QUANTIFICATION OF IN-USE MATERIAL STOCK RATE - CASE STUDY OF JAPAN’S RESIDENTIAL BUILDINGS -

Abstract

 For the establishment of Recycling-based Society, Stock-type Society becomes increasingly important. Material stock plays an important role in the society and serves someone well in one way, whereas it has inevitable impact on material flow. For the reason that material stock is inextricably linked with material flow, the excess material stock can induce unnecessary resource input and increase waste generation from obsolete stock. To bring down high-quality material stock for the future generation, proper management of materials stored or hibernating in the society is required. In order to grasp the status of stock, material stock should be estimated and evaluated with in-use rate. In this study, by the method of lifespan modeling approach, material stock in Japan’s residential buildings and the amount of that obsolete stock/in-use stock were estimated. As a result of the estimation, there were 5.2 billion tons of residential building in 2018. In the amount of material stock in empty houses out of residential buildings, the amount of obsolete stock was estimated at 0.3 billion ton. As the number of residential building keeps increasing, the amount of obsolete stock is expected to increase in future.