No abstract

The narrow land in big cities such as Jakarta, increases the amount of high rise building, especially multi-storey office building. Office building consumes much energy to provide air conditioning to meet the thermal comfort inside the building. On the other hand, the building shape, building envelope, and building orientation to the sun's position are the main factors in building design aspects that affect the amount of cooling load. This study aims to investigate the impact of the aspect ratio or the ratio of the longer dimension of an oblong plan to the shorter, on external heat gain of multi-storey office building. Variables examined include the transparent and solid area of building envelope, the total area of the surface of the building envelope in any orientation, and the volume of the building, as well as the influence of those proportion on the external heat gain. This study uses mathematical calculations to predict the cooling load of the building, particularly external heat gain through the walls, roof and glass, as well as comparative analysis of models studied. The study also aims to generate the design criteria of building form and proportion of multi-storey office buildings envelope with lower external heat gain. In Jakarta climatic conditions, the result on rectangular building plan with aspect ratio of 1 to 4 shows that the external heat gain did not differ significantly, and the smallest heat gain is found on the aspect ratio of 1.8. Results also showed that the greater aspect ratio, the greater reduction of external heat gain obtained by changing the orientation of the longest side facing east-west into the north-south, about 2.79% up to 42.14% on the aspect ratio of 1.1 to 4. In addition, it is known that in same building volume, changing the number of floors from 10 to 50 can improve the external heat gain almost twice.

Tropical climate areas have an advantage in terms of utilizing natural lighting for buildings. On the other hand, deep plan buildings have limitations in natural light penetrations through the sides of the building, while making the natural light enters from the roof risks of blending in with the heat and glare. Cultural heritage buildings are an inheritance that must be preserved and protected. Nowadays, some of them switch functions to be managed as public functions. Cultural heritage buildings with deep floor plans have double problems, specifically their limitations in natural light penetrations from the sides of the building, and also how to maintain the visual appearance of the building as much as possible when renovations are being carried out. This paper aims to explore strategies that can be done to improve natural lighting in the cultural heritage buildings with a deep floor plan. A case of study of cultural heritage buildings was also used in this research to provide a description of specific natural lighting techniques that can be applied. Field measurement methods and digital simulations are used to determine the existing natural lighting conditions of the study object and provide a visualization of design recommendations. The results show that vertical lighting can be used in cultural heritage buildings without changing the building façade. This strategy is carried out by minimizing the incoming glare through the consideration of the vertical angle of the sun's shadow, as well as the reflection of light to maximize the light distributions in the building.