Urban morphology to minimize solar insolation on out door urban spaces in the tropics

Abstract

In the urban environment, a comfortable climate is important for well-being and to attract people to public spaces. Often the urban planning regulations and design concepts used in tropics ignore or poorly adapted to the local climate. As a consequence, urban areas often become unnecessarily uncomfortable as in Putrajayah new administrative center which experiences a 5°C temperature rise compared to surrounding rural area. A similar office cluster design enclosing an outdoor plaza was proposed at Johor State New Administrative Center (JSNAC). Although, JSNAC is at construction phase, no studies have been conducted to evaluate the environmental impact on the outdoor spaces. This implies that solar prevention at the urban scale in the tropics is given little importance in planning and design process. Literature review suggests urban geometry and thermal properties of urban surfaces have been found to be the two main parameters influencing urban climate. This study develops a hypothetical concept of shadow umbrella using urban morphology for radiation reduction in the tropical outdoors during the day. Shadow umbrella concept largely depend on the solar geometry, therefore it is influenced by the bioregional climate conditions as well. This study emphasizes the effectiveness of the shadow umbrella concept in reducing the urban insolation using computer simulation models. To understand and to get the optimal ratio of the proportion, simulations have been done on different width and length of the plaza, height of the surrounding buildings and for different orientations of the plaza. The plaza in office cluster in Johor new administrative is later found to be oversized and inappropriately orientated. The results show that optimal ratio of building cluster geometry is 1: 1.5-2: 0.270.5 (W: L: H), which comply to shadow umbrella theory and proportion theories suggested by other researchers in this field.