This study is to develop the new type of environmentally friendly Ondol system for improvement of energy efficiency, improvement of impact sound insulation of floors and reduction of material & resources in apartment houses. The prototypes for development of the Environmentally Friendly Ondol System of Double layer (E02 System) are designed and are made as the manufactures in order to improve energy efficiency & the impact sound insulation of floors and reduce material & resources in apartment houses.
The performance measurement of impact sound insulation of floors is tested. and the performance on the E02 System is compared with the existing Ondol system. As a result, the impact sound insulation of floors of the E02 System is improved more 15 dB than standard level. The E02 System got the first grade Certificate on the impact sound insulation of floors.
The performance of thermal insulation and energy efficiency is compared the E02 System with the existing Ondol system. The E02 System is evaluated as more 9% of energy efficiency than the existing Ondol system. The component weight per area of the E02 system is 96 kglm', and it is evaluated as reduction of the existing structure weight. Therefore the E02 system will be utilized as solution for pending problems in apartment houses in Korea.

1. Introduction
 2. Development of the Environmentally FriendlyOndol system
 3. Evaluation of the Performance of theEnvironmentally Friendly Ondol system
 4. Results and Discussion
 5. Conclusion
 Reference

• Dongwoo Cho(Head Researcher. Building Research Division, Korea Institute of Construction Technology 231 I Daewha-dong, Ilsan-gu, Gyeonggi-do, 4ll-712, Kore) Corresponding Author
• Kihyung Yu(Head Researcher. Building Research Division, Korea Institute of Construction Technology 231 I Daewha-dong, Ilsan-gu, Gyeonggi-do, 4ll-712, Korea)