Increasing energy consumption for space cooling is a global issue. One of the solutions is passive design through the application of affordable shading elements in the building envelope. This study examines the effect on `indoor temperature and the economic value of L-shaped mini louvers made of aluminum in Yogyakarta, Indonesia using experimental method. Wooden boxes were constructed for experiment, with one side facing west using glass. One box without shading was used for base case. The other three has mini-louvers shading, with the ratio of shading and gap among louvers of 1:1, 1:2, and 1:3. Temperature data logger was put inside each model to record indoor temperature for a certain period. The experimental results show that the use of L-shaped aluminum mini louvers decreased the inside temperature of the experimental models. The average temperature can be reduced from 1.5 to 2.1 °C in comparison with the base case. These mini louvers can also reduce peak temperature during experiment period from 3.1 to 3.7 °C. Assessed from economic value of the construction cost, model D with the ratio of 1:3 was the best since it only required Rp. 14,658.00 to reduce 1°C of indoor temperature.