Evaluation of OTTV Values on Window to Wall Ratio at Abdi Siswa Catholic School Patra Unit, Jakarta

Abstract

OTTV (Overall Thermal Transfer Value) is closely related to WWR (Window to Wall Ratio) and the lighting level of the rooms in it. The OTTV value is directly proportional to the WWR but inversely proportional to the level of lighting, which makes it a challenge to design buildings that have OTTV and lighting according to SNI benchmarks. School buildings whose main activities are learning really need adequate lighting levels to support the productivity of their students, and it is urgent to carry out this research. Using the OTTV standard from SNI 03-6389-2011 with a maximum value of 35 W/m² and room lighting levels from SNI 03-6197-2000, quantitative evaluations and recommendations were carried out at the Sekolah Katolik Abdi Siswa unit Patra using statistical analysis methods to calculate the OTTV available as well as recommendations and experimental methods to find a balance point between OTTV and lighting levels. The update of this research is in the form of research stages that take from the existing building being evaluated, not a new building to be designed. The research focus is also more on changing the level of lighting than the recommendations. The results show that the existing OTTV values of the research objects have met the standards, but the lighting in the rooms where students study is still below standard. Recommendations were made in the form of changing WWR, glass type, and adding artificial lighting as a last resort to achieve sufficient lighting with substandard OTTV. The conclusion shows that classrooms, libraries, and laboratories can reach 30% area with standard room lighting and standard OTTV values. It can also be concluded that the design of green buildings is not only limited to reducing the OTTV value to a minimum but also must pay attention to the level of lighting that is imposed by decreasing WWR.

Keywords: OTTV; WWR; lighting levels; productivity; schools