European Journal of Sustainable Development (EJSD)

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44 European Journal of Sustainable Development (2014), 3, 4, 43-52 Recently, the principal objective of thermal comfort criteria is mostly for standardization of buildings types and its equipments in order to achieve energy efficiency and indoor environmental friendly. However, from the view point of thermal perception, the problem occurred at outdoor space may be different from the indoor situation and may lead to the different concept of thermal comfort for outdoor spaces. The mean radiant temperature of inner surfaces in such indoor spaces is same or almost same as its indoor air temperature due to the closed characteristic of rooms and that well protected from outdoor thermal environment. But at outdoor, especially in tropical regions, average of radiant temperatures is significantly more influenced by direct solar radiation and surfaces temperature (material of streets, pedestrians, buildings envelop, and other surfaces of urban furniture), and may reach a value that much higher than the outdoor air temperature. This paragraph may leads us to put hypothesis that the mean radiant temperature contribute as the most sensitive micro climate component on outdoor comfort of human activities in humid tropical region. 1.2. The City of Manado and its climate Manado is one of the cities that geographically positioned at warm and humid climate region, in Indonesia. The climate is characterized by relatively high air temperature, much sun-lighhabitat of about 410 thousands people in 2012.The population density is about 2650 and high humidity. Manado is the coastal city located in 1,5 N and 125 E, with people/km 2 . The average diurnal air temperature is varied between about 20 0 C to 32 0 C. Relative air humidity, in average is about 70% to 90%. Daily solar radiation may reach more than 4000 Wh/m 2 (Fig.2 & 3). Manado is a waterfront city that consisted 20 km long of coastal lines, having sloping landscape natural scenery and plenty of smalll rivers flow into the sea. Manado as the capital of province of Sulawesi Utara (North Sulawesi, Indonesia), has great opportunity to develop outdoor space as public places at some strategic areas for providing the need of outdoor activities. As an enjoyable place in the city, open space design should begin with an understanding of the future use of the property, and the proper design willl be unique to a specific site and should be based on a careful review process. In case of Manado, urban changed occurred significantly in very short term. Figure.1. Aerial view of Manado City (source: YP Photography and authors) 1.3. Related studies There are fundamental differences concerning the method of calculation of the thermal comfort for indoor and outdoor, especially in tropical humid environment. At outdoor penetration of direct solar radiation and its radiant temperature can affect significantly Published by ECSDEV, Via dei Fiori, 34, 00172, Rome, Italy http://ecsdev.org
S. Sangkertadi and R. Syafriny 45 34 32 MAX AVG MIN 34 32 MAX AVG MIN Deg. Celcius 30 28 26 24 Deg. Celcius 30 28 26 24 22 20 18 Air Temperature January 2011 22 20 18 Air Temperature July 2011 Local Time Local Time Figure.2. Air temperature profile (source: Meteorology Station of Manado 2011) Wh/m2 2 7000 6000 5000 4000 3000 2000 1000 0 Solar Radiation % 100 80 60 40 20 0 Relative Humidity Jan Feb Mar Avr May Jun Jul Aug Sep Oct Nov Dec Month the level of human thermal comfort. Contrary in the closed room, the radiant temperature (as average of radiant temperatures of internal surfaces: wall-ceiling-floor) is similar or has little difference than indoor air temperature. Figure.3. Monthly average solar Radiation and humidity (source: Meteorology Station of Manado 2011) Figure.4. Some open spaces in Manado That’s why in closed space the radiant temperature may not strong enough as determinant variable to influence the perception of thermal comfort. At the outdoor the radiant temperature from solar radiation (direct or indirect) may sting the body skin and cause a feel of uncomfortable thermally. In addition, at outside air velocity is generally greater than in closed room, fortunately the air mass may support the process of achievement of thermal comfort by convection and sweat evaporation. In this context, Arens E and Ballanti D (1997) through a field study, has found significant effect of wind speed on human comfort for walking people in open space. © 2014 The Authors. Journal Compilation © 2014 European Center of Sustainable Development.
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