Impacts of Different Urban Surfaces on Summer Thermal Performance

Title & Authors
Impacts of Different Urban Surfaces on Summer Thermal Performance
Jo, Hyun-Kil; Wu, Qian;

Abstract
This study measured temperatures and albedos of urban surfaces for different colors and materials during summer, and calculated the energy budget over different urban surfaces to find out the thermal performance affecting the heat built-up. The study selected six surface colors and 13 materials common in urban landscape. Their surface temperatures (Ts) and albedos were measured at a given time interval in the daytime from June to August. Average Ts over summer season for asphalt-colored brick was $\small{4.0^{\circ}C}$ higher than that for light red-colored one and $\small{9.7^{\circ}C}$ higher than that for white-colored one. The Ts for artificial surface materials of asphalt paving, brown brick wall, and green concrete wall was $\small{6.0^{\circ}C}$ higher than that for natural and semi-natural ones of grass, grassy block, and planted concrete wall. There was the greatest difference of $\small{16.3^{\circ}C}$ at midafternoon in the Ts between asphalt paving and planted concrete wall. Average albedo over summer season of surface materials ranged from 0.08 for asphalt paving to 0.67 for white concrete wall. This difference in the albedo was associated with a maximum of $\small{15.7^{\circ}C}$ difference at midafternoon in the Ts. Increasing the albedo by 0.1 (from 0.22 to 0.32) reduced the Ts by about $\small{1.3^{\circ}C}$. Average storage heat at midday by natural and semi-natural surfaces of grass and grassy block was about 10% lower than that by artificial ones of asphalt, light-red brick, and concrete. Reflected radiation, which ultimately contributes to heating the urban atmosphere, was 3.7 times greater for light-red brick and concrete surfaces than for asphalt surface. Thus, surfaces with in-between tone and color are more effective than dark- or white-colored ones, and natural or semi-natural surfaces are much greater than artificial ones in improving the urban thermal environment. This study provides new information on correlation between Ts and air temperature, relationship between albedo and Ts, and the energy budget.
Keywords
Material;Color;Surface temperature;Albedo;Energy budget;
Language
English
Cited by
References
1.
Andreou, E., 2014, The effect of urban layout, street geometry and orientation on shading conditions in urban canyons in the Mediterranean, Renewable Energy, 63, 587-596.

2.
Arthur, H. R., Hashem, A., Sarah, B., Beth, L. F., Dan, M. K., David, S., Haider, T., 1995, Mitigation of urban heat islands: materials, utility programs, updates, Energy and Buildings, 22(3), 255-265.

3.
Brown, R. D., Gillespie, T. J., 1995, Microclimatic Landscape Design, John Wiley & Sons, New York.

4.
Jo, H. K., Ahn, T. W., 1999, Function of microclimate amelioration by urban greenspace, Journal of The Korean Institute of Landscape Architecture, 27(4), 23-28.

5.
Jo, H. K., Ahn, T. W., 2010, A study on greenspace planning strategies for thermal comfort and energy savings, Journal of The Korean Institute of Land-scape Architecture, 38(3), 23-32.

6.
Karlessi, T., Santamouris, M., Synnefa, A., Assima-kopoulos, D., Didaskalopoulos, P., Apostolakis, K., 2011, Development and testing of PCM doped cool colored coatings to mitigate urban heat island and cool buildings, Building and Environment, 46(3), 570-576.

7.
Kim, S. C., Park, B. J., 2013, Assessment of temperature reduction and heat budget of extensive modular green roof system, Korean Journal of Horticultural Science and Technology, 31(4), 503-511.

8.
Korea Meteorological Administration, 2014, Climate data, http://sts.kma.go.kr (accessed 9/14).

9.
Li, H., Harvey, J., Kendall, A., 2013, Field measurement of albedo for different land cover materials and effects on thermal performance, Building and Environment, 59, 536-546.

10.
Livada, I., Santamouris, M., Niachou, K., Papanikolaou, N., Mihalakakou, G., 2002, Determination of places in the great Athens area where the heat island effect is observed, Theoretical and Applied Climatology, 71(3), 219-230.

11.
Miller, G. T., 1990, Resource Conservation and Management, Wadsworth Publishing Co., Belmont.

12.
Oke, T. R., Kalanda, B. D., Steyn, D. G., 1981, Parameterization of heat storage in urban areas, Urban Ecology, 5(1), 45-54.

13.
Racine, T. A. P., Fabiana, L. F., 2005, Measurement of albedo and analysis of its influence the surface temperature of building roof materials, Energy and Buildings, 37(4), 295-300.

14.
Simpson, J. R., McPherson, E. G., 1997, The effects of roof albedo modification on cooling loads of scale model residences in Tucson Arizona, Energy and Buildings, 25(2), 127-137.

15.
Synnefa, A., Karlessi, T., Gaitani, N., Santamouris, M., Assimakopoulos, D., 2011, Experimental testing of cool colored thin layer asphalt and estimation of its potential to improve the urban microclimate, Building and Environment, 46(1), 38-44.

16.
Synnefa, A., Santamouris, M., Apostolakis, K., 2007, On the development, optical properties and thermal performance of cool colored coatings for the urban environment, Solar Energy, 81(4), 488-497.

17.
Wu, Q., Jo, H. K., 2014, Temperatures and albedos of various urban surfaces, Proceedings of the Korean Environmental Sciences Society Conference, 23, 36-38.