# Calculation Methods for Construction Material Stocks: A Systematic Review
## 3 Results
### Content Analysis
#### 3.2.2 Material Stock Calculation Methods
GIS can be used to estimate the total building area, as well as categorizing different building types based upon the type of construction and year built. However, each building's area individually, as in the case of the bottom-up methodology in the study area, is not estimated; instead, statistical estimates based upon the category of the building in the area of research are done. GIS is applied to georeferencethe aerial images of the study area. For instance, [PERSON] et al. [9], calculated the total material stock and demolition waste flow for Padua, a medium-sized Italian city, for the period 1902-2007. The study was conducted by using the photos of the different periods to estimate the new construction by georeferencing it on GIS. Using the statistical data of the average building life and buildings' material intensity constructed, the study estimated the total material stock. It was found that the stock of building materials increased from 134 to 209 tonnes per capita between 1902 and 2007. It was also reported that waste flows accounted for 985 kg per capita in 2007 and were expected to rise to 1.9 tonnes per capita in 2030. [PERSON] et al. [21] also presented an analytical method for urban building metabolism by using four-dimensional Geographical Information Systems (4d-GIS). The study was done by georeferencing the aerial images and CAD drawings on the GIS. The statistical data provided by government sources was employed to estimate the total floor area and the average material intensity. It was found that the material stock increased from 24,750 tons in 1970 to 927,552 tons in 2013. GIS is also used to estimate the material stock by combining the building data about location, type, and year built gathered through different sources. [PERSON] et al. [33] analyzed the material stock of buildings and their spatial distribution at the city level of Vienna. The study used the previous GIS data of individual buildings to calculate the material stock of the region. They managed to obtain GIS data of the previous construction from government sources. Afterward, the total material stock was estimated by combining the data with the average material intensity. The results showed that the material stock of Vienna was 380 million metric tons (t), which equals 210 tons per capita (t/cap). [PERSON] et al. [38] also analyzed the material stock in buildings and its spatial distribution of the city of Chiclayo in Peru. The study used the government census data to find the number of dwellings and the average floor area. Subsequently, the material intensity was found by using the drawings and expert opinions. The results showed that the total material stock of buildings in 2007 was 24.4 million tons (Mt) or 47 tonnes per capita. Similarly, [PERSON] et al. [39] integrated material flow analysis with the GIS map of Shanghai. The government sources were used to gather data about the number of dwellings and average floor areas of buildings. The data on the year built, length and width of roads, railways, and subways were also extracted from governmental sources. The findings showed that the material stock increased from 83 million tons to 561 million tons from 1980 to 2010. It was further found that the waste outputs were increased from 2 to 17 million tons during this time. [PERSON] et al. [22] used the top-down methodology to calculate the infrastructure's material stock. The study aimed to estimate the material stock of Gothenburg, Sweden using a cluster model. They developed an innovative approach to discovering material intensity at the neighborhood level via analyzing the similarity between various regions found in different clusters. The study was then able to find the material stock of buildings, roads, and pipelines of the entire city. The results suggested that the total material stock was 84 million metric tons. In this regard, buildings accounted for 73% of the stock, while road transports and pipes were 26% and 1%, respectively. In another study, [PERSON] et al.