This study discussed the estimation of wastes of plasterboard by scenario analysis by comparing three possible future outcomes, from “Optimism Scenario”, “Pessimism Scenario” and “Previously Used Scenario”, and the results are as follows,
1. “Optimism Scenario” estimated plasterboard wastes at about 1,000,000 ton a year in 2050, but both “Pessimism Scenario” and “Previously Used Scenario” estimated them over 3,000,000 ton.
2. “Pessimism Scenario” and “Previously Used Scenario” showed a similar in some respects. If the time of the latter is delayed for ten-odd years, the outcome is very much like the former, though “Optimism Scenario” is like neither.
3. Plasterboard is an object of case study of the analysis method and it is applicable to many other building materials. This study showed the way of the long-term forecast estimation of building materials, which helps environmental problems and policies.