Depok | 150 sqm | completed in 2022
Back to 2019, the existing was one storey building and occupied by the family for at least 20 years. They used to live with air conditioner and became depending on it since Depok temperature and humidity is quite high. In the aftermath, electricity bills soared and getting higher as impact of energy crisis. To tackle those issues, we tried to focus on create less carbon emission house by preserve some parts of existing building which could reduce carbon footprint, and do some passive design method approach by using measurable data on specific context in terms of design and geolocation.
With such limited land area, the building has to be compact so it could get open air space. Two-storey building were putted in the middle of the land with setbacks at front and back for garden area. First storey consist of communal area with open plan concept, meanwhile the upper storey was dedicated for master bedroom. Void at living room was designed to create visual connection between storeys and plays important part to create air movement through stack effect concept.
Transparent materials were used at highest point of building roof to create skylight and let hot air coming out. When direct sunlight stroke skylight, it will increase temperature differences between first floor area and ceiling at second floor. The greater difference, the greater buoyancy force, and thus stack effect. In short, we expected fresh air will come from both front and backyard and push hot air through gap opening at skylight ceiling.
To save energy from artificial light usage during daytime, wide glass door and window were installed facing outdoor area with careful consideration in order to maintain owner privacy and prevent excessive direct sunlight which could increase building temperature and led to another energy problem. For privacy issue, secondary skin from perforated red bricks wall were composed as visual buffer with sufficient opening to let natural air comes in and out.
Those passive design strategy were calculated using some building model simulation software to analyze it performance on natural and artificial light, natural airflow, OTTV (overall thermal transfer value), and building energy consumption. For natural light, the result was most of main area are well lit with sufficient light. For thermal comfort based on humidity and dry bulb temperature, it could perform without air conditioner but needs ceiling fan to improve air movement. Result for OTTV is 24.40 W/m2, which means better than local requirement (35 W/m2) and could lower building temperature.
As final result, we could save approximately 50% energy usage or 7.824 kWh (kilo watt per hour) per year by not using air conditioner. Maximum energy usage per month is 6.8 kWh/m2 and based on energy index, it categorized as “extremely efficient.”