Practical formula to calculate solar factor in Semarang.

To get the OTTV value, you must first calculate the solar radiation value. Solar radiation occurs as a result of the sun's heat being exposed to the surface of the building and then goes inside so that the air temperature inside the building gets hotter. The solar factor is one of the elements of solar radiation which is important in determining the overall thermal transfer value for each outer area of a building. The availability of solar factor data in one place is very important to use for building design purposes. Calculating the solar factor is very difficult, moreover, SNI only contains data for the city of Jakarta. There are several ways to calculate the solar factor, with available SNI tables or by laboratory experiments or direct measurements of sunlight. So to make it easier for the designer, we propose to use the rule of thumb formula. The method used is based on local solar factor data, then a radian angle is made from 0 ° -360 °, which results in an ellipse shape in an equation. This paper concludes that the Rule of thumb formula is very helpful for architects in calculating the SF value and can also complete the table in SNI: 2011, which only contains the SF value for the city of Jakarta, meaning that it only applies in Jakarta, so similar research is needed to get the SF value for other cities in Indonesia. [ABSTRACT FROM AUTHOR]