External Insulation Finishing System (EIFS) have been focused on mainly in cold districts in Japan. But EIFS is effective not only in cold districts but also in other districts in terms of elongation improving. Today in Japan, EIFS is not often used and the cost of EIFS is higher than that of conventional repair. The purpose of this study is to examine the payback period of the cost increment by the use of EIFS. This study is LCC simulation of the cost increment and focuses on electric cost reduction by the use of EIFS, specifically that of air conditioners. The main results are:
1. It is difficult to collect cost increment only by longer repair cycle and cost reduction of materials.
2. For Rooftop repair, built-up roofing with wear course is less expensive than with single-ply roofing in terms of total LCC.
3. In consideration electric cost reduction, payback period of cost increment can be examined 40 years.
4. By extending the time for usage, for example open school after school, payback period of cost increment is extended by 0-15 years.
