot and humid climate Abundant sunshine & solar radiation Wind: generally light 4 wind change season: southwest monsoon, northeast monsoon, and two shorter inter-monsoon season High relative humidity East coast, Sabah and Sarawak experienced heavy rain during November to January Average temperature 27 C Highest mean daily wind speed 3.8 m/s Average annual rainfall 1,623 mm Average relative humidity 80% Source: Malaysian Meteorological Department 3

4 MONSOON SEASON IN MALAYSIA N Southwest Monsoon late May-Sept relatively drier weather Northeast Monsoon November-March heavy rainfall 4

5 RESEARCH MOTIVATION Global Issue: population growth Environmental issue: Greenhouse gases, pollution, urbanization, waste Urban climate issue: UHI Developing countries are facing huge population growth in the future Less study regarding urban climates and effect of green at tropical developing country Developing country Urbanization Greenery replaced by Artificial materials 5

6 RESEARCH OBJECTIVES To clarify the quantitative mitigation effects of roadside trees on the thermal environment of an urban street canyon To investigate the effects of the density of roadside trees to thermal environment 6

7 Urban Environment 7

8 TARGET AREA (KLANG VALLEY) Population [million] 1,8 1,7 1,6 1,5 1,4 1,3 1,2 1,1 1 Kuala Lumpur Population Year Source: UNdata Average temperature 28.2 C Average sunlight hours/day 6h 6 Average monthly rainfall 219 mm Average relative humidity 81% Source: Google Maps 8

9 FIELD MEASUREMENT DETAILS 1. Street R 2. Street P Field measurement at two different street 1. Jalan Raja Muda Aziz (Street R), and 2. Jalan Produktiviti (Street P) Street R is located in the capital city of Malaysia, Kuala Lumpur. Street P is located in Petaling Jaya, about 15.5km southwest from Kuala Lumpur Measurement period: o Street R 8 th April, 18 th May, 0900 to 1330 o Street P 28 th May, 3 rd June, 0900 to 1330 Source: Google Maps 9

10 FIELD MEASUREMENT PARAMATERS Parameters Instruments / Measurement Interval Air Temperature & Relative Humidity Thermistor thermometer/ capacitive hygrometer sensor (Hobo U12-013) / 1 min Globe Temperature Thermistor thermometer (T&D TR-52i) / 1 min Surface Temperature Solar Radiation Wind Speed IR thermal camera (InfRec) /1 hour Pyranometer (Kipp&Zonen CMP11) / 1 min 2-D ultrasonic anemometer (R.M. Young 86000) / 1 min 10

11 TARGET AREA- STREET R Jalan Raja Muda Abdul Aziz (Street R) N Commercial Building 130m Commercial Shop lots roadside hawker stall Fig. Aerial view and measurement points of Street R 11

12 TARGET AREA- STREET P Jalan Produktiviti (Street P) N Meteorology Department Building Public Swimming Pool Meteorology Department Building 130m Fig. Aerial view and measurement points of Street P 12

13 MEASUREMENT SITE STREET R, DENSE SVF = Photo of environment, monochrome fisheye photo, SVF for Street R, dense 13

14 MEASUREMENT SITE STREET R, SPARSE SVF = Photo of environment, monochrome fisheye photo, SVF for Street R, sparse 14

15 MEASUREMENT SITE STREET R, OPEN SVF = Photo of environment, monochrome fisheye photo, SVF for Street R, open 15

16 MEASUREMENT SITE COMPARISON AT STREET R Dense Sparse Open SVF= SVF= SVF= Table : Photo of environment, monochrome fisheye photo, SVF for Street R 16

17 MEASUREMENT SITE STREET P, DENSE SVF = Photo of environment, monochrome fisheye photo, SVF for Street P, dense 17

18 MEASUREMENT SITE STREET P, SPARSE SVF = Photo of environment, monochrome fisheye photo, SVF for Street P, sparse 18

19 MEASUREMENT SITE STREET P, OPEN SVF = Photo of environment, monochrome fisheye photo, SVF for Street P, open 19

20 MEASUREMENT SITE COMPARISON AT STREET P Dense Sparse Open SVF= SVF= SVF= Table : Photo of environment, monochrome fisheye photo, SVF for Street P 20

