Al Yacouby et al indicated that about of Malaysians

Al Yacouby et al. (2011) indicated that about 75% of Malaysians depend on the air-conditioning system to maintain the indoor temperature within the comfort level. In the residential sector, dwellers use electricity to power the mechanical cooling system, which would increase the expense for operation and maintenance (Cowan and Smith, 1983). The amplified demand of nebivolol hcl issues arise because of concern on modern comfort standards, social customs, and design practices, which made mechanical cooling one of the important factors in daily life (Abdul Rahman et al., 2013). Thus, this study is important to discuss the weaknesses of the current passive design and generate recommendations to improve its local practice, especially in modern house design. The findings from this study would reduce and maintain the indoor temperature of the modern house design. In addition, it would minimize and mitigate the cost of electricity consumption.
Review on the current passive design The 2010 Census revealed that the total population of Malaysia increased from 23.3 million in 2000 to 28.3 million in 2010 (Department of Statistic Malaysia, 2015). In recent years, the growth in population and economy resulted in an increasing number of demands for residential housing among urban areas in Malaysia. Akbari et al. (2008) estimated that roofs and pavements cover 60% of urban areas. Furthermore, the surface temperature in urban areas would greatly increase in the next 10 years or less due to population expansion (Tursilowati, 2007). The color of the roof surface should be one of the elements that need to be considered in passive design. The majority of roof tiles in Malaysia are dark in color, which means that it absorbs more heat (Al-Yacouby et al., 2011). Table 1 shows the variety of roof tile color used in Malaysia. Givoni (1994) found that a roof painted with a gray or dark color records a higher ceiling temperature compared with a roof painted with a lighter color. It was also justified that a dark colored roof has a higher indoor temperature than the outdoor climate. The study concluded that the incidence of solar radiation on the roof surface depends on the color and thermo-physical properties of the roof (Givoni, 1994). A black aluminum sheet for a flat roof or a 0° roof pitch records the highest indoor temperature (Al-Obaidi et al., 2014c). Ibrahim et al. (2014a) showed that the indoor temperature reading is higher than the outdoor temperature for a lower roof pitch because of the large amount of heat it absorbed. Looking at the current modern house design in Malaysia, most parts of the roof are constructed within a 10° roof angle. Abdul Rahman et al. (2009) wrote that a flat roof design in the tropical climate could not be considered as a good elemental design because of some factors that would lead to leakages, such as the ponding of water on the flat roof surface, and would require additional costs for major restructuring. Apart from saving construction costs, developers prefer the easiest and simplest method to design and construct the houses, especially in the upper part of the structure. The material used for building the roofing system is an issue. Lau et al. (2008) estimated that the types of roof materials used for current houses are mostly made of 85% concrete roof tiles, whereas clay tiles and metal deck comprise 10% and 5%, respectively. Contractors would prefer the use of roof tiles because it could prolong the life span of the roofing system and require minimal maintenance compared with other roofing materials. For the design of modern low-cost houses in Malaysia, spandex or metal roof is preferred because of its lower construction costs in contrast with concrete or clay roof tiles. Lau et al. (2008) reported that most of the houses built are affected by high solar radiation transmission due to the non-reflective materials used, which leads to a high temperature inside the building. Ibrahim et al. (2014a) revealed that spandex is not suitable as a roofing material in modern low-cost house design because it creates a higher indoor temperature than outdoor temperature.