21 Urban Environment 21

22 Globe Temperature [ C] 10:30 11:05 11:40 AIR AND GLOBE TEMPERATURE VARIATION, STREET R Dense 12:15 10:47 11:22 11: th April 18 th May Sparse Air Temperature [ C] Open Local time Dense Sparse Open Fig. Globe and air temperature variation for 8 th April and 18 th May 2015 at Street R 22

23 Globe Temperature [ C] (Difference with open area) 10:30 11:05 GLOBE TEMPERATURE DIFFERENCE, STREET R 11:40 12:15 10:47 11:22 11:57 Local time th April 18 th May Dense-Open Sparse-Open Fig. Globe temperature difference (compared to open area) at Street R on 8 th April and 18 th May

24 Air Temperature [ C] Globe Temperature [ C] 10:45 11:20 11:55 AIR AND GLOBE TEMPERATURE VARIATION, STREET P Dense 12:30 10:02 10:37 11:12 11:47 12: Sparse 25 33,5 28 th May 3 rd June 32,5 31,5 30,5 29,5 Open 28,5 27,5 Local time Dense Sparse Open Fig. Globe and air temperature variation for 28 th May and 3 rd June 2015 at Street P 24

25 Globe Temperature [ C] (Difference with open area) 10:45 11:20 GLOBE TEMPERATURE DIFFERENCE, STREET P 11:55 12:30 10:02 10:37 11:12 11:47 12:22 Local time th May 3 rd June Dense-Open Sparse-Open Fig. Globe temperature difference (compared to open area) at Street P on 28 th May and 3 rd June

26 Globe Temperature [ C] AVERAGE OF GLOBE AND AIR TEMPERATURE, STREET R AND P Air Temperature [ C] y = x y = -3,1159x + 40,779 32, ,5 y = -0,2909x + 32, ,5 30 y = -0,383x + 31,529 Street R 28 Open Sparse Dense 29,5 Open Sparse Dense Street P Tree density Tree density Reduction (%) Open-Dense Street R: 16.2 Street P: 22.3 Reduction (%) Open-Dense Street R: 1.8 Street P: 2.5 Fig. Average of globe (left) and air temperature (right) of Street R and Street P at daytime (4 days, 10:30am to 12:30pm) 26

27 THERMAL IMAGES, STREET P 10:00am Unit: ⁰C Open Sparse Dense 12:30pm Fig. : Thermal images of Street P at 10:00am (top row) and 12:30pm (bottom row) on 3 rd June (point (a) refers to tree crown surface temperature, (b) refers to road surface temperature [ C]) 27

28 Mean Radiant Temperature [ C] 10:45 11:20 11:55 MEAN RADIANT TEMPERATURE VARIATION, STREET P Dense 12:30 10:17 10:52 11:27 12: Sparse Open 28 th May 3 rd June Local time Dense Sparse Open Fig. Mean radiant temperature variation for 28 th May and 3 rd June 2015 at Street P 28

29 CONCLUSION 1. The mitigation effects of roadside trees are revealed on the decrease of globe temperature (up to 14.7⁰C) and MRT over three different tree density when compared in this study. However, the effects of trees on air temperature are lower (difference <3.8% or 1.5⁰C even at peak hour). 2. The cooling effects (reduction of globe temperature of 22.3% at Street P) of roadside trees are mainly contributed from the shading and transpiration of trees. 3. Effect of transpiration was indirectly shown by thermal images taken at 12:30am at street P. Under dense tree condition, the surface temperature of the tree crown (a) was about 14 C lower than that of ground (b), similar with the air temperature (within ±2 C). 29

30 FUTURE RESEARCH PLAN Southwest monsoon Northeast monsoon May June July August September November December January February March Next field measurement target: August/September- field measurement at residential area November/December- field measurement in different monsoon season (rainy weather) Wind speed reduction under tree canopy, comparing to different tree density. Fig: Cheras, KL Thank you for listening 30